| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <b66b9b63-5fdb-951b-439e-79b547b33d6a@linux.alibaba.com>
Date: Thu, 18 Aug 2022 12:38:57 +0800
From: Xianting Tian <xianting.tian@...ux.alibaba.com>
To: guoren@...nel.org, palmer@...belt.com, heiko@...ech.de,
conor.dooley@...rochip.com
Cc: linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-riscv@...ts.infradead.org, liaochang1@...wei.com,
mick@....forth.gr, jszhang@...nel.org,
Guo Ren <guoren@...ux.alibaba.com>,
AKASHI Takahiro <takahiro.akashi@...aro.org>
Subject: Re: [PATCH V2 2/2] riscv: kexec: Fixup crash_smp_send_stop with
percpu crash_save_cpu
It is ok for me
Reviewed-by: Xianting Tian <xianting.tian@...ux.alibaba.com>
在 2022/8/18 上午12:12, guoren@...nel.org 写道:
> From: Guo Ren <guoren@...ux.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@...ux.alibaba.com>
> Signed-off-by: Guo Ren <guoren@...nel.org>
> Cc: AKASHI Takahiro <takahiro.akashi@...aro.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);
Powered by blists - more mailing lists