From a8fab0744585c1ab61009bfc1a1958f28e1c864f Mon Sep 17 00:00:00 2001 From: Hannes Frederic Sowa Date: Sat, 19 Oct 2013 21:48:54 +0200 Subject: [PATCH] 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 Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: Steven Rostedt Cc: Jason Baron Cc: Peter Zijlstra Cc: Eric Dumazet Cc: "David S. Miller" Cc: x86@kernel.org Signed-off-by: Hannes Frederic Sowa Signed-off-by: David S. Miller --- 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 ee11b7dfbfbb..26d5a55a2736 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 { -- 2.20.1