linux/arch/x86/lib/thunk_64.S
Oleg Nesterov 0ad6e3c519 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>
2014-09-24 15:15:38 +02:00

56 lines
1.3 KiB
ArmAsm

/*
* Save registers before calling assembly functions. This avoids
* disturbance of register allocation in some inline assembly constructs.
* Copyright 2001,2002 by Andi Kleen, SuSE Labs.
* Added trace_hardirqs callers - Copyright 2007 Steven Rostedt, Red Hat, Inc.
* Subject to the GNU public license, v.2. No warranty of any kind.
*/
#include <linux/linkage.h>
#include <asm/dwarf2.h>
#include <asm/calling.h>
#include <asm/asm.h>
/* rdi: arg1 ... normal C conventions. rax is saved/restored. */
.macro THUNK name, func, put_ret_addr_in_rdi=0
.globl \name
\name:
CFI_STARTPROC
/* this one pushes 9 elems, the next one would be %rIP */
SAVE_ARGS
.if \put_ret_addr_in_rdi
movq_cfi_restore 9*8, rdi
.endif
call \func
jmp restore
CFI_ENDPROC
_ASM_NOKPROBE(\name)
.endm
#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_DEBUG_LOCK_ALLOC
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
restore:
RESTORE_ARGS
ret
CFI_ENDPROC
_ASM_NOKPROBE(restore)