forked from Minki/linux
a7159a87a3
For many sun4v processor types, reading or writing a privileged register
has a latency of 40 to 70 cycles. Use a combination of the low-latency
allclean, otherw, normalw, and nop instructions in etrap and rtrap to
replace 2 rdpr and 5 wrpr instructions and improve etrap/rtrap
performance. allclean, otherw, and normalw are available on NG2 and
later processors.
The average ticks to execute the flush windows trap ("ta 0x3") with and
without this patch on select platforms:
CPU Not patched Patched % Latency Reduction
NG2 1762 1558 -11.58
NG4 3619 3204 -11.47
M7 3015 2624 -12.97
SPARC64-X 829 770 -7.12
Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
349 lines
9.0 KiB
ArmAsm
349 lines
9.0 KiB
ArmAsm
/*
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* rtrap.S: Preparing for return from trap on Sparc V9.
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*
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* Copyright (C) 1997,1998 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
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* Copyright (C) 1997 David S. Miller (davem@caip.rutgers.edu)
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*/
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#include <asm/asi.h>
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#include <asm/pstate.h>
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#include <asm/ptrace.h>
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#include <asm/spitfire.h>
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#include <asm/head.h>
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#include <asm/visasm.h>
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#include <asm/processor.h>
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#ifdef CONFIG_CONTEXT_TRACKING
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# define SCHEDULE_USER schedule_user
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#else
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# define SCHEDULE_USER schedule
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#endif
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.text
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.align 32
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__handle_preemption:
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call SCHEDULE_USER
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wrpr %g0, RTRAP_PSTATE, %pstate
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ba,pt %xcc, __handle_preemption_continue
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wrpr %g0, RTRAP_PSTATE_IRQOFF, %pstate
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__handle_user_windows:
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call fault_in_user_windows
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wrpr %g0, RTRAP_PSTATE, %pstate
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ba,pt %xcc, __handle_preemption_continue
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wrpr %g0, RTRAP_PSTATE_IRQOFF, %pstate
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__handle_userfpu:
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rd %fprs, %l5
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andcc %l5, FPRS_FEF, %g0
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sethi %hi(TSTATE_PEF), %o0
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be,a,pn %icc, __handle_userfpu_continue
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andn %l1, %o0, %l1
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ba,a,pt %xcc, __handle_userfpu_continue
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__handle_signal:
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mov %l5, %o1
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add %sp, PTREGS_OFF, %o0
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mov %l0, %o2
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call do_notify_resume
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wrpr %g0, RTRAP_PSTATE, %pstate
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wrpr %g0, RTRAP_PSTATE_IRQOFF, %pstate
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/* Signal delivery can modify pt_regs tstate, so we must
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* reload it.
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*/
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ldx [%sp + PTREGS_OFF + PT_V9_TSTATE], %l1
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sethi %hi(0xf << 20), %l4
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and %l1, %l4, %l4
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ba,pt %xcc, __handle_preemption_continue
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andn %l1, %l4, %l1
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/* When returning from a NMI (%pil==15) interrupt we want to
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* avoid running softirqs, doing IRQ tracing, preempting, etc.
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*/
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.globl rtrap_nmi
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rtrap_nmi: ldx [%sp + PTREGS_OFF + PT_V9_TSTATE], %l1
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sethi %hi(0xf << 20), %l4
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and %l1, %l4, %l4
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andn %l1, %l4, %l1
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srl %l4, 20, %l4
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ba,pt %xcc, rtrap_no_irq_enable
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nop
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/* Do not actually set the %pil here. We will do that
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* below after we clear PSTATE_IE in the %pstate register.
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* If we re-enable interrupts here, we can recurse down
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* the hardirq stack potentially endlessly, causing a
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* stack overflow.
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*/
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.align 64
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.globl rtrap_irq, rtrap, irqsz_patchme, rtrap_xcall
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rtrap_irq:
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rtrap:
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/* mm/ultra.S:xcall_report_regs KNOWS about this load. */
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ldx [%sp + PTREGS_OFF + PT_V9_TSTATE], %l1
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rtrap_xcall:
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sethi %hi(0xf << 20), %l4
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and %l1, %l4, %l4
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andn %l1, %l4, %l1
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srl %l4, 20, %l4
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#ifdef CONFIG_TRACE_IRQFLAGS
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brnz,pn %l4, rtrap_no_irq_enable
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nop
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call trace_hardirqs_on
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nop
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/* Do not actually set the %pil here. We will do that
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* below after we clear PSTATE_IE in the %pstate register.
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* If we re-enable interrupts here, we can recurse down
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* the hardirq stack potentially endlessly, causing a
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* stack overflow.
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*
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* It is tempting to put this test and trace_hardirqs_on
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* call at the 'rt_continue' label, but that will not work
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* as that path hits unconditionally and we do not want to
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* execute this in NMI return paths, for example.
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*/
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#endif
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rtrap_no_irq_enable:
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andcc %l1, TSTATE_PRIV, %l3
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bne,pn %icc, to_kernel
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nop
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/* We must hold IRQs off and atomically test schedule+signal
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* state, then hold them off all the way back to userspace.
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* If we are returning to kernel, none of this matters. Note
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* that we are disabling interrupts via PSTATE_IE, not using
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* %pil.
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*
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* If we do not do this, there is a window where we would do
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* the tests, later the signal/resched event arrives but we do
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* not process it since we are still in kernel mode. It would
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* take until the next local IRQ before the signal/resched
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* event would be handled.
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*
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* This also means that if we have to deal with user
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* windows, we have to redo all of these sched+signal checks
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* with IRQs disabled.
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*/
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to_user: wrpr %g0, RTRAP_PSTATE_IRQOFF, %pstate
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wrpr 0, %pil
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__handle_preemption_continue:
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ldx [%g6 + TI_FLAGS], %l0
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sethi %hi(_TIF_USER_WORK_MASK), %o0
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or %o0, %lo(_TIF_USER_WORK_MASK), %o0
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andcc %l0, %o0, %g0
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sethi %hi(TSTATE_PEF), %o0
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be,pt %xcc, user_nowork
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andcc %l1, %o0, %g0
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andcc %l0, _TIF_NEED_RESCHED, %g0
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bne,pn %xcc, __handle_preemption
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andcc %l0, _TIF_DO_NOTIFY_RESUME_MASK, %g0
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bne,pn %xcc, __handle_signal
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ldub [%g6 + TI_WSAVED], %o2
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brnz,pn %o2, __handle_user_windows
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nop
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sethi %hi(TSTATE_PEF), %o0
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andcc %l1, %o0, %g0
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/* This fpdepth clear is necessary for non-syscall rtraps only */
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user_nowork:
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bne,pn %xcc, __handle_userfpu
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stb %g0, [%g6 + TI_FPDEPTH]
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__handle_userfpu_continue:
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rt_continue: ldx [%sp + PTREGS_OFF + PT_V9_G1], %g1
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ldx [%sp + PTREGS_OFF + PT_V9_G2], %g2
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ldx [%sp + PTREGS_OFF + PT_V9_G3], %g3
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ldx [%sp + PTREGS_OFF + PT_V9_G4], %g4
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ldx [%sp + PTREGS_OFF + PT_V9_G5], %g5
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brz,pt %l3, 1f
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mov %g6, %l2
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/* Must do this before thread reg is clobbered below. */
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LOAD_PER_CPU_BASE(%g5, %g6, %i0, %i1, %i2)
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1:
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ldx [%sp + PTREGS_OFF + PT_V9_G6], %g6
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ldx [%sp + PTREGS_OFF + PT_V9_G7], %g7
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/* Normal globals are restored, go to trap globals. */
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661: wrpr %g0, RTRAP_PSTATE_AG_IRQOFF, %pstate
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nop
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.section .sun4v_2insn_patch, "ax"
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.word 661b
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wrpr %g0, RTRAP_PSTATE_IRQOFF, %pstate
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SET_GL(1)
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.previous
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mov %l2, %g6
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ldx [%sp + PTREGS_OFF + PT_V9_I0], %i0
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ldx [%sp + PTREGS_OFF + PT_V9_I1], %i1
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ldx [%sp + PTREGS_OFF + PT_V9_I2], %i2
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ldx [%sp + PTREGS_OFF + PT_V9_I3], %i3
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ldx [%sp + PTREGS_OFF + PT_V9_I4], %i4
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ldx [%sp + PTREGS_OFF + PT_V9_I5], %i5
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ldx [%sp + PTREGS_OFF + PT_V9_I6], %i6
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ldx [%sp + PTREGS_OFF + PT_V9_I7], %i7
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ldx [%sp + PTREGS_OFF + PT_V9_TPC], %l2
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ldx [%sp + PTREGS_OFF + PT_V9_TNPC], %o2
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ld [%sp + PTREGS_OFF + PT_V9_Y], %o3
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wr %o3, %g0, %y
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wrpr %l4, 0x0, %pil
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wrpr %g0, 0x1, %tl
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andn %l1, TSTATE_SYSCALL, %l1
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wrpr %l1, %g0, %tstate
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wrpr %l2, %g0, %tpc
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wrpr %o2, %g0, %tnpc
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brnz,pn %l3, kern_rtt
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mov PRIMARY_CONTEXT, %l7
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661: ldxa [%l7 + %l7] ASI_DMMU, %l0
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.section .sun4v_1insn_patch, "ax"
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.word 661b
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ldxa [%l7 + %l7] ASI_MMU, %l0
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.previous
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sethi %hi(sparc64_kern_pri_nuc_bits), %l1
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ldx [%l1 + %lo(sparc64_kern_pri_nuc_bits)], %l1
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or %l0, %l1, %l0
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661: stxa %l0, [%l7] ASI_DMMU
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.section .sun4v_1insn_patch, "ax"
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.word 661b
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stxa %l0, [%l7] ASI_MMU
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.previous
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sethi %hi(KERNBASE), %l7
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flush %l7
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rdpr %wstate, %l1
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rdpr %otherwin, %l2
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srl %l1, 3, %l1
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661: wrpr %l2, %g0, %canrestore
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.section .fast_win_ctrl_1insn_patch, "ax"
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.word 661b
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.word 0x89880000 ! normalw
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.previous
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wrpr %l1, %g0, %wstate
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brnz,pt %l2, user_rtt_restore
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661: wrpr %g0, %g0, %otherwin
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.section .fast_win_ctrl_1insn_patch, "ax"
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.word 661b
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nop
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.previous
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ldx [%g6 + TI_FLAGS], %g3
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wr %g0, ASI_AIUP, %asi
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rdpr %cwp, %g1
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andcc %g3, _TIF_32BIT, %g0
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sub %g1, 1, %g1
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bne,pt %xcc, user_rtt_fill_32bit
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wrpr %g1, %cwp
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ba,a,pt %xcc, user_rtt_fill_64bit
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nop
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user_rtt_fill_fixup_dax:
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ba,pt %xcc, user_rtt_fill_fixup_common
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mov 1, %g3
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user_rtt_fill_fixup_mna:
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ba,pt %xcc, user_rtt_fill_fixup_common
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mov 2, %g3
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user_rtt_fill_fixup:
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ba,pt %xcc, user_rtt_fill_fixup_common
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clr %g3
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user_rtt_pre_restore:
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add %g1, 1, %g1
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wrpr %g1, 0x0, %cwp
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user_rtt_restore:
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restore
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rdpr %canrestore, %g1
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wrpr %g1, 0x0, %cleanwin
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retry
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nop
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kern_rtt: rdpr %canrestore, %g1
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brz,pn %g1, kern_rtt_fill
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nop
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kern_rtt_restore:
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stw %g0, [%sp + PTREGS_OFF + PT_V9_MAGIC]
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restore
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retry
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to_kernel:
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#ifdef CONFIG_PREEMPT
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ldsw [%g6 + TI_PRE_COUNT], %l5
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brnz %l5, kern_fpucheck
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ldx [%g6 + TI_FLAGS], %l5
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andcc %l5, _TIF_NEED_RESCHED, %g0
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be,pt %xcc, kern_fpucheck
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nop
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cmp %l4, 0
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bne,pn %xcc, kern_fpucheck
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nop
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call preempt_schedule_irq
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nop
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ba,pt %xcc, rtrap
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#endif
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kern_fpucheck: ldub [%g6 + TI_FPDEPTH], %l5
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brz,pt %l5, rt_continue
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srl %l5, 1, %o0
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add %g6, TI_FPSAVED, %l6
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ldub [%l6 + %o0], %l2
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sub %l5, 2, %l5
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add %g6, TI_GSR, %o1
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andcc %l2, (FPRS_FEF|FPRS_DU), %g0
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be,pt %icc, 2f
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and %l2, FPRS_DL, %l6
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andcc %l2, FPRS_FEF, %g0
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be,pn %icc, 5f
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sll %o0, 3, %o5
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rd %fprs, %g1
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wr %g1, FPRS_FEF, %fprs
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ldx [%o1 + %o5], %g1
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add %g6, TI_XFSR, %o1
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sll %o0, 8, %o2
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add %g6, TI_FPREGS, %o3
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brz,pn %l6, 1f
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add %g6, TI_FPREGS+0x40, %o4
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membar #Sync
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ldda [%o3 + %o2] ASI_BLK_P, %f0
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ldda [%o4 + %o2] ASI_BLK_P, %f16
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membar #Sync
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1: andcc %l2, FPRS_DU, %g0
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be,pn %icc, 1f
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wr %g1, 0, %gsr
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add %o2, 0x80, %o2
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membar #Sync
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ldda [%o3 + %o2] ASI_BLK_P, %f32
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ldda [%o4 + %o2] ASI_BLK_P, %f48
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1: membar #Sync
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ldx [%o1 + %o5], %fsr
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2: stb %l5, [%g6 + TI_FPDEPTH]
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ba,pt %xcc, rt_continue
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nop
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5: wr %g0, FPRS_FEF, %fprs
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sll %o0, 8, %o2
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add %g6, TI_FPREGS+0x80, %o3
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add %g6, TI_FPREGS+0xc0, %o4
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membar #Sync
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ldda [%o3 + %o2] ASI_BLK_P, %f32
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ldda [%o4 + %o2] ASI_BLK_P, %f48
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membar #Sync
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wr %g0, FPRS_DU, %fprs
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ba,pt %xcc, rt_continue
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stb %l5, [%g6 + TI_FPDEPTH]
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