arch/tile: adopt the new nmi_backtrace framework

Previously tile was rolling its own method of capturing backtrace data
in the NMI handlers, but it was relying on running printk() from the NMI
handler, which is not always safe.  So adopt the nmi_backtrace model
(with the new cpumask extension) instead.

So we can call the nmi_backtrace code directly from the nmi handler,
move the nmi_enter()/exit() into the top-level tile NMI handler.

The semantics of the routine change slightly since it is now synchronous
with the remote cores completing the backtraces.  Previously it was
asynchronous, but with protection to avoid starting a new remote
backtrace if the old one was still in progress.

Link: http://lkml.kernel.org/r/1472487169-14923-4-git-send-email-cmetcalf@mellanox.com
Signed-off-by: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org> [arm]
Cc: Petr Mladek <pmladek@suse.com>
Cc: Aaron Tomlin <atomlin@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 2 deletions

diff --git a/arch/tile/kernel/traps.c b/arch/tile/kernel/traps.c
index 4d9651c5b1ad..39f427bb0de2 100644
--- a/arch/tile/kernel/traps.c
+++ b/arch/tile/kernel/traps.c
@@ -20,6 +20,8 @@
 #include <linux/reboot.h>
 #include <linux/uaccess.h>
 #include <linux/ptrace.h>
+#include <linux/hardirq.h>
+#include <linux/nmi.h>
 #include <asm/stack.h>
 #include <asm/traps.h>
 #include <asm/setup.h>
@@ -392,14 +394,17 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num,
 
 void do_nmi(struct pt_regs *regs, int fault_num, unsigned long reason)
 {
+        nmi_enter();
         switch (reason) {
+#ifdef arch_trigger_cpumask_backtrace
         case TILE_NMI_DUMP_STACK:
-                do_nmi_dump_stack(regs);
+                nmi_cpu_backtrace(regs);
                 break;
+#endif
         default:
                 panic("Unexpected do_nmi type %ld", reason);
-                return;
         }
+        nmi_exit();
 }
 
 /* Deprecated function currently only used here. */