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 <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Jason Baron <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Eric Dumazet <[email protected]> Cc: "David S. Miller" <[email protected]> Cc: [email protected] Signed-off-by: Hannes Frederic Sowa <[email protected]> --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
