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2fde6d20bb
This fixes a problem where a CPU thread coming out of nap mode can think it has valid values in the nonvolatile GPRs (r14 - r31) as saved away in power7_idle, but in fact the values have been trashed because the thread was used for KVM in the mean time. The result is that the thread crashes because code that called power7_idle (e.g., pnv_smp_cpu_kill_self()) goes to use values in registers that have been trashed. The bit field in SRR1 that tells whether state was lost only reflects the most recent nap, which may not have been the nap instruction in power7_idle. So we need an extra PACA field to indicate that state has been lost even if SRR1 indicates that the most recent nap didn't lose state. We clear this field when saving the state in power7_idle, we set it to a non-zero value when we use the thread for KVM, and we test it in power7_wakeup_noloss. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
100 lines
2.1 KiB
ArmAsm
100 lines
2.1 KiB
ArmAsm
/*
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* This file contains the power_save function for 970-family CPUs.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/threads.h>
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#include <asm/processor.h>
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#include <asm/page.h>
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#include <asm/cputable.h>
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#include <asm/thread_info.h>
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#include <asm/ppc_asm.h>
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#include <asm/asm-offsets.h>
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#include <asm/ppc-opcode.h>
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#undef DEBUG
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.text
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_GLOBAL(power7_idle)
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/* Now check if user or arch enabled NAP mode */
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LOAD_REG_ADDRBASE(r3,powersave_nap)
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lwz r4,ADDROFF(powersave_nap)(r3)
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cmpwi 0,r4,0
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beqlr
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/* NAP is a state loss, we create a regs frame on the
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* stack, fill it up with the state we care about and
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* stick a pointer to it in PACAR1. We really only
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* need to save PC, some CR bits and the NV GPRs,
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* but for now an interrupt frame will do.
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*/
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mflr r0
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std r0,16(r1)
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stdu r1,-INT_FRAME_SIZE(r1)
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std r0,_LINK(r1)
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std r0,_NIP(r1)
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#ifndef CONFIG_SMP
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/* Make sure FPU, VSX etc... are flushed as we may lose
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* state when going to nap mode
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*/
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bl .discard_lazy_cpu_state
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#endif /* CONFIG_SMP */
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/* Hard disable interrupts */
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mfmsr r9
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rldicl r9,r9,48,1
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rotldi r9,r9,16
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mtmsrd r9,1 /* hard-disable interrupts */
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li r0,0
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stb r0,PACASOFTIRQEN(r13) /* we'll hard-enable shortly */
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stb r0,PACAHARDIRQEN(r13)
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stb r0,PACA_NAPSTATELOST(r13)
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/* Continue saving state */
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SAVE_GPR(2, r1)
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SAVE_NVGPRS(r1)
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mfcr r3
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std r3,_CCR(r1)
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std r9,_MSR(r1)
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std r1,PACAR1(r13)
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/* Magic NAP mode enter sequence */
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std r0,0(r1)
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ptesync
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ld r0,0(r1)
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1: cmp cr0,r0,r0
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bne 1b
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PPC_NAP
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b .
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_GLOBAL(power7_wakeup_loss)
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ld r1,PACAR1(r13)
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REST_NVGPRS(r1)
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REST_GPR(2, r1)
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ld r3,_CCR(r1)
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ld r4,_MSR(r1)
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ld r5,_NIP(r1)
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addi r1,r1,INT_FRAME_SIZE
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mtcr r3
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mtspr SPRN_SRR1,r4
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mtspr SPRN_SRR0,r5
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rfid
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_GLOBAL(power7_wakeup_noloss)
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lbz r0,PACA_NAPSTATELOST(r13)
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cmpwi r0,0
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bne .power7_wakeup_loss
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ld r1,PACAR1(r13)
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ld r4,_MSR(r1)
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ld r5,_NIP(r1)
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addi r1,r1,INT_FRAME_SIZE
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mtspr SPRN_SRR1,r4
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mtspr SPRN_SRR0,r5
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rfid
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