From: Alan Modra <amodra@gmail.com>
Date: Sat, 3 Jan 2026 03:21:21 +0000 (+1030)
Subject: ELF OSABI matching
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ef6aff2be44b172a874df036c7d270301b47005a;p=thirdparty%2Fbinutils-gdb.git

ELF OSABI matching

Currently a binutils ELF target with ELF_OSABI defined to something
other than the default ELFOSABI_NONE will only accept object files
with e_ident[EI_OSABI] having the value ELF_OSABI.  An ELF target with
ELF_OSABI as ELFOSABI_NONE will match any e_ident[EI_OSABI] value, and
typically that target's object files will have ELFOSABI_NONE or one
other value in e_ident[EI_OSABI].  Given an object file with that
"other value" we'd like to be able to choose the correct target but
currently have no way to do so.  This patch is a step towards
implementing better target matching.

It does so by adding an ELF_OSABI_EXACT to the target description,
setting that true for all targets that currently define ELF_OSABI, and
testing the new flag for exact matching.  This will allow a future
patch to define ELF_OSABI without forcing exact matching but giving a
hint as to the best target match.

Some other tweaks are done as shown by the changelog below but no
user functional changes should be seen with this patch.

	* elf-bfd.h (struct elf_backend_data): Add osabi_exact.
	* elf.c (_bfd_elf_final_write_processing): Only set e_ident
	from elf_osabi when osabi_exact.
	* elfcode.h (elf_object_p): Test osabi_exact to reject
	mismatching e_ident.  Remove unnecessary EM_NONE test.
	* elfcore.h (elf_core_file_p): Likewise.
	* elfxx-target.h (ELF_OSABI_EXACT): Provide default of 0,
	and init elfNN_bed.
	(elf_match_priority): Handle ELF_OSABI_EXACT.
	* elf32-arm.c (ELF_OSABI_EXACT): Define and undef along with
	ELF_OSABI.
	* elf32-hppa.c: Likewise.
	* elf32-i386.c: Likewise.
	* elf32-mips.c: Likewise.
	* elf32-ppc.c: Likewise.
	* elf32-tic6x.c: Likewise.
	* elf32-visium.c: Likewise.
	* elf64-alpha.c: Likewise.
	* elf64-hppa.c: Likewise.
	* elf64-ia64-vms.c: Likewise.
	* elf64-mips.c: Likewise.
	* elf64-ppc.c: Likewise.
	* elf64-sparc.c: Likewise.
	* elf64-x86-64.c: Likewise.
	* elfn32-mips.c: Likewise.
	* elfnn-ia64.c: Likewise.
	* elf32-msp430.c: Likewise.  Don't define ELF_OSABI to
	ELFOSABI_NONE.
---

diff --git a/bfd/elf-bfd.h b/bfd/elf-bfd.h
index efe40e10605..b2aeb2ba0ca 100644
--- a/bfd/elf-bfd.h
+++ b/bfd/elf-bfd.h
@@ -1023,6 +1023,10 @@ struct elf_backend_data
   /* Target OS.  */
   ENUM_BITFIELD (elf_target_os) target_os : 2;
 
+  /* True if object files must have exactly matching osabi.  False if
+     other osabi values are allowed.  */
+  unsigned osabi_exact : 1;
+
   /* The maximum page size for this backend.  */
   unsigned maxpagesize;
 
diff --git a/bfd/elf.c b/bfd/elf.c
index d2cf2bb4b9c..8b6dd3ce370 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -13486,7 +13486,7 @@ _bfd_elf_final_write_processing (bfd *abfd)
   Elf_Internal_Ehdr *i_ehdrp = elf_elfheader (abfd);
   elf_backend_data *bed = get_elf_backend_data (abfd);
 
-  if (i_ehdrp->e_ident[EI_OSABI] == ELFOSABI_NONE)
+  if (bed->osabi_exact && i_ehdrp->e_ident[EI_OSABI] == ELFOSABI_NONE)
     i_ehdrp->e_ident[EI_OSABI] = bed->elf_osabi;
 
   if (i_ehdrp->e_ident[EI_OSABI] == ELFOSABI_SOLARIS
diff --git a/bfd/elf32-arm.c b/bfd/elf32-arm.c
index 9465efc5953..e0573d53ef0 100644
--- a/bfd/elf32-arm.c
+++ b/bfd/elf32-arm.c
@@ -20277,6 +20277,8 @@ elf32_arm_backend_symbol_processing (bfd *abfd, asymbol *sym)
 #define elf_match_priority		128
 #undef ELF_OSABI
 #define ELF_OSABI		ELFOSABI_ARM_FDPIC
+#undef ELF_OSABI_EXACT
+#define ELF_OSABI_EXACT		1
 
 /* Like elf32_arm_link_hash_table_create -- but overrides
    appropriately for FDPIC.  */
@@ -20335,6 +20337,7 @@ elf32_arm_fdpic_omit_section_dynsym (bfd *output_bfd ATTRIBUTE_UNUSED,
 
 #undef elf_match_priority
 #undef ELF_OSABI
+#undef ELF_OSABI_EXACT
 #undef elf_backend_omit_section_dynsym
 
 /* VxWorks Targets.  */
diff --git a/bfd/elf32-hppa.c b/bfd/elf32-hppa.c
index 260844985d3..e3aa67c3fc6 100644
--- a/bfd/elf32-hppa.c
+++ b/bfd/elf32-hppa.c
@@ -4539,6 +4539,7 @@ elf32_hppa_elf_get_symbol_type (Elf_Internal_Sym *elf_sym, int type)
 #define ELF_MACHINE_CODE	EM_PARISC
 #define ELF_MAXPAGESIZE		0x1000
 #define ELF_OSABI		ELFOSABI_HPUX
+#define ELF_OSABI_EXACT		1
 #define elf32_bed		elf32_hppa_hpux_bed
 
 #include "elf32-target.h"
diff --git a/bfd/elf32-i386.c b/bfd/elf32-i386.c
index a367fd9f6f0..be8c676c833 100644
--- a/bfd/elf32-i386.c
+++ b/bfd/elf32-i386.c
@@ -4617,6 +4617,8 @@ elf_i386_add_glibc_version_dependency
 #define	TARGET_LITTLE_NAME		"elf32-i386-freebsd"
 #undef	ELF_OSABI
 #define	ELF_OSABI			ELFOSABI_FREEBSD
+#undef	ELF_OSABI_EXACT
+#define	ELF_OSABI_EXACT			1
 
 /* The kernel recognizes executables as valid only if they carry a
    "FreeBSD" label in the ELF header.  So we put this label on all
@@ -4665,6 +4667,7 @@ elf_i386_fbsd_init_file_header (bfd *abfd, struct bfd_link_info *info)
 /* Restore default: we cannot use ELFOSABI_SOLARIS, otherwise ELFOSABI_NONE
    objects won't be recognized.  */
 #undef ELF_OSABI
+#undef ELF_OSABI_EXACT
 
 #undef	elf32_bed
 #define	elf32_bed			elf32_i386_sol2_bed
@@ -4708,6 +4711,7 @@ elf32_iamcu_elf_object_p (bfd *abfd)
 
 #undef	ELF_TARGET_OS
 #undef	ELF_OSABI
+#undef	ELF_OSABI_EXACT
 
 #undef  elf32_bed
 #define elf32_bed			elf32_iamcu_bed
@@ -4735,7 +4739,6 @@ elf32_iamcu_elf_object_p (bfd *abfd)
 #define TARGET_LITTLE_SYM		i386_elf32_vxworks_vec
 #undef	TARGET_LITTLE_NAME
 #define TARGET_LITTLE_NAME		"elf32-i386-vxworks"
-#undef	ELF_OSABI
 #undef	ELF_MAXPAGESIZE
 #define ELF_MAXPAGESIZE			0x1000
 #undef	elf_backend_plt_alignment
@@ -4743,6 +4746,8 @@ elf32_iamcu_elf_object_p (bfd *abfd)
 
 #undef	ELF_TARGET_OS
 #define ELF_TARGET_OS		is_vxworks
+#undef	ELF_OSABI
+#undef	ELF_OSABI_EXACT
 
 #undef elf_backend_relocs_compatible
 #undef elf_backend_add_symbol_hook
diff --git a/bfd/elf32-mips.c b/bfd/elf32-mips.c
index 1df60bda04b..12a95b08ff8 100644
--- a/bfd/elf32-mips.c
+++ b/bfd/elf32-mips.c
@@ -4165,6 +4165,8 @@ static const struct ecoff_debug_swap mips_elf32_ecoff_debug_swap = {
 
 #undef	ELF_OSABI
 #define	ELF_OSABI			ELFOSABI_FREEBSD
+#undef	ELF_OSABI_EXACT
+#define	ELF_OSABI_EXACT			1
 
 #undef	elf32_bed
 #define elf32_bed				elf32_fbsd_tradbed
@@ -4194,6 +4196,7 @@ mips_vxworks_final_write_processing (bfd *abfd)
 #define TARGET_BIG_SYM			mips_elf32_vxworks_be_vec
 #define TARGET_BIG_NAME			"elf32-bigmips-vxworks"
 #undef	ELF_OSABI
+#undef	ELF_OSABI_EXACT
 
 #undef elf32_bed
 #define elf32_bed			elf32_mips_vxworks_bed
diff --git a/bfd/elf32-msp430.c b/bfd/elf32-msp430.c
index cb83f5692be..d7d7730063f 100644
--- a/bfd/elf32-msp430.c
+++ b/bfd/elf32-msp430.c
@@ -2953,6 +2953,7 @@ elf32_msp430_eh_frame_address_size (bfd *abfd,
 #define ELF_MACHINE_ALT1	EM_MSP430_OLD
 #define ELF_MAXPAGESIZE		4
 #define	ELF_OSABI		ELFOSABI_STANDALONE
+#define ELF_OSABI_EXACT		1
 
 #define TARGET_LITTLE_SYM	msp430_elf32_vec
 #define TARGET_LITTLE_NAME	"elf32-msp430"
@@ -2980,7 +2981,7 @@ elf32_msp430_eh_frame_address_size (bfd *abfd,
 #define elf32_bed		elf32_msp430_ti_bed
 
 #undef	ELF_OSABI
-#define	ELF_OSABI		ELFOSABI_NONE
+#undef	ELF_OSABI_EXACT
 
 static const struct bfd_elf_special_section msp430_ti_elf_special_sections[] =
 {
diff --git a/bfd/elf32-ppc.c b/bfd/elf32-ppc.c
index ecbdb91c667..ba9e59ab3b9 100644
--- a/bfd/elf32-ppc.c
+++ b/bfd/elf32-ppc.c
@@ -10433,6 +10433,8 @@ ppc_elf_finish_dynamic_sections (bfd *output_bfd,
 
 #undef  ELF_OSABI
 #define ELF_OSABI	ELFOSABI_FREEBSD
+#undef	ELF_OSABI_EXACT
+#define	ELF_OSABI_EXACT	1
 
 #undef  elf32_bed
 #define elf32_bed	elf32_powerpc_fbsd_bed
@@ -10450,6 +10452,7 @@ ppc_elf_finish_dynamic_sections (bfd *output_bfd,
 #define TARGET_BIG_NAME		"elf32-powerpc-vxworks"
 
 #undef  ELF_OSABI
+#undef	ELF_OSABI_EXACT
 
 #undef ELF_TARGET_OS
 #define ELF_TARGET_OS		is_vxworks
diff --git a/bfd/elf32-tic6x.c b/bfd/elf32-tic6x.c
index c776f31092e..d5f1259d1f4 100644
--- a/bfd/elf32-tic6x.c
+++ b/bfd/elf32-tic6x.c
@@ -4285,6 +4285,8 @@ elf32_tic6x_write_section (bfd *output_bfd,
 #define	TARGET_BIG_NAME			"elf32-tic6x-linux-be"
 #undef ELF_OSABI
 #define	ELF_OSABI			ELFOSABI_C6000_LINUX
+#undef ELF_OSABI_EXACT
+#define ELF_OSABI_EXACT			1
 
 #include "elf32-target.h"
 
@@ -4301,5 +4303,7 @@ elf32_tic6x_write_section (bfd *output_bfd,
 #define	TARGET_BIG_NAME			"elf32-tic6x-elf-be"
 #undef ELF_OSABI
 #define	ELF_OSABI			ELFOSABI_C6000_ELFABI
+#undef ELF_OSABI_EXACT
+#define ELF_OSABI_EXACT			1
 
 #include "elf32-target.h"
diff --git a/bfd/elf32-visium.c b/bfd/elf32-visium.c
index 1771c444c22..7f28c81fda3 100644
--- a/bfd/elf32-visium.c
+++ b/bfd/elf32-visium.c
@@ -852,6 +852,7 @@ visium_elf_print_private_bfd_data (bfd *abfd, void *ptr)
 #define ELF_ARCH		bfd_arch_visium
 #define ELF_MACHINE_CODE	EM_VISIUM
 #define ELF_OSABI		ELFOSABI_STANDALONE
+#define	ELF_OSABI_EXACT		1
 #define ELF_MAXPAGESIZE		1
 
 #define TARGET_BIG_SYM		visium_elf32_vec
diff --git a/bfd/elf64-alpha.c b/bfd/elf64-alpha.c
index 71b2cb4e57d..199505d17a5 100644
--- a/bfd/elf64-alpha.c
+++ b/bfd/elf64-alpha.c
@@ -5499,6 +5499,8 @@ static const struct elf_size_info alpha_elf_size_info =
 #define TARGET_LITTLE_NAME	"elf64-alpha-freebsd"
 #undef	ELF_OSABI
 #define	ELF_OSABI		ELFOSABI_FREEBSD
+#undef	ELF_OSABI_EXACT
+#define	ELF_OSABI_EXACT		1
 
 /* The kernel recognizes executables as valid only if they carry a
    "FreeBSD" label in the ELF header.  So we put this label on all
diff --git a/bfd/elf64-hppa.c b/bfd/elf64-hppa.c
index d0bc3c33d68..2df62923ee5 100644
--- a/bfd/elf64-hppa.c
+++ b/bfd/elf64-hppa.c
@@ -4166,6 +4166,7 @@ static const struct elf_size_info hppa64_elf_size_info =
    64M.  But everything still uses 4k.  */
 #define ELF_MAXPAGESIZE			0x1000
 #define ELF_OSABI			ELFOSABI_HPUX
+#define ELF_OSABI_EXACT			1
 
 #define bfd_elf64_bfd_reloc_type_lookup elf_hppa_reloc_type_lookup
 #define bfd_elf64_bfd_reloc_name_lookup elf_hppa_reloc_name_lookup
diff --git a/bfd/elf64-ia64-vms.c b/bfd/elf64-ia64-vms.c
index bdd1b5b9753..4403688ec96 100644
--- a/bfd/elf64-ia64-vms.c
+++ b/bfd/elf64-ia64-vms.c
@@ -5568,6 +5568,8 @@ static const struct elf_size_info elf64_ia64_vms_size_info = {
 
 #undef  ELF_OSABI
 #define ELF_OSABI			ELFOSABI_OPENVMS
+#undef	ELF_OSABI_EXACT
+#define	ELF_OSABI_EXACT			1
 
 #undef  ELF_MAXPAGESIZE
 #define ELF_MAXPAGESIZE			0x10000	/* 64KB */
diff --git a/bfd/elf64-mips.c b/bfd/elf64-mips.c
index 26e3c602bba..8824214f18a 100644
--- a/bfd/elf64-mips.c
+++ b/bfd/elf64-mips.c
@@ -4868,6 +4868,8 @@ static const struct elf_size_info mips_elf64_size_info =
 
 #undef	ELF_OSABI
 #define	ELF_OSABI			ELFOSABI_FREEBSD
+#undef	ELF_OSABI_EXACT
+#define	ELF_OSABI_EXACT			1
 
 #undef	elf64_bed
 #define elf64_bed				elf64_fbsd_tradbed
diff --git a/bfd/elf64-ppc.c b/bfd/elf64-ppc.c
index be41efe10bd..7e41085ed91 100644
--- a/bfd/elf64-ppc.c
+++ b/bfd/elf64-ppc.c
@@ -18451,6 +18451,8 @@ ppc64_elf_free_cached_info (bfd *abfd)
 
 #undef  ELF_OSABI
 #define	ELF_OSABI       ELFOSABI_FREEBSD
+#undef	ELF_OSABI_EXACT
+#define	ELF_OSABI_EXACT 1
 
 #undef  elf64_bed
 #define elf64_bed	elf64_powerpc_fbsd_bed
diff --git a/bfd/elf64-sparc.c b/bfd/elf64-sparc.c
index 06c4e492ff8..cf0826f52b8 100644
--- a/bfd/elf64-sparc.c
+++ b/bfd/elf64-sparc.c
@@ -994,6 +994,8 @@ static const struct elf_size_info elf64_sparc_size_info =
 #define TARGET_BIG_NAME "elf64-sparc-freebsd"
 #undef	ELF_OSABI
 #define	ELF_OSABI ELFOSABI_FREEBSD
+#undef	ELF_OSABI_EXACT
+#define	ELF_OSABI_EXACT 1
 
 #undef  elf64_bed
 #define elf64_bed				elf64_sparc_fbsd_bed
@@ -1013,6 +1015,7 @@ static const struct elf_size_info elf64_sparc_size_info =
 /* Restore default: we cannot use ELFOSABI_SOLARIS, otherwise ELFOSABI_NONE
    objects won't be recognized.  */
 #undef	ELF_OSABI
+#undef	ELF_OSABI_EXACT
 
 #undef  elf64_bed
 #define elf64_bed				elf64_sparc_sol2_bed
diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c
index 72a828a8c13..47d24e0e776 100644
--- a/bfd/elf64-x86-64.c
+++ b/bfd/elf64-x86-64.c
@@ -6426,6 +6426,8 @@ elf_x86_64_special_sections[]=
 
 #undef	ELF_OSABI
 #define	ELF_OSABI			    ELFOSABI_FREEBSD
+#undef	ELF_OSABI_EXACT
+#define	ELF_OSABI_EXACT			    1
 
 #undef	elf64_bed
 #define elf64_bed elf64_x86_64_fbsd_bed
@@ -6448,6 +6450,7 @@ elf_x86_64_special_sections[]=
 /* Restore default: we cannot use ELFOSABI_SOLARIS, otherwise ELFOSABI_NONE
    objects won't be recognized.  */
 #undef ELF_OSABI
+#undef ELF_OSABI_EXACT
 
 #undef  elf64_bed
 #define elf64_bed			    elf64_x86_64_sol2_bed
@@ -6468,6 +6471,7 @@ elf_x86_64_special_sections[]=
 
 /* Restore defaults.  */
 #undef	ELF_OSABI
+#undef	ELF_OSABI_EXACT
 #undef	elf_backend_static_tls_alignment
 #undef	elf_backend_want_plt_sym
 #define elf_backend_want_plt_sym	0
@@ -6489,6 +6493,7 @@ elf_x86_64_special_sections[]=
 
 #undef	ELF_TARGET_OS
 #undef	ELF_OSABI
+#undef	ELF_OSABI_EXACT
 
 #define bfd_elf32_bfd_copy_private_section_data \
   elf_x86_64_copy_private_section_data
diff --git a/bfd/elfcode.h b/bfd/elfcode.h
index 3fde79c9c53..d7c82f0797c 100644
--- a/bfd/elfcode.h
+++ b/bfd/elfcode.h
@@ -628,9 +628,7 @@ elf_object_p (bfd *abfd)
 	goto got_no_match;
     }
 
-  if (ebd->elf_machine_code != EM_NONE
-      && i_ehdrp->e_ident[EI_OSABI] != ebd->elf_osabi
-      && ebd->elf_osabi != ELFOSABI_NONE)
+  if (ebd->osabi_exact && i_ehdrp->e_ident[EI_OSABI] != ebd->elf_osabi)
     goto got_wrong_format_error;
 
   if (i_ehdrp->e_shoff >= sizeof (x_ehdr))
diff --git a/bfd/elfcore.h b/bfd/elfcore.h
index c570479c2ac..7932faff287 100644
--- a/bfd/elfcore.h
+++ b/bfd/elfcore.h
@@ -152,9 +152,7 @@ elf_core_file_p (bfd *abfd)
       && ebd->elf_machine_code != EM_NONE)
     goto wrong;
 
-  if (ebd->elf_machine_code != EM_NONE
-      && i_ehdrp->e_ident[EI_OSABI] != ebd->elf_osabi
-      && ebd->elf_osabi != ELFOSABI_NONE)
+  if (ebd->osabi_exact && i_ehdrp->e_ident[EI_OSABI] != ebd->elf_osabi)
     goto wrong;
 
   /* If there is no program header, or the type is not a core file, then
diff --git a/bfd/elfn32-mips.c b/bfd/elfn32-mips.c
index 97c859f7d25..a23333765a6 100644
--- a/bfd/elfn32-mips.c
+++ b/bfd/elfn32-mips.c
@@ -4254,6 +4254,8 @@ static const struct ecoff_debug_swap mips_elf32_ecoff_debug_swap = {
 
 #undef	ELF_OSABI
 #define	ELF_OSABI			ELFOSABI_FREEBSD
+#undef	ELF_OSABI_EXACT
+#define	ELF_OSABI_EXACT			1
 
 #undef	elf32_bed
 #define elf32_bed				elf32_fbsd_tradbed
diff --git a/bfd/elfnn-ia64.c b/bfd/elfnn-ia64.c
index fd1ac180b06..03a31f41beb 100644
--- a/bfd/elfnn-ia64.c
+++ b/bfd/elfnn-ia64.c
@@ -5108,6 +5108,8 @@ ignore_errors (const char *fmt ATTRIBUTE_UNUSED, ...)
 #undef ELF_COMMONPAGESIZE
 #undef ELF_OSABI
 #define ELF_OSABI			ELFOSABI_HPUX
+#undef ELF_OSABI_EXACT
+#define ELF_OSABI_EXACT			1
 
 #undef  elfNN_bed
 #define elfNN_bed elfNN_ia64_hpux_bed
diff --git a/bfd/elfxx-target.h b/bfd/elfxx-target.h
index 88f8a041ea8..48fb3082e8e 100644
--- a/bfd/elfxx-target.h
+++ b/bfd/elfxx-target.h
@@ -368,6 +368,10 @@
 #define ELF_OSABI ELFOSABI_NONE
 #endif
 
+#ifndef ELF_OSABI_EXACT
+#define ELF_OSABI_EXACT 0
+#endif
+
 #ifndef ELF_MAXPAGESIZE
 # error ELF_MAXPAGESIZE is not defined
 #define ELF_MAXPAGESIZE 1
@@ -799,7 +803,9 @@
  
 #ifndef elf_match_priority
 #define elf_match_priority \
-  (ELF_ARCH == bfd_arch_unknown ? 2 : ELF_OSABI == ELFOSABI_NONE ? 1 : 0)
+  (ELF_ARCH == bfd_arch_unknown ? 2 \
+   : ELF_OSABI == ELFOSABI_NONE || !ELF_OSABI_EXACT ? 1 \
+   : 0)
 #endif
 
 extern const struct elf_size_info _bfd_elfNN_size_info ATTRIBUTE_HIDDEN;
@@ -811,6 +817,7 @@ static const struct elf_backend_data elfNN_bed =
   ELF_MACHINE_CODE,
   ELF_TARGET_ID,
   ELF_TARGET_OS,
+  ELF_OSABI_EXACT,
   ELF_MAXPAGESIZE,
   ELF_MINPAGESIZE,
   ELF_COMMONPAGESIZE,