Messages in this thread | | | Date | Thu, 18 Aug 2022 12:38:57 +0800 | Subject | Re: [PATCH V2 2/2] riscv: kexec: Fixup crash_smp_send_stop with percpu crash_save_cpu | From | Xianting Tian <> |
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It is ok for me
Reviewed-by: Xianting Tian <xianting.tian@linux.alibaba.com>
在 2022/8/18 上午12:12, guoren@kernel.org 写道: > From: Guo Ren <guoren@linux.alibaba.com> > > Current crash_smp_send_stop is the same as the generic one in > kernel/panic and misses crash_save_cpu in percpu. This patch is inspired > by 78fd584cdec0 ("arm64: kdump: implement machine_crash_shutdown()") > and adds the same mechanism for riscv. > > Fixes: ad943893d5f1 ("RISC-V: Fixup schedule out issue in machine_crash_shutdown()") > Signed-off-by: Guo Ren <guoren@linux.alibaba.com> > Signed-off-by: Guo Ren <guoren@kernel.org> > Cc: AKASHI Takahiro <takahiro.akashi@linaro.org> > --- > arch/riscv/include/asm/smp.h | 6 +++ > arch/riscv/kernel/machine_kexec.c | 19 ++----- > arch/riscv/kernel/smp.c | 89 ++++++++++++++++++++++++++++++- > 3 files changed, 96 insertions(+), 18 deletions(-) > > diff --git a/arch/riscv/include/asm/smp.h b/arch/riscv/include/asm/smp.h > index d3443be7eedc..8b40e15bea36 100644 > --- a/arch/riscv/include/asm/smp.h > +++ b/arch/riscv/include/asm/smp.h > @@ -50,6 +50,12 @@ void riscv_set_ipi_ops(const struct riscv_ipi_ops *ops); > /* Clear IPI for current CPU */ > void riscv_clear_ipi(void); > > +/* stop and save status for other CPUs */ > +void crash_smp_send_stop(void); > + > +/* Check other CPUs stop or not */ > +bool smp_crash_stop_failed(void); > + > /* Secondary hart entry */ > asmlinkage void smp_callin(void); > > diff --git a/arch/riscv/kernel/machine_kexec.c b/arch/riscv/kernel/machine_kexec.c > index db41c676e5a2..34c86d337448 100644 > --- a/arch/riscv/kernel/machine_kexec.c > +++ b/arch/riscv/kernel/machine_kexec.c > @@ -140,22 +140,6 @@ void machine_shutdown(void) > #endif > } > > -/* Override the weak function in kernel/panic.c */ > -void crash_smp_send_stop(void) > -{ > - static int cpus_stopped; > - > - /* > - * This function can be called twice in panic path, but obviously > - * we execute this only once. > - */ > - if (cpus_stopped) > - return; > - > - smp_send_stop(); > - cpus_stopped = 1; > -} > - > static void machine_kexec_mask_interrupts(void) > { > unsigned int i; > @@ -230,6 +214,9 @@ machine_kexec(struct kimage *image) > void *control_code_buffer = page_address(image->control_code_page); > riscv_kexec_method kexec_method = NULL; > > + WARN(smp_crash_stop_failed(), > + "Some CPUs may be stale, kdump will be unreliable.\n"); > + > if (image->type != KEXEC_TYPE_CRASH) > kexec_method = control_code_buffer; > else > diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c > index 760a64518c58..a75ad9c373cd 100644 > --- a/arch/riscv/kernel/smp.c > +++ b/arch/riscv/kernel/smp.c > @@ -12,6 +12,7 @@ > #include <linux/clockchips.h> > #include <linux/interrupt.h> > #include <linux/module.h> > +#include <linux/kexec.h> > #include <linux/profile.h> > #include <linux/smp.h> > #include <linux/sched.h> > @@ -27,6 +28,7 @@ enum ipi_message_type { > IPI_RESCHEDULE, > IPI_CALL_FUNC, > IPI_CPU_STOP, > + IPI_CPU_CRASH_STOP, > IPI_IRQ_WORK, > IPI_TIMER, > IPI_MAX > @@ -71,6 +73,22 @@ static void ipi_stop(void) > wait_for_interrupt(); > } > > +#ifdef CONFIG_KEXEC_CORE > +static atomic_t waiting_for_crash_ipi = ATOMIC_INIT(0); > + > +static void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs) > +{ > + crash_save_cpu(regs, cpu); > + > + atomic_dec(&waiting_for_crash_ipi); > + > + local_irq_disable(); > + > + while(1) > + wait_for_interrupt(); > +} > +#endif > + > static const struct riscv_ipi_ops *ipi_ops __ro_after_init; > > void riscv_set_ipi_ops(const struct riscv_ipi_ops *ops) > @@ -124,8 +142,9 @@ void arch_irq_work_raise(void) > > void handle_IPI(struct pt_regs *regs) > { > - unsigned long *pending_ipis = &ipi_data[smp_processor_id()].bits; > - unsigned long *stats = ipi_data[smp_processor_id()].stats; > + unsigned int cpu = smp_processor_id(); > + unsigned long *pending_ipis = &ipi_data[cpu].bits; > + unsigned long *stats = ipi_data[cpu].stats; > > riscv_clear_ipi(); > > @@ -154,6 +173,13 @@ void handle_IPI(struct pt_regs *regs) > ipi_stop(); > } > > + if (ops & (1 << IPI_CPU_CRASH_STOP)) { > +#ifdef CONFIG_KEXEC_CORE > + ipi_cpu_crash_stop(cpu, get_irq_regs()); > +#endif > + unreachable(); > + } > + > if (ops & (1 << IPI_IRQ_WORK)) { > stats[IPI_IRQ_WORK]++; > irq_work_run(); > @@ -176,6 +202,7 @@ static const char * const ipi_names[] = { > [IPI_RESCHEDULE] = "Rescheduling interrupts", > [IPI_CALL_FUNC] = "Function call interrupts", > [IPI_CPU_STOP] = "CPU stop interrupts", > + [IPI_CPU_CRASH_STOP] = "CPU stop (for crash dump) interrupts", > [IPI_IRQ_WORK] = "IRQ work interrupts", > [IPI_TIMER] = "Timer broadcast interrupts", > }; > @@ -235,6 +262,64 @@ void smp_send_stop(void) > cpumask_pr_args(cpu_online_mask)); > } > > +#ifdef CONFIG_KEXEC_CORE > +/* > + * The number of CPUs online, not counting this CPU (which may not be > + * fully online and so not counted in num_online_cpus()). > + */ > +static inline unsigned int num_other_online_cpus(void) > +{ > + unsigned int this_cpu_online = cpu_online(smp_processor_id()); > + > + return num_online_cpus() - this_cpu_online; > +} > + > +void crash_smp_send_stop(void) > +{ > + static int cpus_stopped; > + cpumask_t mask; > + unsigned long timeout; > + > + /* > + * This function can be called twice in panic path, but obviously > + * we execute this only once. > + */ > + if (cpus_stopped) > + return; > + > + cpus_stopped = 1; > + > + /* > + * If this cpu is the only one alive at this point in time, online or > + * not, there are no stop messages to be sent around, so just back out. > + */ > + if (num_other_online_cpus() == 0) > + return; > + > + cpumask_copy(&mask, cpu_online_mask); > + cpumask_clear_cpu(smp_processor_id(), &mask); > + > + atomic_set(&waiting_for_crash_ipi, num_other_online_cpus()); > + > + pr_crit("SMP: stopping secondary CPUs\n"); > + send_ipi_mask(&mask, IPI_CPU_CRASH_STOP); > + > + /* Wait up to one second for other CPUs to stop */ > + timeout = USEC_PER_SEC; > + while ((atomic_read(&waiting_for_crash_ipi) > 0) && timeout--) > + udelay(1); > + > + if (atomic_read(&waiting_for_crash_ipi) > 0) > + pr_warn("SMP: failed to stop secondary CPUs %*pbl\n", > + cpumask_pr_args(&mask)); > +} > + > +bool smp_crash_stop_failed(void) > +{ > + return (atomic_read(&waiting_for_crash_ipi) > 0); > +} > +#endif > + > void smp_send_reschedule(int cpu) > { > send_ipi_single(cpu, IPI_RESCHEDULE);
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