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
  19 DEFINE_PER_CPU(irq_cpustat_t, irq_stat) ____cacheline_maxaligned_in_smp;
  20 EXPORT_PER_CPU_SYMBOL(irq_stat);
  21
  22 #ifndef CONFIG_X86_LOCAL_APIC
  23 /*
  24  * 'what should we do if we get a hw irq event on an illegal vector'.
  25  * each architecture has to answer this themselves.
  26  */
  27 void ack_bad_irq(unsigned int irq)
  28 {
  29         printk("unexpected IRQ trap at vector %02x\n", irq);
  30 }
  31 #endif
  32
  33 #ifdef CONFIG_4KSTACKS
  34 /*
  35  * per-CPU IRQ handling contexts (thread information and stack)
  36  */
  37 union irq_ctx {
  38         struct thread_info      tinfo;
  39         u32                     stack[THREAD_SIZE/sizeof(u32)];
  40 };
  41
  42 static union irq_ctx *hardirq_ctx[NR_CPUS];
  43 static union irq_ctx *softirq_ctx[NR_CPUS];
  44 #endif
  45
  46 /*
  47  * do_IRQ handles all normal device IRQ's (the special
  48  * SMP cross-CPU interrupts have their own specific
  49  * handlers).
  50  */
  51 fastcall unsigned int do_IRQ(struct pt_regs *regs)
  52 {
  53         /* high bits used in ret_from_ code */
  54         int irq = regs->orig_eax & 0xff;
  55 #ifdef CONFIG_4KSTACKS
  56         union irq_ctx *curctx, *irqctx;
  57         u32 *isp;
  58 #endif
  59
  60         irq_enter();
  61 #ifdef CONFIG_DEBUG_STACKOVERFLOW
  62         /* Debugging check for stack overflow: is there less than 1KB free? */
  63         {
  64                 long esp;
  65
  66                 __asm__ __volatile__("andl %%esp,%0" :
  67                                         "=r" (esp) : "0" (THREAD_SIZE - 1));
  68                 if (unlikely(esp < (sizeof(struct thread_info) + STACK_WARN))) {
  69                         printk("do_IRQ: stack overflow: %ld\n",
  70                                 esp - sizeof(struct thread_info));
  71                         dump_stack();
  72                 }
  73         }
  74 #endif
  75
  76 #ifdef CONFIG_4KSTACKS
  77
  78         curctx = (union irq_ctx *) current_thread_info();
  79         irqctx = hardirq_ctx[smp_processor_id()];
  80
  81         /*
  82          * this is where we switch to the IRQ stack. However, if we are
  83          * already using the IRQ stack (because we interrupted a hardirq
  84          * handler) we can't do that and just have to keep using the
  85          * current stack (which is the irq stack already after all)
  86          */
  87         if (curctx != irqctx) {
  88                 int arg1, arg2, ebx;
  89
  90                 /* build the stack frame on the IRQ stack */
  91                 isp = (u32*) ((char*)irqctx + sizeof(*irqctx));
  92                 irqctx->tinfo.task = curctx->tinfo.task;
  93                 irqctx->tinfo.previous_esp = current_stack_pointer;
  94
  95                 asm volatile(
  96                         "       xchgl   %%ebx,%%esp      \n"
  97                         "       call    __do_IRQ         \n"
  98                         "       movl   %%ebx,%%esp      \n"
  99                         : "=a" (arg1), "=d" (arg2), "=b" (ebx)
 100                         :  "0" (irq),   "1" (regs),  "2" (isp)
 101                         : "memory", "cc", "ecx"
 102                 );
 103         } else
 104 #endif
 105                 __do_IRQ(irq, regs);
 106
 107         irq_exit();
 108
 109         return 1;
 110 }
 111
 112 #ifdef CONFIG_4KSTACKS
 113
 114 /*
 115  * These should really be __section__(".bss.page_aligned") as well, but
 116  * gcc's 3.0 and earlier don't handle that correctly.
 117  */
 118 static char softirq_stack[NR_CPUS * THREAD_SIZE]
 119                 __attribute__((__aligned__(THREAD_SIZE)));
 120
 121 static char hardirq_stack[NR_CPUS * THREAD_SIZE]
 122                 __attribute__((__aligned__(THREAD_SIZE)));
 123
 124 /*
 125  * allocate per-cpu stacks for hardirq and for softirq processing
 126  */
 127 void irq_ctx_init(int cpu)
 128 {
 129         union irq_ctx *irqctx;
 130
 131         if (hardirq_ctx[cpu])
 132                 return;
 133
 134         irqctx = (union irq_ctx*) &hardirq_stack[cpu*THREAD_SIZE];
 135         irqctx->tinfo.task              = NULL;
 136         irqctx->tinfo.exec_domain       = NULL;
 137         irqctx->tinfo.cpu               = cpu;
 138         irqctx->tinfo.preempt_count     = HARDIRQ_OFFSET;
 139         irqctx->tinfo.addr_limit        = MAKE_MM_SEG(0);
 140
 141         hardirq_ctx[cpu] = irqctx;
 142
 143         irqctx = (union irq_ctx*) &softirq_stack[cpu*THREAD_SIZE];
 144         irqctx->tinfo.task              = NULL;
 145         irqctx->tinfo.exec_domain       = NULL;
 146         irqctx->tinfo.cpu               = cpu;
 147         irqctx->tinfo.preempt_count     = SOFTIRQ_OFFSET;
 148         irqctx->tinfo.addr_limit        = MAKE_MM_SEG(0);
 149
 150         softirq_ctx[cpu] = irqctx;
 151
 152         printk("CPU %u irqstacks, hard=%p soft=%p\n",
 153                 cpu,hardirq_ctx[cpu],softirq_ctx[cpu]);
 154 }
 155
 156 extern asmlinkage void __do_softirq(void);
 157
 158 asmlinkage void do_softirq(void)
 159 {
 160         unsigned long flags;
 161         struct thread_info *curctx;
 162         union irq_ctx *irqctx;
 163         u32 *isp;
 164
 165         if (in_interrupt())
 166                 return;
 167
 168         local_irq_save(flags);
 169
 170         if (local_softirq_pending()) {
 171                 curctx = current_thread_info();
 172                 irqctx = softirq_ctx[smp_processor_id()];
 173                 irqctx->tinfo.task = curctx->task;
 174                 irqctx->tinfo.previous_esp = current_stack_pointer;
 175
 176                 /* build the stack frame on the softirq stack */
 177                 isp = (u32*) ((char*)irqctx + sizeof(*irqctx));
 178
 179                 asm volatile(
 180                         "       xchgl   %%ebx,%%esp     \n"
 181                         "       call    __do_softirq    \n"
 182                         "       movl    %%ebx,%%esp     \n"
 183                         : "=b"(isp)
 184                         : "0"(isp)
 185                         : "memory", "cc", "edx", "ecx", "eax"
 186                 );
 187         }
 188
 189         local_irq_restore(flags);
 190 }
 191
 192 EXPORT_SYMBOL(do_softirq);
 193 #endif
 194
 195 /*
 196  * Interrupt statistics:
 197  */
 198
 199 atomic_t irq_err_count;
 200
 201 /*
 202  * /proc/interrupts printing:
 203  */
 204
 205 int show_interrupts(struct seq_file *p, void *v)
 206 {
 207         int i = *(loff_t *) v, j;
 208         struct irqaction * action;
 209         unsigned long flags;
 210
 211         if (i == 0) {
 212                 seq_printf(p, "           ");
 213                 for (j=0; j<NR_CPUS; j++)
 214                         if (cpu_online(j))
 215                                 seq_printf(p, "CPU%d       ",j);
 216                 seq_putc(p, '\n');
 217         }
 218
 219         if (i < NR_IRQS) {
 220                 spin_lock_irqsave(&irq_desc[i].lock, flags);
 221                 action = irq_desc[i].action;
 222                 if (!action)
 223                         goto skip;
 224                 seq_printf(p, "%3d: ",i);
 225 #ifndef CONFIG_SMP
 226                 seq_printf(p, "%10u ", kstat_irqs(i));
 227 #else
 228                 for (j = 0; j < NR_CPUS; j++)
 229                         if (cpu_online(j))
 230                                 seq_printf(p, "%10u ", kstat_cpu(j).irqs[i]);
 231 #endif
 232                 seq_printf(p, " %14s", irq_desc[i].handler->typename);
 233                 seq_printf(p, "  %s", action->name);
 234
 235                 for (action=action->next; action; action = action->next)
 236                         seq_printf(p, ", %s", action->name);
 237
 238                 seq_putc(p, '\n');
 239 skip:
 240                 spin_unlock_irqrestore(&irq_desc[i].lock, flags);
 241         } else if (i == NR_IRQS) {
 242                 seq_printf(p, "NMI: ");
 243                 for (j = 0; j < NR_CPUS; j++)
 244                         if (cpu_online(j))
 245                                 seq_printf(p, "%10u ", nmi_count(j));
 246                 seq_putc(p, '\n');
 247 #ifdef CONFIG_X86_LOCAL_APIC
 248                 seq_printf(p, "LOC: ");
 249                 for (j = 0; j < NR_CPUS; j++)
 250                         if (cpu_online(j))
 251                                 seq_printf(p, "%10u ",
 252                                         per_cpu(irq_stat,j).apic_timer_irqs);
 253                 seq_putc(p, '\n');
 254 #endif
 255                 seq_printf(p, "ERR: %10u\n", atomic_read(&irq_err_count));
 256 #if defined(CONFIG_X86_IO_APIC)
 257                 seq_printf(p, "MIS: %10u\n", atomic_read(&irq_mis_count));
 258 #endif
 259         }
 260         return 0;
 261 }