Really skip the original instruction flow, instead of letting it
continue with NOPs.
Since the alternative code flow already continues after the original
instructions, only the alt-original is skipped.
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
---
tools/objtool/check.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -31,6 +31,7 @@
struct alternative {
struct list_head list;
struct instruction *insn;
+ bool skip_orig;
};
const char *objname;
@@ -623,9 +624,6 @@ static int add_call_destinations(struct
* conditionally jumps to the _end_ of the entry. We have to modify these
* jumps' destinations to point back to .text rather than the end of the
* entry in .altinstr_replacement.
- *
- * 4. It has been requested that we don't validate the !POPCNT feature path
- * which is a "very very small percentage of machines".
*/
static int handle_group_alt(struct objtool_file *file,
struct special_alt *special_alt,
@@ -641,9 +639,6 @@ static int handle_group_alt(struct objto
if (insn->offset >= special_alt->orig_off +
special_alt->orig_len)
break;
- if (special_alt->skip_orig)
- insn->type = INSN_NOP;
-
insn->alt_group = true;
last_orig_insn = insn;
}
@@ -808,6 +803,7 @@ static int add_special_section_alts(stru
}
alt->insn = new_insn;
+ alt->skip_orig = special_alt->skip_orig;
list_add_tail(&alt->list, &orig_insn->alts);
list_del(&special_alt->list);
@@ -1883,7 +1879,12 @@ static int validate_branch(struct objtoo
insn->visited = true;
if (!insn->ignore_alts) {
+ bool skip_orig = false;
+
list_for_each_entry(alt, &insn->alts, list) {
+ if (alt->skip_orig)
+ skip_orig = true;
+
ret = validate_branch(file, alt->insn, state);
if (ret) {
if (backtrace)
@@ -1891,6 +1892,9 @@ static int validate_branch(struct objtoo
return ret;
}
}
+
+ if (skip_orig)
+ return 0;
}
switch (insn->type) {
