arch/i386/kernel/irq.c

   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 <linux/module.h>
  14 #include <linux/seq_file.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/kernel_stat.h>
  17 #include <linux/notifier.h>
  18 #include <linux/cpu.h>
  19 #include <linux/delay.h>
  20
  21 #include <asm/apic.h>
  22 #include <asm/uaccess.h>
  23
  24 DEFINE_PER_CPU(irq_cpustat_t, irq_stat) ____cacheline_internodealigned_in_smp;
  25 EXPORT_PER_CPU_SYMBOL(irq_stat);
  26
  27 /*
  28  * 'what should we do if we get a hw irq event on an illegal vector'.
  29  * each architecture has to answer this themselves.
  30  */
  31 void ack_bad_irq(unsigned int irq)
  32 {
  33         printk(KERN_ERR "unexpected IRQ trap at vector %02x\n", irq);
  34
  35 #ifdef CONFIG_X86_LOCAL_APIC
  36         /*
  37          * Currently unexpected vectors happen only on SMP and APIC.
  38          * We _must_ ack these because every local APIC has only N
  39          * irq slots per priority level, and a 'hanging, unacked' IRQ
  40          * holds up an irq slot - in excessive cases (when multiple
  41          * unexpected vectors occur) that might lock up the APIC
  42          * completely.
  43          * But only ack when the APIC is enabled -AK
  44          */
  45         if (cpu_has_apic)
  46                 ack_APIC_irq();
  47 #endif
  48 }
  49
  50 #ifdef CONFIG_4KSTACKS
  51 /*
  52  * per-CPU IRQ handling contexts (thread information and stack)
  53  */
  54 union irq_ctx {
  55         struct thread_info      tinfo;
  56         u32                     stack[THREAD_SIZE/sizeof(u32)];
  57 };
  58
  59 static union irq_ctx *hardirq_ctx[NR_CPUS] __read_mostly;
  60 static union irq_ctx *softirq_ctx[NR_CPUS] __read_mostly;
  61 #endif
  62
  63 /*
  64  * do_IRQ handles all normal device IRQ's (the special
  65  * SMP cross-CPU interrupts have their own specific
  66  * handlers).
  67  */
  68 fastcall unsigned int do_IRQ(struct pt_regs *regs)
  69 {
  70         struct pt_regs *old_regs;
  71         /* high bit used in ret_from_ code */
  72         int irq = ~regs->orig_eax;
  73         struct irq_desc *desc = irq_desc + irq;
  74 #ifdef CONFIG_4KSTACKS
  75         union irq_ctx *curctx, *irqctx;
  76         u32 *isp;
  77 #endif
  78
  79         if (unlikely((unsigned)irq >= NR_IRQS)) {
  80                 printk(KERN_EMERG "%s: cannot handle IRQ %d\n",
  81                                         __FUNCTION__, irq);
  82                 BUG();
  83         }
  84
  85         old_regs = set_irq_regs(regs);
  86         irq_enter();
  87 #ifdef CONFIG_DEBUG_STACKOVERFLOW
  88         /* Debugging check for stack overflow: is there less than 1KB free? */
  89         {
  90                 long esp;
  91
  92                 __asm__ __volatile__("andl %%esp,%0" :
  93                                         "=r" (esp) : "0" (THREAD_SIZE - 1));
  94                 if (unlikely(esp < (sizeof(struct thread_info) + STACK_WARN))) {
  95                         printk("do_IRQ: stack overflow: %ld\n",
  96                                 esp - sizeof(struct thread_info));
  97                         dump_stack();
  98                 }
  99         }
 100 #endif
 101
 102 #ifdef CONFIG_4KSTACKS
 103
 104         curctx = (union irq_ctx *) current_thread_info();
 105         irqctx = hardirq_ctx[smp_processor_id()];
 106
 107         /*
 108          * this is where we switch to the IRQ stack. However, if we are
 109          * already using the IRQ stack (because we interrupted a hardirq
 110          * handler) we can't do that and just have to keep using the
 111          * current stack (which is the irq stack already after all)
 112          */
 113         if (curctx != irqctx) {
 114                 int arg1, arg2, ebx;
 115
 116                 /* build the stack frame on the IRQ stack */
 117                 isp = (u32*) ((char*)irqctx + sizeof(*irqctx));
 118                 irqctx->tinfo.task = curctx->tinfo.task;
 119                 irqctx->tinfo.previous_esp = current_stack_pointer;
 120
 121                 /*
 122                  * Copy the softirq bits in preempt_count so that the
 123                  * softirq checks work in the hardirq context.
 124                  */
 125                 irqctx->tinfo.preempt_count =
 126                         (irqctx->tinfo.preempt_count & ~SOFTIRQ_MASK) |
 127                         (curctx->tinfo.preempt_count & SOFTIRQ_MASK);
 128
 129                 asm volatile(
 130                         "       xchgl  %%ebx,%%esp      \n"
 131                         "       call   *%%edi           \n"
 132                         "       movl   %%ebx,%%esp      \n"
 133                         : "=a" (arg1), "=d" (arg2), "=b" (ebx)
 134                         :  "0" (irq),   "1" (desc),  "2" (isp),
 135                            "D" (desc->handle_irq)
 136                         : "memory", "cc"
 137                 );
 138         } else
 139 #endif
 140                 desc->handle_irq(irq, desc);
 141
 142         irq_exit();
 143         set_irq_regs(old_regs);
 144         return 1;
 145 }
 146
 147 #ifdef CONFIG_4KSTACKS
 148
 149 /*
 150  * These should really be __section__(".bss.page_aligned") as well, but
 151  * gcc's 3.0 and earlier don't handle that correctly.
 152  */
 153 static char softirq_stack[NR_CPUS * THREAD_SIZE]
 154                 __attribute__((__aligned__(THREAD_SIZE)));
 155
 156 static char hardirq_stack[NR_CPUS * THREAD_SIZE]
 157                 __attribute__((__aligned__(THREAD_SIZE)));
 158
 159 /*
 160  * allocate per-cpu stacks for hardirq and for softirq processing
 161  */
 162 void irq_ctx_init(int cpu)
 163 {
 164         union irq_ctx *irqctx;
 165
 166         if (hardirq_ctx[cpu])
 167                 return;
 168
 169         irqctx = (union irq_ctx*) &hardirq_stack[cpu*THREAD_SIZE];
 170         irqctx->tinfo.task              = NULL;
 171         irqctx->tinfo.exec_domain       = NULL;
 172         irqctx->tinfo.cpu               = cpu;
 173         irqctx->tinfo.preempt_count     = HARDIRQ_OFFSET;
 174         irqctx->tinfo.addr_limit        = MAKE_MM_SEG(0);
 175
 176         hardirq_ctx[cpu] = irqctx;
 177
 178         irqctx = (union irq_ctx*) &softirq_stack[cpu*THREAD_SIZE];
 179         irqctx->tinfo.task              = NULL;
 180         irqctx->tinfo.exec_domain       = NULL;
 181         irqctx->tinfo.cpu               = cpu;
 182         irqctx->tinfo.preempt_count     = 0;
 183         irqctx->tinfo.addr_limit        = MAKE_MM_SEG(0);
 184
 185         softirq_ctx[cpu] = irqctx;
 186
 187         printk("CPU %u irqstacks, hard=%p soft=%p\n",
 188                 cpu,hardirq_ctx[cpu],softirq_ctx[cpu]);
 189 }
 190
 191 void irq_ctx_exit(int cpu)
 192 {
 193         hardirq_ctx[cpu] = NULL;
 194 }
 195
 196 extern asmlinkage void __do_softirq(void);
 197
 198 asmlinkage void do_softirq(void)
 199 {
 200         unsigned long flags;
 201         struct thread_info *curctx;
 202         union irq_ctx *irqctx;
 203         u32 *isp;
 204
 205         if (in_interrupt())
 206                 return;
 207
 208         local_irq_save(flags);
 209
 210         if (local_softirq_pending()) {
 211                 curctx = current_thread_info();
 212                 irqctx = softirq_ctx[smp_processor_id()];
 213                 irqctx->tinfo.task = curctx->task;
 214                 irqctx->tinfo.previous_esp = current_stack_pointer;
 215
 216                 /* build the stack frame on the softirq stack */
 217                 isp = (u32*) ((char*)irqctx + sizeof(*irqctx));
 218
 219                 asm volatile(
 220                         "       xchgl   %%ebx,%%esp     \n"
 221                         "       call    __do_softirq    \n"
 222                         "       movl    %%ebx,%%esp     \n"
 223                         : "=b"(isp)
 224                         : "0"(isp)
 225                         : "memory", "cc", "edx", "ecx", "eax"
 226                 );
 227                 /*
 228                  * Shouldnt happen, we returned above if in_interrupt():
 229                  */
 230                 WARN_ON_ONCE(softirq_count());
 231         }
 232
 233         local_irq_restore(flags);
 234 }
 235
 236 EXPORT_SYMBOL(do_softirq);
 237 #endif
 238
 239 /*
 240  * Interrupt statistics:
 241  */
 242
 243 atomic_t irq_err_count;
 244
 245 /*
 246  * /proc/interrupts printing:
 247  */
 248
 249 int show_interrupts(struct seq_file *p, void *v)
 250 {
 251         int i = *(loff_t *) v, j;
 252         struct irqaction * action;
 253         unsigned long flags;
 254
 255         if (i == 0) {
 256                 seq_printf(p, "           ");
 257                 for_each_online_cpu(j)
 258                         seq_printf(p, "CPU%-8d",j);
 259                 seq_putc(p, '\n');
 260         }
 261
 262         if (i < NR_IRQS) {
 263                 spin_lock_irqsave(&irq_desc[i].lock, flags);
 264                 action = irq_desc[i].action;
 265                 if (!action)
 266                         goto skip;
 267                 seq_printf(p, "%3d: ",i);
 268 #ifndef CONFIG_SMP
 269                 seq_printf(p, "%10u ", kstat_irqs(i));
 270 #else
 271                 for_each_online_cpu(j)
 272                         seq_printf(p, "%10u ", kstat_cpu(j).irqs[i]);
 273 #endif
 274                 seq_printf(p, " %8s", irq_desc[i].chip->name);
 275                 seq_printf(p, "-%-8s", irq_desc[i].name);
 276                 seq_printf(p, "  %s", action->name);
 277
 278                 for (action=action->next; action; action = action->next)
 279                         seq_printf(p, ", %s", action->name);
 280
 281                 seq_putc(p, '\n');
 282 skip:
 283                 spin_unlock_irqrestore(&irq_desc[i].lock, flags);
 284         } else if (i == NR_IRQS) {
 285                 seq_printf(p, "NMI: ");
 286                 for_each_online_cpu(j)
 287                         seq_printf(p, "%10u ", nmi_count(j));
 288                 seq_putc(p, '\n');
 289 #ifdef CONFIG_X86_LOCAL_APIC
 290                 seq_printf(p, "LOC: ");
 291                 for_each_online_cpu(j)
 292                         seq_printf(p, "%10u ",
 293                                 per_cpu(irq_stat,j).apic_timer_irqs);
 294                 seq_putc(p, '\n');
 295 #endif
 296                 seq_printf(p, "ERR: %10u\n", atomic_read(&irq_err_count));
 297 #if defined(CONFIG_X86_IO_APIC)
 298                 seq_printf(p, "MIS: %10u\n", atomic_read(&irq_mis_count));
 299 #endif
 300         }
 301         return 0;
 302 }
 303
 304 #ifdef CONFIG_HOTPLUG_CPU
 305 #include <mach_apic.h>
 306
 307 void fixup_irqs(cpumask_t map)
 308 {
 309         unsigned int irq;
 310         static int warned;
 311
 312         for (irq = 0; irq < NR_IRQS; irq++) {
 313                 cpumask_t mask;
 314                 if (irq == 2)
 315                         continue;
 316
 317                 cpus_and(mask, irq_desc[irq].affinity, map);
 318                 if (any_online_cpu(mask) == NR_CPUS) {
 319                         printk("Breaking affinity for irq %i\n", irq);
 320                         mask = map;
 321                 }
 322                 if (irq_desc[irq].chip->set_affinity)
 323                         irq_desc[irq].chip->set_affinity(irq, mask);
 324                 else if (irq_desc[irq].action && !(warned++))
 325                         printk("Cannot set affinity for irq %i\n", irq);
 326         }
 327
 328 #if 0
 329         barrier();
 330         /* Ingo Molnar says: "after the IO-APIC masks have been redirected
 331            [note the nop - the interrupt-enable boundary on x86 is two
 332            instructions from sti] - to flush out pending hardirqs and
 333            IPIs. After this point nothing is supposed to reach this CPU." */
 334         __asm__ __volatile__("sti; nop; cli");
 335         barrier();
 336 #else
 337         /* That doesn't seem sufficient.  Give it 1ms. */
 338         local_irq_enable();
 339         mdelay(1);
 340         local_irq_disable();
 341 #endif
 342 }
 343 #endif
 344