objtool: Default ignore INT3 for unreachable

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>

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index a8320f0..d3e0ec9 100644 (file)
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2965,9 +2965,8 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
                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 objtool_file *file, struct symbol *func,
                        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(struct objtool_file *file, struct instructio
        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;
 
        /*