sparc64: Run NMIs on the hardirq stack.

Otherwise we can overflow the main stack with the function tracer
enabled.
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/kernel/irq_64.c

@@ -47,6 +47,7 @@
 
 #include "entry.h"
 #include "cpumap.h"
+#include "kstack.h"
 
 #define NUM_IVECS	(IMAP_INR + 1)
 
@@ -713,24 +714,6 @@ void ack_bad_irq(unsigned int virt_irq)
 void *hardirq_stack[NR_CPUS];
 void *softirq_stack[NR_CPUS];
 
-static __attribute__((always_inline)) void *set_hardirq_stack(void)
-{
-	void *orig_sp, *sp = hardirq_stack[smp_processor_id()];
-
-	__asm__ __volatile__("mov %%sp, %0" : "=r" (orig_sp));
-	if (orig_sp < sp ||
-	    orig_sp > (sp + THREAD_SIZE)) {
-		sp += THREAD_SIZE - 192 - STACK_BIAS;
-		__asm__ __volatile__("mov %0, %%sp" : : "r" (sp));
-	}
-
-	return orig_sp;
-}
-static __attribute__((always_inline)) void restore_hardirq_stack(void *orig_sp)
-{
-	__asm__ __volatile__("mov %0, %%sp" : : "r" (orig_sp));
-}
-
 void __irq_entry handler_irq(int irq, struct pt_regs *regs)
 {
 	unsigned long pstate, bucket_pa;

arch/sparc/kernel/kstack.h

@@ -61,4 +61,23 @@ static inline bool kstack_is_trap_frame(struct thread_info *tp, struct pt_regs *
 
 }
 
+static inline __attribute__((always_inline)) void *set_hardirq_stack(void)
+{
+	void *orig_sp, *sp = hardirq_stack[smp_processor_id()];
+
+	__asm__ __volatile__("mov %%sp, %0" : "=r" (orig_sp));
+	if (orig_sp < sp ||
+	    orig_sp > (sp + THREAD_SIZE)) {
+		sp += THREAD_SIZE - 192 - STACK_BIAS;
+		__asm__ __volatile__("mov %0, %%sp" : : "r" (sp));
+	}
+
+	return orig_sp;
+}
+
+static inline __attribute__((always_inline)) void restore_hardirq_stack(void *orig_sp)
+{
+	__asm__ __volatile__("mov %0, %%sp" : : "r" (orig_sp));
+}
+
 #endif /* _KSTACK_H */

arch/sparc/kernel/nmi.c

@@ -23,6 +23,8 @@
 #include <asm/ptrace.h>
 #include <asm/pcr.h>
 
+#include "kstack.h"
+
 /* We don't have a real NMI on sparc64, but we can fake one
  * up using profiling counter overflow interrupts and interrupt
  * levels.
@@ -92,6 +94,7 @@ static void die_nmi(const char *str, struct pt_regs *regs, int do_panic)
 notrace __kprobes void perfctr_irq(int irq, struct pt_regs *regs)
 {
 	unsigned int sum, touched = 0;
+	void *orig_sp;
 
 	clear_softint(1 << irq);
 
@@ -99,6 +102,8 @@ notrace __kprobes void perfctr_irq(int irq, struct pt_regs *regs)
 
 	nmi_enter();
 
+	orig_sp = set_hardirq_stack();
+
 	if (notify_die(DIE_NMI, "nmi", regs, 0,
 		       pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
 		touched = 1;
@@ -124,6 +129,8 @@ notrace __kprobes void perfctr_irq(int irq, struct pt_regs *regs)
 		pcr_ops->write(pcr_enable);
 	}
 
+	restore_hardirq_stack(orig_sp);
+
 	nmi_exit();
 }