mips/panic: replace smp_send_stop() with kdump friendly version in panic path

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.hitachi.co.jp
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: Ben Hutchings <ben@decadent.org.uk>

diff --git a/arch/mips/cavium-octeon/setup.c b/arch/mips/cavium-octeon/setup.c
index c9d9c627e244fc9b4fc0b0a502d8ff0c11a68f34..0391557ce452982b119c6ba0b580165f9fd6e933 100644 (file)
--- a/arch/mips/cavium-octeon/setup.c
+++ b/arch/mips/cavium-octeon/setup.c
@@ -247,6 +247,17 @@ 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
@@ -827,6 +838,9 @@ 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 ee25ebbf2a28809c73f68311c24284c53fe87907..493a3cc7c39ad5a412d6d460061b740260dfff9c 100644 (file)
--- 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 d21264681e97d805b6a6ef1defffd8ccfb8fb08b..5b5275f8cc1f964c95d1b767e502ccb1b2b7c252 100644 (file)
--- a/arch/mips/kernel/crash.c
+++ b/arch/mips/kernel/crash.c
@@ -37,9 +37,14 @@ static void crash_shutdown_secondary(void *ignore)
 
 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();
@@ -54,6 +59,17 @@ 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 992e18474da5da89f1ff4b878dbbc8e8db47e919..4f9f22809e776853c7d10b6f2248aed207399e58 100644 (file)
--- 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