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objtool,x86: Replace alternatives with .retpoline_sites

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Instead of writing complete alternatives, simply provide a list of all
the retpoline thunk calls. Then the kernel is free to do with them as
it pleases. Simpler code all-round.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20211026120309.850007165@infradead.org
This commit is contained in:
Peter Zijlstra
2021-10-26 14:01:36 +02:00
parent c509331b41
commit 134ab5bd18
6 changed files with 107 additions and 252 deletions
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84
tools/objtool/elf.c
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@@ -740,90 +740,6 @@ 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, *symtab_shndx;
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;
data->d_type = ELF_T_SYM;
sym->idx = symtab->sh.sh_size / sizeof(sym->sym);
symtab->sh.sh_size += 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->sh.sh_size += 4;
symtab_shndx->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)
{