Commit dca778c5 authored by Russell King's avatar Russell King
Browse files

ARM: avoid saving and restoring registers unnecessarily 



Avoid repeatedly saving and restoring registers around the calls to
trace_hardirqs_on() and context_tracking_user_exit().  With the
previous changes, we no longer need to preserve "lr" across these
calls, and if we re-load r0-r3 later, we can avoid preserving these
regsiters too.

Signed-off-by: default avatarRussell King <rmk+kernel@armlinux.org.uk>
parent fcea4523

arch/arm/kernel/entry-common.S

+8 −2
Original line number Diff line number Diff line
@@ -157,8 +157,9 @@ ENTRY(vector_swi) 
#endif

	zero_fp

	alignment_trap r10, ip, __cr_alignment

	enable_irq

	ct_user_exit

	asm_trace_hardirqs_on save=0

	enable_irq_notrace

	ct_user_exit save=0



	/*

	 * Get the system call number.
@@ -216,6 +217,11 @@ ENTRY(vector_swi) 
	eor	scno, scno, #__NR_SYSCALL_BASE	@ check OS number

#endif

	get_thread_info tsk

	/*

	 * Reload the registers that may have been corrupted on entry to

	 * the syscall assembly (by tracing or context tracking.)

	 */

 TRACE(	ldmia	sp, {r0 - r3}		)



local_restart:

	ldr	r10, [tsk, #TI_FLAGS]		@ check for syscall tracing