Messages in this thread Patch in this message | | | Date | Mon, 25 Jun 2018 15:48:51 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v12 01/11] x86: text_poke() may access uninitialized struct pages |
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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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