objtool: Fix .symtab_shndx handling for elf_create_undef_symbol()
The following commit has been merged into the objtool/urgent branch of tip:
Commit-ID: f17777cc267523a21815a4ae7489f0d796b1fc07 Gitweb: https://git.kernel.org/tip/f17777cc267523a21815a4ae7489f0d796b1fc07 Author: Peter Zijlstra <[email protected]> AuthorDate: Mon, 07 Jun 2021 11:45:58 +02:00 Committer: Peter Zijlstra <[email protected]> CommitterDate: Tue, 08 Jun 2021 20:04:02 +02:00
objtool: Fix .symtab_shndx handling for elf_create_undef_symbol()
When an ELF object uses extended symbol section indexes (IOW it has a .symtab_shndx section), these must be kept in sync with the regular symbol table (.symtab).
So for every new symbol we emit, make sure to also emit a .symtab_shndx value to keep the arrays of equal size.
Note: since we're writing an UNDEF symbol, most GElf_Sym fields will be 0 and we can repurpose one (st_size) to host the 0 for the xshndx value.
--- tools/objtool/elf.c | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-)
tools/objtool/elf.c +24 -1
@@ -717,7 +717,7 @@ static int elf_add_string(struct elf *elf, struct section *strtab, char *str)struct symbol *elf_create_undef_symbol (struct elf *elf,const char *name) { -struct section *symtab; +struct section *symtab, *symtab_shndx;struct symbol *sym;Elf_Data *data;Elf_Scn *s;
@@ -769,6 +769,29 @@ struct symbol *elf_create_undef_symbol(struct elf *elf, const char *name) symtab->len += data->d_size; symtab->changed = true; + symtab_shndx =find_section_by_name (elf,".symtab_shndx" ); +if (symtab_shndx) { + s =elf_getscn (elf->elf, symtab_shndx->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.st_size;/* conveniently 0 */ + data->d_size =sizeof (Elf32_Word); + data->d_align =4 ; + data->d_type =ELF_T_WORD ; + + symtab_shndx->len +=4 ; + symtab_shndx->changed = true; + } + sym->sec =find_section_by_index (elf,0 );elf_add_symbol (elf, sym);
The following commit has been merged into the objtool/urgent branch of tip:
The following commit has been merged into the objtool/urgent branch of tip:
Commit-ID: 584fd3b31889852d0d6f3dd1e3d8e9619b660d2c Gitweb: https://git.kernel.org/tip/584fd3b31889852d0d6f3dd1e3d8e9619b660d2c Author: Peter Zijlstra <[email protected]> AuthorDate: Mon, 07 Jun 2021 11:45:58 +02:00 Committer: Peter Zijlstra <[email protected]> CommitterDate: Thu, 10 Jun 2021 10:08:24 +02:00
objtool: Fix .symtab_shndx handling for elf_create_undef_symbol()
When an ELF object uses extended symbol section indexes (IOW it has a .symtab_shndx section), these must be kept in sync with the regular symbol table (.symtab).
So for every new symbol we emit, make sure to also emit a .symtab_shndx value to keep the arrays of equal size.
Note: since we're writing an UNDEF symbol, most GElf_Sym fields will be 0 and we can repurpose one (st_size) to host the 0 for the xshndx value.
--- tools/objtool/elf.c | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-)
tools/objtool/elf.c +24 -1
@@ -717,7 +717,7 @@ static int elf_add_string(struct elf *elf, struct section *strtab, char *str)struct symbol *elf_create_undef_symbol (struct elf *elf,const char *name) { -struct section *symtab; +struct section *symtab, *symtab_shndx;struct symbol *sym;Elf_Data *data;Elf_Scn *s;
@@ -769,6 +769,29 @@ struct symbol *elf_create_undef_symbol(struct elf *elf, const char *name) symtab->len += data->d_size; symtab->changed = true; + symtab_shndx =find_section_by_name (elf,".symtab_shndx" ); +if (symtab_shndx) { + s =elf_getscn (elf->elf, symtab_shndx->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.st_size;/* conveniently 0 */ + data->d_size =sizeof (Elf32_Word); + data->d_align =4 ; + data->d_type =ELF_T_WORD ; + + symtab_shndx->len +=4 ; + symtab_shndx->changed = true; + } + sym->sec =find_section_by_index (elf,0 );elf_add_symbol (elf, sym);