net_get_random_once(intrduced in the next patch) uses static_keys in
a way that they get enabled on boot-up instead of replaced with an
ideal_nop. So check for default_nop on initial enabling.
Other architectures don't check for this.
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: "H. Peter Anvin" <h...@zytor.com>
Cc: Steven Rostedt <rost...@goodmis.org>
Cc: Jason Baron <jba...@redhat.com>
Cc: Peter Zijlstra <a.p.zijls...@chello.nl>
Cc: Eric Dumazet <eduma...@google.com>
Cc: "David S. Miller" <da...@davemloft.net>
Cc: x...@kernel.org
Signed-off-by: Hannes Frederic Sowa <han...@stressinduktion.org>
---
arch/x86/kernel/jump_label.c | 25 ++++++++++++++++++-------
1 file changed, 18 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
index ee11b7d..26d5a55 100644
--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -42,15 +42,27 @@ static void __jump_label_transform(struct jump_entry *entry,
int init)
{
union jump_code_union code;
+ const unsigned char default_nop[] = { STATIC_KEY_INIT_NOP };
const unsigned char *ideal_nop = ideal_nops[NOP_ATOMIC5];
if (type == JUMP_LABEL_ENABLE) {
- /*
- * We are enabling this jump label. If it is not a nop
- * then something must have gone wrong.
- */
- if (unlikely(memcmp((void *)entry->code, ideal_nop, 5) != 0))
- bug_at((void *)entry->code, __LINE__);
+ if (init) {
+ /*
+ * Jump label is enabled for the first time.
+ * So we expect a default_nop...
+ */
+ if (unlikely(memcmp((void *)entry->code, default_nop, 5)
+ != 0))
+ bug_at((void *)entry->code, __LINE__);
+ } else {
+ /*
+ * ...otherwise expect an ideal_nop. Otherwise
+ * something went horribly wrong.
+ */
+ if (unlikely(memcmp((void *)entry->code, ideal_nop, 5)
+ != 0))
+ bug_at((void *)entry->code, __LINE__);
+ }
code.jump = 0xe9;
code.offset = entry->target -
@@ -63,7 +75,6 @@ static void __jump_label_transform(struct jump_entry *entry,
* are converting the default nop to the ideal nop.
*/
if (init) {
- const unsigned char default_nop[] = {
STATIC_KEY_INIT_NOP };
if (unlikely(memcmp((void *)entry->code, default_nop,
5) != 0))
bug_at((void *)entry->code, __LINE__);
} else {
--
1.8.3.1
--
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