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Subject[PATCH] x86_64: sync up probe_roms() with i386
Hi Andrew.

This syncs up the x86_64 probe_roms() with the i386 version as just
submitted.

===
Sync up with i386. Specifically, be careful about touching the
legacy ROMs; in virtualized environments they may not be mapped.

Crosscompiled, but not booted due to lack of hardware.

Signed-off-by: Rene Herman <rene.herman@gmail.com>
===

Rene
diff --git a/arch/x86_64/kernel/setup.c b/arch/x86_64/kernel/setup.c
index af425a8..0b3d237 100644
--- a/arch/x86_64/kernel/setup.c
+++ b/arch/x86_64/kernel/setup.c
@@ -183,22 +183,31 @@ static struct resource video_ram_resourc
.flags = IORESOURCE_RAM,
};

-#define romsignature(x) (*(unsigned short *)(x) == 0xaa55)
+#define ROMSIGNATURE 0xaa55

-static int __init romchecksum(unsigned char *rom, unsigned long length)
+static int __init romsignature(const unsigned char *rom)
{
- unsigned char *p, sum = 0;
+ const unsigned short * const ptr = (const unsigned short *)rom;
+ unsigned short sig;

- for (p = rom; p < rom + length; p++)
- sum += *p;
- return sum == 0;
+ return probe_kernel_address(ptr, sig) == 0 && sig == ROMSIGNATURE;
+}
+
+static int __init romchecksum(const unsigned char *rom, unsigned long length)
+{
+ unsigned char sum, c;
+
+ 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;
@@ -209,8 +218,11 @@ static void __init probe_roms(void)

video_rom_resource.start = start;

+ if (probe_kernel_address(rom, 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))
@@ -245,8 +257,11 @@ static void __init probe_roms(void)
if (!romsignature(rom))
continue;

+ if (probe_kernel_address(rom, 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))
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