tablet/grub
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
grub/grub-core/disk/i386/pc/biosdisk.c
Michael Chang acffb81485 build: Fix -Werror=array-bounds array subscript 0 is outside array bounds 
The GRUB is failing to build with GCC-12 in many places like this:

  In function 'init_cbfsdisk',
      inlined from 'grub_mod_init' at ../../grub-core/fs/cbfs.c:391:3:
  ../../grub-core/fs/cbfs.c:345:7: error: array subscript 0 is outside array bounds of 'grub_uint32_t[0]' {aka 'unsigned int[]'} [-Werror=array-bounds]
    345 |   ptr = *(grub_uint32_t *) 0xfffffffc;
        |   ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This is caused by GCC regression in 11/12 [1]. In a nut shell, the
warning is about detected invalid accesses at non-zero offsets to NULL
pointers. Since hardwired constant address is treated as NULL plus an
offset in the same underlying code, the warning is therefore triggered.

Instead of inserting #pragma all over the places where literal pointers
are accessed to avoid diagnosing array-bounds, we can try to borrow the
idea from Linux kernel that the absolute_pointer() macro [2][3] is used
to disconnect a pointer using literal address from it's original object,
hence GCC won't be able to make assumptions on the boundary while doing
pointer arithmetic. With that we can greatly reduce the code we have to
cover up by making initial literal pointer assignment to use the new
wrapper but not having to track everywhere literal pointers are
accessed. This also makes code looks cleaner.

Please note the grub_absolute_pointer() macro requires to be invoked in
a function as long as it is compound expression. Some global variables
with literal pointers has been changed to local ones in order to use
grub_absolute_pointer() to initialize it. The shuffling is basically done
in a selective and careful way that the variable's scope doesn't matter
being local or global, for example, the global variable must not get
modified at run time throughout. For the record, here's the list of
global variables got shuffled in this patch:

  grub-core/commands/i386/pc/drivemap.c:int13slot
  grub-core/term/i386/pc/console.c:bios_data_area
  grub-core/term/ns8250.c:serial_hw_io_addr

[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578
[2] https://elixir.bootlin.com/linux/v5.16.14/source/include/linux/compiler.h#L180
[3] https://elixir.bootlin.com/linux/v5.16.14/source/include/linux/compiler-gcc.h#L31

Signed-off-by: Michael Chang <mchang@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2022-04-20 18:27:52 +02:00

689 lines
18 KiB
C
Raw Blame History

/*
* 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/kernel.h>
#include <grub/machine/memory.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>
#include <grub/i18n.h>
GRUB_MOD_LICENSE ("GPLv3+");
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] == 'c' && name[1] == 'd' && name[2] == 0 && cd_drive)
return cd_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 (grub_disk_dev_iterate_hook_t hook, void *hook_data,
int drive)
{
char name[10];
if (cd_drive && drive == cd_drive)
return hook ("cd", hook_data);
grub_snprintf (name, sizeof (name),
(drive & 0x80) ? "hd%d" : "fd%d", drive & (~0x80));
return hook (name, hook_data);
}
static int
grub_biosdisk_iterate (grub_disk_dev_iterate_hook_t hook, void *hook_data,
grub_disk_pull_t pull)
{
int num_floppies;
int drive;
/* For hard disks, attempt to read the MBR. */
switch (pull)
{
case GRUB_DISK_PULL_NONE:
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, hook_data, drive))
return 1;
}
return 0;
case GRUB_DISK_PULL_REMOVABLE:
if (cd_drive)
{
if (grub_biosdisk_call_hook (hook, hook_data, 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, hook_data, drive))
return 1;
return 0;
default:
return 0;
}
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->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 = 8;
disk->log_sector_size = 11;
/* TODO: get the correct size. */
total_sectors = GRUB_DISK_SIZE_UNKNOWN;
}
else
{
/* HDD */
int version;
disk->log_sector_size = 9;
version = grub_biosdisk_check_int13_extensions (drive);
if (version)
{
struct grub_biosdisk_drp *drp
= (struct grub_biosdisk_drp *) grub_absolute_pointer (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 = ((grub_uint64_t) drp->cylinders)
* drp->heads * drp->sectors;
if (drp->bytes_per_sector
&& !(drp->bytes_per_sector & (drp->bytes_per_sector - 1))
&& drp->bytes_per_sector >= 512
&& drp->bytes_per_sector <= 16384)
{
for (disk->log_sector_size = 0;
(1 << disk->log_sector_size) < drp->bytes_per_sector;
disk->log_sector_size++);
}
}
}
}
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 (data->sectors == 0)
data->sectors = 63;
if (data->heads == 0)
data->heads = 255;
if (! total_sectors)
total_sectors = ((grub_uint64_t) data->cylinders)
* data->heads * data->sectors;
}
disk->total_sectors = total_sectors;
/* Limit the max to 0x7f because of Phoenix EDD. */
disk->max_agglomerate = 0x7f >> GRUB_DISK_CACHE_BITS;
COMPILE_TIME_ASSERT ((0x7f >> GRUB_DISK_CACHE_BITS
<< (GRUB_DISK_SECTOR_BITS + GRUB_DISK_CACHE_BITS))
+ sizeof (struct grub_biosdisk_dap)
< GRUB_MEMORY_MACHINE_SCRATCH_SIZE);
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;
/* VirtualBox fails with sectors above 2T on CDs.
Since even BD-ROMS are never that big anyway, return error. */
if ((data->flags & GRUB_BIOSDISK_FLAG_CDROM)
&& (sector >> 32))
return grub_error (GRUB_ERR_OUT_OF_RANGE,
N_("attempt to read or write outside of disk `%s'"),
disk->name);
if (data->flags & GRUB_BIOSDISK_FLAG_LBA)
{
struct grub_biosdisk_dap *dap;
dap = (struct grub_biosdisk_dap *) (GRUB_MEMORY_MACHINE_SCRATCH_ADDR
+ (data->sectors
<< disk->log_sector_size));
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, N_("cannot write to CD-ROM"));
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, N_("failure reading sector 0x%llx "
"from `%s'"),
(unsigned long long) sector,
disk->name);
}
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,
N_("attempt to read or write outside of disk `%s'"),
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,
N_("attempt to read or write outside of disk `%s'"),
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, N_("failure reading sector 0x%llx "
"from `%s'"),
(unsigned long long) sector,
disk->name);
case GRUB_BIOSDISK_WRITE:
return grub_error (GRUB_ERR_WRITE_ERROR, N_("failure writing sector 0x%llx "
"to `%s'"),
(unsigned long long) sector,
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_t disk, grub_disk_addr_t sector)
{
grub_size_t size;
grub_uint64_t offset;
struct grub_biosdisk_data *data = disk->data;
grub_uint32_t sectors = data->sectors;
/* OFFSET = SECTOR % SECTORS */
grub_divmod64 (sector, sectors, &offset);
size = sectors - offset;
return size;
}
static grub_err_t
grub_biosdisk_read (grub_disk_t disk, grub_disk_addr_t sector,
grub_size_t size, char *buf)
{
while (size)
{
grub_size_t len;
len = get_safe_sectors (disk, sector);
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,
len << disk->log_sector_size);
buf += len << disk->log_sector_size;
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, N_("cannot write to CD-ROM"));
while (size)
{
grub_size_t len;
len = get_safe_sectors (disk, sector);
if (len > size)
len = size;
grub_memcpy ((void *) GRUB_MEMORY_MACHINE_SCRATCH_ADDR, buf,
len << disk->log_sector_size);
if (grub_biosdisk_rw (GRUB_BIOSDISK_WRITE, disk, sector, len,
GRUB_MEMORY_MACHINE_SCRATCH_SEG))
return grub_errno;
buf += len << disk->log_sector_size;
sector += len;
size -= len;
}
return grub_errno;
}
static struct grub_disk_dev grub_biosdisk_dev =
{
.name = "biosdisk",
.id = GRUB_DISK_DEVICE_BIOSDISK_ID,
.disk_iterate = grub_biosdisk_iterate,
.disk_open = grub_biosdisk_open,
.disk_close = grub_biosdisk_close,
.disk_read = grub_biosdisk_read,
.disk_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_absolute_pointer (GRUB_MEMORY_MACHINE_SCRATCH_ADDR);
grub_uint8_t boot_drive;
if (grub_disk_firmware_is_tainted)
{
grub_puts_ (N_("Native disk drivers are in use. "
"Refusing to use firmware disk interface."));
return;
}
grub_disk_firmware_fini = grub_disk_biosdisk_fini;
grub_memset (cdrp, 0, sizeof (*cdrp));
cdrp->size = sizeof (*cdrp);
cdrp->media_type = 0xFF;
boot_drive = (grub_boot_device >> 24);
if ((! grub_biosdisk_get_cdinfo_int13_extensions (boot_drive, cdrp))
&& ((cdrp->media_type & GRUB_BIOSDISK_CDTYPE_MASK)
== GRUB_BIOSDISK_CDTYPE_NO_EMUL))
cd_drive = cdrp->drive_no;
/* Since diskboot.S rejects devices over 0x90 it must be a CD booted with
cdboot.S
*/
if (boot_drive >= 0x90)
cd_drive = boot_drive;
grub_disk_dev_register (&grub_biosdisk_dev);
}
GRUB_MOD_FINI(biosdisk)
{
grub_disk_biosdisk_fini ();
}
Reference in New Issue View Git Blame Copy Permalink