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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: 92b0729c34 ("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>
This commit is contained in:
Tony Luck 2016-03-14 15:33:39 -07:00 committed by Ingo Molnar
parent ba4e06d68e
commit cbf8b5a2b6
2 changed files with 6 additions and 5 deletions
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4
arch/x86/include/asm/string_64.h
View File

@ -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__ */

7
arch/x86/lib/memcpy_64.S
View File

@ -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