hardirq.h revision bcdb714c8856c76383ca455294f0074168705eab 
1#ifndef LINUX_HARDIRQ_H
2#define LINUX_HARDIRQ_H
3
4#include <linux/preempt.h>
5#ifdef CONFIG_PREEMPT
6#include <linux/smp_lock.h>
7#endif
8#include <linux/lockdep.h>
9#include <linux/ftrace_irq.h>
10#include <asm/hardirq.h>
11
12/*
13 * We put the hardirq and softirq counter into the preemption
14 * counter. The bitmask has the following meaning:
15 *
16 * - bits 0-7 are the preemption count (max preemption depth: 256)
17 * - bits 8-15 are the softirq count (max # of softirqs: 256)
18 *
19 * The hardirq count can in theory reach the same as NR_IRQS.
20 * In reality, the number of nested IRQS is limited to the stack
21 * size as well. For archs with over 1000 IRQS it is not practical
22 * to expect that they will all nest. We give a max of 10 bits for
23 * hardirq nesting. An arch may choose to give less than 10 bits.
24 * m68k expects it to be 8.
25 *
26 * - bits 16-25 are the hardirq count (max # of nested hardirqs: 1024)
27 * - bit 26 is the NMI_MASK
28 * - bit 28 is the PREEMPT_ACTIVE flag
29 *
30 * PREEMPT_MASK: 0x000000ff
31 * SOFTIRQ_MASK: 0x0000ff00
32 * HARDIRQ_MASK: 0x03ff0000
33 *     NMI_MASK: 0x04000000
34 */
35#define PREEMPT_BITS	8
36#define SOFTIRQ_BITS	8
37#define NMI_BITS	1
38
39#define MAX_HARDIRQ_BITS 10
40
41#ifndef HARDIRQ_BITS
42# define HARDIRQ_BITS	MAX_HARDIRQ_BITS
43#endif
44
45#if HARDIRQ_BITS > MAX_HARDIRQ_BITS
46#error HARDIRQ_BITS too high!
47#endif
48
49#define PREEMPT_SHIFT	0
50#define SOFTIRQ_SHIFT	(PREEMPT_SHIFT + PREEMPT_BITS)
51#define HARDIRQ_SHIFT	(SOFTIRQ_SHIFT + SOFTIRQ_BITS)
52#define NMI_SHIFT	(HARDIRQ_SHIFT + HARDIRQ_BITS)
53
54#define __IRQ_MASK(x)	((1UL << (x))-1)
55
56#define PREEMPT_MASK	(__IRQ_MASK(PREEMPT_BITS) << PREEMPT_SHIFT)
57#define SOFTIRQ_MASK	(__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
58#define HARDIRQ_MASK	(__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
59#define NMI_MASK	(__IRQ_MASK(NMI_BITS)     << NMI_SHIFT)
60
61#define PREEMPT_OFFSET	(1UL << PREEMPT_SHIFT)
62#define SOFTIRQ_OFFSET	(1UL << SOFTIRQ_SHIFT)
63#define HARDIRQ_OFFSET	(1UL << HARDIRQ_SHIFT)
64#define NMI_OFFSET	(1UL << NMI_SHIFT)
65
66#ifndef PREEMPT_ACTIVE
67#define PREEMPT_ACTIVE_BITS	1
68#define PREEMPT_ACTIVE_SHIFT	(NMI_SHIFT + NMI_BITS)
69#define PREEMPT_ACTIVE	(__IRQ_MASK(PREEMPT_ACTIVE_BITS) << PREEMPT_ACTIVE_SHIFT)
70#endif
71
72#if PREEMPT_ACTIVE < (1 << (NMI_SHIFT + NMI_BITS))
73#error PREEMPT_ACTIVE is too low!
74#endif
75
76#define hardirq_count()	(preempt_count() & HARDIRQ_MASK)
77#define softirq_count()	(preempt_count() & SOFTIRQ_MASK)
78#define irq_count()	(preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \
79				 | NMI_MASK))
80
81/*
82 * Are we doing bottom half or hardware interrupt processing?
83 * Are we in a softirq context? Interrupt context?
84 */
85#define in_irq()		(hardirq_count())
86#define in_softirq()		(softirq_count())
87#define in_interrupt()		(irq_count())
88
89/*
90 * Are we in NMI context?
91 */
92#define in_nmi()	(preempt_count() & NMI_MASK)
93
94#if defined(CONFIG_PREEMPT)
95# define PREEMPT_INATOMIC_BASE kernel_locked()
96# define PREEMPT_CHECK_OFFSET 1
97#else
98# define PREEMPT_INATOMIC_BASE 0
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) != PREEMPT_INATOMIC_BASE)
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#ifndef CONFIG_VIRT_CPU_ACCOUNTING
135static inline void account_system_vtime(struct task_struct *tsk)
136{
137}
138#endif
139
140#if defined(CONFIG_NO_HZ)
141#if defined(CONFIG_TINY_RCU)
142extern void rcu_enter_nohz(void);
143extern void rcu_exit_nohz(void);
144
145static inline void rcu_irq_enter(void)
146{
147	rcu_exit_nohz();
148}
149
150static inline void rcu_irq_exit(void)
151{
152	rcu_enter_nohz();
153}
154
155static inline void rcu_nmi_enter(void)
156{
157}
158
159static inline void rcu_nmi_exit(void)
160{
161}
162
163#else
164extern void rcu_irq_enter(void);
165extern void rcu_irq_exit(void);
166extern void rcu_nmi_enter(void);
167extern void rcu_nmi_exit(void);
168#endif
169#else
170# define rcu_irq_enter() do { } while (0)
171# define rcu_irq_exit() do { } while (0)
172# define rcu_nmi_enter() do { } while (0)
173# define rcu_nmi_exit() do { } while (0)
174#endif /* #if defined(CONFIG_NO_HZ) */
175
176/*
177 * It is safe to do non-atomic ops on ->hardirq_context,
178 * because NMI handlers may not preempt and the ops are
179 * always balanced, so the interrupted value of ->hardirq_context
180 * will always be restored.
181 */
182#define __irq_enter()					\
183	do {						\
184		account_system_vtime(current);		\
185		add_preempt_count(HARDIRQ_OFFSET);	\
186		trace_hardirq_enter();			\
187	} while (0)
188
189/*
190 * Enter irq context (on NO_HZ, update jiffies):
191 */
192extern void irq_enter(void);
193
194/*
195 * Exit irq context without processing softirqs:
196 */
197#define __irq_exit()					\
198	do {						\
199		trace_hardirq_exit();			\
200		account_system_vtime(current);		\
201		sub_preempt_count(HARDIRQ_OFFSET);	\
202	} while (0)
203
204/*
205 * Exit irq context and process softirqs if needed:
206 */
207extern void irq_exit(void);
208
209#define nmi_enter()						\
210	do {							\
211		ftrace_nmi_enter();				\
212		BUG_ON(in_nmi());				\
213		add_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET);	\
214		lockdep_off();					\
215		rcu_nmi_enter();				\
216		trace_hardirq_enter();				\
217	} while (0)
218
219#define nmi_exit()						\
220	do {							\
221		trace_hardirq_exit();				\
222		rcu_nmi_exit();					\
223		lockdep_on();					\
224		BUG_ON(!in_nmi());				\
225		sub_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET);	\
226		ftrace_nmi_exit();				\
227	} while (0)
228
229#endif /* LINUX_HARDIRQ_H */
230