include/linux/hardirq.h

   1 #ifndef LINUX_HARDIRQ_H
   2 #define LINUX_HARDIRQ_H
   3
   4 #include <linux/preempt.h>
   5 #include <linux/lockdep.h>
   6 #include <linux/ftrace_irq.h>
   7 #include <asm/hardirq.h>
   8
   9 /*
  10  * We put the hardirq and softirq counter into the preemption
  11  * counter. The bitmask has the following meaning:
  12  *
  13  * - bits 0-7 are the preemption count (max preemption depth: 256)
  14  * - bits 8-15 are the softirq count (max # of softirqs: 256)
  15  *
  16  * The hardirq count can in theory reach the same as NR_IRQS.
  17  * In reality, the number of nested IRQS is limited to the stack
  18  * size as well. For archs with over 1000 IRQS it is not practical
  19  * to expect that they will all nest. We give a max of 10 bits for
  20  * hardirq nesting. An arch may choose to give less than 10 bits.
  21  * m68k expects it to be 8.
  22  *
  23  * - bits 16-25 are the hardirq count (max # of nested hardirqs: 1024)
  24  * - bit 26 is the NMI_MASK
  25  * - bit 28 is the PREEMPT_ACTIVE flag
  26  *
  27  * PREEMPT_MASK: 0x000000ff
  28  * SOFTIRQ_MASK: 0x0000ff00
  29  * HARDIRQ_MASK: 0x03ff0000
  30  *     NMI_MASK: 0x04000000
  31  */
  32 #define PREEMPT_BITS    8
  33 #define SOFTIRQ_BITS    8
  34 #define NMI_BITS        1
  35
  36 #define MAX_HARDIRQ_BITS 10
  37
  38 #ifndef HARDIRQ_BITS
  39 # define HARDIRQ_BITS   MAX_HARDIRQ_BITS
  40 #endif
  41
  42 #if HARDIRQ_BITS > MAX_HARDIRQ_BITS
  43 #error HARDIRQ_BITS too high!
  44 #endif
  45
  46 #define PREEMPT_SHIFT   0
  47 #define SOFTIRQ_SHIFT   (PREEMPT_SHIFT + PREEMPT_BITS)
  48 #define HARDIRQ_SHIFT   (SOFTIRQ_SHIFT + SOFTIRQ_BITS)
  49 #define NMI_SHIFT       (HARDIRQ_SHIFT + HARDIRQ_BITS)
  50
  51 #define __IRQ_MASK(x)   ((1UL << (x))-1)
  52
  53 #define PREEMPT_MASK    (__IRQ_MASK(PREEMPT_BITS) << PREEMPT_SHIFT)
  54 #define SOFTIRQ_MASK    (__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
  55 #define HARDIRQ_MASK    (__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
  56 #define NMI_MASK        (__IRQ_MASK(NMI_BITS)     << NMI_SHIFT)
  57
  58 #define PREEMPT_OFFSET  (1UL << PREEMPT_SHIFT)
  59 #define SOFTIRQ_OFFSET  (1UL << SOFTIRQ_SHIFT)
  60 #define HARDIRQ_OFFSET  (1UL << HARDIRQ_SHIFT)
  61 #define NMI_OFFSET      (1UL << NMI_SHIFT)
  62
  63 #define SOFTIRQ_DISABLE_OFFSET  (2 * SOFTIRQ_OFFSET)
  64
  65 #ifndef PREEMPT_ACTIVE
  66 #define PREEMPT_ACTIVE_BITS     1
  67 #define PREEMPT_ACTIVE_SHIFT    (NMI_SHIFT + NMI_BITS)
  68 #define PREEMPT_ACTIVE  (__IRQ_MASK(PREEMPT_ACTIVE_BITS) << PREEMPT_ACTIVE_SHIFT)
  69 #endif
  70
  71 #if PREEMPT_ACTIVE < (1 << (NMI_SHIFT + NMI_BITS))
  72 #error PREEMPT_ACTIVE is too low!
  73 #endif
  74
  75 #define hardirq_count() (preempt_count() & HARDIRQ_MASK)
  76 #define softirq_count() (preempt_count() & SOFTIRQ_MASK)
  77 #define irq_count()     (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \
  78                                  | NMI_MASK))
  79
  80 /*
  81  * Are we doing bottom half or hardware interrupt processing?
  82  * Are we in a softirq context? Interrupt context?
  83  * in_softirq - Are we currently processing softirq or have bh disabled?
  84  * in_serving_softirq - Are we currently processing softirq?
  85  */
  86 #define in_irq()                (hardirq_count())
  87 #define in_softirq()            (softirq_count())
  88 #define in_interrupt()          (irq_count())
  89 #define in_serving_softirq()    (softirq_count() & SOFTIRQ_OFFSET)
  90
  91 /*
  92  * Are we in NMI context?
  93  */
  94 #define in_nmi()        (preempt_count() & NMI_MASK)
  95
  96 #if defined(CONFIG_PREEMPT)
  97 # define PREEMPT_CHECK_OFFSET 1
  98 #else
  99 # define PREEMPT_CHECK_OFFSET 0
 100 #endif
 101
 102 /*
 103  * Are we running in atomic context?  WARNING: this macro cannot
 104  * always detect atomic context; in particular, it cannot know about
 105  * held spinlocks in non-preemptible kernels.  Thus it should not be
 106  * used in the general case to determine whether sleeping is possible.
 107  * Do not use in_atomic() in driver code.
 108  */
 109 #define in_atomic()     ((preempt_count() & ~PREEMPT_ACTIVE) != 0)
 110
 111 /*
 112  * Check whether we were atomic before we did preempt_disable():
 113  * (used by the scheduler, *after* releasing the kernel lock)
 114  */
 115 #define in_atomic_preempt_off() \
 116                 ((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_CHECK_OFFSET)
 117
 118 #ifdef CONFIG_PREEMPT
 119 # define preemptible()  (preempt_count() == 0 && !irqs_disabled())
 120 # define IRQ_EXIT_OFFSET (HARDIRQ_OFFSET-1)
 121 #else
 122 # define preemptible()  0
 123 # define IRQ_EXIT_OFFSET HARDIRQ_OFFSET
 124 #endif
 125
 126 #if defined(CONFIG_SMP) || defined(CONFIG_GENERIC_HARDIRQS)
 127 extern void synchronize_irq(unsigned int irq);
 128 #else
 129 # define synchronize_irq(irq)   barrier()
 130 #endif
 131
 132 struct task_struct;
 133
 134 #if !defined(CONFIG_VIRT_CPU_ACCOUNTING) && !defined(CONFIG_IRQ_TIME_ACCOUNTING)
 135 static inline void account_system_vtime(struct task_struct *tsk)
 136 {
 137 }
 138 #else
 139 extern void account_system_vtime(struct task_struct *tsk);
 140 #endif
 141
 142 #if defined(CONFIG_NO_HZ)
 143 #if defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU)
 144 extern void rcu_enter_nohz(void);
 145 extern void rcu_exit_nohz(void);
 146
 147 static inline void rcu_irq_enter(void)
 148 {
 149         rcu_exit_nohz();
 150 }
 151
 152 static inline void rcu_irq_exit(void)
 153 {
 154         rcu_enter_nohz();
 155 }
 156
 157 static inline void rcu_nmi_enter(void)
 158 {
 159 }
 160
 161 static inline void rcu_nmi_exit(void)
 162 {
 163 }
 164
 165 #else
 166 extern void rcu_irq_enter(void);
 167 extern void rcu_irq_exit(void);
 168 extern void rcu_nmi_enter(void);
 169 extern void rcu_nmi_exit(void);
 170 #endif
 171 #else
 172 # define rcu_irq_enter() do { } while (0)
 173 # define rcu_irq_exit() do { } while (0)
 174 # define rcu_nmi_enter() do { } while (0)
 175 # define rcu_nmi_exit() do { } while (0)
 176 #endif /* #if defined(CONFIG_NO_HZ) */
 177
 178 /*
 179  * It is safe to do non-atomic ops on ->hardirq_context,
 180  * because NMI handlers may not preempt and the ops are
 181  * always balanced, so the interrupted value of ->hardirq_context
 182  * will always be restored.
 183  */
 184 #define __irq_enter()                                   \
 185         do {                                            \
 186                 account_system_vtime(current);          \
 187                 add_preempt_count(HARDIRQ_OFFSET);      \
 188                 trace_hardirq_enter();                  \
 189         } while (0)
 190
 191 /*
 192  * Enter irq context (on NO_HZ, update jiffies):
 193  */
 194 extern void irq_enter(void);
 195
 196 /*
 197  * Exit irq context without processing softirqs:
 198  */
 199 #define __irq_exit()                                    \
 200         do {                                            \
 201                 trace_hardirq_exit();                   \
 202                 account_system_vtime(current);          \
 203                 sub_preempt_count(HARDIRQ_OFFSET);      \
 204         } while (0)
 205
 206 /*
 207  * Exit irq context and process softirqs if needed:
 208  */
 209 extern void irq_exit(void);
 210
 211 #define nmi_enter()                                             \
 212         do {                                                    \
 213                 ftrace_nmi_enter();                             \
 214                 BUG_ON(in_nmi());                               \
 215                 add_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET); \
 216                 lockdep_off();                                  \
 217                 rcu_nmi_enter();                                \
 218                 trace_hardirq_enter();                          \
 219         } while (0)
 220
 221 #define nmi_exit()                                              \
 222         do {                                                    \
 223                 trace_hardirq_exit();                           \
 224                 rcu_nmi_exit();                                 \
 225                 lockdep_on();                                   \
 226                 BUG_ON(!in_nmi());                              \
 227                 sub_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET); \
 228                 ftrace_nmi_exit();                              \
 229         } while (0)
 230
 231 #endif /* LINUX_HARDIRQ_H */