arch/x86/kernel/irq_32.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_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
  25 EXPORT_PER_CPU_SYMBOL(irq_stat);
  26
  27 DEFINE_PER_CPU(struct pt_regs *, irq_regs);
  28 EXPORT_PER_CPU_SYMBOL(irq_regs);
  29
  30 /*
  31  * 'what should we do if we get a hw irq event on an illegal vector'.
  32  * each architecture has to answer this themselves.
  33  */
  34 void ack_bad_irq(unsigned int irq)
  35 {
  36         printk(KERN_ERR "unexpected IRQ trap at vector %02x\n", irq);
  37
  38 #ifdef CONFIG_X86_LOCAL_APIC
  39         /*
  40          * Currently unexpected vectors happen only on SMP and APIC.
  41          * We _must_ ack these because every local APIC has only N
  42          * irq slots per priority level, and a 'hanging, unacked' IRQ
  43          * holds up an irq slot - in excessive cases (when multiple
  44          * unexpected vectors occur) that might lock up the APIC
  45          * completely.
  46          * But only ack when the APIC is enabled -AK
  47          */
  48         if (cpu_has_apic)
  49                 ack_APIC_irq();
  50 #endif
  51 }
  52
  53 #ifdef CONFIG_4KSTACKS
  54 /*
  55  * per-CPU IRQ handling contexts (thread information and stack)
  56  */
  57 union irq_ctx {
  58         struct thread_info      tinfo;
  59         u32                     stack[THREAD_SIZE/sizeof(u32)];
  60 };
  61
  62 static union irq_ctx *hardirq_ctx[NR_CPUS] __read_mostly;
  63 static union irq_ctx *softirq_ctx[NR_CPUS] __read_mostly;
  64 #endif
  65
  66 /*
  67  * do_IRQ handles all normal device IRQ's (the special
  68  * SMP cross-CPU interrupts have their own specific
  69  * handlers).
  70  */
  71 fastcall unsigned int do_IRQ(struct pt_regs *regs)
  72 {
  73         struct pt_regs *old_regs;
  74         /* high bit used in ret_from_ code */
  75         int irq = ~regs->orig_eax;
  76         struct irq_desc *desc = irq_desc + irq;
  77 #ifdef CONFIG_4KSTACKS
  78         union irq_ctx *curctx, *irqctx;
  79         u32 *isp;
  80 #endif
  81
  82         if (unlikely((unsigned)irq >= NR_IRQS)) {
  83                 printk(KERN_EMERG "%s: cannot handle IRQ %d\n",
  84                                         __FUNCTION__, irq);
  85                 BUG();
  86         }
  87
  88         old_regs = set_irq_regs(regs);
  89         irq_enter();
  90 #ifdef CONFIG_DEBUG_STACKOVERFLOW
  91         /* Debugging check for stack overflow: is there less than 1KB free? */
  92         {
  93                 long esp;
  94
  95                 __asm__ __volatile__("andl %%esp,%0" :
  96                                         "=r" (esp) : "0" (THREAD_SIZE - 1));
  97                 if (unlikely(esp < (sizeof(struct thread_info) + STACK_WARN))) {
  98                         printk("do_IRQ: stack overflow: %ld\n",
  99                                 esp - sizeof(struct thread_info));
 100                         dump_stack();
 101                 }
 102         }
 103 #endif
 104
 105 #ifdef CONFIG_4KSTACKS
 106
 107         curctx = (union irq_ctx *) current_thread_info();
 108         irqctx = hardirq_ctx[smp_processor_id()];
 109
 110         /*
 111          * this is where we switch to the IRQ stack. However, if we are
 112          * already using the IRQ stack (because we interrupted a hardirq
 113          * handler) we can't do that and just have to keep using the
 114          * current stack (which is the irq stack already after all)
 115          */
 116         if (curctx != irqctx) {
 117                 int arg1, arg2, ebx;
 118
 119                 /* build the stack frame on the IRQ stack */
 120                 isp = (u32*) ((char*)irqctx + sizeof(*irqctx));
 121                 irqctx->tinfo.task = curctx->tinfo.task;
 122                 irqctx->tinfo.previous_esp = current_stack_pointer;
 123
 124                 /*
 125                  * Copy the softirq bits in preempt_count so that the
 126                  * softirq checks work in the hardirq context.
 127                  */
 128                 irqctx->tinfo.preempt_count =
 129                         (irqctx->tinfo.preempt_count & ~SOFTIRQ_MASK) |
 130                         (curctx->tinfo.preempt_count & SOFTIRQ_MASK);
 131
 132                 asm volatile(
 133                         "       xchgl  %%ebx,%%esp      \n"
 134                         "       call   *%%edi           \n"
 135                         "       movl   %%ebx,%%esp      \n"
 136                         : "=a" (arg1), "=d" (arg2), "=b" (ebx)
 137                         :  "0" (irq),   "1" (desc),  "2" (isp),
 138                            "D" (desc->handle_irq)
 139                         : "memory", "cc"
 140                 );
 141         } else
 142 #endif
 143                 desc->handle_irq(irq, desc);
 144
 145         irq_exit();
 146         set_irq_regs(old_regs);
 147         return 1;
 148 }
 149
 150 #ifdef CONFIG_4KSTACKS
 151
 152 static char softirq_stack[NR_CPUS * THREAD_SIZE]
 153                 __attribute__((__section__(".bss.page_aligned")));
 154
 155 static char hardirq_stack[NR_CPUS * THREAD_SIZE]
 156                 __attribute__((__section__(".bss.page_aligned")));
 157
 158 /*
 159  * allocate per-cpu stacks for hardirq and for softirq processing
 160  */
 161 void irq_ctx_init(int cpu)
 162 {
 163         union irq_ctx *irqctx;
 164
 165         if (hardirq_ctx[cpu])
 166                 return;
 167
 168         irqctx = (union irq_ctx*) &hardirq_stack[cpu*THREAD_SIZE];
 169         irqctx->tinfo.task              = NULL;
 170         irqctx->tinfo.exec_domain       = NULL;
 171         irqctx->tinfo.cpu               = cpu;
 172         irqctx->tinfo.preempt_count     = HARDIRQ_OFFSET;
 173         irqctx->tinfo.addr_limit        = MAKE_MM_SEG(0);
 174
 175         hardirq_ctx[cpu] = irqctx;
 176
 177         irqctx = (union irq_ctx*) &softirq_stack[cpu*THREAD_SIZE];
 178         irqctx->tinfo.task              = NULL;
 179         irqctx->tinfo.exec_domain       = NULL;
 180         irqctx->tinfo.cpu               = cpu;
 181         irqctx->tinfo.preempt_count     = 0;
 182         irqctx->tinfo.addr_limit        = MAKE_MM_SEG(0);
 183
 184         softirq_ctx[cpu] = irqctx;
 185
 186         printk("CPU %u irqstacks, hard=%p soft=%p\n",
 187                 cpu,hardirq_ctx[cpu],softirq_ctx[cpu]);
 188 }
 189
 190 void irq_ctx_exit(int cpu)
 191 {
 192         hardirq_ctx[cpu] = NULL;
 193 }
 194
 195 extern asmlinkage void __do_softirq(void);
 196
 197 asmlinkage void do_softirq(void)
 198 {
 199         unsigned long flags;
 200         struct thread_info *curctx;
 201         union irq_ctx *irqctx;
 202         u32 *isp;
 203
 204         if (in_interrupt())
 205                 return;
 206
 207         local_irq_save(flags);
 208
 209         if (local_softirq_pending()) {
 210                 curctx = current_thread_info();
 211                 irqctx = softirq_ctx[smp_processor_id()];
 212                 irqctx->tinfo.task = curctx->task;
 213                 irqctx->tinfo.previous_esp = current_stack_pointer;
 214
 215                 /* build the stack frame on the softirq stack */
 216                 isp = (u32*) ((char*)irqctx + sizeof(*irqctx));
 217
 218                 asm volatile(
 219                         "       xchgl   %%ebx,%%esp     \n"
 220                         "       call    __do_softirq    \n"
 221                         "       movl    %%ebx,%%esp     \n"
 222                         : "=b"(isp)
 223                         : "0"(isp)
 224                         : "memory", "cc", "edx", "ecx", "eax"
 225                 );
 226                 /*
 227                  * Shouldnt happen, we returned above if in_interrupt():
 228                  */
 229                 WARN_ON_ONCE(softirq_count());
 230         }
 231
 232         local_irq_restore(flags);
 233 }
 234 #endif
 235
 236 /*
 237  * Interrupt statistics:
 238  */
 239
 240 atomic_t irq_err_count;
 241
 242 /*
 243  * /proc/interrupts printing:
 244  */
 245
 246 int show_interrupts(struct seq_file *p, void *v)
 247 {
 248         int i = *(loff_t *) v, j;
 249         struct irqaction * action;
 250         unsigned long flags;
 251
 252         if (i == 0) {
 253                 seq_printf(p, "           ");
 254                 for_each_online_cpu(j)
 255                         seq_printf(p, "CPU%-8d",j);
 256                 seq_putc(p, '\n');
 257         }
 258
 259         if (i < NR_IRQS) {
 260                 spin_lock_irqsave(&irq_desc[i].lock, flags);
 261                 action = irq_desc[i].action;
 262                 if (!action)
 263                         goto skip;
 264                 seq_printf(p, "%3d: ",i);
 265 #ifndef CONFIG_SMP
 266                 seq_printf(p, "%10u ", kstat_irqs(i));
 267 #else
 268                 for_each_online_cpu(j)
 269                         seq_printf(p, "%10u ", kstat_cpu(j).irqs[i]);
 270 #endif
 271                 seq_printf(p, " %8s", irq_desc[i].chip->name);
 272                 seq_printf(p, "-%-8s", irq_desc[i].name);
 273                 seq_printf(p, "  %s", action->name);
 274
 275                 for (action=action->next; action; action = action->next)
 276                         seq_printf(p, ", %s", action->name);
 277
 278                 seq_putc(p, '\n');
 279 skip:
 280                 spin_unlock_irqrestore(&irq_desc[i].lock, flags);
 281         } else if (i == NR_IRQS) {
 282                 seq_printf(p, "NMI: ");
 283                 for_each_online_cpu(j)
 284                         seq_printf(p, "%10u ", nmi_count(j));
 285                 seq_putc(p, '\n');
 286 #ifdef CONFIG_X86_LOCAL_APIC
 287                 seq_printf(p, "LOC: ");
 288                 for_each_online_cpu(j)
 289                         seq_printf(p, "%10u ",
 290                                 per_cpu(irq_stat,j).apic_timer_irqs);
 291                 seq_putc(p, '\n');
 292 #endif
 293                 seq_printf(p, "ERR: %10u\n", atomic_read(&irq_err_count));
 294 #if defined(CONFIG_X86_IO_APIC)
 295                 seq_printf(p, "MIS: %10u\n", atomic_read(&irq_mis_count));
 296 #endif
 297         }
 298         return 0;
 299 }
 300
 301 #ifdef CONFIG_HOTPLUG_CPU
 302 #include <mach_apic.h>
 303
 304 void fixup_irqs(cpumask_t map)
 305 {
 306         unsigned int irq;
 307         static int warned;
 308
 309         for (irq = 0; irq < NR_IRQS; irq++) {
 310                 cpumask_t mask;
 311                 if (irq == 2)
 312                         continue;
 313
 314                 cpus_and(mask, irq_desc[irq].affinity, map);
 315                 if (any_online_cpu(mask) == NR_CPUS) {
 316                         printk("Breaking affinity for irq %i\n", irq);
 317                         mask = map;
 318                 }
 319                 if (irq_desc[irq].chip->set_affinity)
 320                         irq_desc[irq].chip->set_affinity(irq, mask);
 321                 else if (irq_desc[irq].action && !(warned++))
 322                         printk("Cannot set affinity for irq %i\n", irq);
 323         }
 324
 325 #if 0
 326         barrier();
 327         /* Ingo Molnar says: "after the IO-APIC masks have been redirected
 328            [note the nop - the interrupt-enable boundary on x86 is two
 329            instructions from sti] - to flush out pending hardirqs and
 330            IPIs. After this point nothing is supposed to reach this CPU." */
 331         __asm__ __volatile__("sti; nop; cli");
 332         barrier();
 333 #else
 334         /* That doesn't seem sufficient.  Give it 1ms. */
 335         local_irq_enable();
 336         mdelay(1);
 337         local_irq_disable();
 338 #endif
 339 }
 340 #endif
 341