Big-endian fix for memcpy-armv7m.S

Message ID 20161209135417.15294bf2@squid.athome
State New
Headers show

Commit Message

Julian Brown Dec. 9, 2016, 1:54 p.m.
Hi,

I noticed that memcpy-armv7m.S makes assumptions about little-endian
byte ordering that cause it to get copies with certain sizes/alignments
wrong in big-endian mode. We hit this with a "generic profile" ARMv7
big-endian multilib, but I guess anyone trying to run an M-profile chip
in big-endian mode (if such things exist) could hit the same problem.

I've tested this with (caveat, somewhat experimental!) QEMU patches:

http://lists.nongnu.org/archive/html/qemu-devel/2016-12/msg00972.html

running under the GCC testsuite with an ARMv7 big-endian multilib, and
results show a positive delta for about 15 tests (e.g.
gcc.c-torture/execute/memcpy-2.c, gcc.c-torture/execute/pr65369.c).

OK to apply?

Thanks,

Julian

ChangeLog

    * libc/machine/arm/memcpy-armv7m.S (mis_src_copy): Handle
    big-endian mode.

Comments

Corinna Vinschen Dec. 12, 2016, 10:27 a.m. | #1
On Dec  9 13:54, Julian Brown wrote:
> Hi,

> 

> I noticed that memcpy-armv7m.S makes assumptions about little-endian

> byte ordering that cause it to get copies with certain sizes/alignments

> wrong in big-endian mode. We hit this with a "generic profile" ARMv7

> big-endian multilib, but I guess anyone trying to run an M-profile chip

> in big-endian mode (if such things exist) could hit the same problem.

> 

> I've tested this with (caveat, somewhat experimental!) QEMU patches:

> 

> http://lists.nongnu.org/archive/html/qemu-devel/2016-12/msg00972.html

> 

> running under the GCC testsuite with an ARMv7 big-endian multilib, and

> results show a positive delta for about 15 tests (e.g.

> gcc.c-torture/execute/memcpy-2.c, gcc.c-torture/execute/pr65369.c).

> 

> OK to apply?


Applied.


Thanks,
Corinna

-- 
Corinna Vinschen
Cygwin Maintainer
Red Hat

Patch hide | download patch | download mbox

commit 45cd47548c95b13eed1eb0121ee15ca63df1b466
Author: Julian Brown <julian@codesourcery.com>
Date:   Thu Dec 8 09:56:51 2016 -0800

    Big-endian armv7m memcpy fix.
    
    In the case of memcpy-armv7m.S being built for a big-endian multilib
    (including armv7 without a specific profile), realignment code made
    assumptions about the byte ordering being little-endian.

diff --git a/newlib/libc/machine/arm/memcpy-armv7m.S b/newlib/libc/machine/arm/memcpy-armv7m.S
index 8a70c7d..c8bff36 100644
--- a/newlib/libc/machine/arm/memcpy-armv7m.S
+++ b/newlib/libc/machine/arm/memcpy-armv7m.S
@@ -265,9 +265,17 @@  memcpy:
 
 	.macro mis_src_copy shift
 1:
+#ifdef __ARM_BIG_ENDIAN
+	lsls	r4, r4, \shift
+#else
 	lsrs	r4, r4, \shift
+#endif
 	ldr	r3, [r1], #4
+#ifdef __ARM_BIG_ENDIAN
+	lsrs	r5, r3, 32-\shift
+#else
 	lsls	r5, r3, 32-\shift
+#endif
 	orr	r4, r4, r5
 	str	r4, [r0], #4
 	mov	r4, r3