[v2,10/15] For PPC64: elf_gnu_ifunc_record_cache: handle plt symbols in .text section

Message ID 20180325191943.8246-11-palves@redhat.com
State New
Headers show
  • Fixing GNU ifunc support
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Commit Message

Pedro Alves March 25, 2018, 7:19 p.m.
elf_gnu_ifunc_record_cache doesn't ever record anything on PPC64
(tested on gcc110 on the compile farm, CentOS 7.4, ELFv1), because
that expects to find PLT symbols in the .plt section, while there we

  (gdb) info symbol 'gnu_ifunc@plt'
  gnu_ifunc@plt in section .text

I guess that may be related to the comment in ppc-linux-tdep.c that
says "For secure PLT, stub is in .text".

In any case, this commit fixes the issue by making the function look
at the symbol name instead of at the section.

yyyy-mm-dd  Pedro Alves  <palves@redhat.com>

	* elfread.c (elf_gnu_ifunc_record_cache): Check if the symbol name
	ends in "@plt" instead of looking at the symbol's section.
 gdb/elfread.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)



diff --git a/gdb/elfread.c b/gdb/elfread.c
index 82ab3d891ce..4e79b080e65 100644
--- a/gdb/elfread.c
+++ b/gdb/elfread.c
@@ -687,7 +687,6 @@  static int
 elf_gnu_ifunc_record_cache (const char *name, CORE_ADDR addr)
   struct bound_minimal_symbol msym;
-  asection *sect;
   struct objfile *objfile;
   htab_t htab;
   struct elf_gnu_ifunc_cache entry_local, *entry_p;
@@ -698,14 +697,17 @@  elf_gnu_ifunc_record_cache (const char *name, CORE_ADDR addr)
     return 0;
   if (BMSYMBOL_VALUE_ADDRESS (msym) != addr)
     return 0;
-  /* minimal symbols have always SYMBOL_OBJ_SECTION non-NULL.  */
-  sect = MSYMBOL_OBJ_SECTION (msym.objfile, msym.minsym)->the_bfd_section;
   objfile = msym.objfile;
   /* If .plt jumps back to .plt the symbol is still deferred for later
-     resolution and it has no use for GDB.  Besides ".text" this symbol can
-     reside also in ".opd" for ppc64 function descriptor.  */
-  if (strcmp (bfd_get_section_name (objfile->obfd, sect), ".plt") == 0)
+     resolution and it has no use for GDB.  */
+  const char *target_name = MSYMBOL_LINKAGE_NAME (msym.minsym);
+  size_t len = strlen (target_name);
+  /* Note we check the symbol's name instead of checking whether the
+     symbol is in the .plt section because some systems have @plt
+     symbols in the .text section.  */
+  if (len > 4 && strcmp (target_name + len - 4, "@plt") == 0)
     return 0;
   htab = (htab_t) objfile_data (objfile, elf_objfile_gnu_ifunc_cache_data);