1 files changed, 44 insertions, 29 deletions

diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index 2dfaadbdb2ac..45257475623c 100644
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -15,55 +15,61 @@
  * - bits 0-7 are the preemption count (max preemption depth: 256)
  * - bits 8-15 are the softirq count (max # of softirqs: 256)
  *
- * The hardirq count can be overridden per architecture, the default is:
+ * The hardirq count can in theory reach the same as NR_IRQS.
+ * In reality, the number of nested IRQS is limited to the stack
+ * size as well. For archs with over 1000 IRQS it is not practical
+ * to expect that they will all nest. We give a max of 10 bits for
+ * hardirq nesting. An arch may choose to give less than 10 bits.
+ * m68k expects it to be 8.
  *
- * - bits 16-27 are the hardirq count (max # of hardirqs: 4096)
- * - ( bit 28 is the PREEMPT_ACTIVE flag. )
+ * - bits 16-25 are the hardirq count (max # of nested hardirqs: 1024)
+ * - bit 26 is the NMI_MASK
+ * - bit 28 is the PREEMPT_ACTIVE flag
  *
  * PREEMPT_MASK: 0x000000ff
  * SOFTIRQ_MASK: 0x0000ff00
- * HARDIRQ_MASK: 0x0fff0000
+ * HARDIRQ_MASK: 0x03ff0000
+ *     NMI_MASK: 0x04000000
  */
 #define PREEMPT_BITS    8
 #define SOFTIRQ_BITS    8
+#define NMI_BITS        1
 
-#ifndef HARDIRQ_BITS
-#define HARDIRQ_BITS    12
+#define MAX_HARDIRQ_BITS 10
 
-#ifndef MAX_HARDIRQS_PER_CPU
-#define MAX_HARDIRQS_PER_CPU NR_IRQS
+#ifndef HARDIRQ_BITS
+# define HARDIRQ_BITS   MAX_HARDIRQ_BITS
 #endif
 
-/*
- * The hardirq mask has to be large enough to have space for potentially
- * all IRQ sources in the system nesting on a single CPU.
- */
-#if (1 << HARDIRQ_BITS) < MAX_HARDIRQS_PER_CPU
-# error HARDIRQ_BITS is too low!
-#endif
+#if HARDIRQ_BITS > MAX_HARDIRQ_BITS
+#error HARDIRQ_BITS too high!
 #endif
 
 #define PREEMPT_SHIFT   0
 #define SOFTIRQ_SHIFT   (PREEMPT_SHIFT + PREEMPT_BITS)
 #define HARDIRQ_SHIFT   (SOFTIRQ_SHIFT + SOFTIRQ_BITS)
+#define NMI_SHIFT       (HARDIRQ_SHIFT + HARDIRQ_BITS)
 
 #define __IRQ_MASK(x)   ((1UL << (x))-1)
 
 #define PREEMPT_MASK    (__IRQ_MASK(PREEMPT_BITS) << PREEMPT_SHIFT)
 #define SOFTIRQ_MASK    (__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
 #define HARDIRQ_MASK    (__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
+#define NMI_MASK        (__IRQ_MASK(NMI_BITS)     << NMI_SHIFT)
 
 #define PREEMPT_OFFSET  (1UL << PREEMPT_SHIFT)
 #define SOFTIRQ_OFFSET  (1UL << SOFTIRQ_SHIFT)
 #define HARDIRQ_OFFSET  (1UL << HARDIRQ_SHIFT)
+#define NMI_OFFSET      (1UL << NMI_SHIFT)
 
-#if PREEMPT_ACTIVE < (1 << (HARDIRQ_SHIFT + HARDIRQ_BITS))
+#if PREEMPT_ACTIVE < (1 << (NMI_SHIFT + NMI_BITS))
 #error PREEMPT_ACTIVE is too low!
 #endif
 
 #define hardirq_count() (preempt_count() & HARDIRQ_MASK)
 #define softirq_count() (preempt_count() & SOFTIRQ_MASK)
-#define irq_count()     (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK))
+#define irq_count()     (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \
+                                 | NMI_MASK))
 
 /*
  * Are we doing bottom half or hardware interrupt processing?
@@ -73,6 +79,11 @@
 #define in_softirq()            (softirq_count())
 #define in_interrupt()          (irq_count())
 
+/*
+ * Are we in NMI context?
+ */
+#define in_nmi()        (preempt_count() & NMI_MASK)
+
 #if defined(CONFIG_PREEMPT)
 # define PREEMPT_INATOMIC_BASE kernel_locked()
 # define PREEMPT_CHECK_OFFSET 1
@@ -164,20 +175,24 @@ extern void irq_enter(void);
  */
 extern void irq_exit(void);
 
-#define nmi_enter()                             \
-        do {                                    \
-                ftrace_nmi_enter();             \
-                lockdep_off();                  \
-                rcu_nmi_enter();                \
-                __irq_enter();                  \
+#define nmi_enter()                                             \
+        do {                                                    \
+                ftrace_nmi_enter();                             \
+                BUG_ON(in_nmi());                               \
+                add_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET); \
+                lockdep_off();                                  \
+                rcu_nmi_enter();                                \
+                trace_hardirq_enter();                          \
         } while (0)
 
-#define nmi_exit()                              \
-        do {                                    \
-                __irq_exit();                   \
-                rcu_nmi_exit();                 \
-                lockdep_on();                   \
-                ftrace_nmi_exit();              \
+#define nmi_exit()                                              \
+        do {                                                    \
+                trace_hardirq_exit();                           \
+                rcu_nmi_exit();                                 \
+                lockdep_on();                                   \
+                BUG_ON(!in_nmi());                              \
+                sub_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET); \
+                ftrace_nmi_exit();                              \
         } while (0)
 
 #endif /* LINUX_HARDIRQ_H */