Merge branch 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 apic updates from Ingo Molnar:
 "The main changes in this cycle were:

   - introduce optimized single IPI sending methods on modern APICs
     (Linus Torvalds, Thomas Gleixner)

   - kexec/crash APIC handling fixes and enhancements (Hidehiro Kawai)

   - extend lapic vector saving/restoring to the CMCI (MCE) vector as
     well (Juergen Gross)

   - various fixes and enhancements (Jake Oshins, Len Brown)"

* 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits)
  x86/irq: Export functions to allow MSI domains in modules
  Documentation: Document kernel.panic_on_io_nmi sysctl
  x86/nmi: Save regs in crash dump on external NMI
  x86/apic: Introduce apic_extnmi command line parameter
  kexec: Fix race between panic() and crash_kexec()
  panic, x86: Allow CPUs to save registers even if looping in NMI context
  panic, x86: Fix re-entrance problem due to panic on NMI
  x86/apic: Fix the saving and restoring of lapic vectors during suspend/resume
  x86/smpboot: Re-enable init_udelay=0 by default on modern CPUs
  x86/smp: Remove single IPI wrapper
  x86/apic: Use default send single IPI wrapper
  x86/apic: Provide default send single IPI wrapper
  x86/apic: Implement single IPI for apic_noop
  x86/apic: Wire up single IPI for apic_numachip
  x86/apic: Wire up single IPI for x2apic_uv
  x86/apic: Implement single IPI for x2apic_phys
  x86/apic: Wire up single IPI for bigsmp_apic
  x86/apic: Remove pointless indirections from bigsmp_apic
  x86/apic: Wire up single IPI for apic_physflat
  x86/apic: Remove pointless indirections from apic_physflat
  ...

2 files changed, 30 insertions, 0 deletions

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 350dfb08aee3..7311c3294e25 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -255,6 +255,7 @@ extern long (*panic_blink)(int state);
 __printf(1, 2)
 void panic(const char *fmt, ...)
 	__noreturn __cold;
+void nmi_panic_self_stop(struct pt_regs *);
 extern void oops_enter(void);
 extern void oops_exit(void);
 void print_oops_end_marker(void);
@@ -446,6 +447,33 @@ extern int sysctl_panic_on_stackoverflow;
 extern bool crash_kexec_post_notifiers;
 
 /*
+ * panic_cpu is used for synchronizing panic() and crash_kexec() execution. It
+ * holds a CPU number which is executing panic() currently. A value of
+ * PANIC_CPU_INVALID means no CPU has entered panic() or crash_kexec().
+ */
+extern atomic_t panic_cpu;
+#define PANIC_CPU_INVALID	-1
+
+/*
+ * 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.
+ */
+#define nmi_panic(regs, fmt, ...)					\
+do {									\
+	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(fmt, ##__VA_ARGS__);				\
+	else if (old_cpu != cpu)					\
+		nmi_panic_self_stop(regs);				\
+} while (0)
+
+/*
  * Only to be used by arch init code. If the user over-wrote the default
  * CONFIG_PANIC_TIMEOUT, honor it.
  */
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index d140b1e9faa7..7b68d2788a56 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -237,6 +237,7 @@ extern int kexec_purgatory_get_set_symbol(struct kimage *image,
 					  unsigned int size, bool get_value);
 extern void *kexec_purgatory_get_symbol_addr(struct kimage *image,
 					     const char *name);
+extern void __crash_kexec(struct pt_regs *);
 extern void crash_kexec(struct pt_regs *);
 int kexec_should_crash(struct task_struct *);
 void crash_save_cpu(struct pt_regs *regs, int cpu);
@@ -332,6 +333,7 @@ int __weak arch_kexec_apply_relocations(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
 #else /* !CONFIG_KEXEC_CORE */
 struct pt_regs;
 struct task_struct;
+static inline void __crash_kexec(struct pt_regs *regs) { }
 static inline void crash_kexec(struct pt_regs *regs) { }
 static inline int kexec_should_crash(struct task_struct *p) { return 0; }
 #define kexec_in_progress false