On 08/04, Denys Vlasenko wrote:
>
> --- a/arch/x86/kernel/preempt.S
> +++ b/arch/x86/kernel/preempt.S
> @@ -6,9 +6,13 @@
>
> ENTRY(___preempt_schedule)
> CFI_STARTPROC
> - SAVE_ALL
> + ALLOC_PTREGS_ON_STACK
> + SAVE_C_REGS
> + SAVE_EXTRA_REGS
> call preempt_schedule
> - RESTORE_ALL
> + RESTORE_EXTRA_REGS
> + RESTORE_C_REGS
> + REMOVE_PTREGS_FROM_STACK
> ret
> CFI_ENDPROC
>
> @@ -16,9 +20,13 @@ ENTRY(___preempt_schedule)
>
> ENTRY(___preempt_schedule_context)
> CFI_STARTPROC
> - SAVE_ALL
> + ALLOC_PTREGS_ON_STACK
> + SAVE_C_REGS
> + SAVE_EXTRA_REGS
> call preempt_schedule_context
> - RESTORE_ALL
> + RESTORE_EXTRA_REGS
> + RESTORE_C_REGS
> + REMOVE_PTREGS_FROM_STACK
> ret
> CFI_ENDPROC
Hmm. This part looks fine, but with or without this patch this all is
suboptimal, we do not need SAVE_ALL unless I missed something. Can't we
simply kill preempt.S ?
Peter, what do you think?
Oleg.
----------------------------------------------------------------------------
Subject: [PATCH] x86: reimplement ___preempt_schedule*() using THUNK helpers
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 047f9ff..3f5d657 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 ca7f0d5..0000000
--- 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 28f85c9..dc2b8fd 100644
--- a/arch/x86/lib/thunk_32.S
+++ b/arch/x86/lib/thunk_32.S
@@ -7,7 +7,6 @@
#include <linux/linkage.h>
#include <asm/asm.h>
-#ifdef CONFIG_TRACE_IRQFLAGS
/* put return address in eax (arg1) */
.macro thunk_ra name,func
.globl \name
@@ -25,6 +24,15 @@
_ASM_NOKPROBE(\name)
.endm
+#ifdef CONFIG_TRACE_IRQFLAGS
thunk_ra trace_hardirqs_on_thunk,trace_hardirqs_on_caller
thunk_ra trace_hardirqs_off_thunk,trace_hardirqs_off_caller
#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 92d9fea..b30b5eb 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
--
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