[PATCH 5.15 21/78] objtool: Default ignore INT3 for unreachable

Greg Kroah-Hartman
2022-07-12T19:00:29Z

From: Peter Zijlstra <peterz@infradead.org>

commit 1ffbe4e935f9b7308615c75be990aec07464d1e7 upstream.

Ignore all INT3 instructions for unreachable code warnings, similar to NOP.
This allows using INT3 for various paddings instead of NOPs.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154317.343312938@infradead.org
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
tools/objtool/check.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)

--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2965,9 +2965,8 @@ static int validate_branch(struct objtoo
switch (insn->type) {

case INSN_RETURN:
- if (next_insn && next_insn->type == INSN_TRAP) {
- next_insn->ignore = true;
- } else if (sls && !insn->retpoline_safe) {
+ if (sls && !insn->retpoline_safe &&
+ next_insn && next_insn->type != INSN_TRAP) {
WARN_FUNC("missing int3 after ret",
insn->sec, insn->offset);
}
@@ -3014,9 +3013,8 @@ static int validate_branch(struct objtoo
break;

case INSN_JUMP_DYNAMIC:
- if (next_insn && next_insn->type == INSN_TRAP) {
- next_insn->ignore = true;
- } else if (sls && !insn->retpoline_safe) {
+ if (sls && !insn->retpoline_safe &&
+ next_insn && next_insn->type != INSN_TRAP) {
WARN_FUNC("missing int3 after indirect jump",
insn->sec, insn->offset);
}
@@ -3187,7 +3185,7 @@ static bool ignore_unreachable_insn(stru
int i;
struct instruction *prev_insn;

- if (insn->ignore || insn->type == INSN_NOP)
+ if (insn->ignore || insn->type == INSN_NOP || insn->type == INSN_TRAP)
return true;

/*