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| author |   Peter Zijlstra <peterz@infradead.org> | 2021-03-26 16:12:11 +0100 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2021-04-02 12:45:05 +0200 |
| commit | 2f2f7e47f0525cbaad5dd9675fd9d8aa8da12046 (patch) | |
| tree | d1f3168e53e2fd5976917275a858710ff7b1342f /tools/objtool | |
| parent | objtool: Extract elf_symbol_add() (diff) | |
| download | linux-dev-2f2f7e47f0525cbaad5dd9675fd9d8aa8da12046.tar.xz linux-dev-2f2f7e47f0525cbaad5dd9675fd9d8aa8da12046.zip | |
objtool: Add elf_create_undef_symbol()
Allow objtool to create undefined symbols; this allows creating
relocations to symbols not currently in the symbol table.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151300.064743095@infradead.org
Diffstat (limited to 'tools/objtool')
| -rw-r--r-- | tools/objtool/elf.c | 60 | ||||
| -rw-r--r-- | tools/objtool/include/objtool/elf.h | 1 |
2 files changed, 61 insertions, 0 deletions
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c index 8457218dcf22..d08f5f3670f8 100644 --- a/tools/objtool/elf.c +++ b/tools/objtool/elf.c @@ -715,6 +715,66 @@ static int elf_add_string(struct elf *elf, struct section *strtab, char *str) return len; } +struct symbol *elf_create_undef_symbol(struct elf *elf, const char *name) +{ + struct section *symtab; + struct symbol *sym; + Elf_Data *data; + Elf_Scn *s; + + sym = malloc(sizeof(*sym)); + if (!sym) { + perror("malloc"); + return NULL; + } + memset(sym, 0, sizeof(*sym)); + + sym->name = strdup(name); + + sym->sym.st_name = elf_add_string(elf, NULL, sym->name); + if (sym->sym.st_name == -1) + return NULL; + + sym->sym.st_info = GELF_ST_INFO(STB_GLOBAL, STT_NOTYPE); + // st_other 0 + // st_shndx 0 + // st_value 0 + // st_size 0 + + symtab = find_section_by_name(elf, ".symtab"); + if (!symtab) { + WARN("can't find .symtab"); + return NULL; + } + + s = elf_getscn(elf->elf, symtab->idx); + if (!s) { + WARN_ELF("elf_getscn"); + return NULL; + } + + data = elf_newdata(s); + if (!data) { + WARN_ELF("elf_newdata"); + return NULL; + } + + data->d_buf = &sym->sym; + data->d_size = sizeof(sym->sym); + data->d_align = 1; + + sym->idx = symtab->len / sizeof(sym->sym); + + symtab->len += data->d_size; + symtab->changed = true; + + sym->sec = find_section_by_index(elf, 0); + + elf_add_symbol(elf, sym); + + return sym; +} + struct section *elf_create_section(struct elf *elf, const char *name, unsigned int sh_flags, size_t entsize, int nr) { diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h index 463f329f1c66..45e5ede363b0 100644 --- a/tools/objtool/include/objtool/elf.h +++ b/tools/objtool/include/objtool/elf.h @@ -133,6 +133,7 @@ int elf_write_insn(struct elf *elf, struct section *sec, unsigned long offset, unsigned int len, const char *insn); int elf_write_reloc(struct elf *elf, struct reloc *reloc); +struct symbol *elf_create_undef_symbol(struct elf *elf, const char *name); int elf_write(struct elf *elf); void elf_close(struct elf *elf); |