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authorHidehiro Kawai <hidehiro.kawai.ez@hitachi.com>2016-03-22 14:27:17 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-03-22 15:36:02 -0700
commitebc41f20d77f6ad91f1f2d2af5147dc9bb6b5eea (patch)
tree60550da4896b285024c4fa1467ddeb052413ddc5 /kernel
parenta484c3dd9426e1f450c7ed8ad5a2002ea1b309ea (diff)
panic: change nmi_panic from macro to function
Commit 1717f2096b54 ("panic, x86: Fix re-entrance problem due to panic on NMI") and commit 58c5661f2144 ("panic, x86: Allow CPUs to save registers even if looping in NMI context") introduced nmi_panic() which prevents concurrent/recursive execution of panic(). It also saves registers for the crash dump on x86. However, there are some cases where NMI handlers still use panic(). This patch set partially replaces them with nmi_panic() in those cases. Even this patchset is applied, some NMI or similar handlers (e.g. MCE handler) continue to use panic(). This is because I can't test them well and actual problems won't happen. For example, the possibility that normal panic and panic on MCE happen simultaneously is very low. This patch (of 3): Convert nmi_panic() to a proper function and export it instead of exporting internal implementation details to modules, for obvious reasons. Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Acked-by: Borislav Petkov <bp@suse.de> Acked-by: Michal Nazarewicz <mina86@mina86.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Nicolas Iooss <nicolas.iooss_linux@m4x.org> Cc: Javi Merino <javi.merino@arm.com> Cc: Gobinda Charan Maji <gobinda.cemk07@gmail.com> Cc: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/panic.c20
1 files changed, 20 insertions, 0 deletions
diff --git a/kernel/panic.c b/kernel/panic.c
index fa400852bf6c..535c96510a44 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -73,6 +73,26 @@ void __weak nmi_panic_self_stop(struct pt_regs *regs)
atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);
+/*
+ * A variant of panic() called from NMI context. We return if we've already
+ * panicked on this CPU. If another CPU already panicked, loop in
+ * nmi_panic_self_stop() which can provide architecture dependent code such
+ * as saving register state for crash dump.
+ */
+void nmi_panic(struct pt_regs *regs, const char *msg)
+{
+ int old_cpu, cpu;
+
+ cpu = raw_smp_processor_id();
+ old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu);
+
+ if (old_cpu == PANIC_CPU_INVALID)
+ panic("%s", msg);
+ else if (old_cpu != cpu)
+ nmi_panic_self_stop(regs);
+}
+EXPORT_SYMBOL(nmi_panic);
+
/**
* panic - halt the system
* @fmt: The text string to print