hardirq.h revision 9b2e4f1880b789be1f24f9684f7a54b90310b5c0 
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_COUNT)
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_COUNT
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_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU)
143
144static inline void rcu_nmi_enter(void)
145{
146}
147
148static inline void rcu_nmi_exit(void)
149{
150}
151
152#else
153extern void rcu_nmi_enter(void);
154extern void rcu_nmi_exit(void);
155#endif
156
157/*
158 * It is safe to do non-atomic ops on ->hardirq_context,
159 * because NMI handlers may not preempt and the ops are
160 * always balanced, so the interrupted value of ->hardirq_context
161 * will always be restored.
162 */
163#define __irq_enter()					\
164	do {						\
165		account_system_vtime(current);		\
166		add_preempt_count(HARDIRQ_OFFSET);	\
167		trace_hardirq_enter();			\
168	} while (0)
169
170/*
171 * Enter irq context (on NO_HZ, update jiffies):
172 */
173extern void irq_enter(void);
174
175/*
176 * Exit irq context without processing softirqs:
177 */
178#define __irq_exit()					\
179	do {						\
180		trace_hardirq_exit();			\
181		account_system_vtime(current);		\
182		sub_preempt_count(HARDIRQ_OFFSET);	\
183	} while (0)
184
185/*
186 * Exit irq context and process softirqs if needed:
187 */
188extern void irq_exit(void);
189
190#define nmi_enter()						\
191	do {							\
192		ftrace_nmi_enter();				\
193		BUG_ON(in_nmi());				\
194		add_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET);	\
195		lockdep_off();					\
196		rcu_nmi_enter();				\
197		trace_hardirq_enter();				\
198	} while (0)
199
200#define nmi_exit()						\
201	do {							\
202		trace_hardirq_exit();				\
203		rcu_nmi_exit();					\
204		lockdep_on();					\
205		BUG_ON(!in_nmi());				\
206		sub_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET);	\
207		ftrace_nmi_exit();				\
208	} while (0)
209
210#endif /* LINUX_HARDIRQ_H */
211