Re: Use dl_iterate_phdr in Solaris 11+ unwinder

[Rainer Orth <ro at CeBiTec dot Uni-Bielefeld dot DE>]

"Joseph S. Myers" <joseph@codesourcery.com> writes:

> On Mon, 29 Nov 2010, Rainer Orth wrote:
>
>> diff -r 523125a49e71 gcc/configure.ac
>> --- a/gcc/configure.ac	Sat Nov 27 11:35:42 2010 +0100
>> +++ b/gcc/configure.ac	Mon Nov 29 11:05:51 2010 +0100
>> @@ -977,6 +977,9 @@
>>  	gettimeofday mbstowcs wcswidth mmap mincore setlocale \
>>  	gcc_UNLOCKED_FUNCS)
>>  
>> +# Check for dl_iterate_phdr.
>> +AC_CHECK_FUNCS(dl_iterate_phdr, [have_dl_iterate_phdr=yes])
>
> This is wrong; it's checking for dl_iterate_phdr on the host rather than 
> the target.  You can't do target link tests at this point, but you can 
> examine target headers to determine whether they declare something.  See 
> the logic used by some configure tests to determine glibc_header_dir - 
> since that is actually generic logic for locating target headers and has 
> nothing to do with glibc, it should probably be refactored into a single 
> place.

Thanks for the hint.  I've actually moved the logic up, noticing that
the two versions already diverged slightly (the first took $with_headers
into account, the second did not), and renamed the variable to
target_header_dir to reflect its real meaning.

Here's the updated (and close-to-final) version of the patch.  It
removes all the workarounds for linker bugs, takes your comment into
account, and splits the test for dl_iterate_phdr into two: first check
for a linker which properly supports .eh_frame_hdr, then check for
dl_iterate_phdr in the target libc.

HAVE_LD_EH_FRAME_HDR is more generic now: with GNU ld, it means the
linker understands --eh-frame-hdr (and needs it to create .eh_frame_hdr
sections), with other linkers (Solaris ld only so far) it means the
linker can properly create .eh_frame_hdr sections by whatever means
(none on Solaris, this happens automatically).

I'm now doing away with the separate config/t-sol2-eh since I noticed
that unwind-dw2-fde-glibc.c falls back to use the unwind-dw2-fde.c
unwinder if dl_iterate_phdr is missing, so the same version of LIB2ADDEH
can be used with and without that function.

Solaris 11 <link.h> now works in a largefile environment, so the
previous workaround to redefine _FILE_OFFSET_BITS is gone and replaced
with a configure check for the fixed header file.

With the exception of part of the configure.ac changes, the patch is
completely target specific now, and I think it's safe enough to go in
even in stage3.

I've tested the patch on i386-pc-solaris2.11 with as and gas 2.21 and a
fixed Sun linker, and also with gas and gld 2.21, without regressions.
To make sure unwind-dw2-fde-glibc.c also works with parts of the
dl_iterate_phdr support missing (fixed linker and <link.h> in this
case), I've rebootstrapped with the linker etc. fixes removed, also
without regressions.

I'm now only waiting for a version of Sun ld on SPARC that creates
non-empty search tables in .eh_frame_hdr.  Once that is tested as well,
I plan to commit the patch (provided there are no issues with the build
changes) unless there are strong objections.

Thanks.
	Rainer


2010-01-18  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>

	* configure.ac (gcc_cv_ld_eh_frame_hdr): Only check GNU ld for
	--eh-frame-hdr.
	Check for working Sun ld version.
	(HAVE_LD_EH_FRAME_HDR): Adapt comment.
	(glibc_header_dir): Set only once.
	Rename to ...
	(target_header_dir): ... this.
	Adapt users.
	(gcc_cv_target_dl_iterate_frame_hdr): Check on *-*-solaris2*.
	(TARGET_DL_ITERATE_PHDR): Define if present.
	* configure: Regenerate.
	* config.in: Likewise.
	* config/t-sol2 (LIB2ADDEH, LIB2ADDEHDEP): Define.
	* crtstuff.c (USE_PT_GNU_EH_FRAME): Define for recent Solaris 11
	with linker support and dl_iterate_phdr.
	* unwind-dw2-fde-glibc.c (USE_PT_GNU_EH_FRAME): Likewise.
	(_Unwind_IteratePhdrCallback) [PT_SUNW_UNWIND]: Also accept
	PT_SUNW_UNWIND .eh_frame_hdr sections.
	[CRT_GET_RFIB_DATA && __i386__ && __sun__ && __svr4__]: Add
	load_base to data->dbase.
	[CRT_GET_RFIB_DATA && __x86_64__ && __sun__ && __svr4__]: Handle
	64-bit Solaris 10+/x86.
	* config/sol2-gld.h [TARGET_DL_ITERATE_PHDR && HAVE_LD_EH_FRAME_HDR]
	(LINK_EH_SPEC): Define.
	[HAVE_LD_AS_NEEDED] (USE_LD_AS_NEEDED): Define.

diff -r 8bf39c5cff42 gcc/config/sol2-gld.h
--- a/gcc/config/sol2-gld.h	Sat Dec 11 01:54:46 2010 +0100
+++ b/gcc/config/sol2-gld.h	Sat Dec 11 23:46:40 2010 +0100
@@ -29,3 +29,17 @@
 /* GNU ld needs --export-dynamic to implement -rdynamic.  */
 #undef RDYNAMIC_SPEC
 #define RDYNAMIC_SPEC "--export-dynamic"
+
+/* Solaris 11 build 135+ implements dl_iterate_phdr.  */
+#if defined(HAVE_LD_EH_FRAME_HDR) && defined(TARGET_DL_ITERATE_PHDR)
+
+#define LINK_EH_SPEC "%{!static:--eh-frame-hdr} "
+
+/* Use --as-needed -lgcc_s for eh support, but only with .eh_frame_hdr,
+   otherwise every executable depends on libgcc_s.so.1 due to
+   __register_frame_info_bases/__deregister_frame_info_bases references.  */
+#ifdef HAVE_LD_AS_NEEDED
+#define USE_LD_AS_NEEDED 1
+#endif
+
+#endif /* HAVE_LD_EH_FRAME && TARGET_DL_ITERATE_PHDR */
diff -r 8bf39c5cff42 gcc/config/t-sol2
--- a/gcc/config/t-sol2	Sat Dec 11 01:54:46 2010 +0100
+++ b/gcc/config/t-sol2	Sat Dec 11 23:46:40 2010 +0100
@@ -28,3 +28,9 @@
   tree.h output.h $(TM_H) target.h $(TM_P_H) $(GGC_H)
 	$(COMPILER) -c $(ALL_COMPILERFLAGS) $(ALL_CPPFLAGS) $(INCLUDES) \
 	  $(srcdir)/config/sol2.c
+
+# Use unwind-dw2-fde-glibc.c.  Unless linker support and dl_iterate_phdr
+# are present, automatically falls back to unwind-dw2-fde.c.
+LIB2ADDEH = $(srcdir)/unwind-dw2.c $(srcdir)/unwind-dw2-fde-glibc.c \
+  $(srcdir)/unwind-sjlj.c $(srcdir)/gthr-gnat.c $(srcdir)/unwind-c.c
+LIB2ADDEHDEP = unwind.inc unwind-dw2-fde.h unwind-dw2-fde.c
diff -r 8bf39c5cff42 gcc/configure.ac
--- a/gcc/configure.ac	Sat Dec 11 01:54:46 2010 +0100
+++ b/gcc/configure.ac	Sat Dec 11 23:46:40 2010 +0100
@@ -3979,15 +3979,26 @@
     gcc_cv_ld_eh_frame_hdr=yes
   fi
 elif test x$gcc_cv_ld != x; then
-	# Check if linker supports --eh-frame-hdr option
-	if $gcc_cv_ld --help 2>/dev/null | grep eh-frame-hdr > /dev/null; then
-		gcc_cv_ld_eh_frame_hdr=yes
-	fi
+  if echo "$ld_ver" | grep GNU > /dev/null; then
+    # Check if linker supports --eh-frame-hdr option
+    if $gcc_cv_ld --help 2>/dev/null | grep eh-frame-hdr > /dev/null; then
+      gcc_cv_ld_eh_frame_hdr=yes
+    fi
+  else
+    case "$target" in
+      *-*-solaris2*)
+        # Sun ld has various bugs in .eh_frame_hdr support before version 1.2247.
+        if test "$ld_vers_major" -gt 1 || test "$ld_vers_minor" -ge 2247; then
+          gcc_cv_ld_eh_frame_hdr=yes
+        fi
+        ;;
+    esac
+  fi
 fi
 GCC_TARGET_TEMPLATE([HAVE_LD_EH_FRAME_HDR])
 if test x"$gcc_cv_ld_eh_frame_hdr" = xyes; then
 	AC_DEFINE(HAVE_LD_EH_FRAME_HDR, 1,
-[Define if your linker supports --eh-frame-hdr option.])
+[Define if your linker supports .eh_frame_hdr.])
 fi
 AC_MSG_RESULT($gcc_cv_ld_eh_frame_hdr)
 
@@ -4268,45 +4279,46 @@
 [Define to PREFIX/include if cpp should also search that directory.])
 fi
 
+if test x$host != x$target || test "x$TARGET_SYSTEM_ROOT" != x; then
+  if test "x$with_headers" != x; then
+    target_header_dir=$with_headers
+  elif test "x$with_sysroot" = x; then
+    target_header_dir="${exec_prefix}/${target_noncanonical}/sys-include"
+  elif test "x$with_build_sysroot" != "x"; then
+    target_header_dir="${with_build_sysroot}/usr/include"
+  elif test "x$with_sysroot" = xyes; then
+    target_header_dir="${exec_prefix}/${target_noncanonical}/sys-root/usr/include"
+  else
+    target_header_dir="${with_sysroot}/usr/include"
+  fi
+else
+  target_header_dir=/usr/include
+fi
+
 # Test for stack protector support in target C library.
 AC_CACHE_CHECK(__stack_chk_fail in target C library,
       gcc_cv_libc_provides_ssp,
       [gcc_cv_libc_provides_ssp=no
     case "$target" in
        *-*-linux* | *-*-kfreebsd*-gnu | *-*-knetbsd*-gnu)
-      if test x$host != x$target || test "x$TARGET_SYSTEM_ROOT" != x; then
-	if test "x$with_headers" != x; then
-	  glibc_header_dir=$with_headers
-	elif test "x$with_sysroot" = x; then
-	  glibc_header_dir="${exec_prefix}/${target_noncanonical}/sys-include"
-	elif test "x$with_build_sysroot" != "x"; then
-	  glibc_header_dir="${with_build_sysroot}/usr/include"
-	elif test "x$with_sysroot" = xyes; then
-	  glibc_header_dir="${exec_prefix}/${target_noncanonical}/sys-root/usr/include"
-	else
-	  glibc_header_dir="${with_sysroot}/usr/include"
-	fi
-      else
-	glibc_header_dir=/usr/include
-      fi
       [# glibc 2.4 and later provides __stack_chk_fail and
       # either __stack_chk_guard, or TLS access to stack guard canary.
-      if test -f $glibc_header_dir/features.h \
+      if test -f $target_header_dir/features.h \
 	 && $EGREP '^[ 	]*#[ 	]*define[ 	]+__GNU_LIBRARY__[ 	]+([1-9][0-9]|[6-9])' \
-	    $glibc_header_dir/features.h > /dev/null; then
+	    $target_header_dir/features.h > /dev/null; then
 	if $EGREP '^[ 	]*#[ 	]*define[ 	]+__GLIBC__[ 	]+([1-9][0-9]|[3-9])' \
-	   $glibc_header_dir/features.h > /dev/null; then
+	   $target_header_dir/features.h > /dev/null; then
 	  gcc_cv_libc_provides_ssp=yes
 	elif $EGREP '^[ 	]*#[ 	]*define[ 	]+__GLIBC__[ 	]+2' \
-	     $glibc_header_dir/features.h > /dev/null \
+	     $target_header_dir/features.h > /dev/null \
 	     && $EGREP '^[ 	]*#[ 	]*define[ 	]+__GLIBC_MINOR__[ 	]+([1-9][0-9]|[4-9])' \
-	     $glibc_header_dir/features.h > /dev/null; then
+	     $target_header_dir/features.h > /dev/null; then
 	  gcc_cv_libc_provides_ssp=yes
 	elif $EGREP '^[ 	]*#[ 	]*define[ 	]+__UCLIBC__[ 	]+1' \
-	     $glibc_header_dir/features.h > /dev/null && \
-	     test -f $glibc_header_dir/bits/uClibc_config.h && \
+	     $target_header_dir/features.h > /dev/null && \
+	     test -f $target_header_dir/bits/uClibc_config.h && \
 	     $EGREP '^[ 	]*#[ 	]*define[ 	]+__UCLIBC_HAS_SSP__[ 	]+1' \
-	     $glibc_header_dir/bits/uClibc_config.h > /dev/null; then
+	     $target_header_dir/bits/uClibc_config.h > /dev/null; then
 	  gcc_cv_libc_provides_ssp=yes
 	fi
       fi]
@@ -4342,21 +4354,8 @@
 [  --with-long-double-128  Use 128-bit long double by default.],
       gcc_cv_target_ldbl128="$with_long_double_128",
       [[gcc_cv_target_ldbl128=no
-      if test x$host != x$target || test "x$TARGET_SYSTEM_ROOT" != x; then
-	if test "x$with_sysroot" = x; then
-	  glibc_header_dir="${exec_prefix}/${target_noncanonical}/sys-include"
-	elif test "x$with_build_sysroot" != "x"; then
-	  glibc_header_dir="${with_build_sysroot}/usr/include"
-	elif test "x$with_sysroot" = xyes; then
-	  glibc_header_dir="${exec_prefix}/${target_noncanonical}/sys-root/usr/include"
-	else
-	  glibc_header_dir="${with_sysroot}/usr/include"
-	fi
-      else
-	glibc_header_dir=/usr/include
-      fi
       grep '^[ 	]*#[ 	]*define[ 	][ 	]*__LONG_DOUBLE_MATH_OPTIONAL' \
-        $glibc_header_dir/bits/wordsize.h > /dev/null 2>&1 \
+        $target_header_dir/bits/wordsize.h > /dev/null 2>&1 \
       && gcc_cv_target_ldbl128=yes
       ]])
     ;;
@@ -4366,6 +4365,27 @@
 	    [Define if TFmode long double should be the default])
 fi
 
+AC_MSG_CHECKING(dl_iterate_phdr in target C library)
+gcc_cv_target_dl_iterate_phdr=unknown
+case "$target" in
+  *-*-solaris2*)
+    # <link.h> needs both a dl_iterate_phdr declaration and support for
+    # compilation with largefile support.
+    if grep dl_iterate_phdr $target_header_dir/link.h > /dev/null 2>&1 \
+      && grep 'large file capable' $target_header_dir/link.h > /dev/null 2>&1; then
+      gcc_cv_target_dl_iterate_phdr=yes
+    else
+      gcc_cv_target_dl_iterate_phdr=no
+    fi
+    ;;
+esac
+GCC_TARGET_TEMPLATE([TARGET_DL_ITERATE_PHDR])
+if test x$gcc_cv_target_dl_iterate_phdr = xyes; then
+   AC_DEFINE(TARGET_DL_ITERATE_PHDR, 1,
+[Define if your target C library provides the `dl_iterate_phdr' function.])
+fi
+AC_MSG_RESULT($gcc_cv_target_dl_iterate_phdr)
+
 # Find out what GC implementation we want, or may, use.
 AC_ARG_WITH(gc,
 [  --with-gc={page,zone}   choose the garbage collection mechanism to use
diff -r 8bf39c5cff42 gcc/crtstuff.c
--- a/gcc/crtstuff.c	Sat Dec 11 01:54:46 2010 +0100
+++ b/gcc/crtstuff.c	Sat Dec 11 23:46:40 2010 +0100
@@ -1,7 +1,7 @@
 /* Specialized bits of code needed to support construction and
    destruction of file-scope objects in C++ code.
    Copyright (C) 1991, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001
-   2002, 2003, 2004, 2005, 2006, 2007, 2009 Free Software Foundation, Inc.
+   2002, 2003, 2004, 2005, 2006, 2007, 2009, 2010 Free Software Foundation, Inc.
    Contributed by Ron Guilmette (rfg@monkeys.com).
 
 This file is part of GCC.
@@ -90,6 +90,15 @@
 
 #if defined(OBJECT_FORMAT_ELF) \
     && !defined(OBJECT_FORMAT_FLAT) \
+    && defined(HAVE_LD_EH_FRAME_HDR) && defined(TARGET_DL_ITERATE_PHDR) \
+    && !defined(inhibit_libc) && !defined(CRTSTUFFT_O) \
+    && defined(__sun__) && defined(__svr4__)
+#include <link.h>
+# define USE_PT_GNU_EH_FRAME
+#endif
+
+#if defined(OBJECT_FORMAT_ELF) \
+    && !defined(OBJECT_FORMAT_FLAT) \
     && defined(HAVE_LD_EH_FRAME_HDR) \
     && !defined(inhibit_libc) && !defined(CRTSTUFFT_O) \
     && defined(__GLIBC__) && __GLIBC__ >= 2
diff -r 8bf39c5cff42 gcc/unwind-dw2-fde-glibc.c
--- a/gcc/unwind-dw2-fde-glibc.c	Sat Dec 11 01:54:46 2010 +0100
+++ b/gcc/unwind-dw2-fde-glibc.c	Sat Dec 11 23:46:40 2010 +0100
@@ -1,4 +1,5 @@
-/* Copyright (C) 2001, 2002, 2003, 2004, 2005, 2009 Free Software Foundation, Inc.
+/* Copyright (C) 2001, 2002, 2003, 2004, 2005, 2009, 2010
+   Free Software Foundation, Inc.
    Contributed by Jakub Jelinek <jakub@redhat.com>.
 
    This file is part of GCC.
@@ -57,6 +58,12 @@
 # define USE_PT_GNU_EH_FRAME
 #endif
 
+#if !defined(inhibit_libc) && defined(HAVE_LD_EH_FRAME_HDR) \
+    && defined(TARGET_DL_ITERATE_PHDR) \
+    && defined(__sun__) && defined(__svr4__)
+# define USE_PT_GNU_EH_FRAME
+#endif
+
 #if defined(USE_PT_GNU_EH_FRAME)
 
 #include <link.h>
@@ -256,6 +263,12 @@
 	}
       else if (phdr->p_type == PT_GNU_EH_FRAME)
 	p_eh_frame_hdr = phdr;
+#ifdef PT_SUNW_UNWIND
+      /* Sun ld emits PT_SUNW_UNWIND .eh_frame_hdr sections instead of
+	 PT_SUNW_EH_FRAME/PT_GNU_EH_FRAME, so accept them as well.  */
+      else if (phdr->p_type == PT_SUNW_UNWIND)
+	p_eh_frame_hdr = phdr;
+#endif
       else if (phdr->p_type == PT_DYNAMIC)
 	p_dynamic = phdr;
     }
@@ -305,13 +318,22 @@
       for (; dyn->d_tag != DT_NULL ; dyn++)
 	if (dyn->d_tag == DT_PLTGOT)
 	  {
-	    /* On IA-32, _DYNAMIC is writable and GLIBC has relocated it.  */
 	    data->dbase = (void *) dyn->d_un.d_ptr;
+#if defined __linux__
+	    /* On IA-32 Linux, _DYNAMIC is writable and GLIBC has
+	       relocated it.  */
+#elif defined __sun__ && defined __svr4__
+	    /* On Solaris 2/x86, we need to do this ourselves.  */
+	    data->dbase += load_base;
+#endif
 	    break;
 	  }
     }
 # elif defined __FRV_FDPIC__ && defined __linux__
   data->dbase = load_base.got_value;
+# elif defined __x86_64__ && defined __sun__ && defined __svr4__
+  /* While CRT_GET_RFIB_DATA is also defined for 64-bit Solaris 10+/x86, it
+     doesn't apply since it uses DW_EH_PE_pcrel encoding.  */
 # else
 #  error What is DW_EH_PE_datarel base on this platform?
 # endif


-- 
-----------------------------------------------------------------------------
Rainer Orth, Center for Biotechnology, Bielefeld University