The kernel sets the NX bit in the early page tables without checking whether the CPU actually supports this feature. If it doesn't the first attempt to use them will cause a kernel hang. Since these are temporary page tables marked as initdata this fix takes the approach of not bothering with the NX bit at all.
Noticed when my AMD machine that happened to have the NX feature disabled by the BIOS failed to boot after the update to 3.9. Cc: [email protected] Signed-off-by: Fernando Luis Vazquez Cao <[email protected]> --- diff -urNp linux-3.9/arch/x86/kernel/head64.c linux-3.9-fix/arch/x86/kernel/head64.c --- linux-3.9/arch/x86/kernel/head64.c 2013-04-29 09:36:01.000000000 +0900 +++ linux-3.9-fix/arch/x86/kernel/head64.c 2013-05-02 14:38:52.589276092 +0900 @@ -99,7 +99,7 @@ again: 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) + (__PAGE_KERNEL_LARGE_EXEC & ~_PAGE_GLOBAL); pmd_p[pmd_index(address)] = pmd; return 0; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
