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x86, setup: "glove box" BIOS interrupts in the EDD code

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Impact: BIOS proofing

"Glove box" off BIOS interrupts in the EDD code.

LKML-Reference: <49DE7F79.4030106@zytor.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
H. Peter Anvin 2009-04-01 18:17:17 -07:00 committed by H. Peter Anvin
parent d54ea252e4
commit 3435d3476c
1 changed files with 30 additions and 39 deletions
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69
arch/x86/boot/edd.c
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@ -2,6 +2,7 @@
*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright 2007 rPath, Inc. - All Rights Reserved
* Copyright 2009 Intel Corporation; author H. Peter Anvin
*
* This file is part of the Linux kernel, and is made available under
* the terms of the GNU General Public License version 2.
@ -22,17 +23,17 @@
*/
static int read_mbr(u8 devno, void *buf)
{
u16 ax, bx, cx, dx;
struct biosregs ireg, oreg;
ax = 0x0201; /* Legacy Read, one sector */
cx = 0x0001; /* Sector 0-0-1 */
dx = devno;
bx = (size_t)buf;
asm volatile("pushfl; stc; int $0x13; setc %%al; popfl"
: "+a" (ax), "+c" (cx), "+d" (dx), "+b" (bx)
: : "esi", "edi", "memory");
initregs(&ireg);
ireg.ax = 0x0201; /* Legacy Read, one sector */
ireg.cx = 0x0001; /* Sector 0-0-1 */
ireg.dl = devno;
ireg.bx = (size_t)buf;
return -(u8)ax; /* 0 or -1 */
intcall(0x13, &ireg, &oreg);
return -(oreg.eflags & X86_EFLAGS_CF); /* 0 or -1 */
}
static u32 read_mbr_sig(u8 devno, struct edd_info *ei, u32 *mbrsig)
@ -72,56 +73,46 @@ static u32 read_mbr_sig(u8 devno, struct edd_info *ei, u32 *mbrsig)
static int get_edd_info(u8 devno, struct edd_info *ei)
{
u16 ax, bx, cx, dx, di;
struct biosregs ireg, oreg;
memset(ei, 0, sizeof *ei);
/* Check Extensions Present */
ax = 0x4100;
bx = EDDMAGIC1;
dx = devno;
asm("pushfl; stc; int $0x13; setc %%al; popfl"
: "+a" (ax), "+b" (bx), "=c" (cx), "+d" (dx)
: : "esi", "edi");
initregs(&ireg);
ireg.ah = 0x41;
ireg.bx = EDDMAGIC1;
ireg.dl = devno;
intcall(0x13, &ireg, &oreg);
if ((u8)ax)
if (oreg.eflags & X86_EFLAGS_CF)
return -1; /* No extended information */
if (bx != EDDMAGIC2)
if (oreg.bx != EDDMAGIC2)
return -1;
ei->device = devno;
ei->version = ax >> 8; /* EDD version number */
ei->interface_support = cx; /* EDD functionality subsets */
ei->version = oreg.ah; /* EDD version number */
ei->interface_support = oreg.cx; /* EDD functionality subsets */
/* Extended Get Device Parameters */
ei->params.length = sizeof(ei->params);
ax = 0x4800;
dx = devno;
asm("pushfl; int $0x13; popfl"
: "+a" (ax), "+d" (dx), "=m" (ei->params)
: "S" (&ei->params)
: "ebx", "ecx", "edi");
ireg.ah = 0x48;
ireg.si = (size_t)&ei->params;
intcall(0x13, &ireg, &oreg);
/* Get legacy CHS parameters */
/* Ralf Brown recommends setting ES:DI to 0:0 */
ax = 0x0800;
dx = devno;
di = 0;
asm("pushw %%es; "
"movw %%di,%%es; "
"pushfl; stc; int $0x13; setc %%al; popfl; "
"popw %%es"
: "+a" (ax), "=b" (bx), "=c" (cx), "+d" (dx), "+D" (di)
: : "esi");
ireg.ah = 0x08;
ireg.es = 0;
intcall(0x13, &ireg, &oreg);
if ((u8)ax == 0) {
ei->legacy_max_cylinder = (cx >> 8) + ((cx & 0xc0) << 2);
ei->legacy_max_head = dx >> 8;
ei->legacy_sectors_per_track = cx & 0x3f;
if (!(oreg.eflags & X86_EFLAGS_CF)) {
ei->legacy_max_cylinder = oreg.ch + ((oreg.cl & 0xc0) << 2);
ei->legacy_max_head = oreg.dh;
ei->legacy_sectors_per_track = oreg.cl & 0x3f;
}
return 0;