Merge tag 'efi-next-for-v6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi

Pull EFI updates from Ard Biesheuvel:

 - Decouple mixed mode startup code from the traditional x86
   decompressor

 - Revert zero-length file hack in efivarfs

 - Prevent EFI zboot from using the CopyMem/SetMem boot services after
   ExitBootServices()

 - Update EFI zboot to use the ZLIB/ZSTD library interfaces directly

* tag 'efi-next-for-v6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi:
  efi/libstub: Avoid legacy decompressor zlib/zstd wrappers
  efi/libstub: Avoid CopyMem/SetMem EFI services after ExitBootServices
  efi: efibc: change kmalloc(size * count, ...) to kmalloc_array()
  efivarfs: Revert "allow creation of zero length files"
  x86/efi/mixed: Move mixed mode startup code into libstub
  x86/efi/mixed: Simplify and document thunking logic
  x86/efi/mixed: Remove dependency on legacy startup_32 code
  x86/efi/mixed: Set up 1:1 mapping of lower 4GiB in the stub
  x86/efi/mixed: Factor out and clean up long mode entry
  x86/efi/mixed: Check CPU compatibility without relying on verify_cpu()
  x86/efistub: Merge PE and handover entrypoints

1 files changed, 26 insertions, 0 deletions

diff --git a/drivers/firmware/efi/libstub/intrinsics.c b/drivers/firmware/efi/libstub/intrinsics.c
index 965e734f6f98..418cd2e6dccc 100644
--- a/drivers/firmware/efi/libstub/intrinsics.c
+++ b/drivers/firmware/efi/libstub/intrinsics.c
@@ -15,8 +15,31 @@ void *__memmove(void *__dest, const void *__src, size_t count) __alias(memmove);
 void *__memset(void *s, int c, size_t count) __alias(memset);
 #endif
 
+static void *efistub_memmove(u8 *dst, const u8 *src, size_t len)
+{
+	if (src > dst || dst >= (src + len))
+		for (size_t i = 0; i < len; i++)
+			dst[i] = src[i];
+	else
+		for (ssize_t i = len - 1; i >= 0; i--)
+			dst[i] = src[i];
+
+	return dst;
+}
+
+static void *efistub_memset(void *dst, int c, size_t len)
+{
+	for (u8 *d = dst; len--; d++)
+		*d = c;
+
+	return dst;
+}
+
 void *memcpy(void *dst, const void *src, size_t len)
 {
+	if (efi_table_attr(efi_system_table, boottime) == NULL)
+		return efistub_memmove(dst, src, len);
+
 	efi_bs_call(copy_mem, dst, src, len);
 	return dst;
 }
@@ -25,6 +48,9 @@ extern void *memmove(void *dst, const void *src, size_t len) __alias(memcpy);
 
 void *memset(void *dst, int c, size_t len)
 {
+	if (efi_table_attr(efi_system_table, boottime) == NULL)
+		return efistub_memset(dst, c, len);
+
 	efi_bs_call(set_mem, dst, len, c & U8_MAX);
 	return dst;
 }