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.

3 files changed, 28 insertions, 0 deletions

diff --git a/ld/testsuite/ld-x86-64/mark-plt-1a.rd b/ld/testsuite/ld-x86-64/mark-plt-1a.rd
new file mode 100644
index 0000000..1234fbe
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/mark-plt-1a.rd
@@ -0,0 +1,7 @@
+#...
+Version needs section '.gnu.version_r' contains 1 entry:
+ Addr: 0x[0-9a-f]+ +Offset: 0x[0-9a-f]+ +Link: +[0-9]+ +\(.dynstr\)
+ +0+: Version: 1 +File: libc\.so\.6(|\.1) +Cnt: +[0-9]+
+#...
+  0x[a-f0-9]+:   Name: GLIBC_2.36  Flags: none  Version: [0-9]+
+#pass
diff --git a/ld/testsuite/ld-x86-64/mark-plt-1b.rd b/ld/testsuite/ld-x86-64/mark-plt-1b.rd
new file mode 100644
index 0000000..6556a6d
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/mark-plt-1b.rd
@@ -0,0 +1,7 @@
+#...
+Version needs section '.gnu.version_r' contains 1 entry:
+ Addr: 0x[0-9a-f]+ +Offset: 0x[0-9a-f]+ +Link: +[0-9]+ +\(.dynstr\)
+ +0+: Version: 1 +File: libc\.so\.6(|\.1) +Cnt: +[0-9]+
+#...
+  0x[a-f0-9]+:   Name: GLIBC_ABI_DT_RELR  Flags: none  Version: [0-9]+
+#pass
diff --git a/ld/testsuite/ld-x86-64/x86-64.exp b/ld/testsuite/ld-x86-64/x86-64.exp
index 03266cb..a1a0422 100644
--- a/ld/testsuite/ld-x86-64/x86-64.exp
+++ b/ld/testsuite/ld-x86-64/x86-64.exp
@@ -2259,4 +2259,18 @@ run_dump_test "mark-plt-1b-x32"
 run_dump_test "mark-plt-1c-x32"
 run_dump_test "mark-plt-1d-x32"
 
+if { [check_compiler_available] } {
+    run_cc_link_tests [list \
+	[list \
+	    "Build mark-plt-1.so" \
+	    "-shared -Wl,-z,mark-plt,-z,pack-relative-relocs" \
+	    "-fPIC" \
+	    { mark-plt-1.s } \
+	    {{readelf {-W --version-info} mark-plt-1a.rd} \
+	     {readelf {-W --version-info} mark-plt-1b.rd}} \
+	    "mark-plt-1.so" \
+	] \
+    ]
+}
+
 set ASFLAGS "$saved_ASFLAGS"