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objtool: Don't use ignore flag for fake jumps 

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>
This commit is contained in:
Josh Poimboeuf 2019-05-13 12:01:31 -05:00 committed by Ingo Molnar
parent 82045dd855
commit e6da956795
1 changed files with 5 additions and 3 deletions
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8
tools/objtool/check.c
View File

@ -28,6 +28,8 @@
#include <linux/hashtable.h> #include <linux/hashtable.h>
#include <linux/kernel.h> #include <linux/kernel.h>
#define FAKE_JUMP_OFFSET -1
struct alternative { struct alternative {
struct list_head list; struct list_head list;
struct instruction *insn; struct instruction *insn;
@ -568,7 +570,7 @@ static int add_jump_destinations(struct objtool_file *file)
insn->type != INSN_JUMP_UNCONDITIONAL) insn->type != INSN_JUMP_UNCONDITIONAL)
continue; continue;
if (insn->ignore) if (insn->ignore || insn->offset == FAKE_JUMP_OFFSET)
continue; continue;
rela = find_rela_by_dest_range(insn->sec, insn->offset, rela = find_rela_by_dest_range(insn->sec, insn->offset,
@ -745,10 +747,10 @@ static int handle_group_alt(struct objtool_file *file,
clear_insn_state(&fake_jump->state); clear_insn_state(&fake_jump->state);
fake_jump->sec = special_alt->new_sec; 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->type = INSN_JUMP_UNCONDITIONAL;
fake_jump->jump_dest = list_next_entry(last_orig_insn, list); 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) { if (!special_alt->new_len) {