---

yaml
---
r: 113350
b: refs/heads/master
c: 9f07787
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: bb577f980ef35e2b0d00aeed566724e5032aa5eb
+refs/heads/master: 9f077871ce7237e2387fc76542b3b4033cb05e49

trunk/Documentation/kernel-parameters.txt

@@ -360,11 +360,6 @@ and is between 256 and 4096 characters. It is defined in the file
 			Format: <io>,<irq>,<mode>
 			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).
@@ -1233,6 +1228,29 @@ and is between 256 and 4096 characters. It is defined in the file
 			         or
 			         memmap=0x10000$0x18690000
 
+	memory_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.  Enabling this will
+			both detect corruption and prevent the kernel
+			from using the memory being corrupted.
+			However, its intended as a diagnostic tool; if
+			repeatable BIOS-originated corruption always
+			affects the same memory, you can use memmap=
+			to prevent the kernel from using that memory.
+
+	memory_corruption_check_size=size [X86]
+			By default it checks for corruption in the low
+			64k, making this memory unavailable for normal
+			use.  Use this parameter to scan for
+			corruption in more or less memory.
+
+	memory_corruption_check_period=seconds [X86]
+			By default it checks for corruption every 60
+			seconds.  Use this parameter to check at some
+			other rate.  0 disables periodic checking.
+
 	memtest=	[KNL,X86] Enable memtest
 			Format: <integer>
 			range: 0,4 : pattern number

trunk/arch/x86/Kconfig

@@ -201,9 +201,6 @@ 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"
@@ -1062,6 +1059,29 @@ config HIGHPTE
 	  low memory.  Setting this option will put user-space page table
 	  entries in high memory.
 
+config X86_CHECK_BIOS_CORRUPTION
+        bool "Check for low memory corruption"
+	default y
+	help
+	 Periodically check for memory corruption in low memory, which
+	 is suspected to be caused by BIOS.  Even when enabled in the
+	 configuration, it is disabled at runtime.  Enable it by
+	 setting "memory_corruption_check=1" on the kernel command
+	 line.  By default it scans the low 64k of memory every 60
+	 seconds; see the memory_corruption_check_size and
+	 memory_corruption_check_period parameters in
+	 Documentation/kernel-parameters.txt to adjust this.
+
+	 When enabled with the default parameters, this option has
+	 almost no overhead, as it reserves a relatively small amount
+	 of memory and scans it infrequently.  It both detects corruption
+	 and prevents it from affecting the running system.
+
+	 It is, however, intended as a diagnostic tool; if repeatable
+	 BIOS-originated corruption always affects the same memory,
+	 you can use memmap= to prevent the kernel from using that
+	 memory.
+
 config MATH_EMULATION
 	bool
 	prompt "Math emulation" if X86_32

trunk/arch/x86/kernel/setup.c

@@ -586,22 +586,71 @@ struct x86_quirks *x86_quirks __initdata = &default_x86_quirks;
  */
 #ifdef CONFIG_X86_CHECK_BIOS_CORRUPTION
 #define MAX_SCAN_AREAS	8
+
+static int __read_mostly memory_corruption_check = 0;
+static unsigned __read_mostly corruption_check_size = 64*1024;
+static unsigned __read_mostly corruption_check_period = 60; /* seconds */
+
 static struct e820entry scan_areas[MAX_SCAN_AREAS];
 static int num_scan_areas;
 
+
+static int set_corruption_check(char *arg)
+{
+	char *end;
+
+	memory_corruption_check = simple_strtol(arg, &end, 10);
+
+	return (*end == 0) ? 0 : -EINVAL;
+}
+early_param("memory_corruption_check", set_corruption_check);
+
+static int set_corruption_check_period(char *arg)
+{
+	char *end;
+
+	corruption_check_period = simple_strtoul(arg, &end, 10);
+
+	return (*end == 0) ? 0 : -EINVAL;
+}
+early_param("memory_corruption_check_period", set_corruption_check_period);
+
+static int set_corruption_check_size(char *arg)
+{
+	char *end;
+	unsigned size;
+
+	size = memparse(arg, &end);
+
+	if (*end == '\0')
+		corruption_check_size = size;
+
+	return (size == corruption_check_size) ? 0 : -EINVAL;
+}
+early_param("memory_corruption_check_size", set_corruption_check_size);
+
+
 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) {
+	if (corruption_check_size == 0)
+		memory_corruption_check = 0;
+
+	if (!memory_corruption_check)
+		return;
+
+	corruption_check_size = round_up(corruption_check_size, PAGE_SIZE);
+
+	while(addr < corruption_check_size && 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 ((addr + size) > corruption_check_size)
+			size = corruption_check_size - addr;
 
 		if (size == 0)
 			break;
@@ -617,20 +666,19 @@ static void __init setup_bios_corruption_check(void)
 		addr += size;
 	}
 
-	printk(KERN_INFO "scanning %d areas for BIOS corruption\n",
+	printk(KERN_INFO "Scanning %d areas for low memory corruption\n",
 	       num_scan_areas);
 	update_e820();
 }
 
-static int __read_mostly bios_corruption_check = 1;
 static struct timer_list periodic_check_timer;
 
 void check_for_bios_corruption(void)
 {
 	int i;
 	int corruption = 0;
 
-	if (!bios_corruption_check)
+	if (!memory_corruption_check)
 		return;
 
 	for(i = 0; i < num_scan_areas; i++) {
@@ -647,35 +695,27 @@ void check_for_bios_corruption(void)
 		}
 	}
 
-	if (corruption)
-		dump_stack();
+	WARN(corruption, KERN_ERR "Memory corruption detected in low memory\n");
 }
 
 static void periodic_check_for_corruption(unsigned long data)
 {
 	check_for_bios_corruption();
-	mod_timer(&periodic_check_timer, jiffies + 60*HZ);
+	mod_timer(&periodic_check_timer, jiffies + corruption_check_period*HZ);
 }
 
 void start_periodic_check_for_corruption(void)
 {
-	if (!bios_corruption_check)
+	if (!memory_corruption_check || corruption_check_period == 0)
 		return;
 
+	printk(KERN_INFO "Scanning for low memory corruption every %d seconds\n",
+	       corruption_check_period);
+
 	init_timer(&periodic_check_timer);
 	periodic_check_timer.function = &periodic_check_for_corruption;
 	periodic_check_for_corruption(0);
 }
-
-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
 
 /*