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objtool: Fix overlapping alternatives

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Things like ALTERNATIVE_{2,3}() generate multiple alternatives on the
same place, objtool would override the first orig_alt_group with the
second (or third), failing to check the CFI among all the different
variants.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org> # build only
Tested-by: Thomas Weißschuh <linux@weissschuh.net> # compile and run
Link: https://lore.kernel.org/r/20230208172245.711471461@infradead.org
This commit is contained in:
Peter Zijlstra 2023-02-08 18:18:03 +01:00 committed by Ingo Molnar
parent c6f5dc28fb
commit a706bb08c8
1 changed files with 43 additions and 26 deletions
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69
tools/objtool/check.c
View file

@ -1744,36 +1744,49 @@ static int handle_group_alt(struct objtool_file *file,
struct instruction *orig_insn,
struct instruction **new_insn)
{
struct instruction *last_orig_insn, *last_new_insn = NULL, *insn, *nop = NULL;
struct instruction *last_new_insn = NULL, *insn, *nop = NULL;
struct alt_group *orig_alt_group, *new_alt_group;
unsigned long dest_off;
orig_alt_group = malloc(sizeof(*orig_alt_group));
orig_alt_group = orig_insn->alt_group;
if (!orig_alt_group) {
WARN("malloc failed");
return -1;
}
orig_alt_group->cfi = calloc(special_alt->orig_len,
sizeof(struct cfi_state *));
if (!orig_alt_group->cfi) {
WARN("calloc failed");
return -1;
}
struct instruction *last_orig_insn = NULL;
last_orig_insn = NULL;
insn = orig_insn;
sec_for_each_insn_from(file, insn) {
if (insn->offset >= special_alt->orig_off + special_alt->orig_len)
break;
orig_alt_group = malloc(sizeof(*orig_alt_group));
if (!orig_alt_group) {
WARN("malloc failed");
return -1;
}
orig_alt_group->cfi = calloc(special_alt->orig_len,
sizeof(struct cfi_state *));
if (!orig_alt_group->cfi) {
WARN("calloc failed");
return -1;
}
insn->alt_group = orig_alt_group;
last_orig_insn = insn;
insn = orig_insn;
sec_for_each_insn_from(file, insn) {
if (insn->offset >= special_alt->orig_off + special_alt->orig_len)
break;
insn->alt_group = orig_alt_group;
last_orig_insn = insn;
}
orig_alt_group->orig_group = NULL;
orig_alt_group->first_insn = orig_insn;
orig_alt_group->last_insn = last_orig_insn;
} else {
if (orig_alt_group->last_insn->offset + orig_alt_group->last_insn->len -
orig_alt_group->first_insn->offset != special_alt->orig_len) {
WARN_FUNC("weirdly overlapping alternative! %ld != %d",
orig_insn->sec, orig_insn->offset,
orig_alt_group->last_insn->offset +
orig_alt_group->last_insn->len -
orig_alt_group->first_insn->offset,
special_alt->orig_len);
return -1;
}
}
orig_alt_group->orig_group = NULL;
orig_alt_group->first_insn = orig_insn;
orig_alt_group->last_insn = last_orig_insn;
new_alt_group = malloc(sizeof(*new_alt_group));
if (!new_alt_group) {
@ -1848,7 +1861,7 @@ static int handle_group_alt(struct objtool_file *file,
dest_off = arch_jump_destination(insn);
if (dest_off == special_alt->new_off + special_alt->new_len) {
insn->jump_dest = next_insn_same_sec(file, last_orig_insn);
insn->jump_dest = next_insn_same_sec(file, orig_alt_group->last_insn);
if (!insn->jump_dest) {
WARN_FUNC("can't find alternative jump destination",
insn->sec, insn->offset);
@ -3226,8 +3239,12 @@ static int propagate_alt_cfi(struct objtool_file *file, struct instruction *insn
alt_cfi[group_off] = insn->cfi;
} else {
if (cficmp(alt_cfi[group_off], insn->cfi)) {
WARN_FUNC("stack layout conflict in alternatives",
insn->sec, insn->offset);
struct alt_group *orig_group = insn->alt_group->orig_group ?: insn->alt_group;
struct instruction *orig = orig_group->first_insn;
char *where = offstr(insn->sec, insn->offset);
WARN_FUNC("stack layout conflict in alternatives: %s",
orig->sec, orig->offset, where);
free(where);
return -1;
}
}