From: Hidehiro Kawai hidehiro.kawai.ez@hitachi.com
commit 54c721b857fd45f3ad3bda695ee4f472518db02a upstream.
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.
Fixes: f06e5153f4ae (kernel/panic.c: add "crash_kexec_post_notifiers" option) Link: http://lkml.kernel.org/r/20160810080950.11028.28000.stgit@sysi4-13.yrl.intra... Signed-off-by: Hidehiro Kawai hidehiro.kawai.ez@hitachi.com Reported-by: Daniel Walker dwalker@fifo99.com Cc: Dave Young dyoung@redhat.com Cc: Baoquan He bhe@redhat.com Cc: Vivek Goyal vgoyal@redhat.com Cc: Eric Biederman ebiederm@xmission.com Cc: Masami Hiramatsu mhiramat@kernel.org Cc: Daniel Walker dwalker@fifo99.com Cc: Xunlei Pang xpang@redhat.com Cc: Thomas Gleixner tglx@linutronix.de Cc: Ingo Molnar mingo@redhat.com Cc: "H. Peter Anvin" hpa@zytor.com Cc: Borislav Petkov bp@suse.de Cc: David Vrabel david.vrabel@citrix.com Cc: Toshi Kani toshi.kani@hpe.com Cc: Ralf Baechle ralf@linux-mips.org Cc: David Daney david.daney@cavium.com Cc: Aaro Koskinen aaro.koskinen@iki.fi Cc: "Steven J. Hill" steven.hill@cavium.com Cc: Corey Minyard cminyard@mvista.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- 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(-)
--- a/arch/mips/cavium-octeon/setup.c +++ b/arch/mips/cavium-octeon/setup.c @@ -251,6 +251,17 @@ static void octeon_crash_shutdown(struct 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 @@ -864,6 +875,9 @@ 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(); --- a/arch/mips/include/asm/kexec.h +++ b/arch/mips/include/asm/kexec.h @@ -45,6 +45,7 @@ extern const unsigned char kexec_smp_wai 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
--- a/arch/mips/kernel/crash.c +++ b/arch/mips/kernel/crash.c @@ -50,9 +50,14 @@ static void crash_shutdown_secondary(voi
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(); @@ -67,6 +72,17 @@ static void crash_kexec_prepare_cpus(voi 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) */ --- a/arch/mips/kernel/machine_kexec.c +++ b/arch/mips/kernel/machine_kexec.c @@ -25,6 +25,7 @@ void (*_machine_crash_shutdown)(struct p #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