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authorOleg Nesterov <oleg@redhat.com>2014-09-21 20:41:53 +0200
committerIngo Molnar <mingo@kernel.org>2014-09-24 15:15:38 +0200
commit0ad6e3c5199be12c9745da8f8b9e3c9f8066c235 (patch)
tree581d938c3bf976c54a95b2fd6030c232b7885031 /arch
parentf3670394c29ff3730638762c1760fd2f624e6d7b (diff)
x86: Speed up ___preempt_schedule*() by using THUNK helpers
___preempt_schedule() does SAVE_ALL/RESTORE_ALL but this is suboptimal, we do not need to save/restore the callee-saved register. And we already have arch/x86/lib/thunk_*.S which implements the similar asm wrappers, so it makes sense to redefine ___preempt_schedule() as "THUNK ..." and remove preempt.S altogether. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: Andy Lutomirski <luto@amacapital.net> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20140921184153.GA23727@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/Makefile2
-rw-r--r--arch/x86/kernel/preempt.S25
-rw-r--r--arch/x86/lib/thunk_32.S20
-rw-r--r--arch/x86/lib/thunk_64.S7
4 files changed, 23 insertions, 31 deletions
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index ada2e2d6be3e..8f1e77440b2b 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -39,8 +39,6 @@ obj-y += tsc.o tsc_msr.o io_delay.o rtc.o
obj-y += pci-iommu_table.o
obj-y += resource.o
-obj-$(CONFIG_PREEMPT) += preempt.o
-
obj-y += process.o
obj-y += i387.o xsave.o
obj-y += ptrace.o
diff --git a/arch/x86/kernel/preempt.S b/arch/x86/kernel/preempt.S
deleted file mode 100644
index ca7f0d58a87d..000000000000
--- a/arch/x86/kernel/preempt.S
+++ /dev/null
@@ -1,25 +0,0 @@
-
-#include <linux/linkage.h>
-#include <asm/dwarf2.h>
-#include <asm/asm.h>
-#include <asm/calling.h>
-
-ENTRY(___preempt_schedule)
- CFI_STARTPROC
- SAVE_ALL
- call preempt_schedule
- RESTORE_ALL
- ret
- CFI_ENDPROC
-
-#ifdef CONFIG_CONTEXT_TRACKING
-
-ENTRY(___preempt_schedule_context)
- CFI_STARTPROC
- SAVE_ALL
- call preempt_schedule_context
- RESTORE_ALL
- ret
- CFI_ENDPROC
-
-#endif
diff --git a/arch/x86/lib/thunk_32.S b/arch/x86/lib/thunk_32.S
index 28f85c916712..e9acf5f4fc92 100644
--- a/arch/x86/lib/thunk_32.S
+++ b/arch/x86/lib/thunk_32.S
@@ -7,16 +7,19 @@
#include <linux/linkage.h>
#include <asm/asm.h>
-#ifdef CONFIG_TRACE_IRQFLAGS
/* put return address in eax (arg1) */
- .macro thunk_ra name,func
+ .macro THUNK name, func, put_ret_addr_in_eax=0
.globl \name
\name:
pushl %eax
pushl %ecx
pushl %edx
+
+ .if \put_ret_addr_in_eax
/* Place EIP in the arg1 */
movl 3*4(%esp), %eax
+ .endif
+
call \func
popl %edx
popl %ecx
@@ -25,6 +28,15 @@
_ASM_NOKPROBE(\name)
.endm
- thunk_ra trace_hardirqs_on_thunk,trace_hardirqs_on_caller
- thunk_ra trace_hardirqs_off_thunk,trace_hardirqs_off_caller
+#ifdef CONFIG_TRACE_IRQFLAGS
+ THUNK trace_hardirqs_on_thunk,trace_hardirqs_on_caller,1
+ THUNK trace_hardirqs_off_thunk,trace_hardirqs_off_caller,1
+#endif
+
+#ifdef CONFIG_PREEMPT
+ THUNK ___preempt_schedule, preempt_schedule
+#ifdef CONFIG_CONTEXT_TRACKING
+ THUNK ___preempt_schedule_context, preempt_schedule_context
#endif
+#endif
+
diff --git a/arch/x86/lib/thunk_64.S b/arch/x86/lib/thunk_64.S
index 92d9feaff42b..b30b5ebd614a 100644
--- a/arch/x86/lib/thunk_64.S
+++ b/arch/x86/lib/thunk_64.S
@@ -38,6 +38,13 @@
THUNK lockdep_sys_exit_thunk,lockdep_sys_exit
#endif
+#ifdef CONFIG_PREEMPT
+ THUNK ___preempt_schedule, preempt_schedule
+#ifdef CONFIG_CONTEXT_TRACKING
+ THUNK ___preempt_schedule_context, preempt_schedule_context
+#endif
+#endif
+
/* SAVE_ARGS below is used only for the .cfi directives it contains. */
CFI_STARTPROC
SAVE_ARGS