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Commit 78d77df7 authored by H. Peter Anvin's avatar H. Peter Anvin
Browse files

x86-64, init: Do not set NX bits on non-NX capable hardware 



During early init, we would incorrectly set the NX bit even if the NX
feature was not supported.  Instead, only set this bit if NX is
actually available and enabled.  We already do very early detection of
the NX bit to enable it in EFER, this simply extends this detection to
the early page table mask.

Reported-by: default avatarFernando Luis Vázquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1367476850.5660.2.camel@nexus
Cc: <stable@vger.kernel.org> v3.9
parent cc456c4e

arch/x86/kernel/head64.c

+2 −1
Original line number Diff line number Diff line
@@ -34,6 +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);



/* Wipe all early page tables except for the kernel symbol map */

static void __init reset_early_page_tables(void)
@@ -99,7 +100,7 @@ int __init early_make_pgtable(unsigned long address) 
			pmd_p[i] = 0;

		*pud_p = (pudval_t)pmd_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;

	}

	pmd = (physaddr & PMD_MASK) + (__PAGE_KERNEL_LARGE & ~_PAGE_GLOBAL);

	pmd = (physaddr & PMD_MASK) + early_pmd_flags;

	pmd_p[pmd_index(address)] = pmd;



	return 0;

arch/x86/kernel/head_64.S

+1 −0
Original line number Diff line number Diff line
@@ -200,6 +200,7 @@ ENTRY(secondary_startup_64) 
	btl	$20,%edi		/* No Execute supported? */

	jnc     1f

	btsl	$_EFER_NX, %eax

	btsq	$_PAGE_BIT_NX,early_pmd_flags(%rip)

1:	wrmsr				/* Make changes effective */



	/* Setup cr0 */