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Date: Mon, 10 Sep 2012 13:38:19 +0100
From: "Jan Beulich" <JBeulich@...e.com>
To: <mingo@...e.hu>, <tglx@...utronix.de>, <hpa@...or.com>
Cc: <linux-kernel@...r.kernel.org>
Subject: [PATCH 2/4] x86/xor: improve XMM register spill/fill
Provided a new enough gcc is in use, we can avoid using the potentially
much slower MOVUPS by making sure stack frame and spilled to variables
are suitably aligned.
Signed-off-by: Jan Beulich <jbeulich@...e.com>
---
arch/x86/include/asm/xor.h | 56 ++++++++++++++++++++++++++++++++-------------
1 file changed, 40 insertions(+), 16 deletions(-)
--- 3.6-rc5-x86-xor.orig/arch/x86/include/asm/xor.h
+++ 3.6-rc5-x86-xor/arch/x86/include/asm/xor.h
@@ -36,16 +36,37 @@
* no advantages to be gotten from x86-64 here anyways.
*/
+#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 4)
+# ifdef CONFIG_X86_32
+# define XOR_ALIGN_STACK __attribute__((force_align_arg_pointer))
+# define XOR_ALIGN 16
+# else
+/*
+ * By forcing the alignment beyond the default of 16 bytes, we make the
+ * compiler guarantee the alignment. Passing -mincoming-stack-boundary=3
+ * (which would have been the better global alternative, as the kernel
+ * never guarantees better stack alignment) isn't permitted on x86-64.
+ */
+# define XOR_ALIGN_STACK
+# define XOR_ALIGN 32
+# endif
+# define XOR_MOV "movaps"
+#else
+# define XOR_ALIGN_STACK
+# define XOR_ALIGN 16
+# define XOR_MOV "movups"
+#endif
+
#define XMMS_SAVE \
do { \
preempt_disable(); \
cr0 = read_cr0(); \
clts(); \
asm volatile( \
- "movups %%xmm0,(%0) ;\n\t" \
- "movups %%xmm1,0x10(%0) ;\n\t" \
- "movups %%xmm2,0x20(%0) ;\n\t" \
- "movups %%xmm3,0x30(%0) ;\n\t" \
+ XOR_MOV " %%xmm0,(%0) ;\n\t" \
+ XOR_MOV " %%xmm1,0x10(%0);\n\t" \
+ XOR_MOV " %%xmm2,0x20(%0);\n\t" \
+ XOR_MOV " %%xmm3,0x30(%0);\n\t" \
: \
: "r" (xmm_save) \
: "memory"); \
@@ -55,10 +76,10 @@ do { \
do { \
asm volatile( \
"sfence ;\n\t" \
- "movups (%0),%%xmm0 ;\n\t" \
- "movups 0x10(%0),%%xmm1 ;\n\t" \
- "movups 0x20(%0),%%xmm2 ;\n\t" \
- "movups 0x30(%0),%%xmm3 ;\n\t" \
+ XOR_MOV " (%0),%%xmm0 ;\n\t" \
+ XOR_MOV " 0x10(%0),%%xmm1;\n\t" \
+ XOR_MOV " 0x20(%0),%%xmm2;\n\t" \
+ XOR_MOV " 0x30(%0),%%xmm3;\n\t" \
: \
: "r" (xmm_save) \
: "memory"); \
@@ -87,11 +108,11 @@ do { \
#define XO3(x, y) " xorps "OFFS(x)"(%[p4]), %%xmm"#y" ;\n"
#define XO4(x, y) " xorps "OFFS(x)"(%[p5]), %%xmm"#y" ;\n"
-static void
+static void XOR_ALIGN_STACK
xor_sse_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
{
unsigned long cr0, lines = bytes >> 8;
- char xmm_save[16*4] __aligned(16);
+ char xmm_save[16*4] __aligned(XOR_ALIGN);
XMMS_SAVE;
@@ -139,12 +160,12 @@ xor_sse_2(unsigned long bytes, unsigned
XMMS_RESTORE;
}
-static void
+static void XOR_ALIGN_STACK
xor_sse_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
unsigned long *p3)
{
unsigned long cr0, lines = bytes >> 8;
- char xmm_save[16*4] __aligned(16);
+ char xmm_save[16*4] __aligned(XOR_ALIGN);
XMMS_SAVE;
@@ -199,12 +220,12 @@ xor_sse_3(unsigned long bytes, unsigned
XMMS_RESTORE;
}
-static void
+static void XOR_ALIGN_STACK
xor_sse_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
unsigned long *p3, unsigned long *p4)
{
unsigned long cr0, lines = bytes >> 8;
- char xmm_save[16*4] __aligned(16);
+ char xmm_save[16*4] __aligned(XOR_ALIGN);
XMMS_SAVE;
@@ -266,12 +287,12 @@ xor_sse_4(unsigned long bytes, unsigned
XMMS_RESTORE;
}
-static void
+static void XOR_ALIGN_STACK
xor_sse_5(unsigned long bytes, unsigned long *p1, unsigned long *p2,
unsigned long *p3, unsigned long *p4, unsigned long *p5)
{
unsigned long cr0, lines = bytes >> 8;
- char xmm_save[16*4] __aligned(16);
+ char xmm_save[16*4] __aligned(XOR_ALIGN);
XMMS_SAVE;
@@ -348,6 +369,9 @@ xor_sse_5(unsigned long bytes, unsigned
#undef ST
#undef BLOCK
+#undef XOR_ALIGN_STACK
+#undef XOR_ALIGN
+#undef XOR_MOV
#undef XOR_CONSTANT_CONSTRAINT
#ifdef CONFIG_X86_32
--
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