[PATCH v0 02/15] Build attributes: add new abstractions for subsections and attributes
Matthieu Longo
matthieu.longo@arm.com
Mon Mar 10 17:51:15 GMT 2025
From: Richard Ball <richard.ball@arm.com>
Co-Authored-By: Matthieu Longo <matthieu.longo@arm.com>
---
bfd/Makefile.am | 2 +-
bfd/Makefile.in | 2 +-
bfd/elf-attrs.c | 209 +++++++++++++++++++++++++++++++++++++++++
bfd/elf-attrs.h | 102 ++++++++++++++++++++
bfd/elf-bfd.h | 42 ++++++++-
bfd/elfnn-aarch64.c | 13 +++
bfd/elfxx-target.h | 6 +-
bfd/po/SRC-POTFILES.in | 1 +
8 files changed, 372 insertions(+), 5 deletions(-)
create mode 100644 bfd/elf-attrs.h
diff --git a/bfd/Makefile.am b/bfd/Makefile.am
index 4987ac9cccc..0339db6b2b6 100644
--- a/bfd/Makefile.am
+++ b/bfd/Makefile.am
@@ -707,7 +707,7 @@ SOURCE_HFILES = \
elf32-metag.h elf32-nds32.h elf32-ppc.h \
elf32-rx.h elf32-score.h elf32-sh-relocs.h elf32-spu.h \
elf32-tic6x.h elf32-tilegx.h elf32-tilepro.h elf32-v850.h \
- elf64-hppa.h elf64-ppc.h elf64-tilegx.h \
+ elf64-hppa.h elf64-ppc.h elf64-tilegx.h elf-attrs.h \
elf-bfd.h elfcode.h elfcore.h elf-hppa.h elf-linker-x86.h \
elf-linux-core.h elf-nacl.h elf-s390.h elf-vxworks.h \
elfxx-aarch64.h elfxx-ia64.h elfxx-mips.h elfxx-riscv.h \
diff --git a/bfd/Makefile.in b/bfd/Makefile.in
index 1543af7984a..ecc91d733af 100644
--- a/bfd/Makefile.in
+++ b/bfd/Makefile.in
@@ -1171,7 +1171,7 @@ SOURCE_HFILES = \
elf32-metag.h elf32-nds32.h elf32-ppc.h \
elf32-rx.h elf32-score.h elf32-sh-relocs.h elf32-spu.h \
elf32-tic6x.h elf32-tilegx.h elf32-tilepro.h elf32-v850.h \
- elf64-hppa.h elf64-ppc.h elf64-tilegx.h \
+ elf64-hppa.h elf64-ppc.h elf64-tilegx.h elf-attrs.h \
elf-bfd.h elfcode.h elfcore.h elf-hppa.h elf-linker-x86.h \
elf-linux-core.h elf-nacl.h elf-s390.h elf-vxworks.h \
elfxx-aarch64.h elfxx-ia64.h elfxx-mips.h elfxx-riscv.h \
diff --git a/bfd/elf-attrs.c b/bfd/elf-attrs.c
index a6a72369afd..634843b5162 100644
--- a/bfd/elf-attrs.c
+++ b/bfd/elf-attrs.c
@@ -20,6 +20,7 @@
#include "sysdep.h"
#include "bfd.h"
+#include "double-linked-list.h"
#include "libiberty.h"
#include "libbfd.h"
#include "elf-bfd.h"
@@ -476,6 +477,19 @@ gnu_obj_attrs_arg_type (unsigned int tag)
int
_bfd_elf_obj_attrs_arg_type (bfd *abfd, int vendor, unsigned int tag)
{
+ if (get_elf_backend_data (abfd)->obj_attrs_version == 2)
+ {
+ BFD_ASSERT (elf_obj_attr_subsections (abfd).last_ != NULL);
+ switch (elf_obj_attr_subsections (abfd).last_->encoding)
+ {
+ case ULEB128:
+ return ATTR_TYPE_FLAG_INT_VAL;
+ case NTBS:
+ return ATTR_TYPE_FLAG_STR_VAL;
+ }
+ }
+
+ /* Version 1. */
switch (vendor)
{
case OBJ_ATTR_PROC:
@@ -822,6 +836,201 @@ _bfd_elf_merge_unknown_attribute_list (bfd *ibfd, bfd *obfd)
return result;
}
+obj_attr_v2 *
+_bfd_elf_obj_attr_v2_init (unsigned int tag,
+ union obj_attr_value_v2 vals)
+{
+ obj_attr_v2 *attr = (obj_attr_v2*) malloc (sizeof (obj_attr_v2));
+ memset ((void *) attr, 0, sizeof (obj_attr_v2));
+ attr->tag = tag;
+ attr->vals = vals;
+ return attr;
+}
+
+void
+_bfd_elf_obj_attr_v2_free (obj_attr_v2 * attr, obj_attr_encoding_v2 encoding)
+{
+ if (encoding == NTBS && attr->vals.string_val != NULL)
+ free ((void *) attr->vals.string_val);
+ free (attr);
+}
+
+obj_attr_v2 *
+_bfd_elf_obj_attr_v2_copy (obj_attr_v2 *other,
+ obj_attr_encoding_v2 encoding)
+{
+ union obj_attr_value_v2 vals;
+ if (encoding == NTBS)
+ vals.string_val =
+ (other->vals.string_val != NULL)
+ ? strdup (other->vals.string_val)
+ : NULL;
+ else
+ vals.uint_val = other->vals.uint_val;
+
+ obj_attr_v2 *copy =_bfd_elf_obj_attr_v2_init (other->tag, vals);
+ copy->status = other->status;
+ return copy;
+}
+
+#define SWAP(a, b) do { typeof(a) temp = a; a = b; b = temp; } while (0)
+
+void
+_bfd_elf_obj_attr_v2_swap (obj_attr_subsection_v2 *s,
+ obj_attr_v2 *a1, obj_attr_v2 *a2)
+{
+ SWAP (a1->next, a2->next);
+ SWAP (a1->prev, a2->prev);
+
+ if (s->first_ == a1)
+ s->first_ = a2;
+ else if (s->first_ == a2)
+ s->first_ = a1;
+
+ if (s->last_ == a1)
+ s->last_ = a2;
+ else if (s->last_ == a2)
+ s->last_ = a1;
+}
+
+int
+_bfd_elf_obj_attr_v2_cmp (obj_attr_v2 *a1, obj_attr_v2 *a2)
+{
+ if (a1->tag < a2->tag)
+ return -1;
+ else if (a1->tag > a2->tag)
+ return 1;
+ else
+ return 0;
+}
+
+/* Find the object attribute matching the given tag (object attributes v2 only).
+ Note: The parameter 'sorted' specifies whether the given list is sorted or
+ not. If the list of attributes is sorted, the linear search stops as soon as
+ it finds an attribute with a greater tag. */
+obj_attr_v2 *
+obj_attr_v2_find_by_tag (obj_attr_subsection_v2 *subsec,
+ uint32_t tag,
+ bool sorted)
+{
+ for (obj_attr_v2 *attr = subsec->first_;
+ attr != NULL;
+ attr = attr->next)
+ if (attr->tag == tag)
+ return attr;
+ else if (sorted && attr->tag > tag)
+ break;
+ return NULL;
+}
+
+LINKED_LIST_MUTATIVE_OPS_DECL(obj_attr_subsection_v2, obj_attr_v2, /* public */)
+LINKED_LIST_MERGE_SORT_DECL(obj_attr_subsection_v2, obj_attr_v2, /* public */)
+
+obj_attr_subsection_v2 *
+_bfd_elf_obj_attr_subsection_v2_init (const char* name,
+ obj_attr_subsection_scope_v2 scope,
+ bool optional,
+ obj_attr_encoding_v2 encoding)
+{
+ obj_attr_subsection_v2* subsection = (obj_attr_subsection_v2*)
+ malloc (sizeof (obj_attr_subsection_v2));
+ memset ((void *) subsection, 0, sizeof (obj_attr_subsection_v2));
+ subsection->name = name;
+ subsection->scope = scope;
+ subsection->optional = optional;
+ subsection->encoding = encoding;
+ return subsection;
+}
+
+void
+_bfd_elf_obj_attr_subsection_v2_free (obj_attr_subsection_v2 *subsec)
+{
+ for (obj_attr_v2 *attr = subsec->first_; attr != NULL; attr = attr->next)
+ _bfd_elf_obj_attr_v2_free (attr, subsec->encoding);
+ free (subsec);
+}
+
+obj_attr_subsection_v2 *
+_bfd_elf_obj_attr_subsection_v2_copy (obj_attr_subsection_v2 const *other)
+{
+ obj_attr_subsection_v2* new_subsec =
+ _bfd_elf_obj_attr_subsection_v2_init (other->name, other->scope,
+ other->optional, other->encoding);
+ for (obj_attr_v2* attr = other->first_;
+ attr != NULL;
+ attr = attr->next)
+ {
+ obj_attr_v2* new_attr = _bfd_elf_obj_attr_v2_copy (attr, other->encoding);
+ LINKED_LIST_APPEND(obj_attr_v2) (new_subsec, new_attr);
+ }
+ return new_subsec;
+}
+
+void
+_bfd_elf_obj_attr_subsection_v2_swap (obj_attr_subsection_list *plist,
+ obj_attr_subsection_v2 *s1,
+ obj_attr_subsection_v2 *s2)
+{
+ SWAP (s1->next, s2->next);
+ SWAP (s1->prev, s2->prev);
+
+ if (plist->first_ == s1)
+ plist->first_ = s2;
+ else if (plist->first_ == s2)
+ plist->first_ = s1;
+
+ if (plist->last_ == s1)
+ plist->last_ = s2;
+ else if (plist->last_ == s2)
+ plist->last_ = s1;
+}
+
+int
+_bfd_elf_obj_attr_subsection_v2_cmp (obj_attr_subsection_v2 *s1,
+ obj_attr_subsection_v2 *s2)
+{
+ int res = strcmp (s1->name, s2->name);
+ if (res != 0)
+ return res;
+
+ if (s1->optional < s2->optional)
+ return -1;
+ else if (s1->optional > s2->optional)
+ return 1;
+
+ if (s1->encoding < s2->encoding)
+ return -1;
+ if (s1->encoding > s2->encoding)
+ return 1;
+ else
+ return 0;
+}
+
+/* Find the subsection matching the given name.
+ Note: The parameter sorted specified whether the given list is sorted or not.
+ If the list of subsections is sorted, the linear search stops as soon as it
+ finds a subsection name with a greater order. */
+obj_attr_subsection_v2 *
+obj_attr_subsection_v2_find_by_name (obj_attr_subsection_v2 *first,
+ const char *name,
+ bool sorted)
+{
+ for (obj_attr_subsection_v2 *s = first;
+ s != NULL;
+ s = s->next)
+ {
+ int cmp = strcmp (s->name, name);
+ if (cmp == 0)
+ return s;
+ else if (sorted && cmp > 0)
+ break;
+ }
+ return NULL;
+}
+
+LINKED_LIST_MUTATIVE_OPS_DECL(obj_attr_subsection_list, obj_attr_subsection_v2, /* public */)
+LINKED_LIST_MERGE_SORT_DECL(obj_attr_subsection_list, obj_attr_subsection_v2, /* public */)
+
bool _bfd_elf_write_section_build_attributes (bfd *abfd,
struct bfd_link_info *info ATTRIBUTE_UNUSED)
{
diff --git a/bfd/elf-attrs.h b/bfd/elf-attrs.h
new file mode 100644
index 00000000000..5d41bb98538
--- /dev/null
+++ b/bfd/elf-attrs.h
@@ -0,0 +1,102 @@
+/* ELF attributes support (based on ARM EABI attributes).
+ Copyright (C) 2025 Free Software Foundation, Inc.
+ Written by Cygnus Support.
+
+ This file is part of BFD, the Binary File Descriptor library.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+ MA 02110-1301, USA. */
+
+#pragma once
+
+#include <stdint.h>
+
+/* --------------------
+ Object attributes v2
+ -------------------- */
+
+typedef enum obj_attr_encoding_v2
+{
+ ULEB128 = 0,
+ NTBS = 1,
+} obj_attr_encoding_v2;
+
+typedef union obj_attr_value_v2 {
+ uint32_t uint_val;
+ const char* string_val;
+} obj_attr_value_v2;
+
+typedef struct obj_attr_v2 {
+ /* The name/tag of an attribute. */
+ uint32_t tag;
+
+ /* The value assigned to an attribute, can be ULEB128 or NTBS. */
+ union obj_attr_value_v2 vals;
+
+ /* The next attribute in the list or NULL. */
+ struct obj_attr_v2 *next;
+
+ /* The previous attribute in the list or NULL. */
+ struct obj_attr_v2 *prev;
+
+} obj_attr_v2;
+
+typedef enum obj_attr_subsection_scope_v2
+{
+ SUBSEC_PUBLIC = 0,
+ SUBSEC_PRIVATE = 1,
+} obj_attr_subsection_scope_v2;
+
+typedef struct obj_attr_subsection_v2 {
+ /* The name of the subsection. */
+ const char *name;
+
+ /* The scope of the subsection. */
+ obj_attr_subsection_scope_v2 scope;
+
+ /* Is this subsection optional ? Can it be skipped ? */
+ bool optional;
+
+ /* The value encoding of attributes in this subsection. */
+ obj_attr_encoding_v2 encoding;
+
+ /* The next subsection in the list, or NULL. */
+ struct obj_attr_subsection_v2 *next;
+
+ /* The previous subsection in the list, or NULL. */
+ struct obj_attr_subsection_v2 *prev;
+
+ /* A pointer to the first node of the list. */
+ struct obj_attr_v2* first_;
+
+ /* A pointer to the last node of the list. */
+ struct obj_attr_v2* last_;
+
+ /* The size of the list. */
+ uint32_t size;
+
+} obj_attr_subsection_v2;
+
+typedef struct obj_attr_subsection_list
+{
+ /* A pointer to the first node of the list. */
+ obj_attr_subsection_v2 *first_;
+
+ /* A pointer to the last node of the list. */
+ obj_attr_subsection_v2 *last_;
+
+ /* The size of the list. */
+ uint64_t size;
+} obj_attr_subsection_list;
diff --git a/bfd/elf-bfd.h b/bfd/elf-bfd.h
index 5903d857faa..6c326d5db72 100644
--- a/bfd/elf-bfd.h
+++ b/bfd/elf-bfd.h
@@ -24,9 +24,11 @@
#include <stdlib.h>
+#include "double-linked-list.h"
#include "elf/common.h"
#include "elf/external.h"
#include "elf/internal.h"
+#include "elf-attrs.h"
#include "bfdlink.h"
#ifndef ENABLE_CHECKING
@@ -1630,13 +1632,15 @@ struct elf_backend_data
/* The section name to use for a processor-standard attributes section. */
const char *obj_attrs_section;
- /* Return 1, 2 or 3 to indicate what type of arguments a
- processor-specific tag takes. */
+ /* Return 1, 2 or 3 to indicate what type of arguments a tag takes. */
int (*obj_attrs_arg_type) (int);
/* The section type to use for an attributes section. */
unsigned int obj_attrs_section_type;
+ /* The version of object attributes (1 or 2). */
+ unsigned int obj_attrs_version;
+
/* This function determines the order in which any attributes are
written. It must be defined for input in the range
LEAST_KNOWN_OBJ_ATTRIBUTE..NUM_KNOWN_OBJ_ATTRIBUTES-1 (this range
@@ -2160,6 +2164,11 @@ struct elf_obj_tdata
obj_attribute known_obj_attributes[2][NUM_KNOWN_OBJ_ATTRIBUTES];
obj_attribute_list *other_obj_attributes[2];
+ /* Object attributes v2: attributes of the same category are stored inside
+ the same subsection. A subsection can only hold attributes with the same
+ data type. */
+ obj_attr_subsection_list obj_attr_subsections;
+
/* Linked-list containing information about every Systemtap section
found in the object file. Each section corresponds to one entry
in the list. */
@@ -2253,6 +2262,7 @@ struct elf_obj_tdata
(elf_known_obj_attributes (bfd) [OBJ_ATTR_PROC])
#define elf_other_obj_attributes_proc(bfd) \
(elf_other_obj_attributes (bfd) [OBJ_ATTR_PROC])
+#define elf_obj_attr_subsections(bfd) (elf_tdata (bfd) -> obj_attr_subsections)
#define elf_properties(bfd) (elf_tdata (bfd) -> properties)
#define elf_has_no_copy_on_protected(bfd) \
(elf_tdata(bfd) -> has_no_copy_on_protected)
@@ -3083,6 +3093,34 @@ extern bool _bfd_elf_merge_unknown_attribute_list (bfd *, bfd *);
extern Elf_Internal_Shdr *_bfd_elf_single_rel_hdr (asection *sec);
extern bool elf_read_notes (bfd *, file_ptr, bfd_size_type, size_t);
+extern obj_attr_v2 *_bfd_elf_obj_attr_v2_init (unsigned int,
+ union obj_attr_value_v2);
+extern void _bfd_elf_obj_attr_v2_free (obj_attr_v2 *, obj_attr_encoding_v2);
+extern obj_attr_v2 *_bfd_elf_obj_attr_v2_copy (obj_attr_v2 *,
+ obj_attr_encoding_v2);
+extern void _bfd_elf_obj_attr_v2_swap (obj_attr_subsection_v2 *,
+ obj_attr_v2 *, obj_attr_v2 *);
+extern int _bfd_elf_obj_attr_v2_cmp (obj_attr_v2 *, obj_attr_v2 *);
+extern obj_attr_v2 *
+obj_attr_v2_find_by_tag (obj_attr_subsection_v2 *, uint32_t, bool);
+LINKED_LIST_MUTATIVE_OPS_PROTOTYPE(obj_attr_subsection_v2, obj_attr_v2, extern);
+_LINKED_LIST_MERGE_SORT_PROTOTYPE(obj_attr_v2, extern);
+LINKED_LIST_MERGE_SORT_PROTOTYPE(obj_attr_subsection_v2, obj_attr_v2, extern);
+extern obj_attr_subsection_v2 *_bfd_elf_obj_attr_subsection_v2_init (const char*,
+ obj_attr_subsection_scope_v2, bool, obj_attr_encoding_v2);
+extern void _bfd_elf_obj_attr_subsection_v2_free (obj_attr_subsection_v2 *);
+extern obj_attr_subsection_v2 *_bfd_elf_obj_attr_subsection_v2_copy
+ (obj_attr_subsection_v2 const*);
+extern void _bfd_elf_obj_attr_subsection_v2_swap (obj_attr_subsection_list *,
+ obj_attr_subsection_v2 *, obj_attr_subsection_v2 *);
+extern int _bfd_elf_obj_attr_subsection_v2_cmp (obj_attr_subsection_v2 *,
+ obj_attr_subsection_v2 *s2);
+extern obj_attr_subsection_v2 * obj_attr_subsection_v2_find_by_name
+ (obj_attr_subsection_v2 *, const char *, bool);
+LINKED_LIST_MUTATIVE_OPS_PROTOTYPE(obj_attr_subsection_list, obj_attr_subsection_v2, extern);
+_LINKED_LIST_MERGE_SORT_PROTOTYPE(obj_attr_subsection_v2, extern);
+LINKED_LIST_MERGE_SORT_PROTOTYPE(obj_attr_subsection_list, obj_attr_subsection_v2, extern);
+
extern bool _bfd_elf_parse_gnu_properties
(bfd *, Elf_Internal_Note *);
extern elf_property_list * _bfd_elf_find_property
diff --git a/bfd/elfnn-aarch64.c b/bfd/elfnn-aarch64.c
index 548da1f8b30..21fc99c4c98 100644
--- a/bfd/elfnn-aarch64.c
+++ b/bfd/elfnn-aarch64.c
@@ -10760,8 +10760,21 @@ const struct elf_size_info elfNN_aarch64_size_info =
#define elf_backend_extern_protected_data 0
#define elf_backend_hash_symbol elf_aarch64_hash_symbol
+/* elf_backend_obj_attrs_vendor is unused for AArch64. It is replaced by the
+ concept of subsections, each one having its own name defined by the
+ assembly directive "aeabi_subsection". */
+#undef elf_backend_obj_attrs_vendor
+#define elf_backend_obj_attrs_vendor "aeabi"
#undef elf_backend_obj_attrs_section
#define elf_backend_obj_attrs_section SEC_AARCH64_ATTRIBUTES
+/* elf_backend_obj_attrs_arg_type is unused as the type of an attribute is
+ determined by looking up at the current subsection, not the value of the
+ tag. */
+#define elf_backend_obj_attrs_arg_type NULL
+#undef elf_backend_obj_attrs_section_type
+#define elf_backend_obj_attrs_section_type SHT_AARCH64_ATTRIBUTES
+#undef elf_backend_obj_attrs_version
+#define elf_backend_obj_attrs_version 2
#include "elfNN-target.h"
diff --git a/bfd/elfxx-target.h b/bfd/elfxx-target.h
index 625243cac94..cff508dbbce 100644
--- a/bfd/elfxx-target.h
+++ b/bfd/elfxx-target.h
@@ -556,6 +556,9 @@
#ifndef elf_backend_obj_attrs_section_type
#define elf_backend_obj_attrs_section_type SHT_GNU_ATTRIBUTES
#endif
+#ifndef elf_backend_obj_attrs_version
+#define elf_backend_obj_attrs_version 1 /* Default version. */
+#endif
#ifndef elf_backend_obj_attrs_order
#define elf_backend_obj_attrs_order NULL
#endif
@@ -808,7 +811,7 @@
#ifndef elf_backend_symbol_section_index
#define elf_backend_symbol_section_index NULL
#endif
-
+
#ifndef elf_match_priority
#define elf_match_priority \
(ELF_ARCH == bfd_arch_unknown ? 2 : ELF_OSABI == ELFOSABI_NONE ? 1 : 0)
@@ -934,6 +937,7 @@ static const struct elf_backend_data elfNN_bed =
elf_backend_obj_attrs_section,
elf_backend_obj_attrs_arg_type,
elf_backend_obj_attrs_section_type,
+ elf_backend_obj_attrs_version,
elf_backend_obj_attrs_order,
elf_backend_obj_attrs_handle_unknown,
elf_backend_parse_gnu_properties,
diff --git a/bfd/po/SRC-POTFILES.in b/bfd/po/SRC-POTFILES.in
index 54b078b8295..4b8ccfbe2c8 100644
--- a/bfd/po/SRC-POTFILES.in
+++ b/bfd/po/SRC-POTFILES.in
@@ -132,6 +132,7 @@ ecoff.c
ecofflink.c
ecoffswap.h
elf-attrs.c
+elf-attrs.h
elf-bfd.h
elf-eh-frame.c
elf-hppa.h
--
2.48.1
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