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Message-ID: <20160812031755.GB2983@dhcp-128-65.nay.redhat.com>
Date: Fri, 12 Aug 2016 11:17:55 +0800
From: Dave Young <dyoung@...hat.com>
To: Hidehiro Kawai <hidehiro.kawai.ez@...achi.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
Baoquan He <bhe@...hat.com>,
Ralf Baechle <ralf@...ux-mips.org>,
Corey Minyard <cminyard@...sta.com>, x86@...nel.org,
David Daney <david.daney@...ium.com>,
Xunlei Pang <xpang@...hat.com>,
Aaro Koskinen <aaro.koskinen@....fi>,
kexec@...ts.infradead.org, linux-kernel@...r.kernel.org,
HATAYAMA Daisuke <d.hatayama@...fujitsu.com>,
linux-mips@...ux-mips.org, Masami Hiramatsu <mhiramat@...nel.org>,
"Steven J. Hill" <steven.hill@...ium.com>,
xen-devel@...ts.xenproject.org, Daniel Walker <dwalker@...o99.com>,
Vivek Goyal <vgoyal@...hat.com>
Subject: Re: [V4 PATCH 2/2] mips/panic: Replace smp_send_stop() with kdump
friendly version in panic path
On 08/10/16 at 05:09pm, Hidehiro Kawai wrote:
> Daniel Walker reported problems which happens when
> crash_kexec_post_notifiers kernel option is enabled
> (https://lkml.org/lkml/2015/6/24/44).
>
> In that case, smp_send_stop() is called before entering kdump routines
> which assume other CPUs are still online. As the result, kdump
> routines fail to save other CPUs' registers. Additionally for MIPS
> OCTEON, it misses to stop the watchdog timer.
>
> To fix this problem, call a new kdump friendly function,
> crash_smp_send_stop(), instead of the smp_send_stop() when
> crash_kexec_post_notifiers is enabled. crash_smp_send_stop() is a
> weak function, and it just call smp_send_stop(). Architecture
> codes should override it so that kdump can work appropriately.
> This patch provides MIPS version.
>
> Reported-by: Daniel Walker <dwalker@...o99.com>
> Fixes: f06e5153f4ae (kernel/panic.c: add "crash_kexec_post_notifiers" option)
> Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@...achi.com>
> Cc: Ralf Baechle <ralf@...ux-mips.org>
> Cc: David Daney <david.daney@...ium.com>
> Cc: Aaro Koskinen <aaro.koskinen@....fi>
> Cc: "Steven J. Hill" <steven.hill@...ium.com>
> Cc: Corey Minyard <cminyard@...sta.com>
>
> ---
> I'm not familiar with MIPS, and I don't have a test environment and
> just did build tests only. Please don't apply this patch until
> someone does enough tests, otherwise simply drop this patch.
> ---
> arch/mips/cavium-octeon/setup.c | 14 ++++++++++++++
> arch/mips/include/asm/kexec.h | 1 +
> arch/mips/kernel/crash.c | 18 +++++++++++++++++-
> arch/mips/kernel/machine_kexec.c | 1 +
> 4 files changed, 33 insertions(+), 1 deletion(-)
>
> diff --git a/arch/mips/cavium-octeon/setup.c b/arch/mips/cavium-octeon/setup.c
> index cb16fcc..5537f95 100644
> --- a/arch/mips/cavium-octeon/setup.c
> +++ b/arch/mips/cavium-octeon/setup.c
> @@ -267,6 +267,17 @@ static void octeon_crash_shutdown(struct pt_regs *regs)
> default_machine_crash_shutdown(regs);
> }
>
> +#ifdef CONFIG_SMP
> +void octeon_crash_smp_send_stop(void)
> +{
> + int cpu;
> +
> + /* disable watchdogs */
> + for_each_online_cpu(cpu)
> + cvmx_write_csr(CVMX_CIU_WDOGX(cpu_logical_map(cpu)), 0);
> +}
> +#endif
> +
> #endif /* CONFIG_KEXEC */
>
> #ifdef CONFIG_CAVIUM_RESERVE32
> @@ -911,6 +922,9 @@ void __init prom_init(void)
> _machine_kexec_shutdown = octeon_shutdown;
> _machine_crash_shutdown = octeon_crash_shutdown;
> _machine_kexec_prepare = octeon_kexec_prepare;
> +#ifdef CONFIG_SMP
> + _crash_smp_send_stop = octeon_crash_smp_send_stop;
> +#endif
> #endif
>
> octeon_user_io_init();
> diff --git a/arch/mips/include/asm/kexec.h b/arch/mips/include/asm/kexec.h
> index ee25ebb..493a3cc 100644
> --- a/arch/mips/include/asm/kexec.h
> +++ b/arch/mips/include/asm/kexec.h
> @@ -45,6 +45,7 @@ extern const unsigned char kexec_smp_wait[];
> extern unsigned long secondary_kexec_args[4];
> extern void (*relocated_kexec_smp_wait) (void *);
> extern atomic_t kexec_ready_to_reboot;
> +extern void (*_crash_smp_send_stop)(void);
> #endif
> #endif
>
> diff --git a/arch/mips/kernel/crash.c b/arch/mips/kernel/crash.c
> index 610f0f3..1723b17 100644
> --- a/arch/mips/kernel/crash.c
> +++ b/arch/mips/kernel/crash.c
> @@ -47,9 +47,14 @@ static void crash_shutdown_secondary(void *passed_regs)
>
> static void crash_kexec_prepare_cpus(void)
> {
> + static int cpus_stopped;
> unsigned int msecs;
> + unsigned int ncpus;
>
> - unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
> + if (cpus_stopped)
> + return;
> +
> + ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
>
> dump_send_ipi(crash_shutdown_secondary);
> smp_wmb();
> @@ -64,6 +69,17 @@ static void crash_kexec_prepare_cpus(void)
> cpu_relax();
> mdelay(1);
> }
> +
> + cpus_stopped = 1;
> +}
> +
> +/* Override the weak function in kernel/panic.c */
> +void crash_smp_send_stop(void)
> +{
> + if (_crash_smp_send_stop)
> + _crash_smp_send_stop();
> +
> + crash_kexec_prepare_cpus();
> }
>
> #else /* !defined(CONFIG_SMP) */
> diff --git a/arch/mips/kernel/machine_kexec.c b/arch/mips/kernel/machine_kexec.c
> index 50980bf3..5972520 100644
> --- a/arch/mips/kernel/machine_kexec.c
> +++ b/arch/mips/kernel/machine_kexec.c
> @@ -25,6 +25,7 @@ void (*_machine_crash_shutdown)(struct pt_regs *regs) = NULL;
> #ifdef CONFIG_SMP
> void (*relocated_kexec_smp_wait) (void *);
> atomic_t kexec_ready_to_reboot = ATOMIC_INIT(0);
> +void (*_crash_smp_send_stop)(void) = NULL;
> #endif
>
> int
>
>
Can any mips people review this patch and have a test?
Thanks
Dave
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