[tip:x86/setup] x86, setup: "glove box" BIOS interrupts in the video code

From: H. Peter Anvin
Date: Thu Apr 09 2009 - 19:15:47 EST

Commit-ID: cf06de7b9cdd3efee7a59dced1977b3c21d43732
Gitweb: http://git.kernel.org/tip/cf06de7b9cdd3efee7a59dced1977b3c21d43732
Author: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
AuthorDate: Wed, 1 Apr 2009 18:20:11 -0700
Committer: H. Peter Anvin <hpa@xxxxxxxxx>
CommitDate: Thu, 9 Apr 2009 16:08:12 -0700

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

Impact: BIOS proofing

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

LKML-Reference: <49DE7F79.4030106@xxxxxxxxx>
Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
Cc: Pavel Machek <pavel@xxxxxx>
Cc: Rafael J. Wysocki <rjw@xxxxxxx>


---
arch/x86/boot/video-bios.c | 27 ++++-----
arch/x86/boot/video-vesa.c | 137 +++++++++++++++++++-------------------------
arch/x86/boot/video-vga.c | 95 +++++++++++++++++++------------
arch/x86/boot/video.c | 42 ++++++-------
arch/x86/boot/video.h | 14 -----
5 files changed, 151 insertions(+), 164 deletions(-)

diff --git a/arch/x86/boot/video-bios.c b/arch/x86/boot/video-bios.c
index 3fa979c..d660be4 100644
--- a/arch/x86/boot/video-bios.c
+++ b/arch/x86/boot/video-bios.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.
@@ -29,21 +30,21 @@ static int bios_set_mode(struct mode_info *mi)

static int set_bios_mode(u8 mode)
{
- u16 ax;
+ struct biosregs ireg, oreg;
u8 new_mode;

- ax = mode; /* AH=0x00 Set Video Mode */
- asm volatile(INT10
- : "+a" (ax)
- : : "ebx", "ecx", "edx", "esi", "edi");
+ initregs(&ireg);
+ ireg.al = mode; /* AH=0x00 Set Video Mode */
+ intcall(0x10, &ireg, NULL);

- ax = 0x0f00; /* Get Current Video Mode */
- asm volatile(INT10
- : "+a" (ax)
- : : "ebx", "ecx", "edx", "esi", "edi");
+
+ ireg.ah = 0x0f; /* Get Current Video Mode */
+ intcall(0x10, &ireg, &oreg);

do_restore = 1; /* Assume video contents were lost */
- new_mode = ax & 0x7f; /* Not all BIOSes are clean with the top bit */
+
+ /* Not all BIOSes are clean with the top bit */
+ new_mode = ireg.al & 0x7f;

if (new_mode == mode)
return 0; /* Mode change OK */
@@ -53,10 +54,8 @@ static int set_bios_mode(u8 mode)
/* Mode setting failed, but we didn't end up where we
started. That's bad. Try to revert to the original
video mode. */
- ax = boot_params.screen_info.orig_video_mode;
- asm volatile(INT10
- : "+a" (ax)
- : : "ebx", "ecx", "edx", "esi", "edi");
+ ireg.ax = boot_params.screen_info.orig_video_mode;
+ intcall(0x10, &ireg, NULL);
}
#endif
return -1;
diff --git a/arch/x86/boot/video-vesa.c b/arch/x86/boot/video-vesa.c
index 4a58c8c..c700147 100644
--- a/arch/x86/boot/video-vesa.c
+++ b/arch/x86/boot/video-vesa.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.
@@ -31,7 +32,7 @@ static inline void vesa_store_mode_params_graphics(void) {}
static int vesa_probe(void)
{
#if defined(CONFIG_VIDEO_VESA) || defined(CONFIG_FIRMWARE_EDID)
- u16 ax, cx, di;
+ struct biosregs ireg, oreg;
u16 mode;
addr_t mode_ptr;
struct mode_info *mi;
@@ -39,13 +40,12 @@ static int vesa_probe(void)

video_vesa.modes = GET_HEAP(struct mode_info, 0);

- ax = 0x4f00;
- di = (size_t)&vginfo;
- asm(INT10
- : "+a" (ax), "+D" (di), "=m" (vginfo)
- : : "ebx", "ecx", "edx", "esi");
+ initregs(&ireg);
+ ireg.ax = 0x4f00;
+ ireg.di = (size_t)&vginfo;
+ intcall(0x10, &ireg, &oreg);

- if (ax != 0x004f ||
+ if (ireg.ax != 0x004f ||
vginfo.signature != VESA_MAGIC ||
vginfo.version < 0x0102)
return 0; /* Not present */
@@ -65,14 +65,12 @@ static int vesa_probe(void)

memset(&vminfo, 0, sizeof vminfo); /* Just in case... */

- ax = 0x4f01;
- cx = mode;
- di = (size_t)&vminfo;
- asm(INT10
- : "+a" (ax), "+c" (cx), "+D" (di), "=m" (vminfo)
- : : "ebx", "edx", "esi");
+ ireg.ax = 0x4f01;
+ ireg.cx = mode;
+ ireg.di = (size_t)&vminfo;
+ intcall(0x10, &ireg, &oreg);

- if (ax != 0x004f)
+ if (ireg.ax != 0x004f)
continue;

if ((vminfo.mode_attr & 0x15) == 0x05) {
@@ -111,20 +109,19 @@ static int vesa_probe(void)

static int vesa_set_mode(struct mode_info *mode)
{
- u16 ax, bx, cx, di;
+ struct biosregs ireg, oreg;
int is_graphic;
u16 vesa_mode = mode->mode - VIDEO_FIRST_VESA;

memset(&vminfo, 0, sizeof vminfo); /* Just in case... */

- ax = 0x4f01;
- cx = vesa_mode;
- di = (size_t)&vminfo;
- asm(INT10
- : "+a" (ax), "+c" (cx), "+D" (di), "=m" (vminfo)
- : : "ebx", "edx", "esi");
+ initregs(&ireg);
+ ireg.ax = 0x4f01;
+ ireg.cx = vesa_mode;
+ ireg.di = (size_t)&vminfo;
+ intcall(0x10, &ireg, &oreg);

- if (ax != 0x004f)
+ if (oreg.ax != 0x004f)
return -1;

if ((vminfo.mode_attr & 0x15) == 0x05) {
@@ -141,14 +138,12 @@ static int vesa_set_mode(struct mode_info *mode)
}


- ax = 0x4f02;
- bx = vesa_mode;
- di = 0;
- asm volatile(INT10
- : "+a" (ax), "+b" (bx), "+D" (di)
- : : "ecx", "edx", "esi");
+ initregs(&ireg);
+ ireg.ax = 0x4f02;
+ ireg.bx = vesa_mode;
+ intcall(0x10, &ireg, &oreg);

- if (ax != 0x004f)
+ if (oreg.ax != 0x004f)
return -1;

graphic_mode = is_graphic;
@@ -171,50 +166,45 @@ static int vesa_set_mode(struct mode_info *mode)
/* Switch DAC to 8-bit mode */
static void vesa_dac_set_8bits(void)
{
+ struct biosregs ireg, oreg;
u8 dac_size = 6;

/* If possible, switch the DAC to 8-bit mode */
if (vginfo.capabilities & 1) {
- u16 ax, bx;
-
- ax = 0x4f08;
- bx = 0x0800;
- asm volatile(INT10
- : "+a" (ax), "+b" (bx)
- : : "ecx", "edx", "esi", "edi");
-
- if (ax == 0x004f)
- dac_size = bx >> 8;
+ initregs(&ireg);
+ ireg.ax = 0x4f08;
+ ireg.bh = 0x08;
+ intcall(0x10, &ireg, &oreg);
+ if (oreg.ax == 0x004f)
+ dac_size = oreg.bh;
}

/* Set the color sizes to the DAC size, and offsets to 0 */
- boot_params.screen_info.red_size = dac_size;
+ boot_params.screen_info.red_size = dac_size;
boot_params.screen_info.green_size = dac_size;
- boot_params.screen_info.blue_size = dac_size;
- boot_params.screen_info.rsvd_size = dac_size;
+ boot_params.screen_info.blue_size = dac_size;
+ boot_params.screen_info.rsvd_size = dac_size;

- boot_params.screen_info.red_pos = 0;
- boot_params.screen_info.green_pos = 0;
- boot_params.screen_info.blue_pos = 0;
- boot_params.screen_info.rsvd_pos = 0;
+ boot_params.screen_info.red_pos = 0;
+ boot_params.screen_info.green_pos = 0;
+ boot_params.screen_info.blue_pos = 0;
+ boot_params.screen_info.rsvd_pos = 0;
}

/* Save the VESA protected mode info */
static void vesa_store_pm_info(void)
{
- u16 ax, bx, di, es;
+ struct biosregs ireg, oreg;

- ax = 0x4f0a;
- bx = di = 0;
- asm("pushw %%es; "INT10"; movw %%es,%0; popw %%es"
- : "=d" (es), "+a" (ax), "+b" (bx), "+D" (di)
- : : "ecx", "esi");
+ initregs(&ireg);
+ ireg.ax = 0x4f0a;
+ intcall(0x10, &ireg, &oreg);

- if (ax != 0x004f)
+ if (oreg.ax != 0x004f)
return;

- boot_params.screen_info.vesapm_seg = es;
- boot_params.screen_info.vesapm_off = di;
+ boot_params.screen_info.vesapm_seg = oreg.es;
+ boot_params.screen_info.vesapm_off = oreg.di;
}

/*
@@ -252,7 +242,7 @@ static void vesa_store_mode_params_graphics(void)
void vesa_store_edid(void)
{
#ifdef CONFIG_FIRMWARE_EDID
- u16 ax, bx, cx, dx, di;
+ struct biosregs ireg, oreg;

/* Apparently used as a nonsense token... */
memset(&boot_params.edid_info, 0x13, sizeof boot_params.edid_info);
@@ -260,33 +250,26 @@ void vesa_store_edid(void)
if (vginfo.version < 0x0200)
return; /* EDID requires VBE 2.0+ */

- ax = 0x4f15; /* VBE DDC */
- bx = 0x0000; /* Report DDC capabilities */
- cx = 0; /* Controller 0 */
- di = 0; /* ES:DI must be 0 by spec */
-
- /* Note: The VBE DDC spec is different from the main VESA spec;
- we genuinely have to assume all registers are destroyed here. */
-
- asm("pushw %%es; movw %2,%%es; "INT10"; popw %%es"
- : "+a" (ax), "+b" (bx), "+c" (cx), "+D" (di)
- : : "esi", "edx");
+ initregs(&ireg);
+ ireg.ax = 0x4f15; /* VBE DDC */
+ /* ireg.bx = 0x0000; */ /* Report DDC capabilities */
+ /* ireg.cx = 0; */ /* Controller 0 */
+ ireg.es = 0; /* ES:DI must be 0 by spec */
+ intcall(0x10, &ireg, &oreg);

- if (ax != 0x004f)
+ if (oreg.ax != 0x004f)
return; /* No EDID */

/* BH = time in seconds to transfer EDD information */
/* BL = DDC level supported */

- ax = 0x4f15; /* VBE DDC */
- bx = 0x0001; /* Read EDID */
- cx = 0; /* Controller 0 */
- dx = 0; /* EDID block number */
- di =(size_t) &boot_params.edid_info; /* (ES:)Pointer to block */
- asm(INT10
- : "+a" (ax), "+b" (bx), "+d" (dx), "=m" (boot_params.edid_info),
- "+c" (cx), "+D" (di)
- : : "esi");
+ ireg.ax = 0x4f15; /* VBE DDC */
+ ireg.bx = 0x0001; /* Read EDID */
+ /* ireg.cx = 0; */ /* Controller 0 */
+ /* ireg.dx = 0; */ /* EDID block number */
+ ireg.es = ds();
+ ireg.di =(size_t)&boot_params.edid_info; /* (ES:)Pointer to block */
+ intcall(0x10, &ireg, &oreg);
#endif /* CONFIG_FIRMWARE_EDID */
}

diff --git a/arch/x86/boot/video-vga.c b/arch/x86/boot/video-vga.c
index 9e0587a..8f8d827 100644
--- a/arch/x86/boot/video-vga.c
+++ b/arch/x86/boot/video-vga.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.
@@ -39,30 +40,30 @@ static __videocard video_vga;
/* Set basic 80x25 mode */
static u8 vga_set_basic_mode(void)
{
+ struct biosregs ireg, oreg;
u16 ax;
u8 rows;
u8 mode;

+ initregs(&ireg);
+
#ifdef CONFIG_VIDEO_400_HACK
if (adapter >= ADAPTER_VGA) {
- asm volatile(INT10
- : : "a" (0x1202), "b" (0x0030)
- : "ecx", "edx", "esi", "edi");
+ ireg.ax = 0x1202;
+ ireg.bx = 0x0030;
+ intcall(0x10, &ireg, NULL);
}
#endif

ax = 0x0f00;
- asm volatile(INT10
- : "+a" (ax)
- : : "ebx", "ecx", "edx", "esi", "edi");
-
- mode = (u8)ax;
+ intcall(0x10, &ireg, &oreg);
+ mode = oreg.al;

set_fs(0);
rows = rdfs8(0x484); /* rows minus one */

#ifndef CONFIG_VIDEO_400_HACK
- if ((ax == 0x5003 || ax == 0x5007) &&
+ if ((oreg.ax == 0x5003 || oreg.ax == 0x5007) &&
(rows == 0 || rows == 24))
return mode;
#endif
@@ -71,10 +72,8 @@ static u8 vga_set_basic_mode(void)
mode = 3;

/* Set the mode */
- ax = mode;
- asm volatile(INT10
- : "+a" (ax)
- : : "ebx", "ecx", "edx", "esi", "edi");
+ ireg.ax = mode; /* AH=0: set mode */
+ intcall(0x10, &ireg, NULL);
do_restore = 1;
return mode;
}
@@ -82,43 +81,69 @@ static u8 vga_set_basic_mode(void)
static void vga_set_8font(void)
{
/* Set 8x8 font - 80x43 on EGA, 80x50 on VGA */
+ struct biosregs ireg;
+
+ initregs(&ireg);

/* Set 8x8 font */
- asm volatile(INT10 : : "a" (0x1112), "b" (0));
+ ireg.ax = 0x1112;
+ /* ireg.bl = 0; */
+ intcall(0x10, &ireg, NULL);

/* Use alternate print screen */
- asm volatile(INT10 : : "a" (0x1200), "b" (0x20));
+ ireg.ax = 0x1200;
+ ireg.bl = 0x20;
+ intcall(0x10, &ireg, NULL);

/* Turn off cursor emulation */
- asm volatile(INT10 : : "a" (0x1201), "b" (0x34));
+ ireg.ax = 0x1201;
+ ireg.bl = 0x34;
+ intcall(0x10, &ireg, NULL);

/* Cursor is scan lines 6-7 */
- asm volatile(INT10 : : "a" (0x0100), "c" (0x0607));
+ ireg.ax = 0x0100;
+ ireg.cx = 0x0607;
+ intcall(0x10, &ireg, NULL);
}

static void vga_set_14font(void)
{
/* Set 9x14 font - 80x28 on VGA */
+ struct biosregs ireg;
+
+ initregs(&ireg);

/* Set 9x14 font */
- asm volatile(INT10 : : "a" (0x1111), "b" (0));
+ ireg.ax = 0x1111;
+ /* ireg.bl = 0; */
+ intcall(0x10, &ireg, NULL);

/* Turn off cursor emulation */
- asm volatile(INT10 : : "a" (0x1201), "b" (0x34));
+ ireg.ax = 0x1201;
+ ireg.bl = 0x34;
+ intcall(0x10, &ireg, NULL);

/* Cursor is scan lines 11-12 */
- asm volatile(INT10 : : "a" (0x0100), "c" (0x0b0c));
+ ireg.ax = 0x0100;
+ ireg.cx = 0x0b0c;
+ intcall(0x10, &ireg, NULL);
}

static void vga_set_80x43(void)
{
/* Set 80x43 mode on VGA (not EGA) */
+ struct biosregs ireg;
+
+ initregs(&ireg);

/* Set 350 scans */
- asm volatile(INT10 : : "a" (0x1201), "b" (0x30));
+ ireg.ax = 0x1201;
+ ireg.bl = 0x30;
+ intcall(0x10, &ireg, NULL);

/* Reset video mode */
- asm volatile(INT10 : : "a" (0x0003));
+ ireg.ax = 0x0003;
+ intcall(0x10, &ireg, NULL);

vga_set_8font();
}
@@ -225,8 +250,6 @@ static int vga_set_mode(struct mode_info *mode)
*/
static int vga_probe(void)
{
- u16 ega_bx;
-
static const char *card_name[] = {
"CGA/MDA/HGC", "EGA", "VGA"
};
@@ -240,26 +263,26 @@ static int vga_probe(void)
sizeof(ega_modes)/sizeof(struct mode_info),
sizeof(vga_modes)/sizeof(struct mode_info),
};
- u8 vga_flag;

- asm(INT10
- : "=b" (ega_bx)
- : "a" (0x1200), "b" (0x10) /* Check EGA/VGA */
- : "ecx", "edx", "esi", "edi");
+ struct biosregs ireg, oreg;
+
+ initregs(&ireg);
+
+ ireg.ax = 0x1200;
+ ireg.bl = 0x10; /* Check EGA/VGA */
+ intcall(0x10, &ireg, &oreg);

#ifndef _WAKEUP
- boot_params.screen_info.orig_video_ega_bx = ega_bx;
+ boot_params.screen_info.orig_video_ega_bx = oreg.bx;
#endif

/* If we have MDA/CGA/HGC then BL will be unchanged at 0x10 */
- if ((u8)ega_bx != 0x10) {
+ if (oreg.bl != 0x10) {
/* EGA/VGA */
- asm(INT10
- : "=a" (vga_flag)
- : "a" (0x1a00)
- : "ebx", "ecx", "edx", "esi", "edi");
+ ireg.ax = 0x1a00;
+ intcall(0x10, &ireg, &oreg);

- if (vga_flag == 0x1a) {
+ if (oreg.al == 0x1a) {
adapter = ADAPTER_VGA;
#ifndef _WAKEUP
boot_params.screen_info.orig_video_isVGA = 1;
diff --git a/arch/x86/boot/video.c b/arch/x86/boot/video.c
index 3bef2c1..bad728b 100644
--- a/arch/x86/boot/video.c
+++ b/arch/x86/boot/video.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.
@@ -18,33 +19,29 @@

static void store_cursor_position(void)
{
- u16 curpos;
- u16 ax, bx;
+ struct biosregs ireg, oreg;

- ax = 0x0300;
- bx = 0;
- asm(INT10
- : "=d" (curpos), "+a" (ax), "+b" (bx)
- : : "ecx", "esi", "edi");
+ initregs(&ireg);
+ ireg.ah = 0x03;
+ intcall(0x10, &ireg, &oreg);

- boot_params.screen_info.orig_x = curpos;
- boot_params.screen_info.orig_y = curpos >> 8;
+ boot_params.screen_info.orig_x = oreg.dl;
+ boot_params.screen_info.orig_y = oreg.dh;
}

static void store_video_mode(void)
{
- u16 ax, page;
+ struct biosregs ireg, oreg;

/* N.B.: the saving of the video page here is a bit silly,
since we pretty much assume page 0 everywhere. */
- ax = 0x0f00;
- asm(INT10
- : "+a" (ax), "=b" (page)
- : : "ecx", "edx", "esi", "edi");
+ initregs(&ireg);
+ ireg.ah = 0x0f;
+ intcall(0x10, &ireg, &oreg);

/* Not all BIOSes are clean with respect to the top bit */
- boot_params.screen_info.orig_video_mode = ax & 0x7f;
- boot_params.screen_info.orig_video_page = page >> 8;
+ boot_params.screen_info.orig_video_mode = oreg.al & 0x7f;
+ boot_params.screen_info.orig_video_page = oreg.bh;
}

/*
@@ -257,7 +254,7 @@ static void restore_screen(void)
int y;
addr_t dst = 0;
u16 *src = saved.data;
- u16 ax, bx, dx;
+ struct biosregs ireg;

if (graphic_mode)
return; /* Can't restore onto a graphic mode */
@@ -296,12 +293,11 @@ static void restore_screen(void)
}

/* Restore cursor position */
- ax = 0x0200; /* Set cursor position */
- bx = 0; /* Page number (<< 8) */
- dx = (saved.cury << 8)+saved.curx;
- asm volatile(INT10
- : "+a" (ax), "+b" (bx), "+d" (dx)
- : : "ecx", "esi", "edi");
+ initregs(&ireg);
+ ireg.ah = 0x02; /* Set cursor position */
+ ireg.dh = saved.cury;
+ ireg.dl = saved.curx;
+ intcall(0x10, &ireg, NULL);
}
#else
#define save_screen() ((void)0)
diff --git a/arch/x86/boot/video.h b/arch/x86/boot/video.h
index ee63f5d..5bb174a 100644
--- a/arch/x86/boot/video.h
+++ b/arch/x86/boot/video.h
@@ -112,20 +112,6 @@ extern int force_x, force_y; /* Don't query the BIOS for cols/rows */
extern int do_restore; /* Restore screen contents */
extern int graphic_mode; /* Graphics mode with linear frame buffer */

-/*
- * int $0x10 is notorious for touching registers it shouldn't.
- * gcc doesn't like %ebp being clobbered, so define it as a push/pop
- * sequence here.
- *
- * A number of systems, including the original PC can clobber %bp in
- * certain circumstances, like when scrolling. There exists at least
- * one Trident video card which could clobber DS under a set of
- * circumstances that we are unlikely to encounter (scrolling when
- * using an extended graphics mode of more than 800x600 pixels), but
- * it's cheap insurance to deal with that here.
- */
-#define INT10 "pushl %%ebp; pushw %%ds; int $0x10; popw %%ds; popl %%ebp"
-
/* Accessing VGA indexed registers */
static inline u8 in_idx(u16 port, u8 index)
{
--
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