powerpc/64s: implement arch-specific hardlockup watchdog
Implement an arch-speicfic watchdog rather than use the perf-based hardlockup detector. The new watchdog takes the soft-NMI directly, rather than going through perf. Perf interrupts are to be made maskable in future, so that would prevent the perf detector from working in those regions. Additionally, implement a SMP based detector where all CPUs watch one another by pinging a shared cpumask. This is because powerpc Book3S does not have a true periodic local NMI, but some platforms do implement a true NMI IPI. If a CPU is stuck with interrupts hard disabled, the soft-NMI watchdog does not work, but the SMP watchdog will. Even on platforms without a true NMI IPI to get a good trace from the stuck CPU, other CPUs will notice the lockup sufficiently to report it and panic. [npiggin@gmail.com: honor watchdog disable at boot/hotplug] Link: http://lkml.kernel.org/r/20170621001346.5bb337c9@roar.ozlabs.ibm.com [npiggin@gmail.com: fix false positive warning at CPU unplug] Link: http://lkml.kernel.org/r/20170630080740.20766-1-npiggin@gmail.com [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/20170616065715.18390-6-npiggin@gmail.com Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Reviewed-by: Don Zickus <dzickus@redhat.com> Tested-by: Babu Moger <babu.moger@oracle.com> [sparc] Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Nicholas Piggin
Linus Torvalds
Родитель
a10a842ff8
Коммит
2104180a53
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@ -82,7 +82,7 @@ config NR_IRQS
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config NMI_IPI
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bool
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depends on SMP && (DEBUGGER || KEXEC_CORE)
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depends on SMP && (DEBUGGER || KEXEC_CORE || HARDLOCKUP_DETECTOR)
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default y
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config STACKTRACE_SUPPORT
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@ -192,12 +192,13 @@ config PPC
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select HAVE_MEMBLOCK
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select HAVE_MEMBLOCK_NODE_MAP
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select HAVE_MOD_ARCH_SPECIFIC
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select HAVE_NMI if PERF_EVENTS
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select HAVE_NMI if PERF_EVENTS || (PPC64 && PPC_BOOK3S)
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select HAVE_HARDLOCKUP_DETECTOR_ARCH if (PPC64 && PPC_BOOK3S)
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select HAVE_OPROFILE
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select HAVE_OPTPROBES if PPC64
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select HAVE_PERF_EVENTS
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select HAVE_PERF_EVENTS_NMI if PPC64
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select HAVE_HARDLOCKUP_DETECTOR_PERF if HAVE_PERF_EVENTS_NMI
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select HAVE_HARDLOCKUP_DETECTOR_PERF if HAVE_PERF_EVENTS_NMI && !HAVE_HARDLOCKUP_DETECTOR_ARCH
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select HAVE_PERF_REGS
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select HAVE_PERF_USER_STACK_DUMP
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select HAVE_RCU_TABLE_FREE if SMP
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@ -1,4 +1,15 @@
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#ifndef _ASM_NMI_H
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#define _ASM_NMI_H
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#ifdef CONFIG_HARDLOCKUP_DETECTOR
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extern void arch_touch_nmi_watchdog(void);
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extern void arch_trigger_cpumask_backtrace(const cpumask_t *mask,
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bool exclude_self);
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#define arch_trigger_cpumask_backtrace arch_trigger_cpumask_backtrace
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#else
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static inline void arch_touch_nmi_watchdog(void) {}
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#endif
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#endif /* _ASM_NMI_H */
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@ -55,6 +55,8 @@ struct smp_ops_t {
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int (*cpu_bootable)(unsigned int nr);
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};
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extern void smp_flush_nmi_ipi(u64 delay_us);
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extern int smp_send_nmi_ipi(int cpu, void (*fn)(struct pt_regs *), u64 delay_us);
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extern void smp_send_debugger_break(void);
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extern void start_secondary_resume(void);
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extern void smp_generic_give_timebase(void);
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@ -38,6 +38,7 @@ obj-$(CONFIG_PPC64) += setup_64.o sys_ppc32.o \
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signal_64.o ptrace32.o \
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paca.o nvram_64.o firmware.o
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obj-$(CONFIG_VDSO32) += vdso32/
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obj-$(CONFIG_HARDLOCKUP_DETECTOR) += watchdog.o
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obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
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obj-$(CONFIG_PPC_BOOK3S_64) += cpu_setup_ppc970.o cpu_setup_pa6t.o
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obj-$(CONFIG_PPC_BOOK3S_64) += cpu_setup_power.o
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@ -1314,6 +1314,31 @@ EXC_REAL_NONE(0x1800, 0x100)
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EXC_VIRT_NONE(0x5800, 0x100)
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#endif
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#if defined(CONFIG_HARDLOCKUP_DETECTOR) && defined(CONFIG_HAVE_HARDLOCKUP_DETECTOR_ARCH)
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#define MASKED_DEC_HANDLER_LABEL 3f
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#define MASKED_DEC_HANDLER(_H) \
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3: /* soft-nmi */ \
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std r12,PACA_EXGEN+EX_R12(r13); \
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GET_SCRATCH0(r10); \
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std r10,PACA_EXGEN+EX_R13(r13); \
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EXCEPTION_PROLOG_PSERIES_1(soft_nmi_common, _H)
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EXC_COMMON_BEGIN(soft_nmi_common)
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mr r10,r1
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ld r1,PACAEMERGSP(r13)
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ld r1,PACA_NMI_EMERG_SP(r13)
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subi r1,r1,INT_FRAME_SIZE
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EXCEPTION_COMMON_NORET_STACK(PACA_EXGEN, 0x900,
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system_reset, soft_nmi_interrupt,
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ADD_NVGPRS;ADD_RECONCILE)
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b ret_from_except
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#else
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#define MASKED_DEC_HANDLER_LABEL 2f /* normal return */
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#define MASKED_DEC_HANDLER(_H)
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#endif
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/*
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* An interrupt came in while soft-disabled. We set paca->irq_happened, then:
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@ -1336,7 +1361,7 @@ masked_##_H##interrupt: \
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lis r10,0x7fff; \
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ori r10,r10,0xffff; \
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mtspr SPRN_DEC,r10; \
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b 2f; \
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b MASKED_DEC_HANDLER_LABEL; \
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1: cmpwi r10,PACA_IRQ_DBELL; \
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beq 2f; \
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cmpwi r10,PACA_IRQ_HMI; \
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@ -1351,7 +1376,8 @@ masked_##_H##interrupt: \
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ld r11,PACA_EXGEN+EX_R11(r13); \
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GET_SCRATCH0(r13); \
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##_H##rfid; \
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b .
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b .; \
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MASKED_DEC_HANDLER(_H)
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/*
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* Real mode exceptions actually use this too, but alternate
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@ -25,6 +25,7 @@
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#include <linux/kvm_para.h>
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#include <linux/slab.h>
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#include <linux/of.h>
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#include <linux/nmi.h> /* hardlockup_detector_disable() */
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#include <asm/reg.h>
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#include <asm/sections.h>
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@ -718,6 +719,12 @@ static __init void kvm_free_tmp(void)
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static int __init kvm_guest_init(void)
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{
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/*
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* The hardlockup detector is likely to get false positives in
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* KVM guests, so disable it by default.
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*/
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hardlockup_detector_disable();
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if (!kvm_para_available())
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goto free_tmp;
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@ -751,22 +751,3 @@ unsigned long memory_block_size_bytes(void)
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struct ppc_pci_io ppc_pci_io;
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EXPORT_SYMBOL(ppc_pci_io);
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#endif
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#ifdef CONFIG_HARDLOCKUP_DETECTOR_PERF
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u64 hw_nmi_get_sample_period(int watchdog_thresh)
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{
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return ppc_proc_freq * watchdog_thresh;
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}
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/*
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* The hardlockup detector breaks PMU event based branches and is likely
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* to get false positives in KVM guests, so disable it by default.
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*/
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static int __init disable_hardlockup_detector(void)
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{
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hardlockup_detector_disable();
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return 0;
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}
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early_initcall(disable_hardlockup_detector);
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#endif
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@ -435,13 +435,31 @@ static void do_smp_send_nmi_ipi(int cpu)
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}
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}
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void smp_flush_nmi_ipi(u64 delay_us)
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{
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unsigned long flags;
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nmi_ipi_lock_start(&flags);
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while (nmi_ipi_busy_count) {
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nmi_ipi_unlock_end(&flags);
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udelay(1);
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if (delay_us) {
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delay_us--;
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if (!delay_us)
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return;
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}
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nmi_ipi_lock_start(&flags);
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}
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nmi_ipi_unlock_end(&flags);
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}
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/*
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* - cpu is the target CPU (must not be this CPU), or NMI_IPI_ALL_OTHERS.
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* - fn is the target callback function.
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* - delay_us > 0 is the delay before giving up waiting for targets to
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* enter the handler, == 0 specifies indefinite delay.
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*/
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static int smp_send_nmi_ipi(int cpu, void (*fn)(struct pt_regs *), u64 delay_us)
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int smp_send_nmi_ipi(int cpu, void (*fn)(struct pt_regs *), u64 delay_us)
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{
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unsigned long flags;
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int me = raw_smp_processor_id();
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@ -0,0 +1,386 @@
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/*
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* Watchdog support on powerpc systems.
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*
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* Copyright 2017, IBM Corporation.
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*
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* This uses code from arch/sparc/kernel/nmi.c and kernel/watchdog.c
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*/
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#include <linux/kernel.h>
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#include <linux/param.h>
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#include <linux/init.h>
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#include <linux/percpu.h>
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#include <linux/cpu.h>
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#include <linux/nmi.h>
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#include <linux/module.h>
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#include <linux/export.h>
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#include <linux/kprobes.h>
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#include <linux/hardirq.h>
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#include <linux/reboot.h>
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#include <linux/slab.h>
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#include <linux/kdebug.h>
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#include <linux/sched/debug.h>
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#include <linux/delay.h>
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#include <linux/smp.h>
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#include <asm/paca.h>
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/*
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* The watchdog has a simple timer that runs on each CPU, once per timer
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* period. This is the heartbeat.
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*
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* Then there are checks to see if the heartbeat has not triggered on a CPU
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* for the panic timeout period. Currently the watchdog only supports an
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* SMP check, so the heartbeat only turns on when we have 2 or more CPUs.
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*
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* This is not an NMI watchdog, but Linux uses that name for a generic
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* watchdog in some cases, so NMI gets used in some places.
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*/
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static cpumask_t wd_cpus_enabled __read_mostly;
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static u64 wd_panic_timeout_tb __read_mostly; /* timebase ticks until panic */
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static u64 wd_smp_panic_timeout_tb __read_mostly; /* panic other CPUs */
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static u64 wd_timer_period_ms __read_mostly; /* interval between heartbeat */
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static DEFINE_PER_CPU(struct timer_list, wd_timer);
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static DEFINE_PER_CPU(u64, wd_timer_tb);
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/*
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* These are for the SMP checker. CPUs clear their pending bit in their
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* heartbeat. If the bitmask becomes empty, the time is noted and the
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* bitmask is refilled.
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*
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* All CPUs clear their bit in the pending mask every timer period.
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* Once all have cleared, the time is noted and the bits are reset.
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* If the time since all clear was greater than the panic timeout,
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* we can panic with the list of stuck CPUs.
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*
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* This will work best with NMI IPIs for crash code so the stuck CPUs
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* can be pulled out to get their backtraces.
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*/
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static unsigned long __wd_smp_lock;
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static cpumask_t wd_smp_cpus_pending;
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static cpumask_t wd_smp_cpus_stuck;
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static u64 wd_smp_last_reset_tb;
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static inline void wd_smp_lock(unsigned long *flags)
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{
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/*
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* Avoid locking layers if possible.
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* This may be called from low level interrupt handlers at some
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* point in future.
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*/
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local_irq_save(*flags);
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while (unlikely(test_and_set_bit_lock(0, &__wd_smp_lock)))
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cpu_relax();
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}
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static inline void wd_smp_unlock(unsigned long *flags)
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{
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clear_bit_unlock(0, &__wd_smp_lock);
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local_irq_restore(*flags);
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}
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static void wd_lockup_ipi(struct pt_regs *regs)
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{
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pr_emerg("Watchdog CPU:%d Hard LOCKUP\n", raw_smp_processor_id());
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print_modules();
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print_irqtrace_events(current);
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if (regs)
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show_regs(regs);
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else
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dump_stack();
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if (hardlockup_panic)
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nmi_panic(regs, "Hard LOCKUP");
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}
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static void set_cpu_stuck(int cpu, u64 tb)
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{
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cpumask_set_cpu(cpu, &wd_smp_cpus_stuck);
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cpumask_clear_cpu(cpu, &wd_smp_cpus_pending);
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if (cpumask_empty(&wd_smp_cpus_pending)) {
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wd_smp_last_reset_tb = tb;
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cpumask_andnot(&wd_smp_cpus_pending,
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&wd_cpus_enabled,
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&wd_smp_cpus_stuck);
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}
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}
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static void watchdog_smp_panic(int cpu, u64 tb)
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{
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unsigned long flags;
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int c;
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wd_smp_lock(&flags);
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/* Double check some things under lock */
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if ((s64)(tb - wd_smp_last_reset_tb) < (s64)wd_smp_panic_timeout_tb)
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goto out;
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if (cpumask_test_cpu(cpu, &wd_smp_cpus_pending))
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goto out;
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if (cpumask_weight(&wd_smp_cpus_pending) == 0)
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goto out;
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pr_emerg("Watchdog CPU:%d detected Hard LOCKUP other CPUS:%*pbl\n",
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cpu, cpumask_pr_args(&wd_smp_cpus_pending));
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/*
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* Try to trigger the stuck CPUs.
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*/
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for_each_cpu(c, &wd_smp_cpus_pending) {
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if (c == cpu)
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continue;
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smp_send_nmi_ipi(c, wd_lockup_ipi, 1000000);
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}
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smp_flush_nmi_ipi(1000000);
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/* Take the stuck CPU out of the watch group */
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for_each_cpu(c, &wd_smp_cpus_pending)
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set_cpu_stuck(c, tb);
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out:
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wd_smp_unlock(&flags);
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printk_safe_flush();
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/*
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* printk_safe_flush() seems to require another print
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* before anything actually goes out to console.
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*/
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if (sysctl_hardlockup_all_cpu_backtrace)
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trigger_allbutself_cpu_backtrace();
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if (hardlockup_panic)
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nmi_panic(NULL, "Hard LOCKUP");
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}
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static void wd_smp_clear_cpu_pending(int cpu, u64 tb)
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{
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if (!cpumask_test_cpu(cpu, &wd_smp_cpus_pending)) {
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if (unlikely(cpumask_test_cpu(cpu, &wd_smp_cpus_stuck))) {
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unsigned long flags;
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pr_emerg("Watchdog CPU:%d became unstuck\n", cpu);
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wd_smp_lock(&flags);
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cpumask_clear_cpu(cpu, &wd_smp_cpus_stuck);
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wd_smp_unlock(&flags);
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}
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return;
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}
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cpumask_clear_cpu(cpu, &wd_smp_cpus_pending);
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if (cpumask_empty(&wd_smp_cpus_pending)) {
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unsigned long flags;
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wd_smp_lock(&flags);
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if (cpumask_empty(&wd_smp_cpus_pending)) {
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wd_smp_last_reset_tb = tb;
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cpumask_andnot(&wd_smp_cpus_pending,
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&wd_cpus_enabled,
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&wd_smp_cpus_stuck);
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}
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wd_smp_unlock(&flags);
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}
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}
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static void watchdog_timer_interrupt(int cpu)
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{
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u64 tb = get_tb();
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per_cpu(wd_timer_tb, cpu) = tb;
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wd_smp_clear_cpu_pending(cpu, tb);
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if ((s64)(tb - wd_smp_last_reset_tb) >= (s64)wd_smp_panic_timeout_tb)
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watchdog_smp_panic(cpu, tb);
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}
|
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|
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void soft_nmi_interrupt(struct pt_regs *regs)
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{
|
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unsigned long flags;
|
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int cpu = raw_smp_processor_id();
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u64 tb;
|
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|
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if (!cpumask_test_cpu(cpu, &wd_cpus_enabled))
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return;
|
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|
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nmi_enter();
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tb = get_tb();
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if (tb - per_cpu(wd_timer_tb, cpu) >= wd_panic_timeout_tb) {
|
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per_cpu(wd_timer_tb, cpu) = tb;
|
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|
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wd_smp_lock(&flags);
|
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if (cpumask_test_cpu(cpu, &wd_smp_cpus_stuck)) {
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wd_smp_unlock(&flags);
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goto out;
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}
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set_cpu_stuck(cpu, tb);
|
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|
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pr_emerg("Watchdog CPU:%d Hard LOCKUP\n", cpu);
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print_modules();
|
||||
print_irqtrace_events(current);
|
||||
if (regs)
|
||||
show_regs(regs);
|
||||
else
|
||||
dump_stack();
|
||||
|
||||
wd_smp_unlock(&flags);
|
||||
|
||||
if (sysctl_hardlockup_all_cpu_backtrace)
|
||||
trigger_allbutself_cpu_backtrace();
|
||||
|
||||
if (hardlockup_panic)
|
||||
nmi_panic(regs, "Hard LOCKUP");
|
||||
}
|
||||
if (wd_panic_timeout_tb < 0x7fffffff)
|
||||
mtspr(SPRN_DEC, wd_panic_timeout_tb);
|
||||
|
||||
out:
|
||||
nmi_exit();
|
||||
}
|
||||
|
||||
static void wd_timer_reset(unsigned int cpu, struct timer_list *t)
|
||||
{
|
||||
t->expires = jiffies + msecs_to_jiffies(wd_timer_period_ms);
|
||||
if (wd_timer_period_ms > 1000)
|
||||
t->expires = __round_jiffies_up(t->expires, cpu);
|
||||
add_timer_on(t, cpu);
|
||||
}
|
||||
|
||||
static void wd_timer_fn(unsigned long data)
|
||||
{
|
||||
struct timer_list *t = this_cpu_ptr(&wd_timer);
|
||||
int cpu = smp_processor_id();
|
||||
|
||||
watchdog_timer_interrupt(cpu);
|
||||
|
||||
wd_timer_reset(cpu, t);
|
||||
}
|
||||
|
||||
void arch_touch_nmi_watchdog(void)
|
||||
{
|
||||
int cpu = smp_processor_id();
|
||||
|
||||
watchdog_timer_interrupt(cpu);
|
||||
}
|
||||
EXPORT_SYMBOL(arch_touch_nmi_watchdog);
|
||||
|
||||
static void start_watchdog_timer_on(unsigned int cpu)
|
||||
{
|
||||
struct timer_list *t = per_cpu_ptr(&wd_timer, cpu);
|
||||
|
||||
per_cpu(wd_timer_tb, cpu) = get_tb();
|
||||
|
||||
setup_pinned_timer(t, wd_timer_fn, 0);
|
||||
wd_timer_reset(cpu, t);
|
||||
}
|
||||
|
||||
static void stop_watchdog_timer_on(unsigned int cpu)
|
||||
{
|
||||
struct timer_list *t = per_cpu_ptr(&wd_timer, cpu);
|
||||
|
||||
del_timer_sync(t);
|
||||
}
|
||||
|
||||
static int start_wd_on_cpu(unsigned int cpu)
|
||||
{
|
||||
if (cpumask_test_cpu(cpu, &wd_cpus_enabled)) {
|
||||
WARN_ON(1);
|
||||
return 0;
|
||||
}
|
||||
|
||||
if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED))
|
||||
return 0;
|
||||
|
||||
if (watchdog_suspended)
|
||||
return 0;
|
||||
|
||||
if (!cpumask_test_cpu(cpu, &watchdog_cpumask))
|
||||
return 0;
|
||||
|
||||
cpumask_set_cpu(cpu, &wd_cpus_enabled);
|
||||
if (cpumask_weight(&wd_cpus_enabled) == 1) {
|
||||
cpumask_set_cpu(cpu, &wd_smp_cpus_pending);
|
||||
wd_smp_last_reset_tb = get_tb();
|
||||
}
|
||||
smp_wmb();
|
||||
start_watchdog_timer_on(cpu);
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
static int stop_wd_on_cpu(unsigned int cpu)
|
||||
{
|
||||
if (!cpumask_test_cpu(cpu, &wd_cpus_enabled))
|
||||
return 0; /* Can happen in CPU unplug case */
|
||||
|
||||
stop_watchdog_timer_on(cpu);
|
||||
|
||||
cpumask_clear_cpu(cpu, &wd_cpus_enabled);
|
||||
wd_smp_clear_cpu_pending(cpu, get_tb());
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
static void watchdog_calc_timeouts(void)
|
||||
{
|
||||
wd_panic_timeout_tb = watchdog_thresh * ppc_tb_freq;
|
||||
|
||||
/* Have the SMP detector trigger a bit later */
|
||||
wd_smp_panic_timeout_tb = wd_panic_timeout_tb * 3 / 2;
|
||||
|
||||
/* 2/5 is the factor that the perf based detector uses */
|
||||
wd_timer_period_ms = watchdog_thresh * 1000 * 2 / 5;
|
||||
}
|
||||
|
||||
void watchdog_nmi_reconfigure(void)
|
||||
{
|
||||
int cpu;
|
||||
|
||||
watchdog_calc_timeouts();
|
||||
|
||||
for_each_cpu(cpu, &wd_cpus_enabled)
|
||||
stop_wd_on_cpu(cpu);
|
||||
|
||||
for_each_cpu_and(cpu, cpu_online_mask, &watchdog_cpumask)
|
||||
start_wd_on_cpu(cpu);
|
||||
}
|
||||
|
||||
/*
|
||||
* This runs after lockup_detector_init() which sets up watchdog_cpumask.
|
||||
*/
|
||||
static int __init powerpc_watchdog_init(void)
|
||||
{
|
||||
int err;
|
||||
|
||||
watchdog_calc_timeouts();
|
||||
|
||||
err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "powerpc/watchdog:online",
|
||||
start_wd_on_cpu, stop_wd_on_cpu);
|
||||
if (err < 0)
|
||||
pr_warn("Watchdog could not be initialized");
|
||||
|
||||
return 0;
|
||||
}
|
||||
arch_initcall(powerpc_watchdog_init);
|
||||
|
||||
static void handle_backtrace_ipi(struct pt_regs *regs)
|
||||
{
|
||||
nmi_cpu_backtrace(regs);
|
||||
}
|
||||
|
||||
static void raise_backtrace_ipi(cpumask_t *mask)
|
||||
{
|
||||
unsigned int cpu;
|
||||
|
||||
for_each_cpu(cpu, mask) {
|
||||
if (cpu == smp_processor_id())
|
||||
handle_backtrace_ipi(NULL);
|
||||
else
|
||||
smp_send_nmi_ipi(cpu, handle_backtrace_ipi, 1000000);
|
||||
}
|
||||
}
|
||||
|
||||
void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
|
||||
{
|
||||
nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace_ipi);
|
||||
}
|
||||
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