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

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>

1 files changed, 14 insertions, 0 deletions

diff --git a/arch/mips/cavium-octeon/setup.c b/arch/mips/cavium-octeon/setup.c
index cb16fcc5f8f0..5537f95b28c9 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();