[binutils-gdb] sparc: define _GLOBAL_OFFSET_TABLE_ when referenced

[Alexandre Oliva]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=fd82d5ddf57a2f77491241521569535a8c7b3782

commit fd82d5ddf57a2f77491241521569535a8c7b3782
Author: Alexandre Oliva <oliva@adacore.com>
Date:   Sat Feb 8 03:12:24 2025 -0300

    sparc: define _GLOBAL_OFFSET_TABLE_ when referenced
    
    GCC testsuite gcc.dg/20050321-2.c hit link errors on undefined
    _GLOBAL_OFFSET_TABLE_.  The compiler output referenced only
    _GLOBAL_OFFSET_TABLE_-offsets to set it up, and to compute the
    GOT-relative address of local symbols, none of which triggered the
    machinery that enabled the creation of the dynamic section, so
    _GLOBAL_OFFSET_TABLE_ ended up undefined.
    
    Enable the dynamic section if we find a relocation involving
    _GLOBAL_OFFSET_TABLE_.  While at that, optimize checks for references
    to it.
    
    
    for  bfd/ChangeLog
    
            * elfxx-sparc.c (_bfd_sparc_elf_check_relocs): Check for
            _GLOBAL_OFFSET_TABLE_ references early, then compare hashed
            symbols instead of strings.
            (_bfd_sparc_elf_relocate_section): Compare hashed symbols.
    
    for  ld/ChangeLog
    
            * testsuite/ld-sparc/got-def.s: New test.
            * testsuite/ld-sparc/sparc.exp: Add it.

Diff:
---
 bfd/ChangeLog                   |  7 +++++++
 bfd/elfxx-sparc.c               | 16 ++++++++++++----
 ld/ChangeLog                    |  5 +++++
 ld/testsuite/ld-sparc/got-def.s | 15 +++++++++++++++
 ld/testsuite/ld-sparc/sparc.exp |  8 ++++++++
 5 files changed, 47 insertions(+), 4 deletions(-)

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index d8facc241c9..3f0248717b2 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,10 @@
+2025-02-08  Alexandre Oliva <oliva@adacore.com>
+
+	* elfxx-sparc.c (_bfd_sparc_elf_check_relocs): Check for
+	_GLOBAL_OFFSET_TABLE_ references early, then compare hashed
+	symbols instead of strings.
+	(_bfd_sparc_elf_relocate_section): Compare hashed symbols.
+
 2025-01-23  Jose E. Marchesi  <jose.marchesi@oracle.com>
 
 	* doc/local.mk (AM_MAKEINFOFLAGS): Prepend the build directory to
diff --git a/bfd/elfxx-sparc.c b/bfd/elfxx-sparc.c
index 71061621e8b..1cf280f050f 100644
--- a/bfd/elfxx-sparc.c
+++ b/bfd/elfxx-sparc.c
@@ -1426,6 +1426,16 @@ _bfd_sparc_elf_check_relocs (bfd *abfd, struct bfd_link_info *info,
 	  h->plt.refcount += 1;
 	}
 
+      /* If a relocation refers to _GLOBAL_OFFSET_TABLE_, create the .got.  */
+      if (h != NULL
+	  && htab->elf.sgot == NULL
+	  && strcmp (h->root.root.string, "_GLOBAL_OFFSET_TABLE_") == 0)
+	{
+	  if (!_bfd_elf_create_got_section (htab->elf.dynobj, info))
+	    return false;
+	  BFD_ASSERT (h == htab->elf.hgot);
+	}
+
       /* Compatibility with old R_SPARC_REV32 reloc conflicting
 	 with R_SPARC_TLS_GD_HI22.  */
       if (! ABI_64_P (abfd) && ! checked_tlsgd)
@@ -1645,8 +1655,7 @@ _bfd_sparc_elf_check_relocs (bfd *abfd, struct bfd_link_info *info,
 	  if (h != NULL)
 	    h->non_got_ref = 1;
 
-	  if (h != NULL
-	      && strcmp (h->root.root.string, "_GLOBAL_OFFSET_TABLE_") == 0)
+	  if (h != NULL && h == htab->elf.hgot)
 	    break;
 	  /* Fall through.  */
 
@@ -3252,8 +3261,7 @@ _bfd_sparc_elf_relocate_section (bfd *output_bfd,
 	case R_SPARC_PC_HH22:
 	case R_SPARC_PC_HM10:
 	case R_SPARC_PC_LM22:
-	  if (h != NULL
-	      && strcmp (h->root.root.string, "_GLOBAL_OFFSET_TABLE_") == 0)
+	  if (h != NULL && h == htab->elf.hgot)
 	    break;
 	  /* Fall through.  */
 	case R_SPARC_DISP8:
diff --git a/ld/ChangeLog b/ld/ChangeLog
index 7b47a4d8ec4..69dad59018f 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,8 @@
+2025-02-08  Alexandre Oliva <oliva@adacore.com>
+
+	* testsuite/ld-sparc/got-def.s: New test.
+	* testsuite/ld-sparc/sparc.exp: Add it.
+
 2025-01-19  Nick Clifton  <nickc@redhat.com>
 
 	* 2.44 Branch point.
diff --git a/ld/testsuite/ld-sparc/got-def.s b/ld/testsuite/ld-sparc/got-def.s
new file mode 100644
index 00000000000..efca9109dfc
--- /dev/null
+++ b/ld/testsuite/ld-sparc/got-def.s
@@ -0,0 +1,15 @@
+	.text
+.LLGETPC0:
+	retl
+	 add	%o7, %l7, %l7
+	.global got
+	.type got, #function
+	.proc   04
+got:
+	save    %sp, -160, %sp
+	sethi	%hi(_GLOBAL_OFFSET_TABLE_-4), %l7
+	call	.LLGETPC0
+	 add	%l7, %lo(_GLOBAL_OFFSET_TABLE_+4), %l7
+	mov	%l7, %o0
+	ret
+	 restore
diff --git a/ld/testsuite/ld-sparc/sparc.exp b/ld/testsuite/ld-sparc/sparc.exp
index 9d684899ee2..3e21ed738c4 100644
--- a/ld/testsuite/ld-sparc/sparc.exp
+++ b/ld/testsuite/ld-sparc/sparc.exp
@@ -94,6 +94,10 @@ set sparctests {
     {"32-bit: TLS -fpie" "-melf32_sparc -pie tmpdir/libtlslib32.so" ""
      "--32 -K PIC" {tlspie32.s}
      {{objdump -drj.text tlspie32.dd}} "tlspie32"}
+    {"32-bit: GOT definition"
+     "-melf32_sparc" ""
+     "--32 -K PIC" {got-def.s}
+     {} "got-def"}
     {"32-bit: GOTDATA relocations"
      "-shared -melf32_sparc --hash-style=sysv" ""
      "--32 -K PIC" {gotop32.s}
@@ -134,6 +138,10 @@ set sparc64tests {
      "-melf64_sparc -pie -Ttext-segment=0x100000 tmpdir/libtlslib64.so" ""
      "--64 -Av9 -K PIC" {tlspie64.s}
      {{objdump -drj.text tlspie64.dd}} "tlspie64"}
+    {"64-bit: GOT definition"
+     "-melf64_sparc" ""
+     "--64 -Av9 -K PIC" {got-def.s}
+     {} "got-def"}
     {"64-bit: GOTDATA relocations"
      "-shared -melf64_sparc --hash-style=sysv" ""
      "--64 -Av9 -K PIC" {gotop64.s}