[PATCH 4.14 22/81] objtool: Dont use ignore flag for fake jumps

Greg Kroah-Hartman
2019-06-13T16:29:15Z

[ Upstream commit e6da9567959e164f82bc81967e0d5b10dee870b4 ]

The ignore flag is set on fake jumps in order to keep
add_jump_destinations() from setting their jump_dest, since it already
got set when the fake jump was created.

But using the ignore flag is a bit of a hack. It's normally used to
skip validation of an instruction, which doesn't really make sense for
fake jumps.

Also, after the next patch, using the ignore flag for fake jumps can
trigger a false "why am I validating an ignored function?" warning.

Instead just add an explicit check in add_jump_destinations() to skip
fake jumps.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/71abc072ff48b2feccc197723a9c52859476c068.1557766718.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/objtool/check.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index ae3446768181..95326c6a7a24 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -28,6 +28,8 @@
#include <linux/hashtable.h>
#include <linux/kernel.h>

+#define FAKE_JUMP_OFFSET -1
+
struct alternative {
struct list_head list;
struct instruction *insn;
@@ -498,7 +500,7 @@ static int add_jump_destinations(struct objtool_file *file)
insn->type != INSN_JUMP_UNCONDITIONAL)
continue;

- if (insn->ignore)
+ if (insn->ignore || insn->offset == FAKE_JUMP_OFFSET)
continue;

rela = find_rela_by_dest_range(insn->sec, insn->offset,
@@ -645,10 +647,10 @@ static int handle_group_alt(struct objtool_file *file,
clear_insn_state(&fake_jump->state);

fake_jump->sec = special_alt->new_sec;
- fake_jump->offset = -1;
+ fake_jump->offset = FAKE_JUMP_OFFSET;
fake_jump->type = INSN_JUMP_UNCONDITIONAL;
fake_jump->jump_dest = list_next_entry(last_orig_insn, list);
- fake_jump->ignore = true;
+ fake_jump->func = orig_insn->func;
}

if (!special_alt->new_len) {
--
2.20.1