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authorHannes Frederic Sowa <hannes@stressinduktion.org>2013-10-19 19:48:54 (GMT)
committerDavid S. Miller <davem@davemloft.net>2013-10-19 23:45:35 (GMT)
commita8fab0744585c1ab61009bfc1a1958f28e1c864f (patch)
treefee8d9ecb58cbcb46465cf2f97c542cd70a85687 /arch/x86/kernel/jump_label.c
parentc4b2c0c5f647aa1093e8f9097a30c17ce0f94d4d (diff)
x86/jump_label: expect default_nop if static_key gets enabled on boot-up
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 <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Jason Baron <jbaron@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Eric Dumazet <edumazet@google.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: x86@kernel.org Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch/x86/kernel/jump_label.c')
-rw-r--r--arch/x86/kernel/jump_label.c25
1 files 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 {

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