On Thu, Mar 18, 2021 at 06:11:14PM +0100, Peter Zijlstra wrote:
> Allow objtool to create undefined symbols; this allows creating
> relocations to symbols not currently in the symbol table.
>
> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
> ---
> tools/objtool/elf.c | 63
> ++++++++++++++++++++++++++++++++++++
> tools/objtool/include/objtool/elf.h | 1
> 2 files changed, 64 insertions(+)
>
> --- a/tools/objtool/elf.c
> +++ b/tools/objtool/elf.c
> @@ -724,6 +724,69 @@ static int elf_strtab_concat(struct elf
> 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_strtab_concat(elf, sym->name, NULL);
> + if (sym->sym.st_name == -1)
> + return NULL;
> +
> + sym->sym.st_info = 0x10; /* STB_GLOBAL, STT_NOTYPE */
There's a generic macro for this:
sym->sym.st_info = GELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
And sym->bind and sym->type should probably get set.
--
Josh
