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ARM: avoid saving and restoring registers unnecessarily

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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: Russell King <rmk+kernel@armlinux.org.uk>
This commit is contained in:
Russell King 2017-03-24 16:23:25 +00:00
parent fcea45236d
commit dca778c5bb
1 changed files with 8 additions and 2 deletions
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10
arch/arm/kernel/entry-common.S
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@ -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