Re: [patches] [PATCH for 2.6.22] [9/10] i386: Disablealternative()patching after boot with DEBUG_RO

From: Jan Beulich
Date: Wed Jun 20 2007 - 07:55:22 EST


>>> Andi Kleen <ak@xxxxxxx> 20.06.07 12:23 >>>
>
>Kernel text is protected now so this won't work.
>
>We'll fix it better next time.
>
>Signed-off-by: Andi Kleen <ak@xxxxxxx>
>
>---
> arch/i386/kernel/alternative.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
>Index: linux/arch/i386/kernel/alternative.c
>===================================================================
>--- linux.orig/arch/i386/kernel/alternative.c
>+++ linux/arch/i386/kernel/alternative.c
>@@ -308,6 +308,11 @@ void alternatives_smp_switch(int smp)
> printk("lockdep: not fixing up alternatives.\n");
> return;
> #endif
>+#ifdef CONFIG_DEBUG_RODATA
>+ /* To be fixed properly post 2.6.22 -- need to get writable
>+ mappings of the kernel text */
>+ return;
>+#endif
>
> if (noreplace_smp || smp_alt_once)
> return;

Why would we need this? mark_rodata_ro() already accounts for the
CONFIG_HOTPLUG_CPU case in that it doesn't write protect .text then.

Jan

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