include/linux/hardirq.h

   1 #ifndef LINUX_HARDIRQ_H
   2 #define LINUX_HARDIRQ_H
   3
   4 #include <linux/preempt.h>
   5 #ifdef CONFIG_PREEMPT
   6 #endif
   7 #include <linux/lockdep.h>
   8 #include <linux/ftrace_irq.h>
   9 #include <asm/hardirq.h>
  10
  11 /*
  12  * We put the hardirq and softirq counter into the preemption
  13  * counter. The bitmask has the following meaning:
  14  *
  15  * - bits 0-7 are the preemption count (max preemption depth: 256)
  16  * - bits 8-15 are the softirq count (max # of softirqs: 256)
  17  *
  18  * The hardirq count can in theory reach the same as NR_IRQS.
  19  * In reality, the number of nested IRQS is limited to the stack
  20  * size as well. For archs with over 1000 IRQS it is not practical
  21  * to expect that they will all nest. We give a max of 10 bits for
  22  * hardirq nesting. An arch may choose to give less than 10 bits.
  23  * m68k expects it to be 8.
  24  *
  25  * - bits 16-25 are the hardirq count (max # of nested hardirqs: 1024)
  26  * - bit 26 is the NMI_MASK
  27  * - bit 28 is the PREEMPT_ACTIVE flag
  28  *
  29  * PREEMPT_MASK: 0x000000ff
  30  * SOFTIRQ_MASK: 0x0000ff00
  31  * HARDIRQ_MASK: 0x03ff0000
  32  *     NMI_MASK: 0x04000000
  33  */
  34 #define PREEMPT_BITS    8
  35 #define SOFTIRQ_BITS    8
  36 #define NMI_BITS        1
  37
  38 #define MAX_HARDIRQ_BITS 10
  39
  40 #ifndef HARDIRQ_BITS
  41 # define HARDIRQ_BITS   MAX_HARDIRQ_BITS
  42 #endif
  43
  44 #if HARDIRQ_BITS > MAX_HARDIRQ_BITS
  45 #error HARDIRQ_BITS too high!
  46 #endif
  47
  48 #define PREEMPT_SHIFT   0
  49 #define SOFTIRQ_SHIFT   (PREEMPT_SHIFT + PREEMPT_BITS)
  50 #define HARDIRQ_SHIFT   (SOFTIRQ_SHIFT + SOFTIRQ_BITS)
  51 #define NMI_SHIFT       (HARDIRQ_SHIFT + HARDIRQ_BITS)
  52
  53 #define __IRQ_MASK(x)   ((1UL << (x))-1)
  54
  55 #define PREEMPT_MASK    (__IRQ_MASK(PREEMPT_BITS) << PREEMPT_SHIFT)
  56 #define SOFTIRQ_MASK    (__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
  57 #define HARDIRQ_MASK    (__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
  58 #define NMI_MASK        (__IRQ_MASK(NMI_BITS)     << NMI_SHIFT)
  59
  60 #define PREEMPT_OFFSET  (1UL << PREEMPT_SHIFT)
  61 #define SOFTIRQ_OFFSET  (1UL << SOFTIRQ_SHIFT)
  62 #define HARDIRQ_OFFSET  (1UL << HARDIRQ_SHIFT)
  63 #define NMI_OFFSET      (1UL << NMI_SHIFT)
  64
  65 #define SOFTIRQ_DISABLE_OFFSET  (2 * SOFTIRQ_OFFSET)
  66
  67 #ifndef PREEMPT_ACTIVE
  68 #define PREEMPT_ACTIVE_BITS     1
  69 #define PREEMPT_ACTIVE_SHIFT    (NMI_SHIFT + NMI_BITS)
  70 #define PREEMPT_ACTIVE  (__IRQ_MASK(PREEMPT_ACTIVE_BITS) << PREEMPT_ACTIVE_SHIFT)
  71 #endif
  72
  73 #if PREEMPT_ACTIVE < (1 << (NMI_SHIFT + NMI_BITS))
  74 #error PREEMPT_ACTIVE is too low!
  75 #endif
  76
  77 #define hardirq_count() (preempt_count() & HARDIRQ_MASK)
  78 #define softirq_count() (preempt_count() & SOFTIRQ_MASK)
  79 #define irq_count()     (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \
  80                                  | NMI_MASK))
  81
  82 /*
  83  * Are we doing bottom half or hardware interrupt processing?
  84  * Are we in a softirq context? Interrupt context?
  85  * in_softirq - Are we currently processing softirq or have bh disabled?
  86  * in_serving_softirq - Are we currently processing softirq?
  87  */
  88 #define in_irq()                (hardirq_count())
  89 #define in_softirq()            (softirq_count())
  90 #define in_interrupt()          (irq_count())
  91 #define in_serving_softirq()    (softirq_count() & SOFTIRQ_OFFSET)
  92
  93 /*
  94  * Are we in NMI context?
  95  */
  96 #define in_nmi()        (preempt_count() & NMI_MASK)
  97
  98 #if defined(CONFIG_PREEMPT) && defined(CONFIG_BKL)
  99 # define PREEMPT_INATOMIC_BASE kernel_locked()
 100 #else
 101 # define PREEMPT_INATOMIC_BASE 0
 102 #endif
 103
 104 #if defined(CONFIG_PREEMPT)
 105 # define PREEMPT_CHECK_OFFSET 1
 106 #else
 107 # define PREEMPT_CHECK_OFFSET 0
 108 #endif
 109
 110 /*
 111  * Are we running in atomic context?  WARNING: this macro cannot
 112  * always detect atomic context; in particular, it cannot know about
 113  * held spinlocks in non-preemptible kernels.  Thus it should not be
 114  * used in the general case to determine whether sleeping is possible.
 115  * Do not use in_atomic() in driver code.
 116  */
 117 #define in_atomic()     ((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_INATOMIC_BASE)
 118
 119 /*
 120  * Check whether we were atomic before we did preempt_disable():
 121  * (used by the scheduler, *after* releasing the kernel lock)
 122  */
 123 #define in_atomic_preempt_off() \
 124                 ((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_CHECK_OFFSET)
 125
 126 #ifdef CONFIG_PREEMPT
 127 # define preemptible()  (preempt_count() == 0 && !irqs_disabled())
 128 # define IRQ_EXIT_OFFSET (HARDIRQ_OFFSET-1)
 129 #else
 130 # define preemptible()  0
 131 # define IRQ_EXIT_OFFSET HARDIRQ_OFFSET
 132 #endif
 133
 134 #if defined(CONFIG_SMP) || defined(CONFIG_GENERIC_HARDIRQS)
 135 extern void synchronize_irq(unsigned int irq);
 136 #else
 137 # define synchronize_irq(irq)   barrier()
 138 #endif
 139
 140 struct task_struct;
 141
 142 #if !defined(CONFIG_VIRT_CPU_ACCOUNTING) && !defined(CONFIG_IRQ_TIME_ACCOUNTING)
 143 static inline void account_system_vtime(struct task_struct *tsk)
 144 {
 145 }
 146 #else
 147 extern void account_system_vtime(struct task_struct *tsk);
 148 #endif
 149
 150 #if defined(CONFIG_NO_HZ)
 151 #if defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU)
 152 extern void rcu_enter_nohz(void);
 153 extern void rcu_exit_nohz(void);
 154
 155 static inline void rcu_irq_enter(void)
 156 {
 157         rcu_exit_nohz();
 158 }
 159
 160 static inline void rcu_irq_exit(void)
 161 {
 162         rcu_enter_nohz();
 163 }
 164
 165 static inline void rcu_nmi_enter(void)
 166 {
 167 }
 168
 169 static inline void rcu_nmi_exit(void)
 170 {
 171 }
 172
 173 #else
 174 extern void rcu_irq_enter(void);
 175 extern void rcu_irq_exit(void);
 176 extern void rcu_nmi_enter(void);
 177 extern void rcu_nmi_exit(void);
 178 #endif
 179 #else
 180 # define rcu_irq_enter() do { } while (0)
 181 # define rcu_irq_exit() do { } while (0)
 182 # define rcu_nmi_enter() do { } while (0)
 183 # define rcu_nmi_exit() do { } while (0)
 184 #endif /* #if defined(CONFIG_NO_HZ) */
 185
 186 /*
 187  * It is safe to do non-atomic ops on ->hardirq_context,
 188  * because NMI handlers may not preempt and the ops are
 189  * always balanced, so the interrupted value of ->hardirq_context
 190  * will always be restored.
 191  */
 192 #define __irq_enter()                                   \
 193         do {                                            \
 194                 account_system_vtime(current);          \
 195                 add_preempt_count(HARDIRQ_OFFSET);      \
 196                 trace_hardirq_enter();                  \
 197         } while (0)
 198
 199 /*
 200  * Enter irq context (on NO_HZ, update jiffies):
 201  */
 202 extern void irq_enter(void);
 203
 204 /*
 205  * Exit irq context without processing softirqs:
 206  */
 207 #define __irq_exit()                                    \
 208         do {                                            \
 209                 trace_hardirq_exit();                   \
 210                 account_system_vtime(current);          \
 211                 sub_preempt_count(HARDIRQ_OFFSET);      \
 212         } while (0)
 213
 214 /*
 215  * Exit irq context and process softirqs if needed:
 216  */
 217 extern void irq_exit(void);
 218
 219 #define nmi_enter()                                             \
 220         do {                                                    \
 221                 ftrace_nmi_enter();                             \
 222                 BUG_ON(in_nmi());                               \
 223                 add_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET); \
 224                 lockdep_off();                                  \
 225                 rcu_nmi_enter();                                \
 226                 trace_hardirq_enter();                          \
 227         } while (0)
 228
 229 #define nmi_exit()                                              \
 230         do {                                                    \
 231                 trace_hardirq_exit();                           \
 232                 rcu_nmi_exit();                                 \
 233                 lockdep_on();                                   \
 234                 BUG_ON(!in_nmi());                              \
 235                 sub_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET); \
 236                 ftrace_nmi_exit();                              \
 237         } while (0)
 238
 239 #endif /* LINUX_HARDIRQ_H */