Commit 6e02493a authored by David S. Miller's avatar David S. Miller
Browse files

[SPARC64]: Fill dead cycles on trap entry with real work. 



As we save trap state onto the stack, the store buffer fills up
mid-way through and we stall for several cycles as the store buffer
trickles out to the L2 cache.  Meanwhile we can do some privileged
register reads and other calculations, essentially for free.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d619d7f1

arch/sparc64/kernel/etrap.S

+15 −12
Original line number Diff line number Diff line
@@ -98,37 +98,40 @@ etrap_save: save %g2, -STACK_BIAS, %sp 
		stxa	%g3, [%l4] ASI_DMMU

		sethi	%hi(KERNBASE), %l4

		flush	%l4

		wr	%g0, ASI_AIUS, %asi

2:		wrpr	%g0, 0x0, %tl

		mov	%g4, %l4

		mov	ASI_AIUS, %l7

2:		mov	%g4, %l4

		mov	%g5, %l5



		mov	%g7, %l2

		add	%g7, 4, %l2

		wrpr	%g0, ETRAP_PSTATE1, %pstate

		stx	%g1, [%sp + PTREGS_OFF + PT_V9_G1]

		stx	%g2, [%sp + PTREGS_OFF + PT_V9_G2]

		sllx	%l7, 24, %l7

		stx	%g3, [%sp + PTREGS_OFF + PT_V9_G3]

		rdpr	%cwp, %l0

		stx	%g4, [%sp + PTREGS_OFF + PT_V9_G4]

		stx	%g5, [%sp + PTREGS_OFF + PT_V9_G5]

		stx	%g6, [%sp + PTREGS_OFF + PT_V9_G6]



		stx	%g7, [%sp + PTREGS_OFF + PT_V9_G7]

		or	%l7, %l0, %l7

		sethi	%hi(TSTATE_RMO | TSTATE_PEF), %l0

		or	%l7, %l0, %l7

		wrpr	%l2, %tnpc

		wrpr	%l7, (TSTATE_PRIV | TSTATE_IE), %tstate

		stx	%i0, [%sp + PTREGS_OFF + PT_V9_I0]

		stx	%i1, [%sp + PTREGS_OFF + PT_V9_I1]

		stx	%i2, [%sp + PTREGS_OFF + PT_V9_I2]

		stx	%i3, [%sp + PTREGS_OFF + PT_V9_I3]

		stx	%i4, [%sp + PTREGS_OFF + PT_V9_I4]

		stx	%i5, [%sp + PTREGS_OFF + PT_V9_I5]



		stx	%i6, [%sp + PTREGS_OFF + PT_V9_I6]

		stx	%i7, [%sp + PTREGS_OFF + PT_V9_I7]

		wrpr	%g0, ETRAP_PSTATE2, %pstate

		mov	%l6, %g6

		stx	%i7, [%sp + PTREGS_OFF + PT_V9_I7]

		LOAD_PER_CPU_BASE(%g5, %g6, %g4, %g3, %l1)

		jmpl	%l2 + 0x4, %g0

		ldx	[%g6 + TI_TASK], %g4

		done



3:		ldub	[%l6 + TI_FPDEPTH], %l5

3:		mov	ASI_P, %l7

		ldub	[%l6 + TI_FPDEPTH], %l5

		add	%l6, TI_FPSAVED + 1, %l4

		srl	%l5, 1, %l3

		add	%l5, 2, %l5

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