elf: Add elf_backend_add_glibc_version_dependency

When -z mark-plt is used to add DT_X86_64_PLT, DT_X86_64_PLTSZ and
DT_X86_64_PLTENT, the r_addend field of the R_X86_64_JUMP_SLOT relocation
stores the offset of the indirect branch instruction.  However, glibc
versions which don't have this commit in glibc 2.36:

commit f8587a61892cbafd98ce599131bf4f103466f084
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Fri May 20 19:21:48 2022 -0700

    x86-64: Ignore r_addend for R_X86_64_GLOB_DAT/R_X86_64_JUMP_SLOT

    According to x86-64 psABI, r_addend should be ignored for R_X86_64_GLOB_DAT
    and R_X86_64_JUMP_SLOT.  Since linkers always set their r_addends to 0, we
    can ignore their r_addends.

    Reviewed-by: Fangrui Song <maskray@google.com>

won't ignore the r_addend value in the R_X86_64_JUMP_SLOT relocation.
Although this commit has been backported to glibc 2.33/2.34/2.35 release
branches, it is safer to require glibc 2.36 for such binaries.

Extend the glibc version dependency of GLIBC_ABI_DT_RELR for DT_RELR to
also add GLIBC_2.36 version dependency for -z mark-plt on the shared C
library if it provides a GLIBC_2.XX symbol version.

	* elflink.c (elf_find_verdep_info): Moved to ...
	* elf-bfd.h (elf_find_verdep_info): Here.
	(elf_backend_data): Add elf_backend_add_glibc_version_dependency.
	(_bfd_elf_link_add_glibc_version_dependency): New function.
	(_bfd_elf_link_add_dt_relr_dependency): Likewise.
	* elf64-x86-64.c (elf_x86_64_add_glibc_version_dependency):
	Likewise.
	(elf_backend_add_glibc_version_dependency): New.
	* elflink.c (elf_link_add_dt_relr_dependency): Renamed to ...
	(elf_link_add_glibc_verneed): This.  Modified to support other
	glibc dependencies.
	(_bfd_elf_link_add_glibc_version_dependency): Likewise.
	(_bfd_elf_link_add_dt_relr_dependency): Likewise.
	(bfd_elf_size_dynamic_sections): Call
	elf_backend_add_glibc_version_dependency instead of
	elf_link_add_dt_relr_dependency.
	* elfxx-target.h (elf_backend_add_glibc_version_dependency): New.
	(elfNN_bed): Add elf_backend_add_glibc_version_dependency.

ld/

	* testsuite/ld-x86-64/mark-plt-1a.rd: New file.
	* testsuite/ld-x86-64/mark-plt-1b.rd: Likewise.
	* testsuite/ld-x86-64/x86-64.exp: Run -z mark-plt test for
	GLIBC_2.36 dependency.

1 files changed, 27 insertions, 0 deletions

diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c
index f8905fb..f125375 100644
--- a/bfd/elf64-x86-64.c
+++ b/bfd/elf64-x86-64.c
@@ -5572,6 +5572,31 @@ elf_x86_64_link_setup_gnu_properties (struct bfd_link_info *info)
   return _bfd_x86_elf_link_setup_gnu_properties (info, &init_table);
 }
 
+static void
+elf_x86_64_add_glibc_version_dependency
+  (struct elf_find_verdep_info *rinfo)
+{
+  unsigned int i = 0;
+  const char *version[3] = { NULL, NULL, NULL };
+  struct elf_x86_link_hash_table *htab;
+
+  if (rinfo->info->enable_dt_relr)
+    {
+      version[i] = "GLIBC_ABI_DT_RELR";
+      i++;
+    }
+
+  htab = elf_x86_hash_table (rinfo->info, X86_64_ELF_DATA);
+  if (htab != NULL && htab->params->mark_plt)
+    {
+      version[i] = "GLIBC_2.36";
+      i++;
+    }
+
+  if (i != 0)
+    _bfd_elf_link_add_glibc_version_dependency (rinfo, version);
+}
+
 static const struct bfd_elf_special_section
 elf_x86_64_special_sections[]=
 {
@@ -5656,6 +5681,8 @@ elf_x86_64_special_sections[]=
   elf_x86_64_link_setup_gnu_properties
 #define elf_backend_hide_symbol \
   _bfd_x86_elf_hide_symbol
+#define elf_backend_add_glibc_version_dependency \
+  elf_x86_64_add_glibc_version_dependency
 
 #undef	elf64_bed
 #define elf64_bed elf64_x86_64_bed