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1/*
2 * 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
11#include <linux/module.h>
12#include <linux/seq_file.h>
13#include <linux/interrupt.h>
14#include <linux/kernel_stat.h>
15#include <linux/notifier.h>
16#include <linux/cpu.h>
17#include <linux/delay.h>
18#include <linux/uaccess.h>
19#include <linux/percpu.h>
20#include <linux/mm.h>
21
22#include <asm/apic.h>
23
24DEFINE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
25EXPORT_PER_CPU_SYMBOL(irq_stat);
26
27DEFINE_PER_CPU(struct pt_regs *, irq_regs);
28EXPORT_PER_CPU_SYMBOL(irq_regs);
29
30#ifdef CONFIG_DEBUG_STACKOVERFLOW
31
32int sysctl_panic_on_stackoverflow __read_mostly;
33
34/* 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();
49 if (sysctl_panic_on_stackoverflow)
50 panic("low stack detected by irq handler - check messages\n");
51}
52
53#else
54static inline int check_stack_overflow(void) { return 0; }
55static inline void print_stack_overflow(void) { }
56#endif
57
58/*
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)];
64} __attribute__((aligned(THREAD_SIZE)));
65
66static DEFINE_PER_CPU(union irq_ctx *, hardirq_ctx);
67static DEFINE_PER_CPU(union irq_ctx *, softirq_ctx);
68
69static 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");
78}
79
80static inline int
81execute_on_irq_stack(int overflow, struct irq_desc *desc, int irq)
82{
83 union irq_ctx *curctx, *irqctx;
84 u32 *isp, arg1, arg2;
85
86 curctx = (union irq_ctx *) current_thread_info();
87 irqctx = __this_cpu_read(hardirq_ctx);
88
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 */
95 if (unlikely(curctx == irqctx))
96 return 0;
97
98 /* build the stack frame on the IRQ stack */
99 isp = (u32 *) ((char *)irqctx + sizeof(*irqctx));
100 irqctx->tinfo.task = curctx->tinfo.task;
101 irqctx->tinfo.previous_esp = current_stack_pointer;
102
103 /* Copy the preempt_count so that the [soft]irq checks work. */
104 irqctx->tinfo.preempt_count = curctx->tinfo.preempt_count;
105
106 if (unlikely(overflow))
107 call_on_stack(print_stack_overflow, isp);
108
109 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");
116 return 1;
117}
118
119/*
120 * allocate per-cpu stacks for hardirq and for softirq processing
121 */
122void __cpuinit irq_ctx_init(int cpu)
123{
124 union irq_ctx *irqctx;
125
126 if (per_cpu(hardirq_ctx, cpu))
127 return;
128
129 irqctx = page_address(alloc_pages_node(cpu_to_node(cpu),
130 THREADINFO_GFP,
131 THREAD_SIZE_ORDER));
132 memset(&irqctx->tinfo, 0, sizeof(struct thread_info));
133 irqctx->tinfo.cpu = cpu;
134 irqctx->tinfo.preempt_count = HARDIRQ_OFFSET;
135 irqctx->tinfo.addr_limit = MAKE_MM_SEG(0);
136
137 per_cpu(hardirq_ctx, cpu) = irqctx;
138
139 irqctx = page_address(alloc_pages_node(cpu_to_node(cpu),
140 THREADINFO_GFP,
141 THREAD_SIZE_ORDER));
142 memset(&irqctx->tinfo, 0, sizeof(struct thread_info));
143 irqctx->tinfo.cpu = cpu;
144 irqctx->tinfo.addr_limit = MAKE_MM_SEG(0);
145
146 per_cpu(softirq_ctx, cpu) = irqctx;
147
148 printk(KERN_DEBUG "CPU %u irqstacks, hard=%p soft=%p\n",
149 cpu, per_cpu(hardirq_ctx, cpu), per_cpu(softirq_ctx, cpu));
150}
151
152asmlinkage 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();
166 irqctx = __this_cpu_read(softirq_ctx);
167 irqctx->tinfo.task = curctx->task;
168 irqctx->tinfo.previous_esp = current_stack_pointer;
169
170 /* build the stack frame on the softirq stack */
171 isp = (u32 *) ((char *)irqctx + sizeof(*irqctx));
172
173 call_on_stack(__do_softirq, isp);
174 /*
175 * Shouldn't happen, we returned above if in_interrupt():
176 */
177 WARN_ON_ONCE(softirq_count());
178 }
179
180 local_irq_restore(flags);
181}
182
183bool 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
194 if (user_mode_vm(regs) || !execute_on_irq_stack(overflow, desc, irq)) {
195 if (unlikely(overflow))
196 print_stack_overflow();
197 desc->handle_irq(irq, desc);
198 }
199
200 return true;
201}
1/*
2 * 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
11#include <linux/seq_file.h>
12#include <linux/interrupt.h>
13#include <linux/kernel_stat.h>
14#include <linux/notifier.h>
15#include <linux/cpu.h>
16#include <linux/delay.h>
17#include <linux/uaccess.h>
18#include <linux/percpu.h>
19#include <linux/mm.h>
20
21#include <asm/apic.h>
22
23#ifdef CONFIG_DEBUG_STACKOVERFLOW
24
25int sysctl_panic_on_stackoverflow __read_mostly;
26
27/* Debugging check for stack overflow: is there less than 1KB free? */
28static int check_stack_overflow(void)
29{
30 long sp;
31
32 __asm__ __volatile__("andl %%esp,%0" :
33 "=r" (sp) : "0" (THREAD_SIZE - 1));
34
35 return sp < (sizeof(struct thread_info) + STACK_WARN);
36}
37
38static void print_stack_overflow(void)
39{
40 printk(KERN_WARNING "low stack detected by irq handler\n");
41 dump_stack();
42 if (sysctl_panic_on_stackoverflow)
43 panic("low stack detected by irq handler - check messages\n");
44}
45
46#else
47static inline int check_stack_overflow(void) { return 0; }
48static inline void print_stack_overflow(void) { }
49#endif
50
51DEFINE_PER_CPU(struct irq_stack *, hardirq_stack);
52DEFINE_PER_CPU(struct irq_stack *, softirq_stack);
53
54static void call_on_stack(void *func, void *stack)
55{
56 asm volatile("xchgl %%ebx,%%esp \n"
57 "call *%%edi \n"
58 "movl %%ebx,%%esp \n"
59 : "=b" (stack)
60 : "0" (stack),
61 "D"(func)
62 : "memory", "cc", "edx", "ecx", "eax");
63}
64
65static inline void *current_stack(void)
66{
67 return (void *)(current_stack_pointer() & ~(THREAD_SIZE - 1));
68}
69
70static inline int execute_on_irq_stack(int overflow, struct irq_desc *desc)
71{
72 struct irq_stack *curstk, *irqstk;
73 u32 *isp, *prev_esp, arg1;
74
75 curstk = (struct irq_stack *) current_stack();
76 irqstk = __this_cpu_read(hardirq_stack);
77
78 /*
79 * this is where we switch to the IRQ stack. However, if we are
80 * already using the IRQ stack (because we interrupted a hardirq
81 * handler) we can't do that and just have to keep using the
82 * current stack (which is the irq stack already after all)
83 */
84 if (unlikely(curstk == irqstk))
85 return 0;
86
87 isp = (u32 *) ((char *)irqstk + sizeof(*irqstk));
88
89 /* Save the next esp at the bottom of the stack */
90 prev_esp = (u32 *)irqstk;
91 *prev_esp = current_stack_pointer();
92
93 if (unlikely(overflow))
94 call_on_stack(print_stack_overflow, isp);
95
96 asm volatile("xchgl %%ebx,%%esp \n"
97 "call *%%edi \n"
98 "movl %%ebx,%%esp \n"
99 : "=a" (arg1), "=b" (isp)
100 : "0" (desc), "1" (isp),
101 "D" (desc->handle_irq)
102 : "memory", "cc", "ecx");
103 return 1;
104}
105
106/*
107 * allocate per-cpu stacks for hardirq and for softirq processing
108 */
109void irq_ctx_init(int cpu)
110{
111 struct irq_stack *irqstk;
112
113 if (per_cpu(hardirq_stack, cpu))
114 return;
115
116 irqstk = page_address(alloc_pages_node(cpu_to_node(cpu),
117 THREADINFO_GFP,
118 THREAD_SIZE_ORDER));
119 per_cpu(hardirq_stack, cpu) = irqstk;
120
121 irqstk = page_address(alloc_pages_node(cpu_to_node(cpu),
122 THREADINFO_GFP,
123 THREAD_SIZE_ORDER));
124 per_cpu(softirq_stack, cpu) = irqstk;
125
126 printk(KERN_DEBUG "CPU %u irqstacks, hard=%p soft=%p\n",
127 cpu, per_cpu(hardirq_stack, cpu), per_cpu(softirq_stack, cpu));
128}
129
130void do_softirq_own_stack(void)
131{
132 struct irq_stack *irqstk;
133 u32 *isp, *prev_esp;
134
135 irqstk = __this_cpu_read(softirq_stack);
136
137 /* build the stack frame on the softirq stack */
138 isp = (u32 *) ((char *)irqstk + sizeof(*irqstk));
139
140 /* Push the previous esp onto the stack */
141 prev_esp = (u32 *)irqstk;
142 *prev_esp = current_stack_pointer();
143
144 call_on_stack(__do_softirq, isp);
145}
146
147bool handle_irq(struct irq_desc *desc, struct pt_regs *regs)
148{
149 int overflow = check_stack_overflow();
150
151 if (IS_ERR_OR_NULL(desc))
152 return false;
153
154 if (user_mode(regs) || !execute_on_irq_stack(overflow, desc)) {
155 if (unlikely(overflow))
156 print_stack_overflow();
157 generic_handle_irq_desc(desc);
158 }
159
160 return true;
161}