tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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#if PREEMPT_ACTIVE < (1 << (NMI_SHIFT + NMI_BITS))
68#error PREEMPT_ACTIVE is too low!
69#endif
70
71#define hardirq_count() (preempt_count() & HARDIRQ_MASK)
72#define softirq_count() (preempt_count() & SOFTIRQ_MASK)
73#define irq_count() (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \
74 | NMI_MASK))
75
76/*
77 * Are we doing bottom half or hardware interrupt processing?
78 * Are we in a softirq context? Interrupt context?
79 */
80#define in_irq() (hardirq_count())
81#define in_softirq() (softirq_count())
82#define in_interrupt() (irq_count())
83
84/*
85 * Are we in NMI context?
86 */
87#define in_nmi() (preempt_count() & NMI_MASK)
88
89#if defined(CONFIG_PREEMPT)
90# define PREEMPT_INATOMIC_BASE kernel_locked()
91# define PREEMPT_CHECK_OFFSET 1
92#else
93# define PREEMPT_INATOMIC_BASE 0
94# define PREEMPT_CHECK_OFFSET 0
95#endif
96
97/*
98 * Are we running in atomic context? WARNING: this macro cannot
99 * always detect atomic context; in particular, it cannot know about
100 * held spinlocks in non-preemptible kernels. Thus it should not be
101 * used in the general case to determine whether sleeping is possible.
102 * Do not use in_atomic() in driver code.
103 */
104#define in_atomic() ((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_INATOMIC_BASE)
105
106/*
107 * Check whether we were atomic before we did preempt_disable():
108 * (used by the scheduler, *after* releasing the kernel lock)
109 */
110#define in_atomic_preempt_off() \
111 ((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_CHECK_OFFSET)
112
113#ifdef CONFIG_PREEMPT
114# define preemptible() (preempt_count() == 0 && !irqs_disabled())
115# define IRQ_EXIT_OFFSET (HARDIRQ_OFFSET-1)
116#else
117# define preemptible() 0
118# define IRQ_EXIT_OFFSET HARDIRQ_OFFSET
119#endif
120
121#if defined(CONFIG_SMP) || defined(CONFIG_GENERIC_HARDIRQS)
122extern void synchronize_irq(unsigned int irq);
123#else
124# define synchronize_irq(irq) barrier()
125#endif
126
127struct task_struct;
128
129#ifndef CONFIG_VIRT_CPU_ACCOUNTING
130static inline void account_system_vtime(struct task_struct *tsk)
131{
132}
133#endif
134
135#if defined(CONFIG_NO_HZ) && !defined(CONFIG_CLASSIC_RCU)
136extern void rcu_irq_enter(void);
137extern void rcu_irq_exit(void);
138extern void rcu_nmi_enter(void);
139extern void rcu_nmi_exit(void);
140#else
141# define rcu_irq_enter() do { } while (0)
142# define rcu_irq_exit() do { } while (0)
143# define rcu_nmi_enter() do { } while (0)
144# define rcu_nmi_exit() do { } while (0)
145#endif /* #if defined(CONFIG_NO_HZ) && !defined(CONFIG_CLASSIC_RCU) */
146
147/*
148 * It is safe to do non-atomic ops on ->hardirq_context,
149 * because NMI handlers may not preempt and the ops are
150 * always balanced, so the interrupted value of ->hardirq_context
151 * will always be restored.
152 */
153#define __irq_enter() \
154 do { \
155 account_system_vtime(current); \
156 add_preempt_count(HARDIRQ_OFFSET); \
157 trace_hardirq_enter(); \
158 } while (0)
159
160/*
161 * Enter irq context (on NO_HZ, update jiffies):
162 */
163extern void irq_enter(void);
164
165/*
166 * Exit irq context without processing softirqs:
167 */
168#define __irq_exit() \
169 do { \
170 trace_hardirq_exit(); \
171 account_system_vtime(current); \
172 sub_preempt_count(HARDIRQ_OFFSET); \
173 } while (0)
174
175/*
176 * Exit irq context and process softirqs if needed:
177 */
178extern void irq_exit(void);
179
180#define nmi_enter() \
181 do { \
182 ftrace_nmi_enter(); \
183 BUG_ON(in_nmi()); \
184 add_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET); \
185 lockdep_off(); \
186 rcu_nmi_enter(); \
187 trace_hardirq_enter(); \
188 } while (0)
189
190#define nmi_exit() \
191 do { \
192 trace_hardirq_exit(); \
193 rcu_nmi_exit(); \
194 lockdep_on(); \
195 BUG_ON(!in_nmi()); \
196 sub_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET); \
197 ftrace_nmi_exit(); \
198 } while (0)
199
200#endif /* LINUX_HARDIRQ_H */