queue-4.19/objtool-don-t-use-ignore-flag-for-fake-jumps.patch

   1 From cb850a68625c520c7b724c6230bd6d7ea3f7bc2f Mon Sep 17 00:00:00 2001
   2 From: Josh Poimboeuf <jpoimboe@redhat.com>
   3 Date: Mon, 13 May 2019 12:01:31 -0500
   4 Subject: objtool: Don't use ignore flag for fake jumps
   5
   6 [ Upstream commit e6da9567959e164f82bc81967e0d5b10dee870b4 ]
   7
   8 The ignore flag is set on fake jumps in order to keep
   9 add_jump_destinations() from setting their jump_dest, since it already
  10 got set when the fake jump was created.
  11
  12 But using the ignore flag is a bit of a hack.  It's normally used to
  13 skip validation of an instruction, which doesn't really make sense for
  14 fake jumps.
  15
  16 Also, after the next patch, using the ignore flag for fake jumps can
  17 trigger a false "why am I validating an ignored function?" warning.
  18
  19 Instead just add an explicit check in add_jump_destinations() to skip
  20 fake jumps.
  21
  22 Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
  23 Cc: Linus Torvalds <torvalds@linux-foundation.org>
  24 Cc: Peter Zijlstra <peterz@infradead.org>
  25 Cc: Thomas Gleixner <tglx@linutronix.de>
  26 Link: http://lkml.kernel.org/r/71abc072ff48b2feccc197723a9c52859476c068.1557766718.git.jpoimboe@redhat.com
  27 Signed-off-by: Ingo Molnar <mingo@kernel.org>
  28 Signed-off-by: Sasha Levin <sashal@kernel.org>
  29 ---
  30  tools/objtool/check.c | 8 +++++---
  31  1 file changed, 5 insertions(+), 3 deletions(-)
  32
  33 diff --git a/tools/objtool/check.c b/tools/objtool/check.c
  34 index 46be34576620..02a47e365e52 100644
  35 --- a/tools/objtool/check.c
  36 +++ b/tools/objtool/check.c
  37 @@ -28,6 +28,8 @@
  38  #include <linux/hashtable.h>
  39  #include <linux/kernel.h>
  40
  41 +#define FAKE_JUMP_OFFSET -1
  42 +
  43  struct alternative {
  44         struct list_head list;
  45         struct instruction *insn;
  46 @@ -501,7 +503,7 @@ static int add_jump_destinations(struct objtool_file *file)
  47                     insn->type != INSN_JUMP_UNCONDITIONAL)
  48                         continue;
  49
  50 -               if (insn->ignore)
  51 +               if (insn->ignore || insn->offset == FAKE_JUMP_OFFSET)
  52                         continue;
  53
  54                 rela = find_rela_by_dest_range(insn->sec, insn->offset,
  55 @@ -670,10 +672,10 @@ static int handle_group_alt(struct objtool_file *file,
  56                 clear_insn_state(&fake_jump->state);
  57
  58                 fake_jump->sec = special_alt->new_sec;
  59 -               fake_jump->offset = -1;
  60 +               fake_jump->offset = FAKE_JUMP_OFFSET;
  61                 fake_jump->type = INSN_JUMP_UNCONDITIONAL;
  62                 fake_jump->jump_dest = list_next_entry(last_orig_insn, list);
  63 -               fake_jump->ignore = true;
  64 +               fake_jump->func = orig_insn->func;
  65         }
  66
  67         if (!special_alt->new_len) {
  68 --
  69 2.20.1
  70