ARM: entry: efficiency cleanups
Make the "fast" syscall return path fast again. The addition of IRQ
tracing and context tracking has made this path grossly inefficient.
We can do much better if these options are enabled if we save the
syscall return code on the stack - we then don't need to save a bunch
of registers around every single callout to C code.
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
index 742495e..5a5504f 100644
--- a/arch/arm/include/asm/assembler.h
+++ b/arch/arm/include/asm/assembler.h
@@ -108,29 +108,37 @@
.endm
#endif
- .macro asm_trace_hardirqs_off
+ .macro asm_trace_hardirqs_off, save=1
#if defined(CONFIG_TRACE_IRQFLAGS)
+ .if \save
stmdb sp!, {r0-r3, ip, lr}
+ .endif
bl trace_hardirqs_off
+ .if \save
ldmia sp!, {r0-r3, ip, lr}
+ .endif
#endif
.endm
- .macro asm_trace_hardirqs_on, cond=al
+ .macro asm_trace_hardirqs_on, cond=al, save=1
#if defined(CONFIG_TRACE_IRQFLAGS)
/*
* actually the registers should be pushed and pop'd conditionally, but
* after bl the flags are certainly clobbered
*/
+ .if \save
stmdb sp!, {r0-r3, ip, lr}
+ .endif
bl\cond trace_hardirqs_on
+ .if \save
ldmia sp!, {r0-r3, ip, lr}
+ .endif
#endif
.endm
- .macro disable_irq
+ .macro disable_irq, save=1
disable_irq_notrace
- asm_trace_hardirqs_off
+ asm_trace_hardirqs_off \save
.endm
.macro enable_irq