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

Impact: BIOS proofing

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

LKML-Reference: <49DE7F79.4030106@zytor.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 12 insertions, 15 deletions

diff --git a/arch/x86/boot/mca.c b/arch/x86/boot/mca.c
index 911eaae5d696..a95a531148ef 100644
--- a/arch/x86/boot/mca.c
+++ b/arch/x86/boot/mca.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.
@@ -16,26 +17,22 @@
 
 int query_mca(void)
 {
-        u8 err;
-        u16 es, bx, len;
-
-        asm("pushw %%es ; "
-            "int $0x15 ; "
-            "setc %0 ; "
-            "movw %%es, %1 ; "
-            "popw %%es"
-            : "=acd" (err), "=acdSD" (es), "=b" (bx)
-            : "a" (0xc000));
-
-        if (err)
+        struct biosregs ireg, oreg;
+        u16 len;
+
+        initregs(&ireg);
+        ireg.ah = 0xc0;
+        intcall(0x15, &ireg, &oreg);
+
+        if (oreg.eflags & X86_EFLAGS_CF)
                 return -1;      /* No MCA present */
 
-        set_fs(es);
-        len = rdfs16(bx);
+        set_fs(oreg.es);
+        len = rdfs16(oreg.bx);
 
         if (len > sizeof(boot_params.sys_desc_table))
                 len = sizeof(boot_params.sys_desc_table);
 
-        copy_from_fs(&boot_params.sys_desc_table, bx, len);
+        copy_from_fs(&boot_params.sys_desc_table, oreg.bx, len);
         return 0;
 }