On Thu, 2011-12-08 at 17:11 +1100, Anton Blanchard wrote:
> Implement a POWER7 optimised copy_to_user/copy_from_user using VMX.
> For large aligned copies this new loop is over 10% faster, and for
> large unaligned copies it is over 200% faster.
Breaks !CONFIG_ALTIVEC build an pops some WARN's with preempt & lockdep,
this seems to fix them:
diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index b90b3e7..7735a2c 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -17,13 +17,14 @@ obj-$(CONFIG_HAS_IOMEM) += devres.o
obj-$(CONFIG_PPC64) += copypage_64.o copyuser_64.o \
memcpy_64.o usercopy_64.o mem_64.o string.o \
checksum_wrappers_64.o hweight_64.o \
- copyuser_power7.o copyuser_power7_vmx.o
+ copyuser_power7.o
obj-$(CONFIG_XMON) += sstep.o ldstfp.o
obj-$(CONFIG_KPROBES) += sstep.o ldstfp.o
obj-$(CONFIG_HAVE_HW_BREAKPOINT) += sstep.o ldstfp.o
ifeq ($(CONFIG_PPC64),y)
obj-$(CONFIG_SMP) += locks.o
+obj-$(CONFIG_ALTIVEC) += copyuser_power7_vmx.o
endif
obj-$(CONFIG_PPC_LIB_RHEAP) += rheap.o
diff --git a/arch/powerpc/lib/copyuser_power7.S
b/arch/powerpc/lib/copyuser_power7.S
index 4395939..9a21b08 100644
--- a/arch/powerpc/lib/copyuser_power7.S
+++ b/arch/powerpc/lib/copyuser_power7.S
@@ -85,6 +85,7 @@
_GLOBAL(__copy_tofrom_user_power7)
+#ifdef CONFIG_ALTIVEC
cmpldi r5,16
cmpldi cr1,r5,4096
@@ -94,6 +95,15 @@ _GLOBAL(__copy_tofrom_user_power7)
blt .Lshort_copy
bgt cr1,.Lvmx_copy
+#else
+ cmpldi r5,16
+
+ std r3,48(r1)
+ std r4,56(r1)
+ std r5,64(r1)
+
+ blt .Lshort_copy
+#endif
.Lnonvmx_copy:
/* Get the source 8B aligned */
@@ -273,6 +283,7 @@ err1; stb r0,0(r3)
addi r1,r1,STACKFRAMESIZE
b .Lnonvmx_copy
+#ifdef CONFIG_ALTIVEC
.Lvmx_copy:
mflr r0
std r0,16(r1)
@@ -667,3 +678,4 @@ err3; stb r0,0(r3)
15: addi r1,r1,STACKFRAMESIZE
b .exit_vmx_copy /* tail call optimise */
+#endif /* CONFiG_ALTIVEC */
diff --git a/arch/powerpc/lib/copyuser_power7_vmx.c
b/arch/powerpc/lib/copyuser_power7_vmx.c
index c37b949..6e1efad 100644
--- a/arch/powerpc/lib/copyuser_power7_vmx.c
+++ b/arch/powerpc/lib/copyuser_power7_vmx.c
@@ -26,10 +26,16 @@ int enter_vmx_copy(void)
if (in_interrupt())
return 0;
- enable_kernel_altivec();
-
+ /* This acts as preempt_disable() as well and will make
+ * enable_kernel_altivec(). We need to disable page faults
+ * as they can call schedule and thus make us lose the VMX
+ * context. So on page faults, we just fail which will cause
+ * a fallback to the normal non-vmx copy.
+ */
pagefault_disable();
+ enable_kernel_altivec();
+
return 1;
}
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