hardirq.h revision a57eb940d130477a799dfb24a570ee04979c0f7f 
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#include <asm/system.h>
12
13/*
14 * We put the hardirq and softirq counter into the preemption
15 * counter. The bitmask has the following meaning:
16 *
17 * - bits 0-7 are the preemption count (max preemption depth: 256)
18 * - bits 8-15 are the softirq count (max # of softirqs: 256)
19 *
20 * The hardirq count can in theory reach the same as NR_IRQS.
21 * In reality, the number of nested IRQS is limited to the stack
22 * size as well. For archs with over 1000 IRQS it is not practical
23 * to expect that they will all nest. We give a max of 10 bits for
24 * hardirq nesting. An arch may choose to give less than 10 bits.
25 * m68k expects it to be 8.
26 *
27 * - bits 16-25 are the hardirq count (max # of nested hardirqs: 1024)
28 * - bit 26 is the NMI_MASK
29 * - bit 28 is the PREEMPT_ACTIVE flag
30 *
31 * PREEMPT_MASK: 0x000000ff
32 * SOFTIRQ_MASK: 0x0000ff00
33 * HARDIRQ_MASK: 0x03ff0000
34 *     NMI_MASK: 0x04000000
35 */
36#define PREEMPT_BITS	8
37#define SOFTIRQ_BITS	8
38#define NMI_BITS	1
39
40#define MAX_HARDIRQ_BITS 10
41
42#ifndef HARDIRQ_BITS
43# define HARDIRQ_BITS	MAX_HARDIRQ_BITS
44#endif
45
46#if HARDIRQ_BITS > MAX_HARDIRQ_BITS
47#error HARDIRQ_BITS too high!
48#endif
49
50#define PREEMPT_SHIFT	0
51#define SOFTIRQ_SHIFT	(PREEMPT_SHIFT + PREEMPT_BITS)
52#define HARDIRQ_SHIFT	(SOFTIRQ_SHIFT + SOFTIRQ_BITS)
53#define NMI_SHIFT	(HARDIRQ_SHIFT + HARDIRQ_BITS)
54
55#define __IRQ_MASK(x)	((1UL << (x))-1)
56
57#define PREEMPT_MASK	(__IRQ_MASK(PREEMPT_BITS) << PREEMPT_SHIFT)
58#define SOFTIRQ_MASK	(__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
59#define HARDIRQ_MASK	(__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
60#define NMI_MASK	(__IRQ_MASK(NMI_BITS)     << NMI_SHIFT)
61
62#define PREEMPT_OFFSET	(1UL << PREEMPT_SHIFT)
63#define SOFTIRQ_OFFSET	(1UL << SOFTIRQ_SHIFT)
64#define HARDIRQ_OFFSET	(1UL << HARDIRQ_SHIFT)
65#define NMI_OFFSET	(1UL << NMI_SHIFT)
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 */
86#define in_irq()		(hardirq_count())
87#define in_softirq()		(softirq_count())
88#define in_interrupt()		(irq_count())
89
90/*
91 * Are we in NMI context?
92 */
93#define in_nmi()	(preempt_count() & NMI_MASK)
94
95#if defined(CONFIG_PREEMPT)
96# define PREEMPT_INATOMIC_BASE kernel_locked()
97# define PREEMPT_CHECK_OFFSET 1
98#else
99# define PREEMPT_INATOMIC_BASE 0
100# define PREEMPT_CHECK_OFFSET 0
101#endif
102
103/*
104 * Are we running in atomic context?  WARNING: this macro cannot
105 * always detect atomic context; in particular, it cannot know about
106 * held spinlocks in non-preemptible kernels.  Thus it should not be
107 * used in the general case to determine whether sleeping is possible.
108 * Do not use in_atomic() in driver code.
109 */
110#define in_atomic()	((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_INATOMIC_BASE)
111
112/*
113 * Check whether we were atomic before we did preempt_disable():
114 * (used by the scheduler, *after* releasing the kernel lock)
115 */
116#define in_atomic_preempt_off() \
117		((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_CHECK_OFFSET)
118
119#ifdef CONFIG_PREEMPT
120# define preemptible()	(preempt_count() == 0 && !irqs_disabled())
121# define IRQ_EXIT_OFFSET (HARDIRQ_OFFSET-1)
122#else
123# define preemptible()	0
124# define IRQ_EXIT_OFFSET HARDIRQ_OFFSET
125#endif
126
127#if defined(CONFIG_SMP) || defined(CONFIG_GENERIC_HARDIRQS)
128extern void synchronize_irq(unsigned int irq);
129#else
130# define synchronize_irq(irq)	barrier()
131#endif
132
133struct task_struct;
134
135#ifndef CONFIG_VIRT_CPU_ACCOUNTING
136static inline void account_system_vtime(struct task_struct *tsk)
137{
138}
139#endif
140
141#if defined(CONFIG_NO_HZ)
142#if defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU)
143extern void rcu_enter_nohz(void);
144extern void rcu_exit_nohz(void);
145
146static inline void rcu_irq_enter(void)
147{
148	rcu_exit_nohz();
149}
150
151static inline void rcu_irq_exit(void)
152{
153	rcu_enter_nohz();
154}
155
156static inline void rcu_nmi_enter(void)
157{
158}
159
160static inline void rcu_nmi_exit(void)
161{
162}
163
164#else
165extern void rcu_irq_enter(void);
166extern void rcu_irq_exit(void);
167extern void rcu_nmi_enter(void);
168extern void rcu_nmi_exit(void);
169#endif
170#else
171# define rcu_irq_enter() do { } while (0)
172# define rcu_irq_exit() do { } while (0)
173# define rcu_nmi_enter() do { } while (0)
174# define rcu_nmi_exit() do { } while (0)
175#endif /* #if defined(CONFIG_NO_HZ) */
176
177/*
178 * It is safe to do non-atomic ops on ->hardirq_context,
179 * because NMI handlers may not preempt and the ops are
180 * always balanced, so the interrupted value of ->hardirq_context
181 * will always be restored.
182 */
183#define __irq_enter()					\
184	do {						\
185		account_system_vtime(current);		\
186		add_preempt_count(HARDIRQ_OFFSET);	\
187		trace_hardirq_enter();			\
188	} while (0)
189
190/*
191 * Enter irq context (on NO_HZ, update jiffies):
192 */
193extern void irq_enter(void);
194
195/*
196 * Exit irq context without processing softirqs:
197 */
198#define __irq_exit()					\
199	do {						\
200		trace_hardirq_exit();			\
201		account_system_vtime(current);		\
202		sub_preempt_count(HARDIRQ_OFFSET);	\
203	} while (0)
204
205/*
206 * Exit irq context and process softirqs if needed:
207 */
208extern void irq_exit(void);
209
210#define nmi_enter()						\
211	do {							\
212		ftrace_nmi_enter();				\
213		BUG_ON(in_nmi());				\
214		add_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET);	\
215		lockdep_off();					\
216		rcu_nmi_enter();				\
217		trace_hardirq_enter();				\
218	} while (0)
219
220#define nmi_exit()						\
221	do {							\
222		trace_hardirq_exit();				\
223		rcu_nmi_exit();					\
224		lockdep_on();					\
225		BUG_ON(!in_nmi());				\
226		sub_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET);	\
227		ftrace_nmi_exit();				\
228	} while (0)
229
230#endif /* LINUX_HARDIRQ_H */
231