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grub/grub-core/disk/i386/pc/biosdisk.c
Vladimir 'phcoder' Serbinenko 069c9c5fda merge mainline into intwrap
2010-08-29 23:21:21 +02:00

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/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 1999,2000,2001,2002,2003,2004,2005,2006,2007,2008,2009,2010 Free Software Foundation, Inc.
*
* GRUB is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* GRUB is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
*/
#include <grub/machine/biosdisk.h>
#include <grub/machine/memory.h>
#include <grub/machine/kernel.h>
#include <grub/machine/int.h>
#include <grub/disk.h>
#include <grub/dl.h>
#include <grub/mm.h>
#include <grub/types.h>
#include <grub/misc.h>
#include <grub/err.h>
#include <grub/term.h>
static int cd_drive = 0;
static int grub_biosdisk_rw_int13_extensions (int ah, int drive, void *dap);
static int grub_biosdisk_get_num_floppies (void)
{
struct grub_bios_int_registers regs;
int drive;
/* reset the disk system first */
regs.eax = 0;
regs.edx = 0;
regs.flags = GRUB_CPU_INT_FLAGS_DEFAULT;
grub_bios_interrupt (0x13, &regs);
for (drive = 0; drive < 2; drive++)
{
regs.flags = GRUB_CPU_INT_FLAGS_DEFAULT | GRUB_CPU_INT_FLAGS_CARRY;
regs.edx = drive;
/* call GET DISK TYPE */
regs.eax = 0x1500;
grub_bios_interrupt (0x13, &regs);
if (regs.flags & GRUB_CPU_INT_FLAGS_CARRY)
break;
/* check if this drive exists */
if (!(regs.eax & 0x300))
break;
}
return drive;
}
/*
* Call IBM/MS INT13 Extensions (int 13 %ah=AH) for DRIVE. DAP
* is passed for disk address packet. If an error occurs, return
* non-zero, otherwise zero.
*/
static int
grub_biosdisk_rw_int13_extensions (int ah, int drive, void *dap)
{
struct grub_bios_int_registers regs;
regs.eax = ah << 8;
/* compute the address of disk_address_packet */
regs.ds = (((grub_addr_t) dap) & 0xffff0000) >> 4;
regs.esi = (((grub_addr_t) dap) & 0xffff);
regs.edx = drive;
regs.flags = GRUB_CPU_INT_FLAGS_DEFAULT;
grub_bios_interrupt (0x13, &regs);
return (regs.eax >> 8) & 0xff;
}
/*
* Call standard and old INT13 (int 13 %ah=AH) for DRIVE. Read/write
* NSEC sectors from COFF/HOFF/SOFF into SEGMENT. If an error occurs,
* return non-zero, otherwise zero.
*/
static int
grub_biosdisk_rw_standard (int ah, int drive, int coff, int hoff,
int soff, int nsec, int segment)
{
int ret, i;
/* Try 3 times. */
for (i = 0; i < 3; i++)
{
struct grub_bios_int_registers regs;
/* set up CHS information */
/* set %ch to low eight bits of cylinder */
regs.ecx = (coff << 8) & 0xff00;
/* set bits 6-7 of %cl to high two bits of cylinder */
regs.ecx |= (coff >> 2) & 0xc0;
/* set bits 0-5 of %cl to sector */
regs.ecx |= soff & 0x3f;
/* set %dh to head and %dl to drive */
regs.edx = (drive & 0xff) | ((hoff << 8) & 0xff00);
/* set %ah to AH */
regs.eax = (ah << 8) & 0xff00;
/* set %al to NSEC */
regs.eax |= nsec & 0xff;
regs.ebx = 0;
regs.es = segment;
regs.flags = GRUB_CPU_INT_FLAGS_DEFAULT;
grub_bios_interrupt (0x13, &regs);
/* check if successful */
if (!(regs.flags & GRUB_CPU_INT_FLAGS_CARRY))
return 0;
/* save return value */
ret = regs.eax >> 8;
/* if fail, reset the disk system */
regs.eax = 0;
regs.edx = (drive & 0xff);
regs.flags = GRUB_CPU_INT_FLAGS_DEFAULT;
grub_bios_interrupt (0x13, &regs);
}
return ret;
}
/*
* Check if LBA is supported for DRIVE. If it is supported, then return
* the major version of extensions, otherwise zero.
*/
static int
grub_biosdisk_check_int13_extensions (int drive)
{
struct grub_bios_int_registers regs;
regs.edx = drive & 0xff;
regs.eax = 0x4100;
regs.ebx = 0x55aa;
regs.flags = GRUB_CPU_INT_FLAGS_DEFAULT;
grub_bios_interrupt (0x13, &regs);
if (regs.flags & GRUB_CPU_INT_FLAGS_CARRY)
return 0;
if ((regs.ebx & 0xffff) != 0xaa55)
return 0;
/* check if AH=0x42 is supported */
if (!(regs.ecx & 1))
return 0;
return (regs.eax >> 8) & 0xff;
}
/*
* Return the geometry of DRIVE in CYLINDERS, HEADS and SECTORS. If an
* error occurs, then return non-zero, otherwise zero.
*/
static int
grub_biosdisk_get_diskinfo_standard (int drive,
unsigned long *cylinders,
unsigned long *heads,
unsigned long *sectors)
{
struct grub_bios_int_registers regs;
regs.eax = 0x0800;
regs.edx = drive & 0xff;
regs.flags = GRUB_CPU_INT_FLAGS_DEFAULT;
grub_bios_interrupt (0x13, &regs);
/* Check if unsuccessful. Ignore return value if carry isn't set to
workaround some buggy BIOSes. */
if ((regs.flags & GRUB_CPU_INT_FLAGS_CARRY) && ((regs.eax & 0xff00) != 0))
return (regs.eax & 0xff00) >> 8;
/* bogus BIOSes may not return an error number */
/* 0 sectors means no disk */
if (!(regs.ecx & 0x3f))
/* XXX 0x60 is one of the unused error numbers */
return 0x60;
/* the number of heads is counted from zero */
*heads = ((regs.edx >> 8) & 0xff) + 1;
*cylinders = (((regs.ecx >> 8) & 0xff) | ((regs.ecx << 2) & 0x0300)) + 1;
*sectors = regs.ecx & 0x3f;
return 0;
}
static int
grub_biosdisk_get_diskinfo_real (int drive, void *drp, grub_uint16_t ax)
{
struct grub_bios_int_registers regs;
regs.eax = ax;
/* compute the address of drive parameters */
regs.esi = ((grub_addr_t) drp) & 0xf;
regs.ds = ((grub_addr_t) drp) >> 4;
regs.edx = drive & 0xff;
regs.flags = GRUB_CPU_INT_FLAGS_DEFAULT;
grub_bios_interrupt (0x13, &regs);
/* Check if unsuccessful. Ignore return value if carry isn't set to
workaround some buggy BIOSes. */
if ((regs.flags & GRUB_CPU_INT_FLAGS_CARRY) && ((regs.eax & 0xff00) != 0))
return (regs.eax & 0xff00) >> 8;
return 0;
}
/*
* Return the cdrom information of DRIVE in CDRP. If an error occurs,
* then return non-zero, otherwise zero.
*/
static int
grub_biosdisk_get_cdinfo_int13_extensions (int drive, void *cdrp)
{
return grub_biosdisk_get_diskinfo_real (drive, cdrp, 0x4b01);
}
/*
* Return the geometry of DRIVE in a drive parameters, DRP. If an error
* occurs, then return non-zero, otherwise zero.
*/
static int
grub_biosdisk_get_diskinfo_int13_extensions (int drive, void *drp)
{
return grub_biosdisk_get_diskinfo_real (drive, drp, 0x4800);
}
static int
grub_biosdisk_get_drive (const char *name)
{
unsigned long drive;
if ((name[0] != 'f' && name[0] != 'h') || name[1] != 'd')
goto fail;
drive = grub_strtoul (name + 2, 0, 10);
if (grub_errno != GRUB_ERR_NONE)
goto fail;
if (name[0] == 'h')
drive += 0x80;
return (int) drive ;
fail:
grub_error (GRUB_ERR_UNKNOWN_DEVICE, "not a biosdisk");
return -1;
}
static int
grub_biosdisk_call_hook (int (*hook) (const char *name), int drive)
{
char name[10];
grub_snprintf (name, sizeof (name),
(drive & 0x80) ? "hd%d" : "fd%d", drive & (~0x80));
return hook (name);
}
static int
grub_biosdisk_iterate (int (*hook) (const char *name))
{
int drive;
int num_floppies;
/* For hard disks, attempt to read the MBR. */
for (drive = 0x80; drive < 0x90; drive++)
{
if (grub_biosdisk_rw_standard (0x02, drive, 0, 0, 1, 1,
GRUB_MEMORY_MACHINE_SCRATCH_SEG) != 0)
{
grub_dprintf ("disk", "Read error when probing drive 0x%2x\n", drive);
break;
}
if (grub_biosdisk_call_hook (hook, drive))
return 1;
}
if (cd_drive)
{
if (grub_biosdisk_call_hook (hook, cd_drive))
return 1;
}
/* For floppy disks, we can get the number safely. */
num_floppies = grub_biosdisk_get_num_floppies ();
for (drive = 0; drive < num_floppies; drive++)
if (grub_biosdisk_call_hook (hook, drive))
return 1;
return 0;
}
static grub_err_t
grub_biosdisk_open (const char *name, grub_disk_t disk)
{
grub_uint64_t total_sectors = 0;
int drive;
struct grub_biosdisk_data *data;
drive = grub_biosdisk_get_drive (name);
if (drive < 0)
return grub_errno;
disk->has_partitions = 1;
disk->id = drive;
data = (struct grub_biosdisk_data *) grub_zalloc (sizeof (*data));
if (! data)
return grub_errno;
data->drive = drive;
if ((cd_drive) && (drive == cd_drive))
{
data->flags = GRUB_BIOSDISK_FLAG_LBA | GRUB_BIOSDISK_FLAG_CDROM;
data->sectors = 32;
/* TODO: get the correct size. */
total_sectors = GRUB_DISK_SIZE_UNKNOWN;
}
else
{
/* HDD */
int version;
version = grub_biosdisk_check_int13_extensions (drive);
if (version)
{
struct grub_biosdisk_drp *drp
= (struct grub_biosdisk_drp *) GRUB_MEMORY_MACHINE_SCRATCH_ADDR;
/* Clear out the DRP. */
grub_memset (drp, 0, sizeof (*drp));
drp->size = sizeof (*drp);
if (! grub_biosdisk_get_diskinfo_int13_extensions (drive, drp))
{
data->flags = GRUB_BIOSDISK_FLAG_LBA;
if (drp->total_sectors)
total_sectors = drp->total_sectors;
else
/* Some buggy BIOSes doesn't return the total sectors
correctly but returns zero. So if it is zero, compute
it by C/H/S returned by the LBA BIOS call. */
total_sectors = drp->cylinders * drp->heads * drp->sectors;
}
}
}
if (! (data->flags & GRUB_BIOSDISK_FLAG_CDROM))
{
if (grub_biosdisk_get_diskinfo_standard (drive,
&data->cylinders,
&data->heads,
&data->sectors) != 0)
{
if (total_sectors && (data->flags & GRUB_BIOSDISK_FLAG_LBA))
{
data->sectors = 63;
data->heads = 255;
data->cylinders
= grub_divmod64 (total_sectors
+ data->heads * data->sectors - 1,
data->heads * data->sectors, 0);
}
else
{
grub_free (data);
return grub_error (GRUB_ERR_BAD_DEVICE, "%s cannot get C/H/S values", disk->name);
}
}
if (! total_sectors)
total_sectors = data->cylinders * data->heads * data->sectors;
}
disk->total_sectors = total_sectors;
disk->data = data;
return GRUB_ERR_NONE;
}
static void
grub_biosdisk_close (grub_disk_t disk)
{
grub_free (disk->data);
}
/* For readability. */
#define GRUB_BIOSDISK_READ 0
#define GRUB_BIOSDISK_WRITE 1
#define GRUB_BIOSDISK_CDROM_RETRY_COUNT 3
static grub_err_t
grub_biosdisk_rw (int cmd, grub_disk_t disk,
grub_disk_addr_t sector, grub_size_t size,
unsigned segment)
{
struct grub_biosdisk_data *data = disk->data;
if (data->flags & GRUB_BIOSDISK_FLAG_LBA)
{
struct grub_biosdisk_dap *dap;
dap = (struct grub_biosdisk_dap *) (GRUB_MEMORY_MACHINE_SCRATCH_ADDR
+ (data->sectors
<< GRUB_DISK_SECTOR_BITS));
dap->length = sizeof (*dap);
dap->reserved = 0;
dap->blocks = size;
dap->buffer = segment << 16; /* The format SEGMENT:ADDRESS. */
dap->block = sector;
if (data->flags & GRUB_BIOSDISK_FLAG_CDROM)
{
int i;
if (cmd)
return grub_error (GRUB_ERR_WRITE_ERROR, "can\'t write to cdrom");
dap->blocks = ALIGN_UP (dap->blocks, 4) >> 2;
dap->block >>= 2;
for (i = 0; i < GRUB_BIOSDISK_CDROM_RETRY_COUNT; i++)
if (! grub_biosdisk_rw_int13_extensions (0x42, data->drive, dap))
break;
if (i == GRUB_BIOSDISK_CDROM_RETRY_COUNT)
return grub_error (GRUB_ERR_READ_ERROR, "cdrom read error");
}
else
if (grub_biosdisk_rw_int13_extensions (cmd + 0x42, data->drive, dap))
{
/* Fall back to the CHS mode. */
data->flags &= ~GRUB_BIOSDISK_FLAG_LBA;
disk->total_sectors = data->cylinders * data->heads * data->sectors;
return grub_biosdisk_rw (cmd, disk, sector, size, segment);
}
}
else
{
unsigned coff, hoff, soff;
unsigned head;
/* It is impossible to reach over 8064 MiB (a bit less than LBA24) with
the traditional CHS access. */
if (sector >
1024 /* cylinders */ *
256 /* heads */ *
63 /* spt */)
return grub_error (GRUB_ERR_OUT_OF_RANGE, "%s out of disk", disk->name);
soff = ((grub_uint32_t) sector) % data->sectors + 1;
head = ((grub_uint32_t) sector) / data->sectors;
hoff = head % data->heads;
coff = head / data->heads;
if (coff >= data->cylinders)
return grub_error (GRUB_ERR_OUT_OF_RANGE, "%s out of disk", disk->name);
if (grub_biosdisk_rw_standard (cmd + 0x02, data->drive,
coff, hoff, soff, size, segment))
{
switch (cmd)
{
case GRUB_BIOSDISK_READ:
return grub_error (GRUB_ERR_READ_ERROR, "%s read error", disk->name);
case GRUB_BIOSDISK_WRITE:
return grub_error (GRUB_ERR_WRITE_ERROR, "%s write error", disk->name);
}
}
}
return GRUB_ERR_NONE;
}
/* Return the number of sectors which can be read safely at a time. */
static grub_size_t
get_safe_sectors (grub_disk_addr_t sector, grub_uint32_t sectors)
{
grub_size_t size;
grub_uint32_t offset;
/* OFFSET = SECTOR % SECTORS */
grub_divmod64 (sector, sectors, &offset);
size = sectors - offset;
/* Limit the max to 0x7f because of Phoenix EDD. */
if (size > 0x7f)
size = 0x7f;
return size;
}
static grub_err_t
grub_biosdisk_read (grub_disk_t disk, grub_disk_addr_t sector,
grub_size_t size, char *buf)
{
struct grub_biosdisk_data *data = disk->data;
while (size)
{
grub_size_t len;
grub_size_t cdoff = 0;
len = get_safe_sectors (sector, data->sectors);
if (data->flags & GRUB_BIOSDISK_FLAG_CDROM)
{
cdoff = (sector & 3) << GRUB_DISK_SECTOR_BITS;
len = ALIGN_UP (sector + len, 4) - (sector & ~3);
sector &= ~3;
}
if (len > size)
len = size;
if (grub_biosdisk_rw (GRUB_BIOSDISK_READ, disk, sector, len,
GRUB_MEMORY_MACHINE_SCRATCH_SEG))
return grub_errno;
grub_memcpy (buf, (void *) (GRUB_MEMORY_MACHINE_SCRATCH_ADDR + cdoff),
len << GRUB_DISK_SECTOR_BITS);
buf += len << GRUB_DISK_SECTOR_BITS;
sector += len;
size -= len;
}
return grub_errno;
}
static grub_err_t
grub_biosdisk_write (grub_disk_t disk, grub_disk_addr_t sector,
grub_size_t size, const char *buf)
{
struct grub_biosdisk_data *data = disk->data;
if (data->flags & GRUB_BIOSDISK_FLAG_CDROM)
return grub_error (GRUB_ERR_IO, "can't write to CDROM");
while (size)
{
grub_size_t len;
len = get_safe_sectors (sector, data->sectors);
if (len > size)
len = size;
grub_memcpy ((void *) GRUB_MEMORY_MACHINE_SCRATCH_ADDR, buf,
len << GRUB_DISK_SECTOR_BITS);
if (grub_biosdisk_rw (GRUB_BIOSDISK_WRITE, disk, sector, len,
GRUB_MEMORY_MACHINE_SCRATCH_SEG))
return grub_errno;
buf += len << GRUB_DISK_SECTOR_BITS;
sector += len;
size -= len;
}
return grub_errno;
}
static struct grub_disk_dev grub_biosdisk_dev =
{
.name = "biosdisk",
.id = GRUB_DISK_DEVICE_BIOSDISK_ID,
.iterate = grub_biosdisk_iterate,
.open = grub_biosdisk_open,
.close = grub_biosdisk_close,
.read = grub_biosdisk_read,
.write = grub_biosdisk_write,
.next = 0
};
static void
grub_disk_biosdisk_fini (void)
{
grub_disk_dev_unregister (&grub_biosdisk_dev);
}
GRUB_MOD_INIT(biosdisk)
{
struct grub_biosdisk_cdrp *cdrp
= (struct grub_biosdisk_cdrp *) GRUB_MEMORY_MACHINE_SCRATCH_ADDR;
if (grub_disk_firmware_is_tainted)
{
grub_printf ("Firmware is marked as tainted, refusing to initialize.\n");
return;
}
grub_disk_firmware_fini = grub_disk_biosdisk_fini;
grub_memset (cdrp, 0, sizeof (*cdrp));
cdrp->size = sizeof (*cdrp);
cdrp->media_type = 0xFF;
if ((! grub_biosdisk_get_cdinfo_int13_extensions (grub_boot_drive, cdrp)) &&
((cdrp->media_type & GRUB_BIOSDISK_CDTYPE_MASK)
== GRUB_BIOSDISK_CDTYPE_NO_EMUL))
cd_drive = cdrp->drive_no;
grub_disk_dev_register (&grub_biosdisk_dev);
}
GRUB_MOD_FINI(biosdisk)
{
grub_disk_biosdisk_fini ();
}
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