On Mon, Jun 25, 2018 at 08:32:41AM -0400, Pavel Tatashin wrote:
> > It _should_ all work.. but scary, who knows where this early stuff ends
> > up being used.
>
> I have tested this patch
Sure,.. but call me paranoid.
> However, the other way to fix this bug is to change:
> arch/x86/kernel/jump_label.c
>
> -void arch_jump_label_transform(struct jump_entry *entry,
> +void __ref arch_jump_label_transform(struct jump_entry *entry,
> enum jump_label_type type)
> {
> + void *(*poker)(void *, const void *, size_t) = NULL;
> +
> + if (unlikely(!after_bootmem))
> + poker = text_poke_early;
> +
> mutex_lock(&text_mutex);
> - __jump_label_transform(entry, type, NULL, 0);
> + __jump_label_transform(entry, type, poker, 0);
> mutex_unlock(&text_mutex);
> }
No need to elide that mutex I think, by going through the normal
static_key_enable() stuff you already take a whole bunch of them, and
they should work early just fine (no contention etc.).
Also, I think the better condition is @early_boot_irqs_disabled, until
we enable IRQs for the first time, text_poke_early() should be fine. And
once we enable interrupts, all that other crud should really be working.
This gives:
diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
index e56c95be2808..425ba6102828 100644
--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -46,6 +46,9 @@ static void __jump_label_transform(struct jump_entry *entry,
const unsigned char default_nop[] = { STATIC_KEY_INIT_NOP };
const unsigned char *ideal_nop = ideal_nops[NOP_ATOMIC5];
+ if (early_boot_irqs_disabled)
+ poker = text_poke_early;
+
if (type == JUMP_LABEL_JMP) {
if (init) {
/*
> Also, modify text_poke_early to call sync_core().
and that.
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