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