Commit 01f3880d authored by Michael Ellerman's avatar Michael Ellerman Committed by Paul Mackerras

powerpc: Streamline ret_from_except_lite for non-iSeries platforms

There is a small passage of code in ret_from_except_lite which is
only required on iSeries.  For a multi-platform kernel on non-iSeries
machines this means we end up executing ~15 nops in ret_from_except_lite.

It would be nicer if non-iSeries could skip the code entirely, and on
iSeries we can jump out of line to execute the code.

I have no performance numbers to justify this, other than the assertion
that executing 15 nops takes longer than executing 0.
Signed-off-by: default avatarMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent cd5aeb9f
......@@ -512,31 +512,12 @@ _GLOBAL(ret_from_except_lite)
#endif
restore:
ld r5,SOFTE(r1)
#ifdef CONFIG_PPC_ISERIES
BEGIN_FW_FTR_SECTION
cmpdi 0,r5,0
beq 4f
/* Check for pending interrupts (iSeries) */
ld r3,PACALPPACAPTR(r13)
ld r3,LPPACAANYINT(r3)
cmpdi r3,0
beq+ 4f /* skip do_IRQ if no interrupts */
li r3,0
stb r3,PACASOFTIRQEN(r13) /* ensure we are soft-disabled */
#ifdef CONFIG_TRACE_IRQFLAGS
bl .trace_hardirqs_off
mfmsr r10
#endif
ori r10,r10,MSR_EE
mtmsrd r10 /* hard-enable again */
addi r3,r1,STACK_FRAME_OVERHEAD
bl .do_IRQ
b .ret_from_except_lite /* loop back and handle more */
4:
END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES)
#endif
ld r5,SOFTE(r1)
FW_FTR_SECTION_ELSE
b iseries_check_pending_irqs
ALT_FW_FTR_SECTION_END_IFCLR(FW_FEATURE_ISERIES)
2:
TRACE_AND_RESTORE_IRQ(r5);
/* extract EE bit and use it to restore paca->hard_enabled */
......@@ -592,6 +573,30 @@ END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES)
rfid
b . /* prevent speculative execution */
iseries_check_pending_irqs:
#ifdef CONFIG_PPC_ISERIES
ld r5,SOFTE(r1)
cmpdi 0,r5,0
beq 2b
/* Check for pending interrupts (iSeries) */
ld r3,PACALPPACAPTR(r13)
ld r3,LPPACAANYINT(r3)
cmpdi r3,0
beq+ 2b /* skip do_IRQ if no interrupts */
li r3,0
stb r3,PACASOFTIRQEN(r13) /* ensure we are soft-disabled */
#ifdef CONFIG_TRACE_IRQFLAGS
bl .trace_hardirqs_off
mfmsr r10
#endif
ori r10,r10,MSR_EE
mtmsrd r10 /* hard-enable again */
addi r3,r1,STACK_FRAME_OVERHEAD
bl .do_IRQ
b .ret_from_except_lite /* loop back and handle more */
#endif
do_work:
#ifdef CONFIG_PREEMPT
andi. r0,r3,MSR_PR /* Returning to user mode? */
......
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