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efi: libstub: Clone memcmp() into the stub

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We will no longer be able to call into the kernel image once we merge
the decompressor with the EFI stub, so we need our own implementation of
memcmp(). Let's add the one from lib/string.c and simplify it.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
This commit is contained in:
Ard Biesheuvel 2022-10-11 15:15:51 +02:00
parent fa882a1389
commit 52dce39cd2
5 changed files with 19 additions and 13 deletions
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1
arch/arm64/kernel/image-vars.h
View File

@ -21,7 +21,6 @@ PROVIDE(__efistub_primary_entry_offset = primary_entry - _text);
* linked at. The routines below are all implemented in assembler in a
* position independent manner
*/
PROVIDE(__efistub_memcmp = __pi_memcmp);
PROVIDE(__efistub_memchr = __pi_memchr);
PROVIDE(__efistub_strlen = __pi_strlen);
PROVIDE(__efistub_strnlen = __pi_strnlen);

1
arch/loongarch/kernel/image-vars.h
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@ -7,7 +7,6 @@
#ifdef CONFIG_EFI_STUB
__efistub_memcmp = memcmp;
__efistub_memchr = memchr;
__efistub_strcat = strcat;
__efistub_strcmp = strcmp;

1
arch/riscv/kernel/image-vars.h
View File

@ -23,7 +23,6 @@
* linked at. The routines below are all implemented in assembler in a
* position independent manner
*/
__efistub_memcmp = memcmp;
__efistub_memchr = memchr;
__efistub_strlen = strlen;
__efistub_strnlen = strnlen;

18
drivers/firmware/efi/libstub/intrinsics.c
View File

@ -28,3 +28,21 @@ void *memset(void *dst, int c, size_t len)
efi_bs_call(set_mem, dst, len, c & U8_MAX);
return dst;
}
/**
* memcmp - Compare two areas of memory
* @cs: One area of memory
* @ct: Another area of memory
* @count: The size of the area.
*/
#undef memcmp
int memcmp(const void *cs, const void *ct, size_t count)
{
const unsigned char *su1, *su2;
int res = 0;
for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
if ((res = *su1 - *su2) != 0)
break;
return res;
}

11
drivers/firmware/efi/libstub/zboot.c
View File

@ -47,15 +47,6 @@ static void error(char *x)
log(L"error() called from decompressor library\n");
}
// Local version to avoid pulling in memcmp()
static bool guids_eq(const efi_guid_t *a, const efi_guid_t *b)
{
const u32 *l = (u32 *)a;
const u32 *r = (u32 *)b;
return l[0] == r[0] && l[1] == r[1] && l[2] == r[2] && l[3] == r[3];
}
static efi_status_t __efiapi
load_file(efi_load_file_protocol_t *this, efi_device_path_protocol_t *rem,
bool boot_policy, unsigned long *bufsize, void *buffer)
@ -76,7 +67,7 @@ load_file(efi_load_file_protocol_t *this, efi_device_path_protocol_t *rem,
if (rem->type == EFI_DEV_MEDIA &&
rem->sub_type == EFI_DEV_MEDIA_VENDOR) {
vendor_dp = container_of(rem, struct efi_vendor_dev_path, header);
if (!guids_eq(&vendor_dp->vendorguid, &LINUX_EFI_ZBOOT_MEDIA_GUID))
if (efi_guidcmp(vendor_dp->vendorguid, LINUX_EFI_ZBOOT_MEDIA_GUID))
return EFI_NOT_FOUND;
decompress = true;