hardirq.h revision 4ba8216cd90560bc402f52076f64d8546e8aefcb 
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)
127extern void synchronize_irq(unsigned int irq);
128#else
129# define synchronize_irq(irq)	barrier()
130#endif
131
132struct task_struct;
133
134#if !defined(CONFIG_VIRT_CPU_ACCOUNTING) && !defined(CONFIG_IRQ_TIME_ACCOUNTING)
135static inline void account_system_vtime(struct task_struct *tsk)
136{
137}
138#else
139extern 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)
144extern void rcu_enter_nohz(void);
145extern void rcu_exit_nohz(void);
146
147static inline void rcu_irq_enter(void)
148{
149	rcu_exit_nohz();
150}
151
152static inline void rcu_irq_exit(void)
153{
154	rcu_enter_nohz();
155}
156
157static inline void rcu_nmi_enter(void)
158{
159}
160
161static inline void rcu_nmi_exit(void)
162{
163}
164
165#else
166extern void rcu_irq_enter(void);
167extern void rcu_irq_exit(void);
168extern void rcu_nmi_enter(void);
169extern 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 */
194extern 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 */
209extern 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 */
232