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build: Fix -Werror=array-bounds array subscript 0 is outside array bounds

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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>
This commit is contained in:
Michael Chang 2022-03-28 15:00:53 +08:00 committed by Daniel Kiper
parent be8eb0eed6
commit acffb81485
18 changed files with 87 additions and 55 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
grub-core/bus/cs5536.c
View File

@ -331,8 +331,9 @@ grub_cs5536_init_geode (grub_pci_device_t dev)
{
volatile grub_uint32_t *oc;
oc = grub_pci_device_map_range (dev, 0x05022000,
GRUB_CS5536_USB_OPTION_REGS_SIZE);
oc = grub_absolute_pointer (grub_pci_device_map_range (dev, 0x05022000,
GRUB_CS5536_USB_OPTION_REGS_SIZE));
oc[GRUB_CS5536_USB_OPTION_REG_UOCMUX] =
(oc[GRUB_CS5536_USB_OPTION_REG_UOCMUX]

4
grub-core/commands/acpi.c
View File

@ -168,7 +168,7 @@ grub_acpi_create_ebda (void)
struct grub_acpi_rsdp_v10 *v1;
struct grub_acpi_rsdp_v20 *v2;
ebda = (grub_uint8_t *) (grub_addr_t) ((*((grub_uint16_t *)0x40e)) << 4);
ebda = (grub_uint8_t *) (grub_addr_t) ((*((grub_uint16_t *) grub_absolute_pointer (0x40e))) << 4);
grub_dprintf ("acpi", "EBDA @%p\n", ebda);
if (ebda)
ebda_kb_len = *(grub_uint16_t *) ebda;
@ -298,7 +298,7 @@ grub_acpi_create_ebda (void)
*target = 0;
grub_dprintf ("acpi", "Switching EBDA\n");
(*((grub_uint16_t *) 0x40e)) = ((grub_addr_t) targetebda) >> 4;
(*((grub_uint16_t *) grub_absolute_pointer (0x40e))) = ((grub_addr_t) targetebda) >> 4;
grub_dprintf ("acpi", "EBDA switched\n");
return GRUB_ERR_NONE;

9
grub-core/commands/efi/loadbios.c
View File

@ -46,7 +46,7 @@ enable_rom_area (void)
grub_uint32_t *rom_ptr;
grub_pci_device_t dev = { .bus = 0, .device = 0, .function = 0};
rom_ptr = (grub_uint32_t *) VBIOS_ADDR;
rom_ptr = grub_absolute_pointer (VBIOS_ADDR);
if (*rom_ptr != BLANK_MEM)
{
grub_puts_ (N_("ROM image is present."));
@ -96,8 +96,8 @@ fake_bios_data (int use_rom)
void *acpi, *smbios;
grub_uint16_t *ebda_seg_ptr, *low_mem_ptr;
ebda_seg_ptr = (grub_uint16_t *) EBDA_SEG_ADDR;
low_mem_ptr = (grub_uint16_t *) LOW_MEM_ADDR;
ebda_seg_ptr = grub_absolute_pointer (EBDA_SEG_ADDR);
low_mem_ptr = grub_absolute_pointer (LOW_MEM_ADDR);
if ((*ebda_seg_ptr) || (*low_mem_ptr))
return;
@ -132,7 +132,8 @@ fake_bios_data (int use_rom)
*ebda_seg_ptr = FAKE_EBDA_SEG;
*low_mem_ptr = (FAKE_EBDA_SEG >> 6);
*((grub_uint16_t *) (FAKE_EBDA_SEG << 4)) = 640 - *low_mem_ptr;
/* *((grub_uint16_t *) (FAKE_EBDA_SEG << 4)) = 640 - *low_mem_ptr; */
*((grub_uint16_t *) (grub_absolute_pointer (FAKE_EBDA_SEG << 4))) = 640 - *low_mem_ptr;
if (acpi)
grub_memcpy ((char *) ((FAKE_EBDA_SEG << 4) + 16), acpi, 1024 - 16);

8
grub-core/commands/i386/pc/drivemap.c
View File

@ -31,9 +31,6 @@
GRUB_MOD_LICENSE ("GPLv3+");
/* Real mode IVT slot (seg:off far pointer) for interrupt 0x13. */
static grub_uint32_t *const int13slot = (grub_uint32_t *) (4 * 0x13);
/* Remember to update enum opt_idxs accordingly. */
static const struct grub_arg_option options[] = {
/* TRANSLATORS: In this file "mapping" refers to a change GRUB makes so if
@ -280,6 +277,8 @@ install_int13_handler (int noret __attribute__ ((unused)))
grub_uint8_t *handler_base = 0;
/* Address of the map within the deployed bundle. */
int13map_node_t *handler_map;
/* Real mode IVT slot (seg:off far pointer) for interrupt 0x13. */
grub_uint32_t *int13slot = (grub_uint32_t *) grub_absolute_pointer (4 * 0x13);
int i;
int entries = 0;
@ -354,6 +353,9 @@ install_int13_handler (int noret __attribute__ ((unused)))
static grub_err_t
uninstall_int13_handler (void)
{
/* Real mode IVT slot (seg:off far pointer) for interrupt 0x13. */
grub_uint32_t *int13slot = (grub_uint32_t *) grub_absolute_pointer (4 * 0x13);
if (! grub_drivemap_oldhandler)
return GRUB_ERR_NONE;

12
grub-core/commands/i386/pc/sendkey.c
View File

@ -216,12 +216,12 @@ static grub_err_t
grub_sendkey_postboot (void)
{
/* For convention: pointer to flags. */
grub_uint32_t *flags = (grub_uint32_t *) 0x417;
grub_uint32_t *flags = grub_absolute_pointer (0x417);
*flags = oldflags;
*((volatile char *) 0x41a) = 0x1e;
*((volatile char *) 0x41c) = 0x1e;
*((volatile char *) grub_absolute_pointer (0x41a)) = 0x1e;
*((volatile char *) grub_absolute_pointer (0x41c)) = 0x1e;
return GRUB_ERR_NONE;
}
@ -231,13 +231,13 @@ static grub_err_t
grub_sendkey_preboot (int noret __attribute__ ((unused)))
{
/* For convention: pointer to flags. */
grub_uint32_t *flags = (grub_uint32_t *) 0x417;
grub_uint32_t *flags = grub_absolute_pointer (0x417);
oldflags = *flags;
/* Set the sendkey. */
*((volatile char *) 0x41a) = 0x1e;
*((volatile char *) 0x41c) = keylen + 0x1e;
*((volatile char *) grub_absolute_pointer (0x41a)) = 0x1e;
*((volatile char *) grub_absolute_pointer (0x41c)) = keylen + 0x1e;
grub_memcpy ((char *) 0x41e, sendkey, 0x20);
/* Transform "any ctrl" to "right ctrl" flag. */

4
grub-core/disk/i386/pc/biosdisk.c
View File

@ -367,7 +367,7 @@ grub_biosdisk_open (const char *name, grub_disk_t disk)
if (version)
{
struct grub_biosdisk_drp *drp
= (struct grub_biosdisk_drp *) GRUB_MEMORY_MACHINE_SCRATCH_ADDR;
= (struct grub_biosdisk_drp *) grub_absolute_pointer (GRUB_MEMORY_MACHINE_SCRATCH_ADDR);
/* Clear out the DRP. */
grub_memset (drp, 0, sizeof (*drp));
@ -654,7 +654,7 @@ grub_disk_biosdisk_fini (void)
GRUB_MOD_INIT(biosdisk)
{
struct grub_biosdisk_cdrp *cdrp
= (struct grub_biosdisk_cdrp *) GRUB_MEMORY_MACHINE_SCRATCH_ADDR;
= (struct grub_biosdisk_cdrp *) grub_absolute_pointer (GRUB_MEMORY_MACHINE_SCRATCH_ADDR);
grub_uint8_t boot_drive;
if (grub_disk_firmware_is_tainted)

2
grub-core/fs/cbfs.c
View File

@ -342,7 +342,7 @@ init_cbfsdisk (void)
grub_uint32_t ptr;
struct cbfs_header *head;
ptr = *(grub_uint32_t *) 0xfffffffc;
ptr = *((grub_uint32_t *) grub_absolute_pointer (0xfffffffc));
head = (struct cbfs_header *) (grub_addr_t) ptr;
grub_dprintf ("cbfs", "head=%p\n", head);

4
grub-core/kern/i386/pc/acpi.c
View File

@ -27,7 +27,7 @@ grub_machine_acpi_get_rsdpv1 (void)
grub_uint8_t *ebda, *ptr;
grub_dprintf ("acpi", "Looking for RSDP. Scanning EBDA\n");
ebda = (grub_uint8_t *) ((* ((grub_uint16_t *) 0x40e)) << 4);
ebda = (grub_uint8_t *) ((* ((grub_uint16_t *) grub_absolute_pointer (0x40e))) << 4);
ebda_len = * (grub_uint16_t *) ebda;
if (! ebda_len) /* FIXME do we really need this check? */
goto scan_bios;
@ -55,7 +55,7 @@ grub_machine_acpi_get_rsdpv2 (void)
grub_uint8_t *ebda, *ptr;
grub_dprintf ("acpi", "Looking for RSDP. Scanning EBDA\n");
ebda = (grub_uint8_t *) ((* ((grub_uint16_t *) 0x40e)) << 4);
ebda = (grub_uint8_t *) ((* ((grub_uint16_t *) grub_absolute_pointer (0x40e))) << 4);
ebda_len = * (grub_uint16_t *) ebda;
if (! ebda_len) /* FIXME do we really need this check? */
goto scan_bios;

2
grub-core/kern/i386/pc/mmap.c
View File

@ -143,7 +143,7 @@ grub_machine_mmap_iterate (grub_memory_hook_t hook, void *hook_data)
{
grub_uint32_t cont = 0;
struct grub_machine_mmap_entry *entry
= (struct grub_machine_mmap_entry *) GRUB_MEMORY_MACHINE_SCRATCH_ADDR;
= (struct grub_machine_mmap_entry *) grub_absolute_pointer (GRUB_MEMORY_MACHINE_SCRATCH_ADDR);
int e820_works = 0;
while (1)

2
grub-core/loader/i386/multiboot_mbi.c
View File

@ -293,7 +293,7 @@ fill_vbe_info (struct multiboot_info *mbi, grub_uint8_t *ptrorig,
struct grub_vbe_mode_info_block *mode_info;
#if GRUB_MACHINE_HAS_VBE
grub_vbe_status_t status;
void *scratch = (void *) GRUB_MEMORY_MACHINE_SCRATCH_ADDR;
void *scratch = grub_absolute_pointer (GRUB_MEMORY_MACHINE_SCRATCH_ADDR);
status = grub_vbe_bios_get_controller_info (scratch);
if (status != GRUB_VBE_STATUS_OK)

4
grub-core/loader/multiboot_mbi2.c
View File

@ -504,7 +504,7 @@ static void
fill_vbe_tag (struct multiboot_tag_vbe *tag)
{
grub_vbe_status_t status;
void *scratch = (void *) GRUB_MEMORY_MACHINE_SCRATCH_ADDR;
void *scratch = grub_absolute_pointer (GRUB_MEMORY_MACHINE_SCRATCH_ADDR);
tag->type = MULTIBOOT_TAG_TYPE_VBE;
tag->size = 0;
@ -577,7 +577,7 @@ retrieve_video_parameters (grub_properly_aligned_t **ptrorig)
#if defined (GRUB_MACHINE_PCBIOS)
{
grub_vbe_status_t status;
void *scratch = (void *) GRUB_MEMORY_MACHINE_SCRATCH_ADDR;
void *scratch = grub_absolute_pointer (GRUB_MEMORY_MACHINE_SCRATCH_ADDR);
status = grub_vbe_bios_get_mode (scratch);
vbe_mode = *(grub_uint32_t *) scratch;
if (status != GRUB_VBE_STATUS_OK)

26
grub-core/mmap/i386/pc/mmap.c
View File

@ -80,13 +80,13 @@ preboot (int noreturn __attribute__ ((unused)))
= min (grub_mmap_get_post64 (), 0xfc000000ULL) >> 16;
/* Correct BDA. */
*((grub_uint16_t *) 0x413) = grub_mmap_get_lower () >> 10;
*((grub_uint16_t *) grub_absolute_pointer (0x413)) = grub_mmap_get_lower () >> 10;
/* Save old interrupt handlers. */
grub_machine_mmaphook_int12offset = *((grub_uint16_t *) 0x48);
grub_machine_mmaphook_int12segment = *((grub_uint16_t *) 0x4a);
grub_machine_mmaphook_int15offset = *((grub_uint16_t *) 0x54);
grub_machine_mmaphook_int15segment = *((grub_uint16_t *) 0x56);
grub_machine_mmaphook_int12offset = *((grub_uint16_t *) grub_absolute_pointer (0x48));
grub_machine_mmaphook_int12segment = *((grub_uint16_t *) grub_absolute_pointer (0x4a));
grub_machine_mmaphook_int15offset = *((grub_uint16_t *) grub_absolute_pointer (0x54));
grub_machine_mmaphook_int15segment = *((grub_uint16_t *) grub_absolute_pointer (0x56));
grub_dprintf ("mmap", "hooktarget = %p\n", hooktarget);
@ -94,11 +94,11 @@ preboot (int noreturn __attribute__ ((unused)))
grub_memcpy (hooktarget, &grub_machine_mmaphook_start,
&grub_machine_mmaphook_end - &grub_machine_mmaphook_start);
*((grub_uint16_t *) 0x4a) = ((grub_addr_t) hooktarget) >> 4;
*((grub_uint16_t *) 0x56) = ((grub_addr_t) hooktarget) >> 4;
*((grub_uint16_t *) 0x48) = &grub_machine_mmaphook_int12
*((grub_uint16_t *) grub_absolute_pointer (0x4a)) = ((grub_addr_t) hooktarget) >> 4;
*((grub_uint16_t *) grub_absolute_pointer (0x56)) = ((grub_addr_t) hooktarget) >> 4;
*((grub_uint16_t *) grub_absolute_pointer (0x48)) = &grub_machine_mmaphook_int12
- &grub_machine_mmaphook_start;
*((grub_uint16_t *) 0x54) = &grub_machine_mmaphook_int15
*((grub_uint16_t *) grub_absolute_pointer (0x54)) = &grub_machine_mmaphook_int15
- &grub_machine_mmaphook_start;
return GRUB_ERR_NONE;
@ -108,10 +108,10 @@ static grub_err_t
preboot_rest (void)
{
/* Restore old interrupt handlers. */
*((grub_uint16_t *) 0x48) = grub_machine_mmaphook_int12offset;
*((grub_uint16_t *) 0x4a) = grub_machine_mmaphook_int12segment;
*((grub_uint16_t *) 0x54) = grub_machine_mmaphook_int15offset;
*((grub_uint16_t *) 0x56) = grub_machine_mmaphook_int15segment;
*((grub_uint16_t *) grub_absolute_pointer (0x48)) = grub_machine_mmaphook_int12offset;
*((grub_uint16_t *) grub_absolute_pointer (0x4a)) = grub_machine_mmaphook_int12segment;
*((grub_uint16_t *) grub_absolute_pointer (0x54)) = grub_machine_mmaphook_int15offset;
*((grub_uint16_t *) grub_absolute_pointer (0x56)) = grub_machine_mmaphook_int15segment;
return GRUB_ERR_NONE;
}

12
grub-core/net/drivers/i386/pc/pxe.c
View File

@ -174,7 +174,7 @@ grub_pxe_recv (struct grub_net_card *dev __attribute__ ((unused)))
grub_uint8_t *ptr, *end;
struct grub_net_buff *buf;
isr = (void *) GRUB_MEMORY_MACHINE_SCRATCH_ADDR;
isr = (void *) grub_absolute_pointer (GRUB_MEMORY_MACHINE_SCRATCH_ADDR);
if (!in_progress)
{
@ -256,11 +256,11 @@ grub_pxe_send (struct grub_net_card *dev __attribute__ ((unused)),
struct grub_pxe_undi_tbd *tbd;
char *buf;
trans = (void *) GRUB_MEMORY_MACHINE_SCRATCH_ADDR;
trans = (void *) grub_absolute_pointer (GRUB_MEMORY_MACHINE_SCRATCH_ADDR);
grub_memset (trans, 0, sizeof (*trans));
tbd = (void *) (GRUB_MEMORY_MACHINE_SCRATCH_ADDR + 128);
tbd = (void *) grub_absolute_pointer (GRUB_MEMORY_MACHINE_SCRATCH_ADDR + 128);
grub_memset (tbd, 0, sizeof (*tbd));
buf = (void *) (GRUB_MEMORY_MACHINE_SCRATCH_ADDR + 256);
buf = (void *) grub_absolute_pointer (GRUB_MEMORY_MACHINE_SCRATCH_ADDR + 256);
grub_memcpy (buf, pack->data, pack->tail - pack->data);
trans->tbd = SEGOFS ((grub_addr_t) tbd);
@ -287,7 +287,7 @@ static grub_err_t
grub_pxe_open (struct grub_net_card *dev __attribute__ ((unused)))
{
struct grub_pxe_undi_open *ou;
ou = (void *) GRUB_MEMORY_MACHINE_SCRATCH_ADDR;
ou = (void *) grub_absolute_pointer (GRUB_MEMORY_MACHINE_SCRATCH_ADDR);
grub_memset (ou, 0, sizeof (*ou));
ou->pkt_filter = 4;
grub_pxe_call (GRUB_PXENV_UNDI_OPEN, ou, pxe_rm_entry);
@ -382,7 +382,7 @@ GRUB_MOD_INIT(pxe)
if (! pxenv)
return;
ui = (void *) GRUB_MEMORY_MACHINE_SCRATCH_ADDR;
ui = (void *) grub_absolute_pointer (GRUB_MEMORY_MACHINE_SCRATCH_ADDR);
grub_memset (ui, 0, sizeof (*ui));
grub_pxe_call (GRUB_PXENV_UNDI_GET_INFORMATION, ui, pxe_rm_entry);

5
grub-core/term/i386/pc/console.c
View File

@ -238,12 +238,11 @@ grub_console_getkey (struct grub_term_input *term __attribute__ ((unused)))
return (regs.eax & 0xff) + (('a' - 1) | GRUB_TERM_CTRL);
}
static const struct grub_machine_bios_data_area *bios_data_area =
(struct grub_machine_bios_data_area *) GRUB_MEMORY_MACHINE_BIOS_DATA_AREA_ADDR;
static int
grub_console_getkeystatus (struct grub_term_input *term __attribute__ ((unused)))
{
const struct grub_machine_bios_data_area *bios_data_area =
(struct grub_machine_bios_data_area *) grub_absolute_pointer (GRUB_MEMORY_MACHINE_BIOS_DATA_AREA_ADDR);
/* conveniently GRUB keystatus is modelled after BIOS one. */
return bios_data_area->keyboard_flag_lower & ~0x80;
}

6
grub-core/term/i386/pc/vga_text.c
View File

@ -45,15 +45,15 @@ GRUB_MOD_LICENSE ("GPLv3+");
static struct grub_term_coordinate grub_curr_pos;
#ifdef __mips__
#define VGA_TEXT_SCREEN ((grub_uint16_t *) 0xb00b8000)
#define VGA_TEXT_SCREEN ((grub_uint16_t *) grub_absolute_pointer (0xb00b8000))
#define cr_read grub_vga_cr_read
#define cr_write grub_vga_cr_write
#elif defined (MODE_MDA)
#define VGA_TEXT_SCREEN ((grub_uint16_t *) 0xb0000)
#define VGA_TEXT_SCREEN ((grub_uint16_t *) grub_absolute_pointer (0xb0000))
#define cr_read grub_vga_cr_bw_read
#define cr_write grub_vga_cr_bw_write
#else
#define VGA_TEXT_SCREEN ((grub_uint16_t *) 0xb8000)
#define VGA_TEXT_SCREEN ((grub_uint16_t *) grub_absolute_pointer (0xb8000))
#define cr_read grub_vga_cr_read
#define cr_write grub_vga_cr_write
#endif

7
grub-core/term/ns8250.c
View File

@ -28,7 +28,6 @@
#ifdef GRUB_MACHINE_PCBIOS
#include <grub/machine/memory.h>
static const unsigned short *serial_hw_io_addr = (const unsigned short *) GRUB_MEMORY_MACHINE_BIOS_DATA_AREA_ADDR;
#define GRUB_SERIAL_PORT_NUM 4
#else
#include <grub/machine/serial.h>
@ -237,6 +236,9 @@ static struct grub_serial_port com_ports[GRUB_SERIAL_PORT_NUM];
void
grub_ns8250_init (void)
{
#ifdef GRUB_MACHINE_PCBIOS
const unsigned short *serial_hw_io_addr = (const unsigned short *) grub_absolute_pointer (GRUB_MEMORY_MACHINE_BIOS_DATA_AREA_ADDR);
#endif
unsigned i;
for (i = 0; i < GRUB_SERIAL_PORT_NUM; i++)
if (serial_hw_io_addr[i])
@ -272,6 +274,9 @@ grub_ns8250_init (void)
grub_port_t
grub_ns8250_hw_get_port (const unsigned int unit)
{
#ifdef GRUB_MACHINE_PCBIOS
const unsigned short *serial_hw_io_addr = (const unsigned short *) grub_absolute_pointer (GRUB_MEMORY_MACHINE_BIOS_DATA_AREA_ADDR);
#endif
if (unit < GRUB_SERIAL_PORT_NUM
&& !(dead_ports & (1 << unit)))
return serial_hw_io_addr[unit];

6
grub-core/video/i386/pc/vbe.c
View File

@ -514,7 +514,7 @@ grub_vbe_probe (struct grub_vbe_info_block *info_block)
/* Use low memory scratch area as temporary storage
for VESA BIOS call. */
vbe_ib = (struct grub_vbe_info_block *) GRUB_MEMORY_MACHINE_SCRATCH_ADDR;
vbe_ib = (struct grub_vbe_info_block *) grub_absolute_pointer (GRUB_MEMORY_MACHINE_SCRATCH_ADDR);
/* Prepare info block. */
grub_memset (vbe_ib, 0, sizeof (*vbe_ib));
@ -574,7 +574,7 @@ grub_vbe_get_preferred_mode (unsigned int *width, unsigned int *height)
/* Use low memory scratch area as temporary storage for VESA BIOS calls. */
flat_panel_info = (struct grub_vbe_flat_panel_info *)
(GRUB_MEMORY_MACHINE_SCRATCH_ADDR + sizeof (struct grub_video_edid_info));
grub_absolute_pointer (GRUB_MEMORY_MACHINE_SCRATCH_ADDR + sizeof (struct grub_video_edid_info));
if (controller_info.version >= 0x200
&& (grub_vbe_bios_get_ddc_capabilities (&ddc_level) & 0xff)
@ -676,7 +676,7 @@ grub_vbe_set_video_mode (grub_uint32_t vbe_mode,
== GRUB_VBE_MEMORY_MODEL_PACKED_PIXEL)
{
struct grub_vbe_palette_data *palette
= (struct grub_vbe_palette_data *) GRUB_MEMORY_MACHINE_SCRATCH_ADDR;
= (struct grub_vbe_palette_data *) grub_absolute_pointer (GRUB_MEMORY_MACHINE_SCRATCH_ADDR);
unsigned i;
/* Make sure that the BIOS can reach the palette. */

24
include/grub/types.h
View File

@ -340,4 +340,28 @@ static inline void grub_set_unaligned64 (void *ptr, grub_uint64_t val)
dd->d = val;
}
/*
* The grub_absolute_pointer() macro borrows the idea from Linux kernel of using
* RELOC_HIDE() macro to stop GCC from checking the result of pointer arithmetic
* and also it's conversion to be inside the symbol's boundary [1]. The check
* is sometimes false positive, especially it is controversial to emit the array
* bounds [-Warray-bounds] warning on all hardwired literal pointers since GCC
* 11/12 [2]. Unless a good solution can be settled, for the time being we
* would be in favor of the macro instead of GCC pragmas which cannot match the
* places the warning needs to be ignored in an exact way.
*
* [1] https://lists.linuxcoding.com/kernel/2006-q3/msg17979.html
* [2] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578
*/
#if defined(__GNUC__)
# define grub_absolute_pointer(val) \
({ \
grub_addr_t __ptr; \
asm ("" : "=r" (__ptr) : "0" ((void *) (val))); \
(void *) (__ptr); \
})
#else
# define grub_absolute_pointer(val) ((void *) (val))
#endif
#endif /* ! GRUB_TYPES_HEADER */