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

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>

1 files changed, 31 insertions, 40 deletions

diff --git a/arch/x86/boot/edd.c b/arch/x86/boot/edd.c
index 1aae8f3e5ca1..c501a5b466f8 100644
--- a/arch/x86/boot/edd.c
+++ b/arch/x86/boot/edd.c
@@ -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");
-
-        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;
+        ireg.ah = 0x08;
+        ireg.es = 0;
+        intcall(0x13, &ireg, &oreg);
+
+        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;