A page fault can crash the kernel very early if an NX bit is set in a page table entry, if the CPU doesn't support NX (or if NX support is disabled in the CPU). Move the call to x86_configure_nx() earlier than parse_setup_data(), since that calls early_memremap().
Signed-off-by: Stuart Hayes <[email protected]> --- --- linux-3.16-rc3/arch/x86/kernel/setup.c.orig 2014-07-02 12:14:50.196308719 -0400 +++ linux-3.16-rc3/arch/x86/kernel/setup.c 2014-07-02 12:11:11.240301228 -0400 @@ -940,6 +940,17 @@ void __init setup_arch(char **cmdline_p) iomem_resource.end = (1ULL << boot_cpu_data.x86_phys_bits) - 1; setup_memory_map(); + + /* + * x86_configure_nx() is called before parse_setup_data() to detect + * whether hardware doesn't support NX (so that parse_setup_data() + * can safely call early_memremap() without setting the XD bit in + * the PTE, which can cause an unrecoverable page fault). It may + * then be called again from within noexec_setup() during parsing + * early parameters to honor the respective command line option. + */ + x86_configure_nx(); + parse_setup_data(); copy_edd(); @@ -974,15 +985,6 @@ void __init setup_arch(char **cmdline_p) strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE); *cmdline_p = command_line; - /* - * x86_configure_nx() is called before parse_early_param() to detect - * whether hardware doesn't support NX (so that the early EHCI debug - * console setup can safely call set_fixmap()). It may then be called - * again from within noexec_setup() during parsing early parameters - * to honor the respective command line option. - */ - x86_configure_nx(); - parse_early_param(); x86_report_nx(); -- 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/
