1bb49897dd
For very large ELF objects (with many sections), we could get special value SHN_XINDEX (65535) for symbol's st_shndx. This patch is adding code to detect the optional extended section index table and use it to resolve symbol's section index. Adding elf_symtab__for_each_symbol_index macro that returns symbol's section index and usign it in collect functions. Tested by running pahole on kernel compiled with: make KCFLAGS="-ffunction-sections -fdata-sections" -j$(nproc) vmlinux and ensure FUNC records are generated and match normal build (without above KCFLAGS). Also bpf selftest passed and generated kernel BTF, is same as without the patch. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Hao Luo <haoluo@google.com> Cc: Joe Lawrence <joe.lawrence@redhat.com> Cc: John Fastabend <john.fastabend@gmail.com> Cc: KP Singh <kpsingh@chromium.org> Cc: Mark Wieelard <mjw@redhat.com> Cc: Martin KaFai Lau <kafai@fb.com> Cc: Song Liu <songliubraving@fb.com> Cc: Yonghong Song <yhs@fb.com> Cc: bpf@vger.kernel.org Cc: dwarves@vger.kernel.org Cc: netdev@vger.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
106 lines
2.2 KiB
C
106 lines
2.2 KiB
C
/*
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SPDX-License-Identifier: GPL-2.0-only
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Copyright (C) 2009 Red Hat Inc.
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Copyright (C) 2009 Arnaldo Carvalho de Melo <acme@redhat.com>
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*/
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#include <malloc.h>
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#include <stdio.h>
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#include <string.h>
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#include "dutil.h"
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#include "elf_symtab.h"
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#define HASHSYMS__BITS 8
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#define HASHSYMS__SIZE (1UL << HASHSYMS__BITS)
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struct elf_symtab *elf_symtab__new(const char *name, Elf *elf, GElf_Ehdr *ehdr)
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{
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size_t symtab_index;
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if (name == NULL)
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name = ".symtab";
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GElf_Shdr shdr;
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Elf_Scn *sec = elf_section_by_name(elf, ehdr, &shdr, name, &symtab_index);
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if (sec == NULL)
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return NULL;
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if (gelf_getshdr(sec, &shdr) == NULL)
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return NULL;
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struct elf_symtab *symtab = zalloc(sizeof(*symtab));
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if (symtab == NULL)
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return NULL;
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symtab->name = strdup(name);
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if (symtab->name == NULL)
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goto out_delete;
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symtab->syms = elf_getdata(sec, NULL);
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if (symtab->syms == NULL)
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goto out_free_name;
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/*
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* This returns extended section index table's
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* section index, if it exists.
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*/
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int symtab_xindex = elf_scnshndx(sec);
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sec = elf_getscn(elf, shdr.sh_link);
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if (sec == NULL)
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goto out_free_name;
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symtab->symstrs = elf_getdata(sec, NULL);
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if (symtab->symstrs == NULL)
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goto out_free_name;
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/*
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* The .symtab section has optional extended section index
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* table, load its data so it can be used to resolve symbol's
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* section index.
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**/
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if (symtab_xindex > 0) {
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GElf_Shdr shdr_xindex;
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Elf_Scn *sec_xindex;
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sec_xindex = elf_getscn(elf, symtab_xindex);
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if (sec_xindex == NULL)
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goto out_free_name;
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if (gelf_getshdr(sec_xindex, &shdr_xindex) == NULL)
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goto out_free_name;
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/* Extra check to verify it's correct type */
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if (shdr_xindex.sh_type != SHT_SYMTAB_SHNDX)
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goto out_free_name;
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/* Extra check to verify it belongs to the .symtab */
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if (symtab_index != shdr_xindex.sh_link)
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goto out_free_name;
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symtab->syms_sec_idx_table = elf_getdata(elf_getscn(elf, symtab_xindex), NULL);
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if (symtab->syms_sec_idx_table == NULL)
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goto out_free_name;
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}
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symtab->nr_syms = shdr.sh_size / shdr.sh_entsize;
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return symtab;
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out_free_name:
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free(symtab->name);
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out_delete:
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free(symtab);
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return NULL;
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}
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void elf_symtab__delete(struct elf_symtab *symtab)
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{
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if (symtab == NULL)
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return;
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free(symtab->name);
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free(symtab);
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}
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