x86, efi, kasan: #undef memset/memcpy/memmove per arch

In not-instrumented code KASAN replaces instrumented memset/memcpy/memmove
with not-instrumented analogues __memset/__memcpy/__memove.

However, on x86 the EFI stub is not linked with the kernel.  It uses
not-instrumented mem*() functions from arch/x86/boot/compressed/string.c

So we don't replace them with __mem*() variants in EFI stub.

On ARM64 the EFI stub is linked with the kernel, so we should replace
mem*() functions with __mem*(), because the EFI stub runs before KASAN
sets up early shadow.

So let's move these #undef mem* into arch's asm/efi.h which is also
included by the EFI stub.

Also, this will fix the warning in 32-bit build reported by kbuild test
robot:

	efi-stub-helper.c:599:2: warning: implicit declaration of function 'memcpy'

[akpm@linux-foundation.org: use 80 cols in comment]
Signed-off-by: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Reported-by: Fengguang Wu <fengguang.wu@gmail.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Matt Fleming <matt.fleming@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 155162ea0e00..ab5f1d447ef9 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -86,6 +86,16 @@ extern u64 asmlinkage efi_call(void *fp, ...);
 extern void __iomem *__init efi_ioremap(unsigned long addr, unsigned long size,
 					u32 type, u64 attribute);
 
+/*
+ * CONFIG_KASAN may redefine memset to __memset.  __memset function is present
+ * only in kernel binary.  Since the EFI stub linked into a separate binary it
+ * doesn't have __memset().  So we should use standard memset from
+ * arch/x86/boot/compressed/string.c.  The same applies to memcpy and memmove.
+ */
+#undef memcpy
+#undef memset
+#undef memmove
+
 #endif /* CONFIG_X86_32 */
 
 extern struct efi_scratch efi_scratch;