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Commit 78d77df7 authored May 02, 2013 by H. Peter Anvin

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: Fernando Luis Vázquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: H. 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	Original line	Diff line number	Diff line
	@@ -34,6 +34,7 @@
	extern pgd_t early_level4_pgt[PTRS_PER_PGD];		extern pgd_t early_level4_pgt[PTRS_PER_PGD];
	extern pmd_t early_dynamic_pgts[EARLY_DYNAMIC_PAGE_TABLES][PTRS_PER_PMD];		extern pmd_t early_dynamic_pgts[EARLY_DYNAMIC_PAGE_TABLES][PTRS_PER_PMD];
	static unsigned int __initdata next_early_pgt = 2;		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 */		/* Wipe all early page tables except for the kernel symbol map */
	static void __init reset_early_page_tables(void)		static void __init reset_early_page_tables(void)
	@@ -99,7 +100,7 @@ again:
	pmd_p[i] = 0;		pmd_p[i] = 0;
	*pud_p = (pudval_t)pmd_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;		*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;		pmd_p[pmd_index(address)] = pmd;

	return 0;		return 0;

arch/x86/kernel/head_64.S

+1 −0

Original line number	Original line	Diff line number	Diff line
	@@ -200,6 +200,7 @@ ENTRY(secondary_startup_64)
	btl $20,%edi /* No Execute supported? */		btl $20,%edi /* No Execute supported? */
	jnc 1f		jnc 1f
	btsl $_EFER_NX, %eax		btsl $_EFER_NX, %eax
			btsq $_PAGE_BIT_NX,early_pmd_flags(%rip)
	1: wrmsr /* Make changes effective */		1: wrmsr /* Make changes effective */

	/* Setup cr0 */		/* Setup cr0 */