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1 /*
2 * linux/arch/i386/kernel/irq.c
3 *
4 * Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
5 *
6 * This file contains the lowest level x86-specific interrupt
7 * entry, irq-stacks and irq statistics code. All the remaining
8 * irq logic is done by the generic kernel/irq/ code and
9 * by the x86-specific irq controller code. (e.g. i8259.c and
10 * io_apic.c.)
11 */
12
13 #include <asm/uaccess.h>
14 #include <linux/module.h>
15 #include <linux/seq_file.h>
16 #include <linux/interrupt.h>
17 #include <linux/kernel_stat.h>
18 #include <linux/notifier.h>
19 #include <linux/cpu.h>
20 #include <linux/delay.h>
21
22 DEFINE_PER_CPU(irq_cpustat_t, irq_stat) ____cacheline_internodealigned_in_smp;
23 EXPORT_PER_CPU_SYMBOL(irq_stat);
24
25 #ifndef CONFIG_X86_LOCAL_APIC
26 /*
27 * 'what should we do if we get a hw irq event on an illegal vector'.
28 * each architecture has to answer this themselves.
29 */
30 void ack_bad_irq(unsigned int irq)
31 {
32 printk("unexpected IRQ trap at vector %02x\n", irq);
33 }
34 #endif
35
36 #ifdef CONFIG_4KSTACKS
37 /*
38 * per-CPU IRQ handling contexts (thread information and stack)
39 */
40 union irq_ctx {
41 struct thread_info tinfo;
42 u32 stack[THREAD_SIZE/sizeof(u32)];
43 };
44
45 static union irq_ctx *hardirq_ctx[NR_CPUS] __read_mostly;
46 static union irq_ctx *softirq_ctx[NR_CPUS] __read_mostly;
47 #endif
48
49 /*
50 * do_IRQ handles all normal device IRQ's (the special
51 * SMP cross-CPU interrupts have their own specific
52 * handlers).
53 */
54 fastcall unsigned int do_IRQ(struct pt_regs *regs)
55 {
56 /* high bit used in ret_from_ code */
57 int irq = ~regs->orig_eax;
58 #ifdef CONFIG_4KSTACKS
59 union irq_ctx *curctx, *irqctx;
60 u32 *isp;
61 #endif
62
63 if (unlikely((unsigned)irq >= NR_IRQS)) {
64 printk(KERN_EMERG "%s: cannot handle IRQ %d\n",
65 __FUNCTION__, irq);
66 BUG();
67 }
68
69 irq_enter();
70 #ifdef CONFIG_DEBUG_STACKOVERFLOW
71 /* Debugging check for stack overflow: is there less than 1KB free? */
72 {
73 long esp;
74
75 __asm__ __volatile__("andl %%esp,%0" :
76 "=r" (esp) : "0" (THREAD_SIZE - 1));
77 if (unlikely(esp < (sizeof(struct thread_info) + STACK_WARN))) {
78 printk("do_IRQ: stack overflow: %ld\n",
79 esp - sizeof(struct thread_info));
80 dump_stack();
81 }
82 }
83 #endif
84
85 if (!irq_desc[irq].handle_irq) {
86 __do_IRQ(irq, regs);
87 goto out_exit;
88 }
89 #ifdef CONFIG_4KSTACKS
90
91 curctx = (union irq_ctx *) current_thread_info();
92 irqctx = hardirq_ctx[smp_processor_id()];
93
94 /*
95 * this is where we switch to the IRQ stack. However, if we are
96 * already using the IRQ stack (because we interrupted a hardirq
97 * handler) we can't do that and just have to keep using the
98 * current stack (which is the irq stack already after all)
99 */
100 if (curctx != irqctx) {
101 int arg1, arg2, ebx;
102
103 /* build the stack frame on the IRQ stack */
104 isp = (u32*) ((char*)irqctx + sizeof(*irqctx));
105 irqctx->tinfo.task = curctx->tinfo.task;
106 irqctx->tinfo.previous_esp = current_stack_pointer;
107
108 /*
109 * Copy the softirq bits in preempt_count so that the
110 * softirq checks work in the hardirq context.
111 */
112 irqctx->tinfo.preempt_count =
113 (irqctx->tinfo.preempt_count & ~SOFTIRQ_MASK) |
114 (curctx->tinfo.preempt_count & SOFTIRQ_MASK);
115
116 asm volatile(
117 " xchgl %%ebx,%%esp \n"
118 " call __do_IRQ \n"
119 " movl %%ebx,%%esp \n"
120 : "=a" (arg1), "=d" (arg2), "=b" (ebx)
121 : "0" (irq), "1" (regs), "2" (isp)
122 : "memory", "cc", "ecx"
123 );
124 } else
125 #endif
126 __do_IRQ(irq, regs);
127
128 out_exit:
129 irq_exit();
130
131 return 1;
132 }
133
134 #ifdef CONFIG_4KSTACKS
135
136 /*
137 * These should really be __section__(".bss.page_aligned") as well, but
138 * gcc's 3.0 and earlier don't handle that correctly.
139 */
140 static char softirq_stack[NR_CPUS * THREAD_SIZE]
141 __attribute__((__aligned__(THREAD_SIZE)));
142
143 static char hardirq_stack[NR_CPUS * THREAD_SIZE]
144 __attribute__((__aligned__(THREAD_SIZE)));
145
146 /*
147 * allocate per-cpu stacks for hardirq and for softirq processing
148 */
149 void irq_ctx_init(int cpu)
150 {
151 union irq_ctx *irqctx;
152
153 if (hardirq_ctx[cpu])
154 return;
155
156 irqctx = (union irq_ctx*) &hardirq_stack[cpu*THREAD_SIZE];
157 irqctx->tinfo.task = NULL;
158 irqctx->tinfo.exec_domain = NULL;
159 irqctx->tinfo.cpu = cpu;
160 irqctx->tinfo.preempt_count = HARDIRQ_OFFSET;
161 irqctx->tinfo.addr_limit = MAKE_MM_SEG(0);
162
163 hardirq_ctx[cpu] = irqctx;
164
165 irqctx = (union irq_ctx*) &softirq_stack[cpu*THREAD_SIZE];
166 irqctx->tinfo.task = NULL;
167 irqctx->tinfo.exec_domain = NULL;
168 irqctx->tinfo.cpu = cpu;
169 irqctx->tinfo.preempt_count = 0;
170 irqctx->tinfo.addr_limit = MAKE_MM_SEG(0);
171
172 softirq_ctx[cpu] = irqctx;
173
174 printk("CPU %u irqstacks, hard=%p soft=%p\n",
175 cpu,hardirq_ctx[cpu],softirq_ctx[cpu]);
176 }
177
178 void irq_ctx_exit(int cpu)
179 {
180 hardirq_ctx[cpu] = NULL;
181 }
182
183 extern asmlinkage void __do_softirq(void);
184
185 asmlinkage void do_softirq(void)
186 {
187 unsigned long flags;
188 struct thread_info *curctx;
189 union irq_ctx *irqctx;
190 u32 *isp;
191
192 if (in_interrupt())
193 return;
194
195 local_irq_save(flags);
196
197 if (local_softirq_pending()) {
198 curctx = current_thread_info();
199 irqctx = softirq_ctx[smp_processor_id()];
200 irqctx->tinfo.task = curctx->task;
201 irqctx->tinfo.previous_esp = current_stack_pointer;
202
203 /* build the stack frame on the softirq stack */
204 isp = (u32*) ((char*)irqctx + sizeof(*irqctx));
205
206 asm volatile(
207 " xchgl %%ebx,%%esp \n"
208 " call __do_softirq \n"
209 " movl %%ebx,%%esp \n"
210 : "=b"(isp)
211 : "0"(isp)
212 : "memory", "cc", "edx", "ecx", "eax"
213 );
214 /*
215 * Shouldnt happen, we returned above if in_interrupt():
216 */
217 WARN_ON_ONCE(softirq_count());
218 }
219
220 local_irq_restore(flags);
221 }
222
223 EXPORT_SYMBOL(do_softirq);
224 #endif
225
226 /*
227 * Interrupt statistics:
228 */
229
230 atomic_t irq_err_count;
231
232 /*
233 * /proc/interrupts printing:
234 */
235
236 int show_interrupts(struct seq_file *p, void *v)
237 {
238 int i = *(loff_t *) v, j;
239 struct irqaction * action;
240 unsigned long flags;
241
242 if (i == 0) {
243 seq_printf(p, " ");
244 for_each_online_cpu(j)
245 seq_printf(p, "CPU%-8d",j);
246 seq_putc(p, '\n');
247 }
248
249 if (i < NR_IRQS) {
250 spin_lock_irqsave(&irq_desc[i].lock, flags);
251 action = irq_desc[i].action;
252 if (!action)
253 goto skip;
254 seq_printf(p, "%3d: ",i);
255 #ifndef CONFIG_SMP
256 seq_printf(p, "%10u ", kstat_irqs(i));
257 #else
258 for_each_online_cpu(j)
259 seq_printf(p, "%10u ", kstat_cpu(j).irqs[i]);
260 #endif
261 seq_printf(p, " %14s", irq_desc[i].chip->typename);
262 seq_printf(p, " %s", action->name);
263
264 for (action=action->next; action; action = action->next)
265 seq_printf(p, ", %s", action->name);
266
267 seq_putc(p, '\n');
268 skip:
269 spin_unlock_irqrestore(&irq_desc[i].lock, flags);
270 } else if (i == NR_IRQS) {
271 seq_printf(p, "NMI: ");
272 for_each_online_cpu(j)
273 seq_printf(p, "%10u ", nmi_count(j));
274 seq_putc(p, '\n');
275 #ifdef CONFIG_X86_LOCAL_APIC
276 seq_printf(p, "LOC: ");
277 for_each_online_cpu(j)
278 seq_printf(p, "%10u ",
279 per_cpu(irq_stat,j).apic_timer_irqs);
280 seq_putc(p, '\n');
281 #endif
282 seq_printf(p, "ERR: %10u\n", atomic_read(&irq_err_count));
283 #if defined(CONFIG_X86_IO_APIC)
284 seq_printf(p, "MIS: %10u\n", atomic_read(&irq_mis_count));
285 #endif
286 }
287 return 0;
288 }
289
290 #ifdef CONFIG_HOTPLUG_CPU
291 #include <mach_apic.h>
292
293 void fixup_irqs(cpumask_t map)
294 {
295 unsigned int irq;
296 static int warned;
297
298 for (irq = 0; irq < NR_IRQS; irq++) {
299 cpumask_t mask;
300 if (irq == 2)
301 continue;
302
303 cpus_and(mask, irq_desc[irq].affinity, map);
304 if (any_online_cpu(mask) == NR_CPUS) {
305 printk("Breaking affinity for irq %i\n", irq);
306 mask = map;
307 }
308 if (irq_desc[irq].chip->set_affinity)
309 irq_desc[irq].chip->set_affinity(irq, mask);
310 else if (irq_desc[irq].action && !(warned++))
311 printk("Cannot set affinity for irq %i\n", irq);
312 }
313
314 #if 0
315 barrier();
316 /* Ingo Molnar says: "after the IO-APIC masks have been redirected
317 [note the nop - the interrupt-enable boundary on x86 is two
318 instructions from sti] - to flush out pending hardirqs and
319 IPIs. After this point nothing is supposed to reach this CPU." */
320 __asm__ __volatile__("sti; nop; cli");
321 barrier();
322 #else
323 /* That doesn't seem sufficient. Give it 1ms. */
324 local_irq_enable();
325 mdelay(1);
326 local_irq_disable();
327 #endif
328 }
329 #endif
330