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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002 * Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
3 *
4 * This file contains the lowest level x86-specific interrupt
5 * entry, irq-stacks and irq statistics code. All the remaining
6 * irq logic is done by the generic kernel/irq/ code and
7 * by the x86-specific irq controller code. (e.g. i8259.c and
8 * io_apic.c.)
9 */
10
Linus Torvalds1da177e2005-04-16 15:20:36 -070011#include <linux/module.h>
12#include <linux/seq_file.h>
13#include <linux/interrupt.h>
14#include <linux/kernel_stat.h>
Zwane Mwaikambof3705132005-06-25 14:54:50 -070015#include <linux/notifier.h>
16#include <linux/cpu.h>
17#include <linux/delay.h>
Jaswinder Singh Rajput72ade5f2009-01-04 16:32:36 +053018#include <linux/uaccess.h>
Lai Jiangshan42f8fae2009-02-17 11:46:42 +080019#include <linux/percpu.h>
Eric Dumazet5c1eb082010-10-28 16:40:54 +020020#include <linux/mm.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021
Thomas Gleixnere05d7232007-02-16 01:27:58 -080022#include <asm/apic.h>
Thomas Gleixnere05d7232007-02-16 01:27:58 -080023
Fenghua Yuf34e3b62007-07-19 01:48:13 -070024DEFINE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
Linus Torvalds1da177e2005-04-16 15:20:36 -070025EXPORT_PER_CPU_SYMBOL(irq_stat);
26
Jeremy Fitzhardinge7c3576d2007-05-02 19:27:16 +020027DEFINE_PER_CPU(struct pt_regs *, irq_regs);
28EXPORT_PER_CPU_SYMBOL(irq_regs);
29
Thomas Gleixnerde9b10a2008-05-05 15:58:15 +020030#ifdef CONFIG_DEBUG_STACKOVERFLOW
Ingo Molnar53b56502011-12-05 12:25:44 +010031
32int sysctl_panic_on_stackoverflow __read_mostly;
33
Thomas Gleixnerde9b10a2008-05-05 15:58:15 +020034/* Debugging check for stack overflow: is there less than 1KB free? */
35static int check_stack_overflow(void)
36{
37 long sp;
38
39 __asm__ __volatile__("andl %%esp,%0" :
40 "=r" (sp) : "0" (THREAD_SIZE - 1));
41
42 return sp < (sizeof(struct thread_info) + STACK_WARN);
43}
44
45static void print_stack_overflow(void)
46{
47 printk(KERN_WARNING "low stack detected by irq handler\n");
48 dump_stack();
Mitsuo Hayasaka55af7792011-11-29 15:08:36 +090049 if (sysctl_panic_on_stackoverflow)
50 panic("low stack detected by irq handler - check messages\n");
Thomas Gleixnerde9b10a2008-05-05 15:58:15 +020051}
52
53#else
54static inline int check_stack_overflow(void) { return 0; }
55static inline void print_stack_overflow(void) { }
56#endif
57
Linus Torvalds1da177e2005-04-16 15:20:36 -070058/*
59 * per-CPU IRQ handling contexts (thread information and stack)
60 */
61union irq_ctx {
62 struct thread_info tinfo;
63 u32 stack[THREAD_SIZE/sizeof(u32)];
Christoph Hellwig25897372010-07-27 14:13:13 +020064} __attribute__((aligned(THREAD_SIZE)));
Linus Torvalds1da177e2005-04-16 15:20:36 -070065
Lai Jiangshan42f8fae2009-02-17 11:46:42 +080066static DEFINE_PER_CPU(union irq_ctx *, hardirq_ctx);
67static DEFINE_PER_CPU(union irq_ctx *, softirq_ctx);
Linus Torvalds1da177e2005-04-16 15:20:36 -070068
Thomas Gleixner403d8ef2008-05-05 18:13:50 +020069static void call_on_stack(void *func, void *stack)
70{
71 asm volatile("xchgl %%ebx,%%esp \n"
72 "call *%%edi \n"
73 "movl %%ebx,%%esp \n"
74 : "=b" (stack)
75 : "0" (stack),
76 "D"(func)
77 : "memory", "cc", "edx", "ecx", "eax");
Andi Kleen04b361a2008-05-05 12:36:38 +020078}
79
Thomas Gleixnerde9b10a2008-05-05 15:58:15 +020080static inline int
81execute_on_irq_stack(int overflow, struct irq_desc *desc, int irq)
82{
Linus Torvalds1da177e2005-04-16 15:20:36 -070083 union irq_ctx *curctx, *irqctx;
Thomas Gleixner403d8ef2008-05-05 18:13:50 +020084 u32 *isp, arg1, arg2;
Linus Torvalds1da177e2005-04-16 15:20:36 -070085
86 curctx = (union irq_ctx *) current_thread_info();
Tejun Heo0a3aee02010-12-18 16:28:55 +010087 irqctx = __this_cpu_read(hardirq_ctx);
Linus Torvalds1da177e2005-04-16 15:20:36 -070088
89 /*
90 * this is where we switch to the IRQ stack. However, if we are
91 * already using the IRQ stack (because we interrupted a hardirq
92 * handler) we can't do that and just have to keep using the
93 * current stack (which is the irq stack already after all)
94 */
Thomas Gleixnerde9b10a2008-05-05 15:58:15 +020095 if (unlikely(curctx == irqctx))
96 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -070097
Thomas Gleixnerde9b10a2008-05-05 15:58:15 +020098 /* build the stack frame on the IRQ stack */
Jaswinder Singh Rajput72ade5f2009-01-04 16:32:36 +053099 isp = (u32 *) ((char *)irqctx + sizeof(*irqctx));
Thomas Gleixnerde9b10a2008-05-05 15:58:15 +0200100 irqctx->tinfo.task = curctx->tinfo.task;
101 irqctx->tinfo.previous_esp = current_stack_pointer;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102
Linus Torvalds986cb482012-02-19 11:46:36 -0800103 /* Copy the preempt_count so that the [soft]irq checks work. */
104 irqctx->tinfo.preempt_count = curctx->tinfo.preempt_count;
Björn Steinbrinka5d157e2006-06-25 16:24:40 +0200105
Thomas Gleixnerde9b10a2008-05-05 15:58:15 +0200106 if (unlikely(overflow))
Thomas Gleixner403d8ef2008-05-05 18:13:50 +0200107 call_on_stack(print_stack_overflow, isp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108
Thomas Gleixner403d8ef2008-05-05 18:13:50 +0200109 asm volatile("xchgl %%ebx,%%esp \n"
110 "call *%%edi \n"
111 "movl %%ebx,%%esp \n"
112 : "=a" (arg1), "=d" (arg2), "=b" (isp)
113 : "0" (irq), "1" (desc), "2" (isp),
114 "D" (desc->handle_irq)
115 : "memory", "cc", "ecx");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116 return 1;
117}
118
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119/*
120 * allocate per-cpu stacks for hardirq and for softirq processing
121 */
Thomas Gleixner403d8ef2008-05-05 18:13:50 +0200122void __cpuinit irq_ctx_init(int cpu)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123{
124 union irq_ctx *irqctx;
125
Lai Jiangshan42f8fae2009-02-17 11:46:42 +0800126 if (per_cpu(hardirq_ctx, cpu))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127 return;
128
Eric Dumazet5c1eb082010-10-28 16:40:54 +0200129 irqctx = page_address(alloc_pages_node(cpu_to_node(cpu),
Thomas Gleixner38e7c572012-05-05 15:05:42 +0000130 THREADINFO_GFP,
131 THREAD_SIZE_ORDER));
Brian Gerst7b698ea2011-01-17 07:32:10 -0500132 memset(&irqctx->tinfo, 0, sizeof(struct thread_info));
Thomas Gleixner403d8ef2008-05-05 18:13:50 +0200133 irqctx->tinfo.cpu = cpu;
134 irqctx->tinfo.preempt_count = HARDIRQ_OFFSET;
135 irqctx->tinfo.addr_limit = MAKE_MM_SEG(0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136
Lai Jiangshan42f8fae2009-02-17 11:46:42 +0800137 per_cpu(hardirq_ctx, cpu) = irqctx;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138
Eric Dumazet5c1eb082010-10-28 16:40:54 +0200139 irqctx = page_address(alloc_pages_node(cpu_to_node(cpu),
Thomas Gleixner38e7c572012-05-05 15:05:42 +0000140 THREADINFO_GFP,
141 THREAD_SIZE_ORDER));
Brian Gerst7b698ea2011-01-17 07:32:10 -0500142 memset(&irqctx->tinfo, 0, sizeof(struct thread_info));
Thomas Gleixner403d8ef2008-05-05 18:13:50 +0200143 irqctx->tinfo.cpu = cpu;
Thomas Gleixner403d8ef2008-05-05 18:13:50 +0200144 irqctx->tinfo.addr_limit = MAKE_MM_SEG(0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145
Lai Jiangshan42f8fae2009-02-17 11:46:42 +0800146 per_cpu(softirq_ctx, cpu) = irqctx;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147
Thomas Gleixner403d8ef2008-05-05 18:13:50 +0200148 printk(KERN_DEBUG "CPU %u irqstacks, hard=%p soft=%p\n",
Lai Jiangshan42f8fae2009-02-17 11:46:42 +0800149 cpu, per_cpu(hardirq_ctx, cpu), per_cpu(softirq_ctx, cpu));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150}
151
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152asmlinkage void do_softirq(void)
153{
154 unsigned long flags;
155 struct thread_info *curctx;
156 union irq_ctx *irqctx;
157 u32 *isp;
158
159 if (in_interrupt())
160 return;
161
162 local_irq_save(flags);
163
164 if (local_softirq_pending()) {
165 curctx = current_thread_info();
Tejun Heo0a3aee02010-12-18 16:28:55 +0100166 irqctx = __this_cpu_read(softirq_ctx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167 irqctx->tinfo.task = curctx->task;
168 irqctx->tinfo.previous_esp = current_stack_pointer;
169
170 /* build the stack frame on the softirq stack */
Jaswinder Singh Rajput72ade5f2009-01-04 16:32:36 +0530171 isp = (u32 *) ((char *)irqctx + sizeof(*irqctx));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172
Thomas Gleixner403d8ef2008-05-05 18:13:50 +0200173 call_on_stack(__do_softirq, isp);
Ingo Molnar55f327f2006-07-03 00:24:43 -0700174 /*
Lucas De Marchi0d2eb442011-03-17 16:24:16 -0300175 * Shouldn't happen, we returned above if in_interrupt():
Thomas Gleixner403d8ef2008-05-05 18:13:50 +0200176 */
Ingo Molnar55f327f2006-07-03 00:24:43 -0700177 WARN_ON_ONCE(softirq_count());
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178 }
179
180 local_irq_restore(flags);
181}
Thomas Gleixner403d8ef2008-05-05 18:13:50 +0200182
Jeremy Fitzhardinge9b2b76a2009-02-06 14:09:40 -0800183bool handle_irq(unsigned irq, struct pt_regs *regs)
184{
185 struct irq_desc *desc;
186 int overflow;
187
188 overflow = check_stack_overflow();
189
190 desc = irq_to_desc(irq);
191 if (unlikely(!desc))
192 return false;
193
Linus Torvalds986cb482012-02-19 11:46:36 -0800194 if (user_mode_vm(regs) || !execute_on_irq_stack(overflow, desc, irq)) {
Jeremy Fitzhardinge9b2b76a2009-02-06 14:09:40 -0800195 if (unlikely(overflow))
196 print_stack_overflow();
197 desc->handle_irq(irq, desc);
198 }
199
200 return true;
201}