efi: libstub: Clone memcmp() into the stub

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>

diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
index 5a12ca2d7158937f79771e521fbc8e2542e2ffa6..f7c8cdf0c3025e48cd73ef1edace7273dea2dd90 100644 (file)
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -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);

diff --git a/arch/loongarch/kernel/image-vars.h b/arch/loongarch/kernel/image-vars.h
index 88f5d81702dfcf688dd44defac9a1ebd194a6c66..5b6c7f079942477a479435c7ed2fa8b4b3d883f9 100644 (file)
--- a/arch/loongarch/kernel/image-vars.h
+++ b/arch/loongarch/kernel/image-vars.h
@@ -7,7 +7,6 @@
 
 #ifdef CONFIG_EFI_STUB
 
-__efistub_memcmp               = memcmp;
 __efistub_memchr               = memchr;
 __efistub_strcat               = strcat;
 __efistub_strcmp               = strcmp;

diff --git a/arch/riscv/kernel/image-vars.h b/arch/riscv/kernel/image-vars.h
index b46322cb5864e25fb149cd58aca4c9d95bc3c2d3..9229cfe0754d61fd54380ef76ad36eeca7022d97 100644 (file)
--- a/arch/riscv/kernel/image-vars.h
+++ b/arch/riscv/kernel/image-vars.h
@@ -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;

diff --git a/drivers/firmware/efi/libstub/intrinsics.c b/drivers/firmware/efi/libstub/intrinsics.c
index a04ab39292b62d2bf53d69e461967befc4dd1c0f..965e734f6f987314ddb039add234427d76bdfe83 100644 (file)
--- a/drivers/firmware/efi/libstub/intrinsics.c
+++ b/drivers/firmware/efi/libstub/intrinsics.c
@@ -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;
+}

diff --git a/drivers/firmware/efi/libstub/zboot.c b/drivers/firmware/efi/libstub/zboot.c
index ea72c8f27da6cd19eb3752633427cbf9fd3599ac..38173ec29cd5ae53190737dd79427e62f7755d02 100644 (file)
--- a/drivers/firmware/efi/libstub/zboot.c
+++ b/drivers/firmware/efi/libstub/zboot.c
@@ -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;