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

Impact: BIOS proofing

"Glove box" off BIOS interrupts in the core boot code.

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

1 files changed, 28 insertions, 24 deletions

diff --git a/arch/x86/boot/tty.c b/arch/x86/boot/tty.c
index 7e8e8b25f5f..01ec69c901c 100644
--- a/arch/x86/boot/tty.c
+++ b/arch/x86/boot/tty.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.
@@ -22,24 +23,23 @@
 
 void __attribute__((section(".inittext"))) putchar(int ch)
 {
-        unsigned char c = ch;
+        struct biosregs ireg;
 
-        if (c == '\n')
+        if (ch == '\n')
                 putchar('\r');  /* \n -> \r\n */
 
-        /* int $0x10 is known to have bugs involving touching registers
-           it shouldn't.  Be extra conservative... */
-        asm volatile("pushal; pushw %%ds; int $0x10; popw %%ds; popal"
-                     : : "b" (0x0007), "c" (0x0001), "a" (0x0e00|ch));
+        initregs(&ireg);
+        ireg.bx = 0x0007;
+        ireg.cx = 0x0001;
+        ireg.ah = 0x0e;
+        ireg.al = ch;
+        intcall(0x10, &ireg, NULL);
 }
 
 void __attribute__((section(".inittext"))) puts(const char *str)
 {
-        int n = 0;
-        while (*str) {
+        while (*str)
                 putchar(*str++);
-                n++;
-        }
 }
 
 /*
@@ -49,14 +49,13 @@ void __attribute__((section(".inittext"))) puts(const char *str)
 
 static u8 gettime(void)
 {
-        u16 ax = 0x0200;
-        u16 cx, dx;
+        struct biosregs ireg, oreg;
 
-        asm volatile("int $0x1a"
-                     : "+a" (ax), "=c" (cx), "=d" (dx)
-                     : : "ebx", "esi", "edi");
+        initregs(&ireg);
+        ireg.ah = 0x02;
+        intcall(0x1a, &ireg, &oreg);
 
-        return dx >> 8;
+        return oreg.dh;
 }
 
 /*
@@ -64,19 +63,24 @@ static u8 gettime(void)
  */
 int getchar(void)
 {
-        u16 ax = 0;
-        asm volatile("int $0x16" : "+a" (ax));
+        struct biosregs ireg, oreg;
+
+        initregs(&ireg);
+        /* ireg.ah = 0x00; */
+        intcall(0x16, &ireg, &oreg);
 
-        return ax & 0xff;
+        return oreg.al;
 }
 
 static int kbd_pending(void)
 {
-        u8 pending;
-        asm volatile("int $0x16; setnz %0"
-                     : "=qm" (pending)
-                     : "a" (0x0100));
-        return pending;
+        struct biosregs ireg, oreg;
+
+        initregs(&ireg);
+        ireg.ah = 0x01;
+        intcall(0x16, &ireg, &oreg);
+
+        return !(oreg.eflags & X86_EFLAGS_ZF);
 }
 
 void kbd_flush(void)