From cbf8b5a2b649a501758291cb4d4ba1e5711771ba Mon Sep 17 00:00:00 2001
From: Tony Luck <tony.luck@intel.com>
Date: Mon, 14 Mar 2016 15:33:39 -0700
Subject: [PATCH] x86/mm, x86/mce: Fix return type/value for memcpy_mcsafe()
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Returning a 'bool' was very unpopular. Doubly so because the
code was just wrong (returning zero for true, one for false;
great for shell programming, not so good for C).

Change return type to "int". Keep zero as the success indicator
because it matches other similar code and people may be more
comfortable writing:

	if (memcpy_mcsafe(to, from, count)) {
		printk("Sad panda, copy failed\n");
		...
	}

Make the failure return value -EFAULT for now.

Reported by: Mika Penttilä <mika.penttila@nextfour.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: mika.penttila@nextfour.com
Fixes: 92b0729c34ca ("x86/mm, x86/mce: Add memcpy_mcsafe()")
Link: http://lkml.kernel.org/r/695f14233fa7a54fcac4406c706d7fec228e3f4c.1457993040.git.tony.luck@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/include/asm/string_64.h | 4 ++--
 arch/x86/lib/memcpy_64.S         | 7 ++++---
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/string_64.h b/arch/x86/include/asm/string_64.h
index ca6ba3607705..90dbbd9666d4 100644
--- a/arch/x86/include/asm/string_64.h
+++ b/arch/x86/include/asm/string_64.h
@@ -87,9 +87,9 @@ int strcmp(const char *cs, const char *ct);
  *
  * Low level memory copy function that catches machine checks
  *
- * Return true for success, false for fail
+ * Return 0 for success, -EFAULT for fail
  */
-bool memcpy_mcsafe(void *dst, const void *src, size_t cnt);
+int memcpy_mcsafe(void *dst, const void *src, size_t cnt);
 
 #endif /* __KERNEL__ */
 
diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S
index cbb8ee5830ff..2ec0b0abbfaa 100644
--- a/arch/x86/lib/memcpy_64.S
+++ b/arch/x86/lib/memcpy_64.S
@@ -1,6 +1,7 @@
 /* Copyright 2002 Andi Kleen */
 
 #include <linux/linkage.h>
+#include <asm/errno.h>
 #include <asm/cpufeatures.h>
 #include <asm/alternative-asm.h>
 
@@ -268,16 +269,16 @@ ENTRY(memcpy_mcsafe)
 	decl %ecx
 	jnz .L_copy_trailing_bytes
 
-	/* Copy successful. Return true */
+	/* Copy successful. Return zero */
 .L_done_memcpy_trap:
 	xorq %rax, %rax
 	ret
 ENDPROC(memcpy_mcsafe)
 
 	.section .fixup, "ax"
-	/* Return false for any failure */
+	/* Return -EFAULT for any failure */
 .L_memcpy_mcsafe_fail:
-	mov	$1, %rax
+	mov	$-EFAULT, %rax
 	ret
 
 	.previous