[PATCH 3/3] elf: Add _dl_find_eh_frame function

Florian Weimer fweimer@redhat.com
Wed Nov 3 16:28:02 GMT 2021


This function is similar to __gnu_Unwind_Find_exidx as used on arm.
It can be used to speed up the libgcc unwinder.
---
 NEWS                                          |   4 +
 bits/dlfcn_eh_frame.h                         |  33 +
 dlfcn/Makefile                                |   2 +-
 dlfcn/dlfcn.h                                 |   2 +
 elf/Makefile                                  |  31 +-
 elf/Versions                                  |   3 +
 elf/dl-close.c                                |   4 +
 elf/dl-find_eh_frame.c                        | 864 ++++++++++++++++++
 elf/dl-find_eh_frame.h                        |  90 ++
 elf/dl-find_eh_frame_slow.h                   |  55 ++
 elf/dl-libc_freeres.c                         |   2 +
 elf/dl-open.c                                 |   5 +
 elf/rtld.c                                    |   7 +
 elf/tst-dl_find_eh_frame-mod1.c               |  10 +
 elf/tst-dl_find_eh_frame-mod2.c               |  10 +
 elf/tst-dl_find_eh_frame-mod3.c               |  10 +
 elf/tst-dl_find_eh_frame-mod4.c               |  10 +
 elf/tst-dl_find_eh_frame-mod5.c               |  11 +
 elf/tst-dl_find_eh_frame-mod6.c               |  11 +
 elf/tst-dl_find_eh_frame-mod7.c               |  10 +
 elf/tst-dl_find_eh_frame-mod8.c               |  10 +
 elf/tst-dl_find_eh_frame-mod9.c               |  10 +
 elf/tst-dl_find_eh_frame-threads.c            | 237 +++++
 elf/tst-dl_find_eh_frame.c                    | 179 ++++
 include/atomic_wide_counter.h                 |  14 +
 include/bits/dlfcn_eh_frame.h                 |   1 +
 include/link.h                                |   3 +
 manual/Makefile                               |   2 +-
 manual/dynlink.texi                           |  69 ++
 manual/libdl.texi                             |  10 -
 manual/probes.texi                            |   2 +-
 manual/threads.texi                           |   2 +-
 sysdeps/i386/bits/dlfcn_eh_frame.h            |  34 +
 sysdeps/mach/hurd/i386/ld.abilist             |   1 +
 sysdeps/nios2/bits/dlfcn_eh_frame.h           |  34 +
 sysdeps/unix/sysv/linux/aarch64/ld.abilist    |   1 +
 sysdeps/unix/sysv/linux/alpha/ld.abilist      |   1 +
 sysdeps/unix/sysv/linux/arc/ld.abilist        |   1 +
 sysdeps/unix/sysv/linux/arm/be/ld.abilist     |   1 +
 sysdeps/unix/sysv/linux/arm/le/ld.abilist     |   1 +
 sysdeps/unix/sysv/linux/csky/ld.abilist       |   1 +
 sysdeps/unix/sysv/linux/hppa/ld.abilist       |   1 +
 sysdeps/unix/sysv/linux/i386/ld.abilist       |   1 +
 sysdeps/unix/sysv/linux/ia64/ld.abilist       |   1 +
 .../unix/sysv/linux/m68k/coldfire/ld.abilist  |   1 +
 .../unix/sysv/linux/m68k/m680x0/ld.abilist    |   1 +
 sysdeps/unix/sysv/linux/microblaze/ld.abilist |   1 +
 .../unix/sysv/linux/mips/mips32/ld.abilist    |   1 +
 .../sysv/linux/mips/mips64/n32/ld.abilist     |   1 +
 .../sysv/linux/mips/mips64/n64/ld.abilist     |   1 +
 sysdeps/unix/sysv/linux/nios2/ld.abilist      |   1 +
 .../sysv/linux/powerpc/powerpc32/ld.abilist   |   1 +
 .../linux/powerpc/powerpc64/be/ld.abilist     |   1 +
 .../linux/powerpc/powerpc64/le/ld.abilist     |   1 +
 sysdeps/unix/sysv/linux/riscv/rv32/ld.abilist |   1 +
 sysdeps/unix/sysv/linux/riscv/rv64/ld.abilist |   1 +
 .../unix/sysv/linux/s390/s390-32/ld.abilist   |   1 +
 .../unix/sysv/linux/s390/s390-64/ld.abilist   |   1 +
 sysdeps/unix/sysv/linux/sh/be/ld.abilist      |   1 +
 sysdeps/unix/sysv/linux/sh/le/ld.abilist      |   1 +
 .../unix/sysv/linux/sparc/sparc32/ld.abilist  |   1 +
 .../unix/sysv/linux/sparc/sparc64/ld.abilist  |   1 +
 sysdeps/unix/sysv/linux/x86_64/64/ld.abilist  |   1 +
 sysdeps/unix/sysv/linux/x86_64/x32/ld.abilist |   1 +
 64 files changed, 1795 insertions(+), 16 deletions(-)
 create mode 100644 bits/dlfcn_eh_frame.h
 create mode 100644 elf/dl-find_eh_frame.c
 create mode 100644 elf/dl-find_eh_frame.h
 create mode 100644 elf/dl-find_eh_frame_slow.h
 create mode 100644 elf/tst-dl_find_eh_frame-mod1.c
 create mode 100644 elf/tst-dl_find_eh_frame-mod2.c
 create mode 100644 elf/tst-dl_find_eh_frame-mod3.c
 create mode 100644 elf/tst-dl_find_eh_frame-mod4.c
 create mode 100644 elf/tst-dl_find_eh_frame-mod5.c
 create mode 100644 elf/tst-dl_find_eh_frame-mod6.c
 create mode 100644 elf/tst-dl_find_eh_frame-mod7.c
 create mode 100644 elf/tst-dl_find_eh_frame-mod8.c
 create mode 100644 elf/tst-dl_find_eh_frame-mod9.c
 create mode 100644 elf/tst-dl_find_eh_frame-threads.c
 create mode 100644 elf/tst-dl_find_eh_frame.c
 create mode 100644 include/bits/dlfcn_eh_frame.h
 create mode 100644 manual/dynlink.texi
 delete mode 100644 manual/libdl.texi
 create mode 100644 sysdeps/i386/bits/dlfcn_eh_frame.h
 create mode 100644 sysdeps/nios2/bits/dlfcn_eh_frame.h

diff --git a/NEWS b/NEWS
index 82b7016aef..68c9c21458 100644
--- a/NEWS
+++ b/NEWS
@@ -64,6 +64,10 @@ Major new features:
   to be used by compilers for optimizing usage of 'memcmp' when its
   return value is only used for its boolean status.
 
+* The function _dl_find_eh_frame has been added.  In-process unwinders
+  can use it to efficiently locate unwinding information for a code
+  address.
+
 Deprecated and removed features, and other changes affecting compatibility:
 
 * The r_version update in the debugger interface makes the glibc binary
diff --git a/bits/dlfcn_eh_frame.h b/bits/dlfcn_eh_frame.h
new file mode 100644
index 0000000000..fe4c6d6ad7
--- /dev/null
+++ b/bits/dlfcn_eh_frame.h
@@ -0,0 +1,33 @@
+/* System dependent definitions for find unwind information using ld.so.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _DLFCN_H
+# error "Never use <bits/dlfcn_eh_frame.h> directly; include <dlfcn.h> instead."
+#endif
+
+/* This implementation does not use a DBASE pointer argument in
+   _dl_find_eh_frame.  */
+#define DL_FIND_EH_FRAME_DBASE 0
+
+__BEGIN_DECLS
+/* If PC points into an object that has a PT_GNU_EH_FRAME segment,
+   return the pointer to the start of that segment in memory.  If no
+   corresponding object exists or the object has no such segment,
+   returns NULL.  */
+void *_dl_find_eh_frame (void *__pc) __THROW;
+__END_DECLS
diff --git a/dlfcn/Makefile b/dlfcn/Makefile
index 6bbfbb8344..fd6e2a30c5 100644
--- a/dlfcn/Makefile
+++ b/dlfcn/Makefile
@@ -19,7 +19,7 @@ subdir		:= dlfcn
 
 include ../Makeconfig
 
-headers		:= bits/dlfcn.h dlfcn.h
+headers		:= bits/dlfcn.h bits/dlfcn_eh_frame.h dlfcn.h
 extra-libs	:= libdl
 libdl-routines	:= libdl-compat
 routines = \
diff --git a/dlfcn/dlfcn.h b/dlfcn/dlfcn.h
index 4a3b870a48..d5355657c7 100644
--- a/dlfcn/dlfcn.h
+++ b/dlfcn/dlfcn.h
@@ -28,6 +28,8 @@
 
 
 #ifdef __USE_GNU
+#include <bits/dlfcn_eh_frame.h>
+
 /* If the first argument of `dlsym' or `dlvsym' is set to RTLD_NEXT
    the run-time address of the symbol called NAME in the next shared
    object is returned.  The "next" relation is defined by the order
diff --git a/elf/Makefile b/elf/Makefile
index 1c768bdf47..49e35dd4ce 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -36,7 +36,7 @@ dl-routines	= $(addprefix dl-,load lookup object reloc deps \
 				  exception sort-maps lookup-direct \
 				  call-libc-early-init write \
 				  thread_gscope_wait tls_init_tp \
-				  debug-symbols)
+				  debug-symbols find_eh_frame)
 ifeq (yes,$(use-ldconfig))
 dl-routines += dl-cache
 endif
@@ -230,7 +230,8 @@ tests-internal += loadtest unload unload2 circleload1 \
 	 neededtest neededtest2 neededtest3 neededtest4 \
 	 tst-tls3 tst-tls6 tst-tls7 tst-tls8 tst-dlmopen2 \
 	 tst-ptrguard1 tst-stackguard1 \
-	 tst-create_format1 tst-tls-surplus tst-dl-hwcaps_split
+	 tst-create_format1 tst-tls-surplus tst-dl-hwcaps_split \
+	 tst-dl_find_eh_frame tst-dl_find_eh_frame-threads
 tests-container += tst-pldd tst-dlopen-tlsmodid-container \
   tst-dlopen-self-container tst-preload-pthread-libc
 test-srcs = tst-pathopt
@@ -365,6 +366,11 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
 		tst-tls20mod-bad tst-tls21mod tst-dlmopen-dlerror-mod \
 		tst-auxvalmod \
 		tst-dlmopen-gethostbyname-mod tst-ro-dynamic-mod \
+		tst-dl_find_eh_frame-mod1 tst-dl_find_eh_frame-mod2 \
+		tst-dl_find_eh_frame-mod3 tst-dl_find_eh_frame-mod4 \
+		tst-dl_find_eh_frame-mod5 tst-dl_find_eh_frame-mod6 \
+		tst-dl_find_eh_frame-mod7 tst-dl_find_eh_frame-mod8 \
+		tst-dl_find_eh_frame-mod9 \
 
 # Most modules build with _ISOMAC defined, but those filtered out
 # depend on internal headers.
@@ -1957,3 +1963,24 @@ $(objpfx)tst-ro-dynamic-mod.so: $(objpfx)tst-ro-dynamic-mod.os \
 	$(LINK.o) -nostdlib -nostartfiles -shared -o $@ \
 		-Wl,--script=tst-ro-dynamic-mod.map \
 		$(objpfx)tst-ro-dynamic-mod.os
+
+$(objpfx)tst-dl_find_eh_frame.out: \
+  $(objpfx)tst-dl_find_eh_frame-mod1.so $(objpfx)tst-dl_find_eh_frame-mod2.so
+CFLAGS-tst-dl_find_eh_frame.c += -funwind-tables
+CFLAGS-tst-dl_find_eh_frame-mod1.c += -funwind-tables
+CFLAGS-tst-dl_find_eh_frame-mod2.c += -funwind-tables
+LDFLAGS-tst-dl_find_eh_frame-mod2.so += -Wl,--enable-new-dtags,-z,nodelete
+$(objpfx)tst-dl_find_eh_frame-threads: $(shared-thread-library)
+$(objpfx)tst-dl_find_eh_frame-threads.out: \
+  $(objpfx)tst-dl_find_eh_frame-mod1.so $(objpfx)tst-dl_find_eh_frame-mod2.so \
+  $(objpfx)tst-dl_find_eh_frame-mod3.so $(objpfx)tst-dl_find_eh_frame-mod4.so \
+  $(objpfx)tst-dl_find_eh_frame-mod5.so $(objpfx)tst-dl_find_eh_frame-mod6.so \
+  $(objpfx)tst-dl_find_eh_frame-mod7.so $(objpfx)tst-dl_find_eh_frame-mod8.so \
+  $(objpfx)tst-dl_find_eh_frame-mod9.so
+CFLAGS-tst-dl_find_eh_frame-mod3.c += -funwind-tables
+CFLAGS-tst-dl_find_eh_frame-mod4.c += -funwind-tables
+CFLAGS-tst-dl_find_eh_frame-mod5.c += -funwind-tables
+CFLAGS-tst-dl_find_eh_frame-mod6.c += -funwind-tables
+CFLAGS-tst-dl_find_eh_frame-mod7.c += -funwind-tables
+CFLAGS-tst-dl_find_eh_frame-mod8.c += -funwind-tables
+CFLAGS-tst-dl_find_eh_frame-mod9.c += -funwind-tables
diff --git a/elf/Versions b/elf/Versions
index 775aab62af..770a082886 100644
--- a/elf/Versions
+++ b/elf/Versions
@@ -48,6 +48,9 @@ ld {
     # stack canary
     __stack_chk_guard;
   }
+  GLIBC_2.35 {
+    _dl_find_eh_frame;
+  }
   GLIBC_PRIVATE {
     # Those are in the dynamic linker, but used by libc.so.
     __libc_enable_secure;
diff --git a/elf/dl-close.c b/elf/dl-close.c
index 4f5cfcc1c3..1249e964ee 100644
--- a/elf/dl-close.c
+++ b/elf/dl-close.c
@@ -32,6 +32,7 @@
 #include <sysdep-cancel.h>
 #include <tls.h>
 #include <stap-probe.h>
+#include <dl-find_eh_frame.h>
 
 #include <dl-unmap-segments.h>
 
@@ -718,6 +719,9 @@ _dl_close_worker (struct link_map *map, bool force)
 	  if (imap->l_next != NULL)
 	    imap->l_next->l_prev = imap->l_prev;
 
+	  /* Update the data used by _dl_find_eh_frame.  */
+	  _dl_find_eh_frame_dlclose (imap);
+
 	  free (imap->l_versions);
 	  if (imap->l_origin != (char *) -1)
 	    free ((char *) imap->l_origin);
diff --git a/elf/dl-find_eh_frame.c b/elf/dl-find_eh_frame.c
new file mode 100644
index 0000000000..c7313c122d
--- /dev/null
+++ b/elf/dl-find_eh_frame.c
@@ -0,0 +1,864 @@
+/* Locating DWARF unwind information using the dynamic loader.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <atomic_wide_counter.h>
+#include <dlfcn.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include <dl-find_eh_frame_slow.h>
+
+/* Data for the main executable.  There is usually a large gap between
+   the main executable and initially loaded shared objects.  Record
+   the main executable separately, to increase the chance that the
+   range for the non-closeable mappings below covers only the shared
+   objects (and not also the gap between main executable and shared
+   objects).  */
+static uintptr_t _dl_eh_main_map_start attribute_relro;
+static struct dl_eh_frame_info _dl_eh_main_info attribute_relro;
+
+/* Data for initally loaded shared objects that cannot be unlaoded.
+   The mapping base addresses are stored in address order in the
+   _dl_eh_nodelete_mappings_bases array (containing
+   _dl_eh_nodelete_mappings_size elements).  The EH data for a base
+   address is stored in the parallel _dl_eh_nodelete_mappings_infos.
+   These arrays are not modified after initialization.  */
+static uintptr_t _dl_eh_nodelete_mappings_end attribute_relro;
+static size_t _dl_eh_nodelete_mappings_size attribute_relro;
+static uintptr_t *_dl_eh_nodelete_mappings_bases attribute_relro;
+static struct dl_eh_frame_info *_dl_eh_nodelete_mappings_infos
+  attribute_relro;
+
+/* Mappings created by dlopen can go away with dlclose, so a data
+   dynamic data structure with some synchronization is needed.
+   Individual segments are similar to the _dl_eh_nodelete_mappings
+   above (two sorted arrays of the same length for bases/infos).  The
+   previous segment contains lower addresses and is at most half as
+   long.  Checking the address of the base address of the first
+   element during a lookup can therefore approximate a binary search
+   over all segments, even though the data is not stored in one
+   contiguous array.
+
+   During updates, the segments are overwritten in place, and a
+   software transactional memory construct (involving the
+   _dl_eh_loaded_mappings_version variable) is used to detect
+   concurrent modification and retry as necessary.  The memory
+   allocations are never deallocated, but slots used for objects that
+   have been dlclose'd can be reused by dlopen.  The memory can live
+   in the regular C malloc heap.
+
+   The segments are populated from the start of the list, with the
+   mappings with the highest address.  Only if this segment is full,
+   previous segments are used for mappings at lower addresses.  The
+   remaining segments are populated as needed, but after resizing,
+   some of the initial segments (at the end of the linked list) can be
+   empty (with size 0).
+
+   Adding new elements to this data structure is another source of
+   quadratic behavior for dlopen.  If the other causes of quadratic
+   behavior are eliminated, a more complicated data structure will be
+   needed.  */
+struct dl_eh_mappings_segment
+{
+  /* The previous segment has lower base addresses.  */
+  struct dl_eh_mappings_segment *previous;
+
+  /* Used by __libc_freeres to deallocate malloc'ed memory. */
+  void *to_free;
+
+  /* Count of array elements in use and allocated.  */
+  size_t size;
+  size_t allocated;
+  uintptr_t bases[];            /* infos array follows.  */
+};
+
+/* To achieve async-signal-safety, two copies of the data structure
+   are used, so that a signal handler can still use this data even if
+   dlopen or dlclose modify the other copy.  The the MSB in
+   _dl_eh_loaded_mappings_version determins which array element is the
+   currently active region.  */
+static struct dl_eh_mappings_segment *_dl_eh_loaded_mappings[2];
+
+/* Returns the co-allocated struct dl_eh_frame_info array inside
+   *SEG.  */
+static inline struct dl_eh_frame_info *
+_dl_eh_mappings_segment_infos (struct dl_eh_mappings_segment *seg)
+{
+  return (struct dl_eh_frame_info *) &seg->bases[seg->allocated];
+}
+
+/* Returns the number of actually used elements in all segements
+   starting at SEG.  */
+static inline size_t
+_dl_eh_mappings_segment_count_used (struct dl_eh_mappings_segment *seg)
+{
+  size_t count = 0;
+  for (; seg != NULL && seg->size > 0; seg = seg->previous)
+    {
+      struct dl_eh_frame_info *infos = _dl_eh_mappings_segment_infos (seg);
+      for (size_t i = 0; i < seg->size; ++i)
+        /* Exclude elements which have been dlclose'd.  */
+        count += infos[i].size > 0;
+    }
+  return count;
+}
+
+/* Compute the total number of available allocated segments linked
+   from SEG.  */
+static inline size_t
+_dl_eh_mappings_segment_count_allocated (struct dl_eh_mappings_segment *seg)
+{
+  size_t count = 0;
+  for (; seg != NULL; seg = seg->previous)
+    count += seg->allocated;
+  return count;
+}
+
+/* This is essentially an arbitrary value.  dlopen allocates plenty of
+   memory anyway, so over-allocated a bit does not hurt.  Not having
+   many small-ish segments helps to avoid many small binary searches.
+   Not using a power of 2 means that we do not waste an extra page
+   just for the malloc header if a mapped allocation is used in the
+   glibc allocator.  */
+enum { dl_eh_mappings_initial_segment_size = 63 };
+
+/* Allocate an empty segment.  This used for the first ever
+   allocation.  */
+static struct dl_eh_mappings_segment *
+_dl_eh_mappings_segment_allocate_unpadded (size_t size)
+{
+  if (size < dl_eh_mappings_initial_segment_size)
+    size = dl_eh_mappings_initial_segment_size;
+  /* No overflow checks here because the size is a mapping count, and
+     struct link_map is larger than what we allocate here.  */
+  size_t to_allocate = (sizeof (struct dl_eh_mappings_segment)
+                        + size * (sizeof (uintptr_t)
+                                  + sizeof (struct dl_eh_frame_info)));
+  struct dl_eh_mappings_segment *result = malloc (to_allocate);
+  if (result != NULL)
+    {
+      result->previous = NULL;
+      result->to_free = NULL; /* Minimal malloc memory cannot be freed.  */
+      result->size = 0;
+      result->allocated = size;
+    }
+  return result;
+}
+
+/* Allocate an empty segment that is at least SIZE large.  PREVIOUS */
+static struct dl_eh_mappings_segment *
+_dl_eh_mappings_segment_allocate (size_t size,
+                                  struct dl_eh_mappings_segment * previous)
+{
+  /* Exponential sizing policies, so that lookup approximates a binary
+     search.  */
+  {
+    size_t minimum_growth;
+    if (previous == NULL)
+      minimum_growth = dl_eh_mappings_initial_segment_size;
+    else
+      minimum_growth = 2* previous->allocated;
+    if (size < minimum_growth)
+      size = minimum_growth;
+  }
+  enum { cache_line_size_estimate = 128 };
+  /* No overflow checks here because the size is a mapping count, and
+     struct link_map is larger than what we allocate here.  */
+  size_t to_allocate = (sizeof (struct dl_eh_mappings_segment)
+                        + size * (sizeof (uintptr_t)
+                                  + sizeof (struct dl_eh_frame_info))
+                        + 2 * cache_line_size_estimate);
+  char *ptr = malloc (to_allocate);
+  if (ptr == NULL)
+    return NULL;
+  char *original_ptr = ptr;
+  /* Start and end at a (conservative) 128-byte cache line boundary.
+     Do not use memalign for compatibility with partially interposing
+     malloc implementations.  */
+  char *end = PTR_ALIGN_DOWN (ptr + to_allocate, cache_line_size_estimate);
+  ptr = PTR_ALIGN_UP (ptr, cache_line_size_estimate);
+  struct dl_eh_mappings_segment *result
+    = (struct dl_eh_mappings_segment *) ptr;
+  result->previous = previous;
+  result->to_free = original_ptr;
+  result->size = 0;
+  /* We may have obtained slightly more space if malloc happened
+     to provide an over-aligned pointer.  */
+  result->allocated = (((uintptr_t) (end - ptr)
+                        - sizeof (struct dl_eh_mappings_segment))
+                       / (sizeof (uintptr_t)
+                          + sizeof (struct dl_eh_frame_info)));
+  assert (result->allocated >= size);
+  return result;
+}
+
+/* Monotonic counter for software transactional memory.  The lowest
+   bit indicates which element of the _dl_eh_loaded_mappings contains
+   up-to-date data.  */
+static __atomic_wide_counter _dl_eh_loaded_mappings_version;
+
+/* TM version at the start of the read operation.  */
+static inline uint64_t
+_dl_eh_read_start_version (void)
+{
+  /* Acquire MO load synchronizes with the fences at the beginning and
+     end of the TM update region.  */
+  return __atomic_wide_counter_load_acquire (&_dl_eh_loaded_mappings_version);
+}
+
+/* Optimized variant of _dl_eh_start_version which can be called when
+   the loader is write-locked.  */
+static inline uint64_t
+_dl_eh_read_version_locked (void)
+{
+  return __atomic_wide_counter_load_relaxed (&_dl_eh_loaded_mappings_version);
+}
+
+/* Update the version to reflect that an update is happening.  This
+   does not change the bit that controls the active segment chain.
+   Returns the index of the currently active segment chain.  */
+static inline unsigned int
+_dl_eh_mappings_begin_update (void)
+{
+  unsigned int v
+    = __atomic_wide_counter_fetch_add_relaxed (&_dl_eh_loaded_mappings_version,
+                                               2);
+  /* Subsequent stores to the TM data must not be reordered before the
+     store above with the version update.  */
+  atomic_thread_fence_release ();
+  return v & 1;
+}
+
+/* Installs the just-updated version as the active version.  */
+static inline void
+_dl_eh_mappings_end_update (void)
+{
+  /* The previous writes to the TM data must not be reordered after
+     the version update below.  */
+  atomic_thread_fence_release ();
+  __atomic_wide_counter_fetch_add_relaxed (&_dl_eh_loaded_mappings_version,
+                                           1);
+}
+/* Completes an in-place update without switching versions.  */
+static inline void
+_dl_eh_mappings_end_update_no_switch (void)
+{
+  /* The previous writes to the TM data must not be reordered after
+     the version update below.  */
+  atomic_thread_fence_release ();
+  __atomic_wide_counter_fetch_add_relaxed (&_dl_eh_loaded_mappings_version,
+                                           2);
+}
+
+/* Return true if the read was successful, given the start
+   version.  */
+static inline bool
+_dl_eh_read_success (uint64_t start_version)
+{
+  return _dl_eh_read_start_version () == start_version;
+}
+
+/* Returns the active segment identified by the specified start
+   version.  */
+static struct dl_eh_mappings_segment *
+_dl_eh_mappings_active_segment (uint64_t start_version)
+{
+  return _dl_eh_loaded_mappings[start_version & 1];
+}
+
+/* Searches PC amoung the sorted array [FIRST, FIRST + SIZE).  Returns
+   the index of the first element that is not less than PC, or SIZE if
+   there is no such element.  */
+static inline size_t
+_dl_eh_find_lower_bound (uintptr_t pc, const uintptr_t *first1,
+                         size_t size)
+{
+  const uintptr_t *first = first1;
+  while (size > 0)
+    {
+      size_t half = size >> 1;
+      const uintptr_t *middle = first + half;
+      if (*middle < pc)
+        {
+          first = middle + 1;
+          size -= half + 1;
+        }
+      else
+        size = half;
+    }
+  return first - first1;
+}
+
+void *
+_dl_find_eh_frame (void *pc1
+#if DL_FIND_EH_FRAME_DBASE
+                   , void **dbase
+#endif
+                   )
+{
+  uintptr_t pc = (uintptr_t) pc1;
+
+  if (_dl_eh_main_info.size == 0)
+    {
+      /* Not initialized.  No locking is needed here because this can
+         only be called from audit modules, which cannot create
+         threads.  */
+#if DL_FIND_EH_FRAME_DBASE
+      return _dl_find_eh_frame_slow (pc1, dbase);
+#else
+      return _dl_find_eh_frame_slow (pc1);
+#endif
+    }
+
+  /* Main executable.  */
+  if (pc >= _dl_eh_main_map_start
+      && (pc - _dl_eh_main_map_start) < _dl_eh_main_info.size)
+    {
+#if DL_FIND_EH_FRAME_DBASE
+      *dbase = _dl_eh_main_info.dbase;
+#endif
+      return _dl_eh_main_info.eh_frame;
+    }
+
+  /* Other initially loaded objects.  */
+  if (pc >= *_dl_eh_nodelete_mappings_bases
+      && pc < _dl_eh_nodelete_mappings_end)
+    {
+      size_t idx = _dl_eh_find_lower_bound (pc,
+                                            _dl_eh_nodelete_mappings_bases,
+                                            _dl_eh_nodelete_mappings_size);
+      const struct dl_eh_frame_info *info
+        = _dl_eh_nodelete_mappings_infos + idx;
+      bool match;
+      if (idx < _dl_eh_nodelete_mappings_size
+          && pc == _dl_eh_nodelete_mappings_bases[idx])
+        match = true;
+      else
+        {
+          /* PC might be in the previous mapping.  */
+          --idx;
+          --info;
+          match = pc - _dl_eh_nodelete_mappings_bases[idx] < info->size;
+        }
+      if (match)
+        {
+#if DL_FIND_EH_FRAME_DBASE
+          *dbase = info->dbase;
+#endif
+          return info->eh_frame;
+        }
+      /* Fall through to the full search.  The kernel may have mapped
+         the initial mappings with gaps that are later filled by
+         dlopen with other mappings.  */
+    }
+
+  /* Handle audit modules, dlopen, dlopen objects.  This uses software
+     transactional memory, with a retry loop in case the version
+     changes during execution.  */
+  while (true)
+    {
+    retry:
+      ;
+      uint64_t start_version = _dl_eh_read_start_version ();
+
+      /* The read through seg->previous assumes that the CPU
+         recognizes the load dependency, so that no invalid size
+         values is read.  Furthermore, the code assumes that no
+         out-of-thin-air value for seg->size is observed.  Together,
+         this ensures that the observed seg->size value is always less
+         than seg->allocated, so that _dl_eh_mappings_index does not
+         read out-of-bounds.  (This avoids intermediate TM version
+         verification.  A concurrent version update will lead to
+         invalid lookup results, but not to out-of-memory access.)
+
+         Either seg == NULL or seg->size == 0 terminates the segment
+         list.  _dl_eh_frame_frame_update does not bother to clear the
+         size on earlier unused segments.  */
+      for (struct dl_eh_mappings_segment *seg
+             = _dl_eh_mappings_active_segment (start_version);
+           seg != NULL && seg->size > 0; seg = seg->previous)
+        if (pc >= seg->bases[0])
+          {
+            /* PC may lie within this segment.  If it is less than the
+               segment start address, it can only lie in a previous
+               segment, due to the base address sorting.  */
+            size_t idx = _dl_eh_find_lower_bound (pc, seg->bases, seg->size);
+            const struct dl_eh_frame_info *info
+              = _dl_eh_mappings_segment_infos (seg) + idx;
+            bool match;
+            if (idx < seg->size && pc == seg->bases[idx])
+              /* Check for dlcose.  */
+              match = info->size > 0;
+            else
+              {
+                /* The match, if any, must be in the previous mapping.  */
+                --idx;
+                --info;
+                match = pc - seg->bases[idx] < info->size;
+              }
+
+            if (match)
+              {
+                /* Found the right mapping.  Copy out the data prior to
+                   checking if the read transaction was successful.  */
+                void *eh_frame_copy = info->eh_frame;
+#if DL_FIND_EH_FRAME_DBASE
+                void *dbase_copy = info->dbase;
+#endif
+                if (_dl_eh_read_success (start_version))
+                  {
+#if DL_FIND_EH_FRAME_DBASE
+                    *dbase = dbase_copy;
+#endif
+                    return eh_frame_copy;
+                  }
+                else
+                  /* Read transaction failure.  */
+                  goto retry;
+              }
+            else
+              {
+                /* PC is not covered by this mapping.  */
+                if (_dl_eh_read_success (start_version))
+                  return NULL;
+                else
+                  /* Read transaction failure.  */
+                  goto retry;
+              }
+          } /* if: PC might lie within the current seg.  */
+
+      /* PC is not covered by any segment.  */
+      if (_dl_eh_read_success (start_version))
+        return NULL;
+    } /* Transaction retry loop.  */
+}
+
+/* _dl_eh_process_initial is called twice.  First to compute the array
+   sizes from the initial loaded mappings.  Second to fill in the
+   bases and infos arrays with the (still unsorted) data.  Returns the
+   number of loaded (non-nodelete) mappings.  */
+static size_t
+_dl_eh_process_initial (void)
+{
+  struct link_map *main_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
+
+  size_t nodelete = 0;
+  if (!main_map->l_contiguous)
+    {
+      struct dl_eh_frame_info info;
+      _dl_get_eh_frame (main_map, &info);
+
+      /* PT_LOAD segments for a non-contiguous are added to the
+         non-closeable mappings.  */
+      for (const ElfW(Phdr) *ph = main_map->l_phdr,
+             *ph_end = main_map->l_phdr + main_map->l_phnum;
+           ph < ph_end; ++ph)
+        if (ph->p_type == PT_LOAD)
+          {
+            if (_dl_eh_nodelete_mappings_bases != NULL)
+              {
+                /* Second pass only.  */
+                _dl_eh_nodelete_mappings_bases[nodelete]
+                  = ph->p_vaddr + main_map->l_addr;
+                _dl_eh_nodelete_mappings_infos[nodelete].size = ph->p_memsz;
+                _dl_eh_nodelete_mappings_infos[nodelete].eh_frame
+                  = info.eh_frame;
+#if DL_FIND_EH_FRAME_DBASE
+                _dl_eh_nodelete_mappings_infos[nodelete].dbase = info.dbase;
+#endif
+              }
+            ++nodelete;
+          }
+    }
+
+  size_t loaded = 0;
+  for (Lmid_t ns = 0; ns < GL(dl_nns); ++ns)
+    for (struct link_map *l = GL(dl_ns)[ns]._ns_loaded; l != NULL;
+         l = l->l_next)
+      /* Skip the main map processed above, and proxy maps.  */
+      if (l != main_map && l == l->l_real)
+        {
+          /* lt_library link maps are implicitly NODELETE.  */
+          if (l->l_type == lt_library || l->l_nodelete_active)
+            {
+              if (_dl_eh_nodelete_mappings_bases != NULL)
+                {
+                  /* Second pass only.  */
+                  _dl_eh_nodelete_mappings_bases[nodelete] = l->l_map_start;
+                  _dl_get_eh_frame
+                    (l, &_dl_eh_nodelete_mappings_infos[nodelete]);
+                }
+              ++nodelete;
+            }
+          else if (l->l_type == lt_loaded)
+            {
+              if (_dl_eh_loaded_mappings[0] != NULL)
+                {
+                  /* Second pass only.  */
+                  _dl_eh_loaded_mappings[0]->bases[loaded] = l->l_map_start;
+                  _dl_get_eh_frame (l, (_dl_eh_mappings_segment_infos
+                                        (_dl_eh_loaded_mappings[0])
+                                        + loaded));
+                }
+              ++loaded;
+            }
+        }
+
+  _dl_eh_nodelete_mappings_size = nodelete;
+  return loaded;
+}
+
+/* Selection sort based on mapping base address.  The BASES and INFOS
+   arrays are updated at the same time.  */
+void
+_dl_eh_sort_mappings (uintptr_t *bases, struct dl_eh_frame_info *infos,
+                      size_t size)
+{
+  if (size < 2)
+    return;
+
+  for (size_t i = 0; i < size - 1; ++i)
+    {
+      /* Find minimum.  */
+      size_t min_idx = i;
+      size_t min_val = bases[i];
+      for (size_t j = i + 1; j < size; ++j)
+        if (bases[j] < min_val)
+          {
+            min_idx = j;
+            min_val = bases[j];
+          }
+
+      /* Swap into place.  */
+      bases[min_idx] = bases[i];
+      bases[i] = min_val;
+      struct dl_eh_frame_info tmp = infos[min_idx];
+      infos[min_idx] = infos[i];
+      infos[i] = tmp;
+    }
+}
+
+void
+_dl_find_eh_frame_init (void)
+{
+  /* Cover the main mapping.  */
+  {
+    struct link_map *main_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
+
+    if (main_map->l_contiguous)
+      {
+        _dl_eh_main_map_start = main_map->l_map_start;
+        _dl_get_eh_frame (main_map, &_dl_eh_main_info);
+      }
+    else
+      {
+        /* Non-contiguous main maps are handled in
+           _dl_eh_process_initial.  Mark as initialized, but not
+           coverying any valid PC.  */
+        _dl_eh_main_map_start = -1;
+        _dl_eh_main_info.size = 1;
+      }
+  }
+
+  /* Allocate the data structures.  */
+  size_t loaded_size = _dl_eh_process_initial ();
+  _dl_eh_nodelete_mappings_bases
+    = malloc (_dl_eh_nodelete_mappings_size
+              * sizeof (*_dl_eh_nodelete_mappings_bases));
+  _dl_eh_nodelete_mappings_infos
+    = malloc (_dl_eh_nodelete_mappings_size
+              * sizeof (*_dl_eh_nodelete_mappings_infos));
+  if (loaded_size > 0)
+    _dl_eh_loaded_mappings[0] = (_dl_eh_mappings_segment_allocate_unpadded
+                                 (loaded_size));
+  if (_dl_eh_nodelete_mappings_bases == NULL
+      || _dl_eh_nodelete_mappings_infos == NULL
+      || (loaded_size > 0 && _dl_eh_loaded_mappings[0] == NULL))
+    _dl_fatal_printf ("\
+Fatal glibc error: cannot allocate memory for DWARF EH frame data\n");
+  /* Fill in the data with the second call.  */
+  _dl_eh_nodelete_mappings_size = 0;
+  _dl_eh_process_initial ();
+
+  /* Sort both arrays.  */
+  if (_dl_eh_nodelete_mappings_size > 0)
+    {
+      _dl_eh_sort_mappings (_dl_eh_nodelete_mappings_bases,
+                            _dl_eh_nodelete_mappings_infos,
+                            _dl_eh_nodelete_mappings_size);
+      size_t last_idx = _dl_eh_nodelete_mappings_size - 1;
+      _dl_eh_nodelete_mappings_end
+        = (_dl_eh_nodelete_mappings_bases[last_idx]
+           + _dl_eh_nodelete_mappings_infos[last_idx].size);
+    }
+  if (loaded_size > 0)
+    _dl_eh_sort_mappings
+      (_dl_eh_loaded_mappings[0]->bases,
+       _dl_eh_mappings_segment_infos (_dl_eh_loaded_mappings[0]),
+       _dl_eh_loaded_mappings[0]->size);
+}
+
+static void
+_dl_eh_frame_link_map_sort (struct link_map **loaded, size_t size)
+{
+  /* Selection sort based on map_start.  */
+  if (size < 2)
+    return;
+  for (size_t i = 0; i < size - 1; ++i)
+    {
+      /* Find minimum.  */
+      size_t min_idx = i;
+      ElfW(Addr) min_val = loaded[i]->l_map_start;
+      for (size_t j = i + 1; j < size; ++j)
+        if (loaded[j]->l_map_start < min_val)
+          {
+            min_idx = j;
+            min_val = loaded[j]->l_map_start;
+          }
+
+      /* Swap into place.  */
+      struct link_map *tmp = loaded[min_idx];
+      loaded[min_idx] = loaded[i];
+      loaded[i] = tmp;
+    }
+}
+
+/* Initializes the segment for writing.  Returns the target write
+   index (plus 1) in this segment.  The index is chosen so that a
+   partially filled segment still has data at index 0.  */
+static inline size_t
+_dl_eh_frame_update_init_seg (struct dl_eh_mappings_segment *seg,
+                              size_t remaining_to_add)
+{
+  if (remaining_to_add < seg->allocated)
+    /* Partially filled segment.  */
+    seg->size = remaining_to_add;
+  else
+    seg->size = seg->allocated;
+  return seg->size;
+}
+
+/* Invoked from _dl_eh_frame_frame after sorting.  */
+static bool
+_dl_find_eh_frame_update_1 (struct link_map **loaded, size_t count)
+{
+  int active_idx = _dl_eh_mappings_begin_update ();
+
+  struct dl_eh_mappings_segment *current_seg
+    = _dl_eh_loaded_mappings[active_idx];
+  size_t current_used = _dl_eh_mappings_segment_count_used (current_seg);
+
+  struct dl_eh_mappings_segment *target_seg
+    = _dl_eh_loaded_mappings[!active_idx];
+  size_t remaining_to_add = current_used + count;
+
+  /* Ensure that the new segment chain has enough space.  */
+  {
+    size_t new_allocated
+      = _dl_eh_mappings_segment_count_allocated (target_seg);
+    if (new_allocated < remaining_to_add)
+      {
+        size_t more = remaining_to_add - new_allocated;
+        target_seg = _dl_eh_mappings_segment_allocate (more, target_seg);
+        if (target_seg == NULL)
+          /* Out of memory.  */
+          return false;
+        /* The barrier ensures that a concurrent TM read or fork does
+           not see a partially initialized segment.  */
+        atomic_store_release (&_dl_eh_loaded_mappings[!active_idx], target_seg);
+      }
+  }
+  size_t target_seg_index1 = _dl_eh_frame_update_init_seg (target_seg,
+                                                           remaining_to_add);
+
+  /* Merge the current_seg segment list with the loaded array into the
+     target_set.  Merging occurs backwards, in decreasing l_map_start
+     order.  */
+  size_t loaded_index1 = count;
+  size_t current_seg_index1;
+  if (current_seg == NULL)
+    current_seg_index1 = 0;
+  else
+    current_seg_index1 = current_seg->size;
+  while (true)
+    {
+      if (current_seg_index1 == 0)
+        {
+          /* Switch to the previous segment.  */
+          if (current_seg != NULL)
+            current_seg = current_seg->previous;
+          if (current_seg != NULL)
+            {
+              current_seg_index1 = current_seg->size;
+              if (current_seg_index1 == 0)
+                /* No more data in previous segments.  */
+                current_seg = NULL;
+            }
+        }
+
+      if (current_seg != NULL
+          && (_dl_eh_mappings_segment_infos (current_seg)
+              [current_seg_index1 - 1]).size == 0)
+        {
+          /* This mapping has been dlclose'd.  Do not copy it.  */
+          --current_seg_index1;
+          continue;
+        }
+
+      if (loaded_index1 == 0 && current_seg == NULL)
+        /* No more data in either source.  */
+        break;
+
+      /* Make room for another mapping.  */
+      assert (remaining_to_add > 0);
+      if (target_seg_index1 == 0)
+        {
+          /* Switch segments and set the size of the segment.  */
+          target_seg = target_seg->previous;
+          target_seg_index1 = _dl_eh_frame_update_init_seg (target_seg,
+                                                            remaining_to_add);
+        }
+
+      /* Determine where to store the data.  */
+      uintptr_t *pbase = &target_seg->bases[target_seg_index1 - 1];
+      struct dl_eh_frame_info *pinfo
+        = _dl_eh_mappings_segment_infos (target_seg) + target_seg_index1 - 1;
+
+      if (loaded_index1 == 0
+          || (current_seg != NULL
+              && (loaded[loaded_index1 - 1]->l_map_start
+                  < current_seg->bases[current_seg_index1 - 1])))
+        {
+          /* Prefer mapping in current_seg.  */
+          assert (current_seg_index1 > 0);
+          *pbase = current_seg->bases[current_seg_index1 - 1];
+          *pinfo = (_dl_eh_mappings_segment_infos (current_seg)
+                    [current_seg_index1 - 1]);
+          --current_seg_index1;
+        }
+      else
+        {
+          /* Prefer newly loaded linkmap.  */
+          assert (loaded_index1 > 0);
+          struct link_map *l = loaded[loaded_index1 - 1];
+          *pbase = l->l_map_start;
+          _dl_get_eh_frame (l, pinfo);
+          l->l_eh_frame_processed = 1;
+          --loaded_index1;
+        }
+
+      /* Consume space in target segment.  */
+      --target_seg_index1;
+
+      --remaining_to_add;
+    }
+
+  /* Everything has been added.  */
+  assert (remaining_to_add == 0);
+
+  /* The segment must have been filled up to the beginning.  */
+  assert (target_seg_index1 == 0);
+
+  /* Prevent searching further into unused segments.  */
+  if (target_seg->previous != NULL)
+    target_seg->previous->size = 0;
+
+  _dl_eh_mappings_end_update ();
+  return true;
+}
+
+bool
+_dl_find_eh_frame_update (struct link_map *new_map)
+{
+  /* Copy the newly-loaded link maps into an array for sorting.  */
+  size_t count = 0;
+  for (struct link_map *l = new_map; l != NULL; l = l->l_next)
+    count += !l->l_eh_frame_processed;
+  struct link_map **map_array = malloc (count * sizeof (*map_array));
+  if (map_array == NULL)
+    return false;
+  {
+    size_t i = 0;
+    for (struct link_map *l = new_map; l != NULL; l = l->l_next)
+      if (!l->l_eh_frame_processed)
+        map_array[i++] = l;
+  }
+  if (count == 0)
+    return true;
+
+  _dl_eh_frame_link_map_sort (map_array, count);
+  bool ok = _dl_find_eh_frame_update_1 (map_array, count);
+  free (map_array);
+  return ok;
+}
+
+void
+_dl_find_eh_frame_dlclose (struct link_map *map)
+{
+  uint64_t start_version = _dl_eh_read_version_locked ();
+  uintptr_t map_start = map->l_map_start;
+
+
+  /* Directly patch the size information in the mapping to mark it as
+     unused.  See the parallel lookup logic in _dl_find_eh_frame.  Do
+     not check for previous dlclose at the same mapping address
+     because that cannot happen (there would have to be an
+     intermediate dlopen, which drops size-zero mappings).  */
+  for (struct dl_eh_mappings_segment *seg
+         = _dl_eh_mappings_active_segment (start_version);
+       seg != NULL && seg->size > 0; seg = seg->previous)
+    if (map_start >= seg->bases[0])
+      {
+        size_t idx = _dl_eh_find_lower_bound (map_start, seg->bases, seg->size);
+        struct dl_eh_frame_info *info
+          = _dl_eh_mappings_segment_infos (seg) + idx;
+        if (idx == seg->size || map_start != seg->bases[idx])
+          /* Ignore missing link maps because of potential shutdown
+             issues around __libc_freeres.  */
+            return;
+
+        /* The update happens in-place, but given that we do not use
+           atomic accesses on the read side, update the version around
+           the update to trigger re-validation in concurrent
+           readers.  */
+        _dl_eh_mappings_begin_update ();
+
+        /* Mark as closed.  */
+        info->size = 0;
+
+        _dl_eh_mappings_end_update_no_switch ();
+      }
+}
+
+void
+_dl_find_eh_frame_freeres (void)
+{
+  for (int idx = 0; idx < 2; ++idx)
+    {
+      for (struct dl_eh_mappings_segment *seg = _dl_eh_loaded_mappings[idx];
+           seg != NULL; )
+        {
+          struct dl_eh_mappings_segment *previous = seg->previous;
+          free (seg->to_free);
+          seg = previous;
+        }
+      /* Stop searching in shared objects.  */
+      _dl_eh_loaded_mappings[idx] = 0;
+    }
+}
diff --git a/elf/dl-find_eh_frame.h b/elf/dl-find_eh_frame.h
new file mode 100644
index 0000000000..4bde9b14db
--- /dev/null
+++ b/elf/dl-find_eh_frame.h
@@ -0,0 +1,90 @@
+/* Declarations for finding DWARF EH frame information.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _DL_FIND_EH_FRAME_H
+#define _DL_FIND_EH_FRAME_H
+
+#include <assert.h>
+#include <dlfcn.h>
+#include <ldsodefs.h>
+#include <stdbool.h>
+#include <stdint.h>
+
+/* Exception handling information for a mapping (shared object or load
+   segment).  The base address is stored separately to increase cache
+   utilization.  */
+struct dl_eh_frame_info
+{
+  /* Size of the mapping.  dlclose sets this to zero without removing
+     the array element.  */
+  uintptr_t size;
+  void *eh_frame;               /* Corresponding PT_GNU_EH_FRAME.  */
+#if DL_FIND_EH_FRAME_DBASE
+  void *dbase;
+#endif
+
+  /* Note: During the initialization phase, size is used for the base
+     address and eh_frame for a pointer to the link map.
+     _dl_eh_mappings_segment_finish computes the final data for a
+     segment after sorting by base address. */
+};
+
+/* Extract the exception handling data from a link map and writes it
+   to *INFO.  If no such data is available INFO->eh_frame will be
+   NULL.  */
+static void __attribute__ ((unused))
+_dl_get_eh_frame (const struct link_map *l, struct dl_eh_frame_info *info)
+{
+  info->size = l->l_map_end - l->l_map_start;
+#if DL_FIND_EH_FRAME_DBASE
+  info->dbase = (void *) l->l_info[DT_PLTGOT];
+#endif
+
+  for (const ElfW(Phdr) *ph = l->l_phdr, *ph_end = l->l_phdr + l->l_phnum;
+       ph < ph_end; ++ph)
+    if (ph->p_type == PT_GNU_EH_FRAME)
+      {
+        info->eh_frame = (void *) (ph->p_vaddr + l->l_addr);
+        return;
+      }
+
+  /* Object has no PT_GNU_EH_FRAME.  */
+  info->eh_frame = NULL;
+}
+
+
+/* Called by the dynamic linker to set up the data structures for the
+   initially loaded objects.  This creates a few persistent
+   allocations, so it should be called with the minimal malloc.  */
+void _dl_find_eh_frame_init (void) attribute_hidden;
+
+/* Called by dlopen/dlmopen to add new objects to the DWARF EH frame
+   data structures.  NEW_MAP is the dlopen'ed link map.  Link maps on
+   the l_next list are added if l_eh_frame_processed is 0.  Needs to
+   be protected by loader write lock.  Returns true on success, false
+   on malloc failure.  */
+bool _dl_find_eh_frame_update (struct link_map *new_map) attribute_hidden;
+
+/* Called by dlclose to remove the link map from the DWARF EH frame
+   data structures.  Needs to be protected by loader write lock.  */
+void _dl_find_eh_frame_dlclose (struct link_map *l) attribute_hidden;
+
+/* Called from __libc_freeres to deallocate malloc'ed memory.  */
+void _dl_find_eh_frame_freeres (void) attribute_hidden;
+
+#endif /* _DL_FIND_EH_FRAME_H */
diff --git a/elf/dl-find_eh_frame_slow.h b/elf/dl-find_eh_frame_slow.h
new file mode 100644
index 0000000000..355351ce28
--- /dev/null
+++ b/elf/dl-find_eh_frame_slow.h
@@ -0,0 +1,55 @@
+/* Locating DWARF unwind information using the dynamic loader.  Slow version.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <assert.h>
+#include <dlfcn.h>
+#include <ldsodefs.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include <elf/dl-find_eh_frame.h>
+
+/* This function is similar to _dl_find_eh_frame, but travers the link
+   maps directly.  It is used from audit modules before
+   _dl_find_eh_frame_init has been called, and for testing.  */
+static void *
+_dl_find_eh_frame_slow (void *pc
+#if DL_FIND_EH_FRAME_DBASE
+                   , void **dbase
+#endif
+                        )
+{
+  ElfW(Addr) addr = (ElfW(Addr)) pc;
+  for (Lmid_t ns = 0; ns < GL(dl_nns); ++ns)
+    for (struct link_map *l = GL(dl_ns)[ns]._ns_loaded; l != NULL;
+         l = l->l_next)
+      if (addr >= l->l_map_start && addr < l->l_map_end
+          && (l->l_contiguous || _dl_addr_inside_object (l, addr)))
+        {
+          assert (ns == l->l_ns);
+          struct dl_eh_frame_info info;
+          _dl_get_eh_frame (l, &info);
+#if DL_FIND_EH_FRAME_DBASE
+          *dbase = info.dbase;
+#endif
+          return info.eh_frame;
+        }
+
+  /* Object not found.  */
+  return NULL;
+}
diff --git a/elf/dl-libc_freeres.c b/elf/dl-libc_freeres.c
index 68f305a6f9..7822730e7d 100644
--- a/elf/dl-libc_freeres.c
+++ b/elf/dl-libc_freeres.c
@@ -17,8 +17,10 @@
    <https://www.gnu.org/licenses/>.  */
 
 #include <ldsodefs.h>
+#include <dl-find_eh_frame.h>
 
 void
 __rtld_libc_freeres (void)
 {
+  _dl_find_eh_frame_freeres ();
 }
diff --git a/elf/dl-open.c b/elf/dl-open.c
index 6ea5dd2457..c889cc5c54 100644
--- a/elf/dl-open.c
+++ b/elf/dl-open.c
@@ -36,6 +36,7 @@
 #include <array_length.h>
 #include <libc-early-init.h>
 #include <gnu/lib-names.h>
+#include <dl-find_eh_frame.h>
 
 #include <dl-dst.h>
 #include <dl-prop.h>
@@ -749,6 +750,10 @@ dl_open_worker_begin (void *a)
      objects.  */
   update_scopes (new);
 
+  if (!_dl_find_eh_frame_update (new))
+    _dl_signal_error (ENOMEM, new->l_libname->name, NULL,
+		      N_ ("cannot allocate EH frame data"));
+
   /* FIXME: It is unclear whether the order here is correct.
      Shouldn't new objects be made available for binding (and thus
      execution) only after there TLS data has been set up fully?
diff --git a/elf/rtld.c b/elf/rtld.c
index 847141e21d..c379da29cc 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -50,6 +50,7 @@
 #include <gnu/lib-names.h>
 #include <dl-tunables.h>
 #include <get-dynamic-info.h>
+#include <dl-find_eh_frame.h>
 
 #include <assert.h>
 
@@ -2331,6 +2332,9 @@ dl_main (const ElfW(Phdr) *phdr,
 	  rtld_timer_stop (&relocate_time, start);
 	}
 
+      /* Set up the EH frame lookup structures.  */
+      _dl_find_eh_frame_init ();
+
       /* The library defining malloc has already been relocated due to
 	 prelinking.  Resolve the malloc symbols for the dynamic
 	 loader.  */
@@ -2439,6 +2443,9 @@ dl_main (const ElfW(Phdr) *phdr,
 	 re-relocation, we might call a user-supplied function
 	 (e.g. calloc from _dl_relocate_object) that uses TLS data.  */
 
+      /* Set up the EH frame lookup structures.  */
+      _dl_find_eh_frame_init ();
+
       /* The malloc implementation has been relocated, so resolving
 	 its symbols (and potentially calling IFUNC resolvers) is safe
 	 at this point.  */
diff --git a/elf/tst-dl_find_eh_frame-mod1.c b/elf/tst-dl_find_eh_frame-mod1.c
new file mode 100644
index 0000000000..d33ef56efd
--- /dev/null
+++ b/elf/tst-dl_find_eh_frame-mod1.c
@@ -0,0 +1,10 @@
+char mod1_data;
+
+void
+mod1_function (void (*f) (void))
+{
+  /* Make sure this is not a tail call and unwind information is
+     therefore needed.  */
+  f ();
+  f ();
+}
diff --git a/elf/tst-dl_find_eh_frame-mod2.c b/elf/tst-dl_find_eh_frame-mod2.c
new file mode 100644
index 0000000000..7feccf9f57
--- /dev/null
+++ b/elf/tst-dl_find_eh_frame-mod2.c
@@ -0,0 +1,10 @@
+char mod2_data;
+
+void
+mod2_function (void (*f) (void))
+{
+  /* Make sure this is not a tail call and unwind information is
+     therefore needed.  */
+  f ();
+  f ();
+}
diff --git a/elf/tst-dl_find_eh_frame-mod3.c b/elf/tst-dl_find_eh_frame-mod3.c
new file mode 100644
index 0000000000..c1fc20ff9c
--- /dev/null
+++ b/elf/tst-dl_find_eh_frame-mod3.c
@@ -0,0 +1,10 @@
+char mod3_data[4096];
+
+void
+mod3_function (void (*f) (void))
+{
+  /* Make sure this is not a tail call and unwind information is
+     therefore needed.  */
+  f ();
+  f ();
+}
diff --git a/elf/tst-dl_find_eh_frame-mod4.c b/elf/tst-dl_find_eh_frame-mod4.c
new file mode 100644
index 0000000000..27934e6011
--- /dev/null
+++ b/elf/tst-dl_find_eh_frame-mod4.c
@@ -0,0 +1,10 @@
+char mod4_data;
+
+void
+mod4_function (void (*f) (void))
+{
+  /* Make sure this is not a tail call and unwind information is
+     therefore needed.  */
+  f ();
+  f ();
+}
diff --git a/elf/tst-dl_find_eh_frame-mod5.c b/elf/tst-dl_find_eh_frame-mod5.c
new file mode 100644
index 0000000000..3bdbda8ccd
--- /dev/null
+++ b/elf/tst-dl_find_eh_frame-mod5.c
@@ -0,0 +1,11 @@
+/* Slightly larger to get different layouts.  */
+char mod5_data[4096];
+
+void
+mod5_function (void (*f) (void))
+{
+  /* Make sure this is not a tail call and unwind information is
+     therefore needed.  */
+  f ();
+  f ();
+}
diff --git a/elf/tst-dl_find_eh_frame-mod6.c b/elf/tst-dl_find_eh_frame-mod6.c
new file mode 100644
index 0000000000..f78acffb9e
--- /dev/null
+++ b/elf/tst-dl_find_eh_frame-mod6.c
@@ -0,0 +1,11 @@
+/* Large to get different layouts.  */
+char mod6_data[4096];
+
+void
+mod6_function (void (*f) (void))
+{
+  /* Make sure this is not a tail call and unwind information is
+     therefore needed.  */
+  f ();
+  f ();
+}
diff --git a/elf/tst-dl_find_eh_frame-mod7.c b/elf/tst-dl_find_eh_frame-mod7.c
new file mode 100644
index 0000000000..71353880da
--- /dev/null
+++ b/elf/tst-dl_find_eh_frame-mod7.c
@@ -0,0 +1,10 @@
+char mod7_data;
+
+void
+mod7_function (void (*f) (void))
+{
+  /* Make sure this is not a tail call and unwind information is
+     therefore needed.  */
+  f ();
+  f ();
+}
diff --git a/elf/tst-dl_find_eh_frame-mod8.c b/elf/tst-dl_find_eh_frame-mod8.c
new file mode 100644
index 0000000000..41f8f1ea09
--- /dev/null
+++ b/elf/tst-dl_find_eh_frame-mod8.c
@@ -0,0 +1,10 @@
+char mod8_data;
+
+void
+mod8_function (void (*f) (void))
+{
+  /* Make sure this is not a tail call and unwind information is
+     therefore needed.  */
+  f ();
+  f ();
+}
diff --git a/elf/tst-dl_find_eh_frame-mod9.c b/elf/tst-dl_find_eh_frame-mod9.c
new file mode 100644
index 0000000000..dc2e7a20cb
--- /dev/null
+++ b/elf/tst-dl_find_eh_frame-mod9.c
@@ -0,0 +1,10 @@
+char mod9_data;
+
+void
+mod9_function (void (*f) (void))
+{
+  /* Make sure this is not a tail call and unwind information is
+     therefore needed.  */
+  f ();
+  f ();
+}
diff --git a/elf/tst-dl_find_eh_frame-threads.c b/elf/tst-dl_find_eh_frame-threads.c
new file mode 100644
index 0000000000..355241a354
--- /dev/null
+++ b/elf/tst-dl_find_eh_frame-threads.c
@@ -0,0 +1,237 @@
+/* _dl_find_eh_frame test with parallelism.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <array_length.h>
+#include <dlfcn.h>
+#include <elf/dl-find_eh_frame.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+#include <support/support.h>
+#include <support/xdlfcn.h>
+#include <support/xthread.h>
+#include <support/xunistd.h>
+
+struct find_result
+{
+  void *eh_frame;
+#if DL_FIND_EH_FRAME_DBASE
+  void *dbase;
+#endif
+};
+
+/* _dl_find_eh_frame with uniform calling convetion.  */
+static struct find_result
+find (void *pc)
+{
+  struct find_result result;
+#if DL_FIND_EH_FRAME_DBASE
+  result.eh_frame = _dl_find_eh_frame (pc, &result.dbase);
+#else
+  result.eh_frame = _dl_find_eh_frame (pc);
+#endif
+  return result;
+}
+
+/* Returns the soname for the test object NUMBER.  */
+static char *
+soname (int number)
+{
+  return xasprintf ("tst-dl_find_eh_frame-mod%d.so", number);
+}
+
+/* Returns the data symbol name for the test object NUMBER.  */
+static char *
+symbol (int number)
+{
+  return xasprintf ("mod%d_data", number);
+}
+
+struct verify_data
+{
+  char *soname;
+  struct link_map *link_map;
+  void *address;                /* Address in the shared object.  */
+  void *map_start;              /* Minimum covered address.  */
+  void *map_end;                /* Maximum covered address.  */
+  struct dl_eh_frame_info info;
+  pthread_t thr;
+};
+
+/* Compare _dl_find_eh_frame result with struct dl_eh_frame_info.  */
+static void
+check (struct find_result actual, struct verify_data *expected)
+{
+  if (actual.eh_frame != expected->info.eh_frame)
+    {
+      support_record_failure ();
+      printf ("%s: error: %s EH frame is %p, expected %p\n",
+              __FILE__, expected->soname, actual.eh_frame,
+              expected->info.eh_frame);
+    }
+  if (actual.eh_frame == NULL)
+    /* No result to check.  */
+    return;
+#if DL_FIND_EH_FRAME_DBASE
+  if (actual.dbase != expected->info.dbase)
+    {
+      support_record_failure ();
+      printf ("%s: error: %s data base is %p, expected %p\n",
+              __FILE__, expected->soname, actual.dbase, expected->info.dbase);
+    }
+#endif
+}
+
+/* Request process termination after 3 seconds.  */
+static bool exit_requested;
+static void *
+exit_thread (void *ignored)
+{
+  usleep (3 * 100 * 1000);
+  __atomic_store_n (&exit_requested, true,  __ATOMIC_RELAXED);
+  return NULL;
+}
+
+static void *
+verify_thread (void *closure)
+{
+  struct verify_data *data = closure;
+
+  while (!__atomic_load_n (&exit_requested, __ATOMIC_RELAXED))
+    {
+      check (find (data->address), data);
+      check (find (data->map_start), data);
+      check (find (data->map_end), data);
+    }
+
+  return NULL;
+}
+
+/* Sets up the verification data, dlopen'ing shared object NUMBER, and
+   launches a verification thread.  */
+static void
+start_verify (int number, struct verify_data *data)
+{
+  data->soname = soname (number);
+  data->link_map = xdlopen (data->soname, RTLD_NOW);
+  _dl_get_eh_frame (data->link_map, &data->info);
+  char *sym = symbol (number);
+  data->address = xdlsym (data->link_map, sym);
+  data->map_start = (void *) data->link_map->l_map_start;
+  data->map_end = (void *) (data->link_map->l_map_end - 1);
+  free (sym);
+  data->thr = xpthread_create (NULL, verify_thread, data);
+}
+
+
+static int
+do_test (void)
+{
+  struct verify_data data_mod2;
+  struct verify_data data_mod4;
+  struct verify_data data_mod7;
+
+  /* Load the modules with gaps.  */
+  {
+    void *mod1 = xdlopen ("tst-dl_find_eh_frame-mod1.so", RTLD_NOW);
+    start_verify (2, &data_mod2);
+    void *mod3 = xdlopen ("tst-dl_find_eh_frame-mod3.so", RTLD_NOW);
+    start_verify (4, &data_mod4);
+    void *mod5 = xdlopen ("tst-dl_find_eh_frame-mod5.so", RTLD_NOW);
+    void *mod6 = xdlopen ("tst-dl_find_eh_frame-mod6.so", RTLD_NOW);
+    start_verify (7, &data_mod7);
+    xdlclose (mod6);
+    xdlclose (mod5);
+    xdlclose (mod3);
+    xdlclose (mod1);
+  }
+
+  /* Objects that continuously opened and closed.  */
+  struct temp_object
+  {
+    char *soname;
+    char *symbol;
+    struct link_map *link_map;
+    void *address;
+    void *eh_frame;
+  } temp_objects[] =
+    {
+      { soname (1), symbol (1), },
+      { soname (3), symbol (3), },
+      { soname (5), symbol (5), },
+      { soname (6), symbol (6), },
+      { soname (8), symbol (8), },
+      { soname (9), symbol (9), },
+    };
+
+  pthread_t exit_thr = xpthread_create (NULL, exit_thread, NULL);
+
+  struct drand48_data state;
+  srand48_r (1, &state);
+  while (!__atomic_load_n (&exit_requested, __ATOMIC_RELAXED))
+    {
+      long int idx;
+      lrand48_r (&state, &idx);
+      idx %= array_length (temp_objects);
+      if (temp_objects[idx].link_map == NULL)
+        {
+          temp_objects[idx].link_map = xdlopen (temp_objects[idx].soname,
+                                                RTLD_NOW);
+          temp_objects[idx].address = xdlsym (temp_objects[idx].link_map,
+                                              temp_objects[idx].symbol);
+          temp_objects[idx].eh_frame
+            = find (temp_objects[idx].address).eh_frame;
+        }
+      else
+        {
+          xdlclose (temp_objects[idx].link_map);
+          temp_objects[idx].link_map = NULL;
+          void *eh_frame = find (temp_objects[idx].address).eh_frame;
+          if (eh_frame != NULL)
+            {
+              support_record_failure ();
+              printf ("%s: error: %s EH frame is %p after dclose, was %p\n",
+                      __FILE__, temp_objects[idx].soname, eh_frame,
+                      temp_objects[idx].eh_frame);
+            }
+        }
+    }
+
+  xpthread_join (data_mod2.thr);
+  xpthread_join (data_mod4.thr);
+  xpthread_join (data_mod7.thr);
+  xpthread_join (exit_thr);
+
+  for (size_t i = 0; i < array_length (temp_objects); ++i)
+    {
+      free (temp_objects[i].soname);
+      free (temp_objects[i].symbol);
+      if (temp_objects[i].link_map != NULL)
+        xdlclose (temp_objects[i].link_map);
+    }
+
+  free (data_mod2.soname);
+  free (data_mod4.soname);
+  xdlclose (data_mod4.link_map);
+  free (data_mod7.soname);
+  xdlclose (data_mod7.link_map);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/elf/tst-dl_find_eh_frame.c b/elf/tst-dl_find_eh_frame.c
new file mode 100644
index 0000000000..a532db6cda
--- /dev/null
+++ b/elf/tst-dl_find_eh_frame.c
@@ -0,0 +1,179 @@
+/* Basic tests for _dl_find_eh_frame.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <dl-find_eh_frame.h>
+#include <dlfcn.h>
+#include <gnu/lib-names.h>
+#include <ldsodefs.h>
+#include <link.h>
+#include <stdio.h>
+#include <support/check.h>
+#include <support/xdlfcn.h>
+
+/* Use data objects for testing, so that it is not necessary to decode
+   function descriptors on architectures that have them.  */
+static char main_program_data;
+
+struct find_result
+{
+  void *eh_frame;
+#if DL_FIND_EH_FRAME_DBASE
+  void *dbase;
+#endif
+};
+
+/* _dl_find_eh_frame with uniform calling convetion.  */
+static struct find_result
+find (void *pc)
+{
+  struct find_result result;
+#if DL_FIND_EH_FRAME_DBASE
+  result.eh_frame = _dl_find_eh_frame (pc, &result.dbase);
+#else
+  result.eh_frame = _dl_find_eh_frame (pc);
+#endif
+  return result;
+}
+
+/* Compare _dl_find_eh_frame result with struct dl_eh_frame_info.  */
+static void
+check (struct find_result actual, struct dl_eh_frame_info expected, int line)
+{
+  if (actual.eh_frame != expected.eh_frame)
+    {
+      support_record_failure ();
+      printf ("%s:%d: error: EH frame is %p, expected %p\n",
+              __FILE__, line, actual.eh_frame, expected.eh_frame);
+    }
+  if (actual.eh_frame == NULL)
+    /* No result to check.  */
+    return;
+#if DL_FIND_EH_FRAME_DBASE
+  if (actual.dbase != expected.dbase)
+    {
+      support_record_failure ();
+      printf ("%s:%d: error: data base is %p, expected %p\n",
+              __FILE__, line, actual.dbase, expected.dbase);
+    }
+#endif
+}
+
+/* Check that unwind data for the main executable and the dynamic
+   linker can be found.  */
+static void
+check_initial (void)
+{
+  /* Avoid direct reference, which could lead to copy relocations.  */
+  struct r_debug *debug = xdlsym (NULL, "_r_debug");
+  TEST_VERIFY_EXIT (debug != NULL);
+  char **tzname = xdlsym (NULL, "tzname");
+
+  /* The main executable has an unnamed link map.  */
+  struct link_map *main_map = (struct link_map *) debug->r_map;
+  TEST_COMPARE_STRING (main_map->l_name, "");
+
+  /* The link map of the dynamic linker.  */
+  struct link_map *rtld_map = xdlopen (LD_SO, RTLD_LAZY | RTLD_NOLOAD);
+  TEST_VERIFY_EXIT (rtld_map != NULL);
+
+  /* The link map of libc.so.  */
+  struct link_map *libc_map = xdlopen (LIBC_SO, RTLD_LAZY | RTLD_NOLOAD);
+  TEST_VERIFY_EXIT (libc_map != NULL);
+
+  struct dl_eh_frame_info expected;
+
+  /* Data in the main program.  */
+  _dl_get_eh_frame (main_map, &expected);
+  check (find (&main_program_data), expected, __LINE__);
+  /* Corner cases for the mapping.  */
+  check (find ((void *) main_map->l_map_start), expected, __LINE__);
+  check (find ((void *) (main_map->l_map_end - 1)), expected, __LINE__);
+
+  /* Data in the dynamic loader.  */
+  _dl_get_eh_frame (rtld_map, &expected);
+  check (find (debug), expected, __LINE__);
+  check (find ((void *) rtld_map->l_map_start), expected, __LINE__);
+  check (find ((void *) (rtld_map->l_map_end - 1)), expected, __LINE__);
+
+  /* Data in libc.  */
+  _dl_get_eh_frame (libc_map, &expected);
+  check (find (tzname), expected, __LINE__);
+  check (find ((void *) libc_map->l_map_start), expected, __LINE__);
+  check (find ((void *) (libc_map->l_map_end - 1)), expected, __LINE__);
+}
+
+static int
+do_test (void)
+{
+  printf ("info: main program unwind data: %p\n",
+          find (&main_program_data).eh_frame);
+
+  check_initial ();
+
+  /* dlopen-based test.  First an object that can be dlclosed.  */
+  struct link_map *mod1 = xdlopen ("tst-dl_find_eh_frame-mod1.so", RTLD_NOW);
+  void *mod1_data = xdlsym (mod1, "mod1_data");
+  void *map_start = (void *) mod1->l_map_start;
+  void *map_end = (void *) (mod1->l_map_end - 1);
+  check_initial ();
+
+  struct dl_eh_frame_info expected;
+  _dl_get_eh_frame (mod1, &expected);
+  check (find (mod1_data), expected, __LINE__);
+  check (find (map_start), expected, __LINE__);
+  check (find (map_end), expected, __LINE__);
+
+  /* Unloading must make the unwinding data unavailable.  */
+  xdlclose (mod1);
+  check_initial ();
+  expected.eh_frame = NULL;
+  check (find (mod1_data), expected, __LINE__);
+  check (find (map_start), expected, __LINE__);
+  check (find (map_end), expected, __LINE__);
+
+  /* Now try a NODELETE load.  */
+  struct link_map *mod2 = xdlopen ("tst-dl_find_eh_frame-mod2.so", RTLD_NOW);
+  void *mod2_data = xdlsym (mod1, "mod2_data");
+  map_start = (void *) mod2->l_map_start;
+  map_end = (void *) (mod2->l_map_end - 1);
+  check_initial ();
+  _dl_get_eh_frame (mod2, &expected);
+  check (find (mod2_data), expected, __LINE__);
+  check (find (map_start), expected, __LINE__);
+  check (find (map_end), expected, __LINE__);
+  dlclose (mod2);               /* Does nothing due to NODELETE.  */
+  check_initial ();
+  check (find (mod2_data), expected, __LINE__);
+  check (find (map_start), expected, __LINE__);
+  check (find (map_end), expected, __LINE__);
+
+  /* Now load again the first module.  */
+  mod1 = xdlopen ("tst-dl_find_eh_frame-mod1.so", RTLD_NOW);
+  mod1_data = xdlsym (mod1, "mod1_data");
+  map_start = (void *) mod1->l_map_start;
+  map_end = (void *) (mod1->l_map_end - 1);
+  check_initial ();
+  _dl_get_eh_frame (mod1, &expected);
+  check (find (mod1_data), expected, __LINE__);
+  check (find (map_start), expected, __LINE__);
+  check (find (map_end), expected, __LINE__);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/include/atomic_wide_counter.h b/include/atomic_wide_counter.h
index 31f009d5e6..d1c40cd85f 100644
--- a/include/atomic_wide_counter.h
+++ b/include/atomic_wide_counter.h
@@ -30,6 +30,12 @@ __atomic_wide_counter_load_relaxed (__atomic_wide_counter *c)
   return atomic_load_relaxed (&c->__value64);
 }
 
+static inline uint64_t
+__atomic_wide_counter_load_acquire (__atomic_wide_counter *c)
+{
+  return atomic_load_acquire (&c->__value64);
+}
+
 static inline uint64_t
 __atomic_wide_counter_fetch_add_relaxed (__atomic_wide_counter *c,
                                          unsigned int val)
@@ -64,6 +70,14 @@ __atomic_wide_counter_fetch_xor_release (__atomic_wide_counter *c,
 uint64_t __atomic_wide_counter_load_relaxed (__atomic_wide_counter *c)
   attribute_hidden;
 
+static inline uint64_t
+__atomic_wide_counter_load_acquire (__atomic_wide_counter *c)
+{
+  uint64_t r = __atomic_wide_counter_load_relaxed (c);
+  atomic_thread_fence_acquire ();
+  return r;
+}
+
 uint64_t __atomic_wide_counter_fetch_add_relaxed (__atomic_wide_counter *c,
                                                   unsigned int op)
   attribute_hidden;
diff --git a/include/bits/dlfcn_eh_frame.h b/include/bits/dlfcn_eh_frame.h
new file mode 100644
index 0000000000..3f694c45bc
--- /dev/null
+++ b/include/bits/dlfcn_eh_frame.h
@@ -0,0 +1 @@
+#include_next <bits/dlfcn_eh_frame.h>
diff --git a/include/link.h b/include/link.h
index c1c382ccfa..fa2ecc2f4a 100644
--- a/include/link.h
+++ b/include/link.h
@@ -211,6 +211,9 @@ struct link_map
 				       freed, ie. not allocated with
 				       the dummy malloc in ld.so.  */
     unsigned int l_ld_readonly:1; /* Nonzero if dynamic section is readonly.  */
+    unsigned int l_eh_frame_processed:1; /* Zero if _dl_eh_frame_update
+					    needs to process this
+					    lt_library map.  */
 
     /* NODELETE status of the map.  Only valid for maps of type
        lt_loaded.  Lazy binding sets l_nodelete_active directly,
diff --git a/manual/Makefile b/manual/Makefile
index e83444341e..31678681ef 100644
--- a/manual/Makefile
+++ b/manual/Makefile
@@ -39,7 +39,7 @@ chapters = $(addsuffix .texi, \
 		       pipe socket terminal syslog math arith time	\
 		       resource setjmp signal startup process ipc job	\
 		       nss users sysinfo conf crypt debug threads	\
-		       probes tunables)
+		       dynlink probes tunables)
 appendices = lang.texi header.texi install.texi maint.texi platform.texi \
 	     contrib.texi
 licenses = freemanuals.texi lgpl-2.1.texi fdl-1.3.texi
diff --git a/manual/dynlink.texi b/manual/dynlink.texi
new file mode 100644
index 0000000000..8969a8029d
--- /dev/null
+++ b/manual/dynlink.texi
@@ -0,0 +1,69 @@
+@node Dynamic Linker
+@c @node Dynamic Linker, Internal Probes, Threads, Top
+@c %MENU% Loading programs and shared objects.
+@chapter Dynamic Linker
+@cindex dynamic linker
+@cindex dynamic loader
+
+The @dfn{dynamic linker} is responsible for loading dynamically linked
+programs and their dependencies (in the form of shared objects).  The
+dynamic linker in @theglibc{} also supports loading shared objects (such
+as plugins) later at run time.
+
+Dynamic linkers are sometimes called @dfn{dynamic loaders}.
+
+@menu
+* Dynamic Linker Introspection::    Interfaces for querying mapping information.
+@end menu
+
+@node Dynamic Linker Introspection
+@section Dynamic Linker Introspection
+
+@Theglibc{} provides various functions for querying information from the
+dynamic linker.
+
+@deftypefun {void *} _dl_find_eh_frame (void *@var{pc})
+@standards{GNU, dlfcn.h}
+@safety{@mtsafe{}@assafe{}@acsafe{}}
+This function returns a pointer to the unwinding information for the
+object that contains the program coder @var{pc}.  If the platform uses
+DWARF unwinding information, this is the in-memory address of the
+@code{PT_GNU_EH_FRAME} segment.
+
+In case @var{pc} resides in an object that lacks unwinding information,
+the function returns @code{NULL}.  If no object matches @var{pc},
+@code{NULL} is returned as well.
+
+@code{_dl_find_eh_frame} itself is thread-safe.  However, if the
+application invokes @code{dlclose} for the object that contains @var{pc}
+concurrently with @code{_dl_find_eh_frame} or after the call returns,
+accessing the unwinding data for that object is not safe.  Therefore,
+the application needs to ensure by other means (e.g., by convention)
+that @var{pc} remains a valid code address while the unwinding
+information is processed.
+
+This function is a GNU extension.
+@end deftypefun
+
+@deftypevr Macro int DL_FIND_EH_FRAME_DBASE
+@standards{GNU, dlfcn.h}
+On most targets, this macro is defined as @code{0}.  If it is defined to
+@code{1}, the @code{_dl_find_eh_frame} function expects a second
+argument of type @code{void **}.  In this case, a pointer to a
+@code{void *} object must be passed, and if @code{_dl_find_eh_frame}
+finds any unwinding information, it writes the base address for
+@code{DW_EH_PE_datarel} DWARF encodings to this location.
+
+This macro is a GNU extension.
+@end deftypevr
+
+@c FIXME these are undocumented:
+@c dladdr
+@c dladdr1
+@c dlclose
+@c dlerror
+@c dlinfo
+@c dlmopen
+@c dlopen
+@c dlsym
+@c dlvsym
diff --git a/manual/libdl.texi b/manual/libdl.texi
deleted file mode 100644
index e3fe0452d9..0000000000
--- a/manual/libdl.texi
+++ /dev/null
@@ -1,10 +0,0 @@
-@c FIXME these are undocumented:
-@c dladdr
-@c dladdr1
-@c dlclose
-@c dlerror
-@c dlinfo
-@c dlmopen
-@c dlopen
-@c dlsym
-@c dlvsym
diff --git a/manual/probes.texi b/manual/probes.texi
index 4aae76b819..ee019e6517 100644
--- a/manual/probes.texi
+++ b/manual/probes.texi
@@ -1,5 +1,5 @@
 @node Internal Probes
-@c @node Internal Probes, Tunables, Threads, Top
+@c @node Internal Probes, Tunables, Dynamic Linker, Top
 @c %MENU% Probes to monitor libc internal behavior
 @chapter Internal probes
 
diff --git a/manual/threads.texi b/manual/threads.texi
index 06b6b277a1..7f166bfa87 100644
--- a/manual/threads.texi
+++ b/manual/threads.texi
@@ -1,5 +1,5 @@
 @node Threads
-@c @node Threads, Internal Probes, Debugging Support, Top
+@c @node Threads, Dynamic Linker, Debugging Support, Top
 @c %MENU% Functions, constants, and data types for working with threads
 @chapter Threads
 @cindex threads
diff --git a/sysdeps/i386/bits/dlfcn_eh_frame.h b/sysdeps/i386/bits/dlfcn_eh_frame.h
new file mode 100644
index 0000000000..98f6b37029
--- /dev/null
+++ b/sysdeps/i386/bits/dlfcn_eh_frame.h
@@ -0,0 +1,34 @@
+/* i386 definitions for find unwind information using ld.so.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _DLFCN_H
+# error "Never use <bits/dlfcn_eh_frame.h> directly; include <dlfcn.h> instead."
+#endif
+
+/* This implementation uses a DBASE pointer argument in
+   _dl_find_eh_frame.  */
+#define DL_FIND_EH_FRAME_DBASE 1
+
+__BEGIN_DECLS
+/* If PC points into an object that has a PT_GNU_EH_FRAME segment,
+   return the pointer to the start of that segment in memory, and
+   *DBASE is updated with the base address for DW_EH_PE_datarel DWARF
+   encodings.  If no corresponding object exists or the object has no
+   such segment, returns NULL.  */
+void *_dl_find_eh_frame (void *__pc, void **__dbase) __THROW __nonnull ((2));
+__END_DECLS
diff --git a/sysdeps/mach/hurd/i386/ld.abilist b/sysdeps/mach/hurd/i386/ld.abilist
index 7e20c5e7ce..786cd93810 100644
--- a/sysdeps/mach/hurd/i386/ld.abilist
+++ b/sysdeps/mach/hurd/i386/ld.abilist
@@ -16,3 +16,4 @@ GLIBC_2.2.6 _r_debug D 0x14
 GLIBC_2.2.6 abort F
 GLIBC_2.3 ___tls_get_addr F
 GLIBC_2.3 __tls_get_addr F
+GLIBC_2.35 _dl_find_eh_frame F
diff --git a/sysdeps/nios2/bits/dlfcn_eh_frame.h b/sysdeps/nios2/bits/dlfcn_eh_frame.h
new file mode 100644
index 0000000000..3acc741c6e
--- /dev/null
+++ b/sysdeps/nios2/bits/dlfcn_eh_frame.h
@@ -0,0 +1,34 @@
+/* nios2 definitions for find unwind information using ld.so.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _DLFCN_H
+# error "Never use <bits/dlfcn_eh_frame.h> directly; include <dlfcn.h> instead."
+#endif
+
+/* This implementation uses a DBASE pointer argument in
+   _dl_find_eh_frame.  */
+#define DL_FIND_EH_FRAME_DBASE 1
+
+__BEGIN_DECLS
+/* If PC points into an object that has a PT_GNU_EH_FRAME segment,
+   return the pointer to the start of that segment in memory, and
+   *DBASE is updated with the base address for DW_EH_PE_datarel DWARF
+   encodings.  If no corresponding object exists or the object has no
+   such segment, returns NULL.  */
+void *_dl_find_eh_frame (void *__pc, void **__dbase) __THROW __nonnull ((2));
+__END_DECLS
diff --git a/sysdeps/unix/sysv/linux/aarch64/ld.abilist b/sysdeps/unix/sysv/linux/aarch64/ld.abilist
index 80b2fe6725..4655d8d00f 100644
--- a/sysdeps/unix/sysv/linux/aarch64/ld.abilist
+++ b/sysdeps/unix/sysv/linux/aarch64/ld.abilist
@@ -3,3 +3,4 @@ GLIBC_2.17 __stack_chk_guard D 0x8
 GLIBC_2.17 __tls_get_addr F
 GLIBC_2.17 _dl_mcount F
 GLIBC_2.17 _r_debug D 0x28
+GLIBC_2.35 _dl_find_eh_frame F
diff --git a/sysdeps/unix/sysv/linux/alpha/ld.abilist b/sysdeps/unix/sysv/linux/alpha/ld.abilist
index 98a03f611f..21f873600a 100644
--- a/sysdeps/unix/sysv/linux/alpha/ld.abilist
+++ b/sysdeps/unix/sysv/linux/alpha/ld.abilist
@@ -2,4 +2,5 @@ GLIBC_2.0 _r_debug D 0x28
 GLIBC_2.1 __libc_stack_end D 0x8
 GLIBC_2.1 _dl_mcount F
 GLIBC_2.3 __tls_get_addr F
+GLIBC_2.35 _dl_find_eh_frame F
 GLIBC_2.4 __stack_chk_guard D 0x8
diff --git a/sysdeps/unix/sysv/linux/arc/ld.abilist b/sysdeps/unix/sysv/linux/arc/ld.abilist
index 048f17c848..b1b719ca61 100644
--- a/sysdeps/unix/sysv/linux/arc/ld.abilist
+++ b/sysdeps/unix/sysv/linux/arc/ld.abilist
@@ -3,3 +3,4 @@ GLIBC_2.32 __stack_chk_guard D 0x4
 GLIBC_2.32 __tls_get_addr F
 GLIBC_2.32 _dl_mcount F
 GLIBC_2.32 _r_debug D 0x14
+GLIBC_2.35 _dl_find_eh_frame F
diff --git a/sysdeps/unix/sysv/linux/arm/be/ld.abilist b/sysdeps/unix/sysv/linux/arm/be/ld.abilist
index cc8825c3bc..973f414c35 100644
--- a/sysdeps/unix/sysv/linux/arm/be/ld.abilist
+++ b/sysdeps/unix/sysv/linux/arm/be/ld.abilist
@@ -1,3 +1,4 @@
+GLIBC_2.35 _dl_find_eh_frame F
 GLIBC_2.4 __libc_stack_end D 0x4
 GLIBC_2.4 __stack_chk_guard D 0x4
 GLIBC_2.4 __tls_get_addr F
diff --git a/sysdeps/unix/sysv/linux/arm/le/ld.abilist b/sysdeps/unix/sysv/linux/arm/le/ld.abilist
index cc8825c3bc..973f414c35 100644
--- a/sysdeps/unix/sysv/linux/arm/le/ld.abilist
+++ b/sysdeps/unix/sysv/linux/arm/le/ld.abilist
@@ -1,3 +1,4 @@
+GLIBC_2.35 _dl_find_eh_frame F
 GLIBC_2.4 __libc_stack_end D 0x4
 GLIBC_2.4 __stack_chk_guard D 0x4
 GLIBC_2.4 __tls_get_addr F
diff --git a/sysdeps/unix/sysv/linux/csky/ld.abilist b/sysdeps/unix/sysv/linux/csky/ld.abilist
index 564ac09737..bba19877b0 100644
--- a/sysdeps/unix/sysv/linux/csky/ld.abilist
+++ b/sysdeps/unix/sysv/linux/csky/ld.abilist
@@ -3,3 +3,4 @@ GLIBC_2.29 __stack_chk_guard D 0x4
 GLIBC_2.29 __tls_get_addr F
 GLIBC_2.29 _dl_mcount F
 GLIBC_2.29 _r_debug D 0x14
+GLIBC_2.35 _dl_find_eh_frame F
diff --git a/sysdeps/unix/sysv/linux/hppa/ld.abilist b/sysdeps/unix/sysv/linux/hppa/ld.abilist
index d155a59843..dcee0ece2a 100644
--- a/sysdeps/unix/sysv/linux/hppa/ld.abilist
+++ b/sysdeps/unix/sysv/linux/hppa/ld.abilist
@@ -2,4 +2,5 @@ GLIBC_2.2 __libc_stack_end D 0x4
 GLIBC_2.2 _dl_mcount F
 GLIBC_2.2 _r_debug D 0x14
 GLIBC_2.3 __tls_get_addr F
+GLIBC_2.35 _dl_find_eh_frame F
 GLIBC_2.4 __stack_chk_guard D 0x4
diff --git a/sysdeps/unix/sysv/linux/i386/ld.abilist b/sysdeps/unix/sysv/linux/i386/ld.abilist
index 0478e22071..0c4c02d18e 100644
--- a/sysdeps/unix/sysv/linux/i386/ld.abilist
+++ b/sysdeps/unix/sysv/linux/i386/ld.abilist
@@ -3,3 +3,4 @@ GLIBC_2.1 __libc_stack_end D 0x4
 GLIBC_2.1 _dl_mcount F
 GLIBC_2.3 ___tls_get_addr F
 GLIBC_2.3 __tls_get_addr F
+GLIBC_2.35 _dl_find_eh_frame F
diff --git a/sysdeps/unix/sysv/linux/ia64/ld.abilist b/sysdeps/unix/sysv/linux/ia64/ld.abilist
index 33f91199bf..6ae0cb97b4 100644
--- a/sysdeps/unix/sysv/linux/ia64/ld.abilist
+++ b/sysdeps/unix/sysv/linux/ia64/ld.abilist
@@ -2,3 +2,4 @@ GLIBC_2.2 __libc_stack_end D 0x8
 GLIBC_2.2 _dl_mcount F
 GLIBC_2.2 _r_debug D 0x28
 GLIBC_2.3 __tls_get_addr F
+GLIBC_2.35 _dl_find_eh_frame F
diff --git a/sysdeps/unix/sysv/linux/m68k/coldfire/ld.abilist b/sysdeps/unix/sysv/linux/m68k/coldfire/ld.abilist
index cc8825c3bc..973f414c35 100644
--- a/sysdeps/unix/sysv/linux/m68k/coldfire/ld.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/coldfire/ld.abilist
@@ -1,3 +1,4 @@
+GLIBC_2.35 _dl_find_eh_frame F
 GLIBC_2.4 __libc_stack_end D 0x4
 GLIBC_2.4 __stack_chk_guard D 0x4
 GLIBC_2.4 __tls_get_addr F
diff --git a/sysdeps/unix/sysv/linux/m68k/m680x0/ld.abilist b/sysdeps/unix/sysv/linux/m68k/m680x0/ld.abilist
index 3ba474c27f..1719c1bff0 100644
--- a/sysdeps/unix/sysv/linux/m68k/m680x0/ld.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/m680x0/ld.abilist
@@ -2,4 +2,5 @@ GLIBC_2.0 _r_debug D 0x14
 GLIBC_2.1 __libc_stack_end D 0x4
 GLIBC_2.1 _dl_mcount F
 GLIBC_2.3 __tls_get_addr F
+GLIBC_2.35 _dl_find_eh_frame F
 GLIBC_2.4 __stack_chk_guard D 0x4
diff --git a/sysdeps/unix/sysv/linux/microblaze/ld.abilist b/sysdeps/unix/sysv/linux/microblaze/ld.abilist
index a4933c3541..b915864bd6 100644
--- a/sysdeps/unix/sysv/linux/microblaze/ld.abilist
+++ b/sysdeps/unix/sysv/linux/microblaze/ld.abilist
@@ -3,3 +3,4 @@ GLIBC_2.18 __stack_chk_guard D 0x4
 GLIBC_2.18 __tls_get_addr F
 GLIBC_2.18 _dl_mcount F
 GLIBC_2.18 _r_debug D 0x14
+GLIBC_2.35 _dl_find_eh_frame F
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/ld.abilist b/sysdeps/unix/sysv/linux/mips/mips32/ld.abilist
index be09641a48..6f85418bc8 100644
--- a/sysdeps/unix/sysv/linux/mips/mips32/ld.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips32/ld.abilist
@@ -2,4 +2,5 @@ GLIBC_2.0 _r_debug D 0x14
 GLIBC_2.2 __libc_stack_end D 0x4
 GLIBC_2.2 _dl_mcount F
 GLIBC_2.3 __tls_get_addr F
+GLIBC_2.35 _dl_find_eh_frame F
 GLIBC_2.4 __stack_chk_guard D 0x4
diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n32/ld.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n32/ld.abilist
index be09641a48..6f85418bc8 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/n32/ld.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/n32/ld.abilist
@@ -2,4 +2,5 @@ GLIBC_2.0 _r_debug D 0x14
 GLIBC_2.2 __libc_stack_end D 0x4
 GLIBC_2.2 _dl_mcount F
 GLIBC_2.3 __tls_get_addr F
+GLIBC_2.35 _dl_find_eh_frame F
 GLIBC_2.4 __stack_chk_guard D 0x4
diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n64/ld.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n64/ld.abilist
index 1ea36e13f2..b2621aad3b 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/n64/ld.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/n64/ld.abilist
@@ -2,4 +2,5 @@ GLIBC_2.0 _r_debug D 0x28
 GLIBC_2.2 __libc_stack_end D 0x8
 GLIBC_2.2 _dl_mcount F
 GLIBC_2.3 __tls_get_addr F
+GLIBC_2.35 _dl_find_eh_frame F
 GLIBC_2.4 __stack_chk_guard D 0x8
diff --git a/sysdeps/unix/sysv/linux/nios2/ld.abilist b/sysdeps/unix/sysv/linux/nios2/ld.abilist
index 52178802dd..7a8bd00445 100644
--- a/sysdeps/unix/sysv/linux/nios2/ld.abilist
+++ b/sysdeps/unix/sysv/linux/nios2/ld.abilist
@@ -3,3 +3,4 @@ GLIBC_2.21 __stack_chk_guard D 0x4
 GLIBC_2.21 __tls_get_addr F
 GLIBC_2.21 _dl_mcount F
 GLIBC_2.21 _r_debug D 0x14
+GLIBC_2.35 _dl_find_eh_frame F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/ld.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/ld.abilist
index 4bbfba7a61..f3a533cbdb 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/ld.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/ld.abilist
@@ -4,3 +4,4 @@ GLIBC_2.1 _dl_mcount F
 GLIBC_2.22 __tls_get_addr_opt F
 GLIBC_2.23 __parse_hwcap_and_convert_at_platform F
 GLIBC_2.3 __tls_get_addr F
+GLIBC_2.35 _dl_find_eh_frame F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/ld.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/ld.abilist
index 283fb4510b..63ab18b70f 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/ld.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/ld.abilist
@@ -4,3 +4,4 @@ GLIBC_2.3 __libc_stack_end D 0x8
 GLIBC_2.3 __tls_get_addr F
 GLIBC_2.3 _dl_mcount F
 GLIBC_2.3 _r_debug D 0x28
+GLIBC_2.35 _dl_find_eh_frame F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/ld.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/ld.abilist
index b1f313c7cd..1fec480d9d 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/ld.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/ld.abilist
@@ -4,3 +4,4 @@ GLIBC_2.17 _dl_mcount F
 GLIBC_2.17 _r_debug D 0x28
 GLIBC_2.22 __tls_get_addr_opt F
 GLIBC_2.23 __parse_hwcap_and_convert_at_platform F
+GLIBC_2.35 _dl_find_eh_frame F
diff --git a/sysdeps/unix/sysv/linux/riscv/rv32/ld.abilist b/sysdeps/unix/sysv/linux/riscv/rv32/ld.abilist
index 94ca64c43d..7cec190630 100644
--- a/sysdeps/unix/sysv/linux/riscv/rv32/ld.abilist
+++ b/sysdeps/unix/sysv/linux/riscv/rv32/ld.abilist
@@ -3,3 +3,4 @@ GLIBC_2.33 __stack_chk_guard D 0x4
 GLIBC_2.33 __tls_get_addr F
 GLIBC_2.33 _dl_mcount F
 GLIBC_2.33 _r_debug D 0x14
+GLIBC_2.35 _dl_find_eh_frame F
diff --git a/sysdeps/unix/sysv/linux/riscv/rv64/ld.abilist b/sysdeps/unix/sysv/linux/riscv/rv64/ld.abilist
index 845f356c3c..81795b588d 100644
--- a/sysdeps/unix/sysv/linux/riscv/rv64/ld.abilist
+++ b/sysdeps/unix/sysv/linux/riscv/rv64/ld.abilist
@@ -3,3 +3,4 @@ GLIBC_2.27 __stack_chk_guard D 0x8
 GLIBC_2.27 __tls_get_addr F
 GLIBC_2.27 _dl_mcount F
 GLIBC_2.27 _r_debug D 0x28
+GLIBC_2.35 _dl_find_eh_frame F
diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/ld.abilist b/sysdeps/unix/sysv/linux/s390/s390-32/ld.abilist
index b56f005beb..34d9165bdb 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-32/ld.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-32/ld.abilist
@@ -2,3 +2,4 @@ GLIBC_2.0 _r_debug D 0x14
 GLIBC_2.1 __libc_stack_end D 0x4
 GLIBC_2.1 _dl_mcount F
 GLIBC_2.3 __tls_get_offset F
+GLIBC_2.35 _dl_find_eh_frame F
diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/ld.abilist b/sysdeps/unix/sysv/linux/s390/s390-64/ld.abilist
index 6f788a086d..1175537ca3 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-64/ld.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-64/ld.abilist
@@ -2,3 +2,4 @@ GLIBC_2.2 __libc_stack_end D 0x8
 GLIBC_2.2 _dl_mcount F
 GLIBC_2.2 _r_debug D 0x28
 GLIBC_2.3 __tls_get_offset F
+GLIBC_2.35 _dl_find_eh_frame F
diff --git a/sysdeps/unix/sysv/linux/sh/be/ld.abilist b/sysdeps/unix/sysv/linux/sh/be/ld.abilist
index d155a59843..dcee0ece2a 100644
--- a/sysdeps/unix/sysv/linux/sh/be/ld.abilist
+++ b/sysdeps/unix/sysv/linux/sh/be/ld.abilist
@@ -2,4 +2,5 @@ GLIBC_2.2 __libc_stack_end D 0x4
 GLIBC_2.2 _dl_mcount F
 GLIBC_2.2 _r_debug D 0x14
 GLIBC_2.3 __tls_get_addr F
+GLIBC_2.35 _dl_find_eh_frame F
 GLIBC_2.4 __stack_chk_guard D 0x4
diff --git a/sysdeps/unix/sysv/linux/sh/le/ld.abilist b/sysdeps/unix/sysv/linux/sh/le/ld.abilist
index d155a59843..dcee0ece2a 100644
--- a/sysdeps/unix/sysv/linux/sh/le/ld.abilist
+++ b/sysdeps/unix/sysv/linux/sh/le/ld.abilist
@@ -2,4 +2,5 @@ GLIBC_2.2 __libc_stack_end D 0x4
 GLIBC_2.2 _dl_mcount F
 GLIBC_2.2 _r_debug D 0x14
 GLIBC_2.3 __tls_get_addr F
+GLIBC_2.35 _dl_find_eh_frame F
 GLIBC_2.4 __stack_chk_guard D 0x4
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/ld.abilist b/sysdeps/unix/sysv/linux/sparc/sparc32/ld.abilist
index 0c6610e3c2..21bd7308c0 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc32/ld.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc32/ld.abilist
@@ -2,3 +2,4 @@ GLIBC_2.0 _r_debug D 0x14
 GLIBC_2.1 __libc_stack_end D 0x4
 GLIBC_2.1 _dl_mcount F
 GLIBC_2.3 __tls_get_addr F
+GLIBC_2.35 _dl_find_eh_frame F
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/ld.abilist b/sysdeps/unix/sysv/linux/sparc/sparc64/ld.abilist
index 33f91199bf..6ae0cb97b4 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc64/ld.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc64/ld.abilist
@@ -2,3 +2,4 @@ GLIBC_2.2 __libc_stack_end D 0x8
 GLIBC_2.2 _dl_mcount F
 GLIBC_2.2 _r_debug D 0x28
 GLIBC_2.3 __tls_get_addr F
+GLIBC_2.35 _dl_find_eh_frame F
diff --git a/sysdeps/unix/sysv/linux/x86_64/64/ld.abilist b/sysdeps/unix/sysv/linux/x86_64/64/ld.abilist
index d3cdf7611e..8a8a9e4bb3 100644
--- a/sysdeps/unix/sysv/linux/x86_64/64/ld.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/64/ld.abilist
@@ -2,3 +2,4 @@ GLIBC_2.2.5 __libc_stack_end D 0x8
 GLIBC_2.2.5 _dl_mcount F
 GLIBC_2.2.5 _r_debug D 0x28
 GLIBC_2.3 __tls_get_addr F
+GLIBC_2.35 _dl_find_eh_frame F
diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/ld.abilist b/sysdeps/unix/sysv/linux/x86_64/x32/ld.abilist
index c70bccf782..99bd4f5197 100644
--- a/sysdeps/unix/sysv/linux/x86_64/x32/ld.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/x32/ld.abilist
@@ -2,3 +2,4 @@ GLIBC_2.16 __libc_stack_end D 0x4
 GLIBC_2.16 __tls_get_addr F
 GLIBC_2.16 _dl_mcount F
 GLIBC_2.16 _r_debug D 0x14
+GLIBC_2.35 _dl_find_eh_frame F
-- 
2.31.1



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