Re: [PATCH] Revert "x86-64, init: Do not set NX bits on non-NXcapable hardware"

From: Michal Hocko
Date: Mon May 20 2013 - 14:23:15 EST

On Mon 20-05-13 10:21:09, Linus Torvalds wrote:
> On Mon, May 20, 2013 at 9:43 AM, Michal Hocko <mhocko@xxxxxxx> wrote:
> >
> > The configuration has been posted in the referenced thread:
> >
> Hmm. That's a regular intel i5 Sandybridge CPU. Which certainly has NX.
> Hmm. secondary_startup_64 isn't __initcode, is it? I think it's used
> for resuming the other CPU's too and for CPU hotplug. Yes/no?
> If so early_pmd_flags shouldn't be __initdata, I think.
> Michal, does it work if you don't do the revert, but just remove the
> __initdata instead?

Right you are! The following patch on top of your tree fixes the
problem. Thanks a lot. I will leave the proper changelog to somebody who
is more familiar with the area but AFAIU the real problem is that
early_pmd_flags is no longer available beacause the section is gone.

Anyway, feel free to add my
Tested-by: Michal Hocko <mhocko@xxxxxxx>
and mark it for 3.9 stable tree
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index dab95a8..55b6761 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -34,7 +34,7 @@
extern pgd_t early_level4_pgt[PTRS_PER_PGD];
extern pmd_t early_dynamic_pgts[EARLY_DYNAMIC_PAGE_TABLES][PTRS_PER_PMD];
static unsigned int __initdata next_early_pgt = 2;
-pmdval_t __initdata early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX);
+pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX);

/* Wipe all early page tables except for the kernel symbol map */
static void __init reset_early_page_tables(void)
Michal Hocko
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