From: Jeremy Fitzhardinge Date: Sun, 7 Sep 2008 08:51:32 +0000 (-0700) Subject: x86: check for and defend against BIOS memory corruption X-Git-Tag: v2.6.28-rc1~699^2^6~13 X-Git-Url: http://www.pilppa.org/gitweb/gitweb.cgi?a=commitdiff_plain;h=5394f80f92642c61fc2a95385be85f2fdcfb5adb;p=linux-2.6-omap-h63xx.git x86: check for and defend against BIOS memory corruption Some BIOSes have been observed to corrupt memory in the low 64k. This change: - Reserves all memory which does not have to be in that area, to prevent it from being used as general memory by the kernel. Things like the SMP trampoline are still in the memory, however. - Clears the reserved memory so we can observe changes to it. - Adds a function check_for_bios_corruption() which checks and reports on memory becoming unexpectedly non-zero. Currently it's called in the x86 fault handler, and the powermanagement debug output. Signed-off-by: Jeremy Fitzhardinge Signed-off-by: Ingo Molnar --- diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 1150444a21a..df48af505d1 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -360,6 +360,11 @@ and is between 256 and 4096 characters. It is defined in the file Format: ,, See header of drivers/net/hamradio/baycom_ser_hdx.c. + bios_corruption_check=0/1 [X86] + Some BIOSes seem to corrupt the first 64k of memory + when doing things like suspend/resume. Setting this + option will scan the memory looking for corruption. + boot_delay= Milliseconds to delay each printk during boot. Values larger than 10 seconds (10000) are changed to no delay (0). diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index ed92864d132..1bb52e2ca02 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -201,6 +201,9 @@ config X86_TRAMPOLINE depends on X86_SMP || (X86_VOYAGER && SMP) || (64BIT && ACPI_SLEEP) default y +config X86_CHECK_BIOS_CORRUPTION + def_bool y + config KTIME_SCALAR def_bool X86_32 source "init/Kconfig" diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 362d4e7f2d3..ee89ebc5aab 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -578,6 +578,89 @@ static struct x86_quirks default_x86_quirks __initdata; struct x86_quirks *x86_quirks __initdata = &default_x86_quirks; +/* + * Some BIOSes seem to corrupt the low 64k of memory during events + * like suspend/resume and unplugging an HDMI cable. Reserve all + * remaining free memory in that area and fill it with a distinct + * pattern. + */ +#ifdef CONFIG_X86_CHECK_BIOS_CORRUPTION +#define MAX_SCAN_AREAS 8 +static struct e820entry scan_areas[MAX_SCAN_AREAS]; +static int num_scan_areas; + +static void __init setup_bios_corruption_check(void) +{ + u64 addr = PAGE_SIZE; /* assume first page is reserved anyway */ + + while(addr < 0x10000 && num_scan_areas < MAX_SCAN_AREAS) { + u64 size; + addr = find_e820_area_size(addr, &size, PAGE_SIZE); + + if (addr == 0) + break; + + if ((addr + size) > 0x10000) + size = 0x10000 - addr; + + if (size == 0) + break; + + e820_update_range(addr, size, E820_RAM, E820_RESERVED); + scan_areas[num_scan_areas].addr = addr; + scan_areas[num_scan_areas].size = size; + num_scan_areas++; + + /* Assume we've already mapped this early memory */ + memset(__va(addr), 0, size); + + addr += size; + } + + printk(KERN_INFO "scanning %d areas for BIOS corruption\n", + num_scan_areas); + update_e820(); +} + +static int __read_mostly bios_corruption_check = 1; + +void check_for_bios_corruption(void) +{ + int i; + int corruption = 0; + + if (!bios_corruption_check) + return; + + for(i = 0; i < num_scan_areas; i++) { + unsigned long *addr = __va(scan_areas[i].addr); + unsigned long size = scan_areas[i].size; + + for(; size; addr++, size -= sizeof(unsigned long)) { + if (!*addr) + continue; + printk(KERN_ERR "Corrupted low memory at %p (%lx phys) = %08lx\n", + addr, __pa(addr), *addr); + corruption = 1; + *addr = 0; + } + } + + if (corruption) + dump_stack(); +} + +static int set_bios_corruption_check(char *arg) +{ + char *end; + + bios_corruption_check = simple_strtol(arg, &end, 10); + + return (*end == 0) ? 0 : -EINVAL; +} +early_param("bios_corruption_check", set_bios_corruption_check); +#endif + /* * Determine if we were loaded by an EFI loader. If so, then we have also been * passed the efi memmap, systab, etc., so we should use these data structures @@ -750,6 +833,10 @@ void __init setup_arch(char **cmdline_p) high_memory = (void *)__va(max_pfn * PAGE_SIZE - 1) + 1; #endif +#ifdef CONFIG_X86_CHECK_BIOS_CORRUPTION + setup_bios_corruption_check(); +#endif + /* max_pfn_mapped is updated here */ max_low_pfn_mapped = init_memory_mapping(0, max_low_pfn<