[PATCH] Adjust the symbol for SECTION_LINK_ORDER linked_to section [PR99889]

Kewen.Lin linkw@linux.ibm.com
Wed Aug 24 08:17:07 GMT 2022


Hi,

As discussed in PR98125, -fpatchable-function-entry with
SECTION_LINK_ORDER support doesn't work well on powerpc64
ELFv1 because the filled "Symbol" in

  .section name,"flags"o,@type,Symbol

sits in .opd section instead of in the function_section
like .text or named .text*.

Since we already generates one label LPFE* which sits in
function_section of current_function_decl, this patch is
to reuse it as the symbol for the linked_to section.  It
avoids the above ABI specific issue when using the symbol
concluded from current_function_decl.

Besides, with this support some previous workarounds for
powerpc64 ELFv1 can be reverted.

btw, rs6000_print_patchable_function_entry can be dropped
but there is another rs6000 patch which needs this rs6000
specific hook rs6000_print_patchable_function_entry, not
sure which one gets landed first, so just leave it here.

Bootstrapped and regtested on below:

  1) powerpc64-linux-gnu P8 with default binutils 2.27
     and latest binutils 2.39.
  2) powerpc64le-linux-gnu P9 (default binutils 2.30).
  3) powerpc64le-linux-gnu P10 (default binutils 2.30).
  4) x86_64-redhat-linux with default binutils 2.30
     and latest binutils 2.39.
  5) aarch64-linux-gnu  with default binutils 2.30
     and latest binutils 2.39.

Is it ok for trunk?

BR,
Kewen
-----

	PR target/99889

gcc/ChangeLog:

	* config/rs6000/rs6000.cc (rs6000_print_patchable_function_entry):
	Adjust to call function default_print_patchable_function_entry.
	* targhooks.cc (default_print_patchable_function_entry_1): Remove and
	move the flags preparation ...
	(default_print_patchable_function_entry): ... here, adjust to use
	current_function_funcdef_no for label no.
	* targhooks.h (default_print_patchable_function_entry_1): Remove.
	* varasm.cc (default_elf_asm_named_section): Adjust code for
	__patchable_function_entries section support with LPFE label.

gcc/testsuite/ChangeLog:

	* g++.dg/pr93195a.C: Remove the skip on powerpc*-*-* 64-bit.
	* gcc.target/aarch64/pr92424-2.c: Adjust LPFE1 with LPFE0.
	* gcc.target/aarch64/pr92424-3.c: Likewise.
	* gcc.target/i386/pr93492-2.c: Likewise.
	* gcc.target/i386/pr93492-3.c: Likewise.
	* gcc.target/i386/pr93492-4.c: Likewise.
	* gcc.target/i386/pr93492-5.c: Likewise.
---
 gcc/config/rs6000/rs6000.cc                  | 13 +-----
 gcc/varasm.cc                                | 15 ++++---
 gcc/targhooks.cc                             | 45 +++++++-------------
 gcc/targhooks.h                              |  3 --
 gcc/testsuite/g++.dg/pr93195a.C              |  1 -
 gcc/testsuite/gcc.target/aarch64/pr92424-2.c |  4 +-
 gcc/testsuite/gcc.target/aarch64/pr92424-3.c |  4 +-
 gcc/testsuite/gcc.target/i386/pr93492-2.c    |  4 +-
 gcc/testsuite/gcc.target/i386/pr93492-3.c    |  4 +-
 gcc/testsuite/gcc.target/i386/pr93492-4.c    |  4 +-
 gcc/testsuite/gcc.target/i386/pr93492-5.c    |  4 +-
 11 files changed, 40 insertions(+), 61 deletions(-)

diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
index df491bee2ea..dba28b8e647 100644
--- a/gcc/config/rs6000/rs6000.cc
+++ b/gcc/config/rs6000/rs6000.cc
@@ -14771,18 +14771,9 @@ rs6000_print_patchable_function_entry (FILE *file,
 				       unsigned HOST_WIDE_INT patch_area_size,
 				       bool record_p)
 {
-  unsigned int flags = SECTION_WRITE | SECTION_RELRO;
-  /* When .opd section is emitted, the function symbol
-     default_print_patchable_function_entry_1 is emitted into the .opd section
-     while the patchable area is emitted into the function section.
-     Don't use SECTION_LINK_ORDER in that case.  */
-  if (!(TARGET_64BIT && DEFAULT_ABI != ABI_ELFv2)
-      && HAVE_GAS_SECTION_LINK_ORDER)
-    flags |= SECTION_LINK_ORDER;
-  default_print_patchable_function_entry_1 (file, patch_area_size, record_p,
-					    flags);
+  default_print_patchable_function_entry (file, patch_area_size, record_p);
 }
-

+
 enum rtx_code
 rs6000_reverse_condition (machine_mode mode, enum rtx_code code)
 {
diff --git a/gcc/varasm.cc b/gcc/varasm.cc
index 4db8506b106..d4de6e164ee 100644
--- a/gcc/varasm.cc
+++ b/gcc/varasm.cc
@@ -6906,11 +6906,16 @@ default_elf_asm_named_section (const char *name, unsigned int flags,
 	fprintf (asm_out_file, ",%d", flags & SECTION_ENTSIZE);
       if (flags & SECTION_LINK_ORDER)
 	{
-	  tree id = DECL_ASSEMBLER_NAME (decl);
-	  ultimate_transparent_alias_target (&id);
-	  const char *name = IDENTIFIER_POINTER (id);
-	  name = targetm.strip_name_encoding (name);
-	  fprintf (asm_out_file, ",%s", name);
+	  /* For now, only section "__patchable_function_entries"
+	     adopts flag SECTION_LINK_ORDER, internal label LPFE*
+	     was emitted in default_print_patchable_function_entry,
+	     just place it here for linked_to section.  */
+	  gcc_assert (!strcmp (name, "__patchable_function_entries"));
+	  fprintf (asm_out_file, ",");
+	  char buf[256];
+	  ASM_GENERATE_INTERNAL_LABEL (buf, "LPFE",
+				       current_function_funcdef_no);
+	  assemble_name_raw (asm_out_file, buf);
 	}
       if (HAVE_COMDAT_GROUP && (flags & SECTION_LINKONCE))
 	{
diff --git a/gcc/targhooks.cc b/gcc/targhooks.cc
index b15ae19bcb6..e80caecc418 100644
--- a/gcc/targhooks.cc
+++ b/gcc/targhooks.cc
@@ -1979,15 +1979,17 @@ default_compare_by_pieces_branch_ratio (machine_mode)
   return 1;
 }

-/* Helper for default_print_patchable_function_entry and other
-   print_patchable_function_entry hook implementations.  */
+/* Write PATCH_AREA_SIZE NOPs into the asm outfile FILE around a function
+   entry.  If RECORD_P is true and the target supports named sections,
+   the location of the NOPs will be recorded in a special object section
+   called "__patchable_function_entries".  This routine may be called
+   twice per function to put NOPs before and after the function
+   entry.  */

 void
-default_print_patchable_function_entry_1 (FILE *file,
-					  unsigned HOST_WIDE_INT
-					  patch_area_size,
-					  bool record_p,
-					  unsigned int flags)
+default_print_patchable_function_entry (FILE *file,
+					unsigned HOST_WIDE_INT patch_area_size,
+					bool record_p)
 {
   const char *nop_templ = 0;
   int code_num;
@@ -2001,13 +2003,17 @@ default_print_patchable_function_entry_1 (FILE *file,
   if (record_p && targetm_common.have_named_sections)
     {
       char buf[256];
-      static int patch_area_number;
       section *previous_section = in_section;
       const char *asm_op = integer_asm_op (POINTER_SIZE_UNITS, false);

       gcc_assert (asm_op != NULL);
-      patch_area_number++;
-      ASM_GENERATE_INTERNAL_LABEL (buf, "LPFE", patch_area_number);
+      /* If SECTION_LINK_ORDER is supported, this internal label will
+	 be filled as the symbol for linked_to section.  */
+      ASM_GENERATE_INTERNAL_LABEL (buf, "LPFE", current_function_funcdef_no);
+
+      unsigned int flags = SECTION_WRITE | SECTION_RELRO;
+      if (HAVE_GAS_SECTION_LINK_ORDER)
+	flags |= SECTION_LINK_ORDER;

       section *sect = get_section ("__patchable_function_entries",
 				  flags, current_function_decl);
@@ -2029,25 +2035,6 @@ default_print_patchable_function_entry_1 (FILE *file,
     output_asm_insn (nop_templ, NULL);
 }

-/* Write PATCH_AREA_SIZE NOPs into the asm outfile FILE around a function
-   entry.  If RECORD_P is true and the target supports named sections,
-   the location of the NOPs will be recorded in a special object section
-   called "__patchable_function_entries".  This routine may be called
-   twice per function to put NOPs before and after the function
-   entry.  */
-
-void
-default_print_patchable_function_entry (FILE *file,
-					unsigned HOST_WIDE_INT patch_area_size,
-					bool record_p)
-{
-  unsigned int flags = SECTION_WRITE | SECTION_RELRO;
-  if (HAVE_GAS_SECTION_LINK_ORDER)
-    flags |= SECTION_LINK_ORDER;
-  default_print_patchable_function_entry_1 (file, patch_area_size, record_p,
-					    flags);
-}
-
 bool
 default_profile_before_prologue (void)
 {
diff --git a/gcc/targhooks.h b/gcc/targhooks.h
index ecce55ebe79..5c1216fad0b 100644
--- a/gcc/targhooks.h
+++ b/gcc/targhooks.h
@@ -229,9 +229,6 @@ extern bool default_use_by_pieces_infrastructure_p (unsigned HOST_WIDE_INT,
 						    bool);
 extern int default_compare_by_pieces_branch_ratio (machine_mode);

-extern void default_print_patchable_function_entry_1 (FILE *,
-						      unsigned HOST_WIDE_INT,
-						      bool, unsigned int);
 extern void default_print_patchable_function_entry (FILE *,
 						    unsigned HOST_WIDE_INT,
 						    bool);
diff --git a/gcc/testsuite/g++.dg/pr93195a.C b/gcc/testsuite/g++.dg/pr93195a.C
index b14f1b3e341..26d265da74e 100644
--- a/gcc/testsuite/g++.dg/pr93195a.C
+++ b/gcc/testsuite/g++.dg/pr93195a.C
@@ -1,5 +1,4 @@
 /* { dg-do link { target { ! { nvptx*-*-* visium-*-* } } } } */
-/* { dg-skip-if "not supported" { { powerpc*-*-* } && lp64 } } */
 // { dg-require-effective-target o_flag_in_section }
 /* { dg-options "-O0 -fpatchable-function-entry=1" } */
 /* { dg-additional-options "-fno-pie" { target sparc*-*-* } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/pr92424-2.c b/gcc/testsuite/gcc.target/aarch64/pr92424-2.c
index 0e75657a153..12465213aef 100644
--- a/gcc/testsuite/gcc.target/aarch64/pr92424-2.c
+++ b/gcc/testsuite/gcc.target/aarch64/pr92424-2.c
@@ -1,7 +1,7 @@
 /* { dg-do "compile" } */
 /* { dg-options "-O1" } */

-/* Test the placement of the .LPFE1 label.  */
+/* Test the placement of the .LPFE0 label.  */

 void
 __attribute__ ((target("branch-protection=bti"),
@@ -9,4 +9,4 @@ __attribute__ ((target("branch-protection=bti"),
 f10_bti ()
 {
 }
-/* { dg-final { scan-assembler "f10_bti:\n\thint\t34 // bti c\n.*\.LPFE1:\n\tnop\n.*\tret\n" } } */
+/* { dg-final { scan-assembler "f10_bti:\n\thint\t34 // bti c\n.*\.LPFE0:\n\tnop\n.*\tret\n" } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/pr92424-3.c b/gcc/testsuite/gcc.target/aarch64/pr92424-3.c
index 0a1f74d4096..2c6a73789f0 100644
--- a/gcc/testsuite/gcc.target/aarch64/pr92424-3.c
+++ b/gcc/testsuite/gcc.target/aarch64/pr92424-3.c
@@ -1,7 +1,7 @@
 /* { dg-do "compile" } */
 /* { dg-options "-O1" } */

-/* Test the placement of the .LPFE1 label.  */
+/* Test the placement of the .LPFE0 label.  */

 void
 __attribute__ ((target("branch-protection=bti+pac-ret+leaf"),
@@ -9,4 +9,4 @@ __attribute__ ((target("branch-protection=bti+pac-ret+leaf"),
 f10_pac ()
 {
 }
-/* { dg-final { scan-assembler "f10_pac:\n\thint\t34 // bti c\n.*\.LPFE1:\n\tnop\n.*\thint\t25 // paciasp\n.*\thint\t29 // autiasp\n.*\tret\n" } } */
+/* { dg-final { scan-assembler "f10_pac:\n\thint\t34 // bti c\n.*\.LPFE0:\n\tnop\n.*\thint\t25 // paciasp\n.*\thint\t29 // autiasp\n.*\tret\n" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr93492-2.c b/gcc/testsuite/gcc.target/i386/pr93492-2.c
index 3d67095fd10..ede8c2077b7 100644
--- a/gcc/testsuite/gcc.target/i386/pr93492-2.c
+++ b/gcc/testsuite/gcc.target/i386/pr93492-2.c
@@ -1,7 +1,7 @@
 /* { dg-do "compile" { target *-*-linux* } } */
 /* { dg-options "-O1 -fcf-protection -mmanual-endbr -fasynchronous-unwind-tables" } */

-/* Test the placement of the .LPFE1 label.  */
+/* Test the placement of the .LPFE0 label.  */

 void
 __attribute__ ((cf_check,patchable_function_entry (1, 0)))
@@ -9,4 +9,4 @@ f10_endbr (void)
 {
 }

-/* { dg-final { scan-assembler "\t\.cfi_startproc\n\tendbr(32|64)\n.*\.LPFE1:\n\tnop\n\tret\n" } } */
+/* { dg-final { scan-assembler "\t\.cfi_startproc\n\tendbr(32|64)\n.*\.LPFE0:\n\tnop\n\tret\n" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr93492-3.c b/gcc/testsuite/gcc.target/i386/pr93492-3.c
index a625c927f4f..b68da30bd36 100644
--- a/gcc/testsuite/gcc.target/i386/pr93492-3.c
+++ b/gcc/testsuite/gcc.target/i386/pr93492-3.c
@@ -2,7 +2,7 @@
 /* { dg-require-effective-target mfentry } */
 /* { dg-options "-O1 -fcf-protection -mmanual-endbr -mfentry -pg -fasynchronous-unwind-tables" } */

-/* Test the placement of the .LPFE1 label.  */
+/* Test the placement of the .LPFE0 label.  */

 void
 __attribute__ ((cf_check,patchable_function_entry (1, 0)))
@@ -10,4 +10,4 @@ f10_endbr (void)
 {
 }

-/* { dg-final { scan-assembler "\t\.cfi_startproc\n\tendbr(32|64)\n.*\.LPFE1:\n\tnop\n1:\tcall\t\[^\n\]*__fentry__\[^\n\]*\n\tret\n" } } */
+/* { dg-final { scan-assembler "\t\.cfi_startproc\n\tendbr(32|64)\n.*\.LPFE0:\n\tnop\n1:\tcall\t\[^\n\]*__fentry__\[^\n\]*\n\tret\n" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr93492-4.c b/gcc/testsuite/gcc.target/i386/pr93492-4.c
index 8f205c345b8..c73034a4624 100644
--- a/gcc/testsuite/gcc.target/i386/pr93492-4.c
+++ b/gcc/testsuite/gcc.target/i386/pr93492-4.c
@@ -1,11 +1,11 @@
 /* { dg-do "compile" { target *-*-linux* } } */
 /* { dg-options "-O1 -fpatchable-function-entry=1 -fasynchronous-unwind-tables" } */

-/* Test the placement of the .LPFE1 label.  */
+/* Test the placement of the .LPFE0 label.  */

 void
 foo (void)
 {
 }

-/* { dg-final { scan-assembler "\t\.cfi_startproc\n.*\.LPFE1:\n\tnop\n\tret\n" } } */
+/* { dg-final { scan-assembler "\t\.cfi_startproc\n.*\.LPFE0:\n\tnop\n\tret\n" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr93492-5.c b/gcc/testsuite/gcc.target/i386/pr93492-5.c
index 1ca5ba1fac1..ee9849ae852 100644
--- a/gcc/testsuite/gcc.target/i386/pr93492-5.c
+++ b/gcc/testsuite/gcc.target/i386/pr93492-5.c
@@ -2,11 +2,11 @@
 /* { dg-options "-O1 -fpatchable-function-entry=1 -mfentry -pg -fasynchronous-unwind-tables" } */
 /* { dg-additional-options "-fno-PIE" { target ia32 } } */

-/* Test the placement of the .LPFE1 label.  */
+/* Test the placement of the .LPFE0 label.  */

 void
 foo (void)
 {
 }

-/* { dg-final { scan-assembler "\t\.cfi_startproc\n.*\.LPFE1:\n\tnop\n1:\tcall\t\[^\n\]*__fentry__\[^\n\]*\n\tret\n" } } */
+/* { dg-final { scan-assembler "\t\.cfi_startproc\n.*\.LPFE0:\n\tnop\n1:\tcall\t\[^\n\]*__fentry__\[^\n\]*\n\tret\n" } } */
--


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