diff --git a/arch/i386/kernel/e820.c b/arch/i386/kernel/e820.c
index f391abc..8b8741f 100644
--- a/arch/i386/kernel/e820.c
+++ b/arch/i386/kernel/e820.c
@@ -156,29 +156,31 @@ static struct resource standard_io_resou
.flags = IORESOURCE_BUSY | IORESOURCE_IO
} };
-static int romsignature(const unsigned char *x)
+#define ROMSIGNATURE 0xaa55
+
+static int __init romsignature(const unsigned char *rom)
{
+ const unsigned short * const ptr = (const unsigned short *)rom;
unsigned short sig;
- int ret = 0;
- if (probe_kernel_address((const unsigned short *)x, sig) == 0)
- ret = (sig == 0xaa55);
- return ret;
+
+ return probe_kernel_address(ptr, sig) == 0 && sig == ROMSIGNATURE;
}
-static int __init romchecksum(unsigned char *rom, unsigned long length)
+static int __init romchecksum(const unsigned char *rom, unsigned long length)
{
- unsigned char *p, sum = 0;
+ unsigned char sum, c;
- for (p = rom; p < rom + length; p++)
- sum += *p;
- return sum == 0;
+ for (sum = 0; length && probe_kernel_address(rom++, c) == 0; length--)
+ sum += c;
+ return !length && !sum;
}
static void __init probe_roms(void)
{
+ const unsigned char *rom;
unsigned long start, length, upper;
- unsigned char *rom;
- int i;
+ unsigned char c;
+ int i;
/* video rom */
upper = adapter_rom_resources[0].start;
@@ -189,8 +191,11 @@ static void __init probe_roms(void)
video_rom_resource.start = start;
+ if (probe_kernel_address(rom + 2, c) != 0)
+ continue;
+
/* 0 < length <= 0x7f * 512, historically */
- length = rom[2] * 512;
+ length = c * 512;
/* if checksum okay, trust length byte */
if (length && romchecksum(rom, length))
@@ -224,8 +229,11 @@ static void __init probe_roms(void)
if (!romsignature(rom))
continue;
+ if (probe_kernel_address(rom + 2, c) != 0)
+ continue;
+
/* 0 < length <= 0x7f * 512, historically */
- length = rom[2] * 512;
+ length = c * 512;
/* but accept any length that fits if checksum okay */
if (!length || start + length > upper || !romchecksum(rom, length))