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 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         struct irq_desc *desc = irq_desc + irq;
  59 #ifdef CONFIG_4KSTACKS
  60         union irq_ctx *curctx, *irqctx;
  61         u32 *isp;
  62 #endif
  63
  64         if (unlikely((unsigned)irq >= NR_IRQS)) {
  65                 printk(KERN_EMERG "%s: cannot handle IRQ %d\n",
  66                                         __FUNCTION__, irq);
  67                 BUG();
  68         }
  69
  70         irq_enter();
  71 #ifdef CONFIG_DEBUG_STACKOVERFLOW
  72         /* Debugging check for stack overflow: is there less than 1KB free? */
  73         {
  74                 long esp;
  75
  76                 __asm__ __volatile__("andl %%esp,%0" :
  77                                         "=r" (esp) : "0" (THREAD_SIZE - 1));
  78                 if (unlikely(esp < (sizeof(struct thread_info) + STACK_WARN))) {
  79                         printk("do_IRQ: stack overflow: %ld\n",
  80                                 esp - sizeof(struct thread_info));
  81                         dump_stack();
  82                 }
  83         }
  84 #endif
  85
  86 #ifdef CONFIG_4KSTACKS
  87
  88         curctx = (union irq_ctx *) current_thread_info();
  89         irqctx = hardirq_ctx[smp_processor_id()];
  90
  91         /*
  92          * this is where we switch to the IRQ stack. However, if we are
  93          * already using the IRQ stack (because we interrupted a hardirq
  94          * handler) we can't do that and just have to keep using the
  95          * current stack (which is the irq stack already after all)
  96          */
  97         if (curctx != irqctx) {
  98                 int arg1, arg2, arg3, ebx;
  99
 100                 /* build the stack frame on the IRQ stack */
 101                 isp = (u32*) ((char*)irqctx + sizeof(*irqctx));
 102                 irqctx->tinfo.task = curctx->tinfo.task;
 103                 irqctx->tinfo.previous_esp = current_stack_pointer;
 104
 105                 /*
 106                  * Copy the softirq bits in preempt_count so that the
 107                  * softirq checks work in the hardirq context.
 108                  */
 109                 irqctx->tinfo.preempt_count =
 110                         (irqctx->tinfo.preempt_count & ~SOFTIRQ_MASK) |
 111                         (curctx->tinfo.preempt_count & SOFTIRQ_MASK);
 112
 113                 asm volatile(
 114                         "       xchgl  %%ebx,%%esp      \n"
 115                         "       call   *%%edi           \n"
 116                         "       movl   %%ebx,%%esp      \n"
 117                         : "=a" (arg1), "=d" (arg2), "=c" (arg3), "=b" (ebx)
 118                         :  "0" (irq),   "1" (desc),  "2" (regs),  "3" (isp),
 119                            "D" (desc->handle_irq)
 120                         : "memory", "cc"
 121                 );
 122         } else
 123 #endif
 124                 desc->handle_irq(irq, desc, regs);
 125
 126         irq_exit();
 127
 128         return 1;
 129 }
 130
 131 #ifdef CONFIG_4KSTACKS
 132
 133 /*
 134  * These should really be __section__(".bss.page_aligned") as well, but
 135  * gcc's 3.0 and earlier don't handle that correctly.
 136  */
 137 static char softirq_stack[NR_CPUS * THREAD_SIZE]
 138                 __attribute__((__aligned__(THREAD_SIZE)));
 139
 140 static char hardirq_stack[NR_CPUS * THREAD_SIZE]
 141                 __attribute__((__aligned__(THREAD_SIZE)));
 142
 143 /*
 144  * allocate per-cpu stacks for hardirq and for softirq processing
 145  */
 146 void irq_ctx_init(int cpu)
 147 {
 148         union irq_ctx *irqctx;
 149
 150         if (hardirq_ctx[cpu])
 151                 return;
 152
 153         irqctx = (union irq_ctx*) &hardirq_stack[cpu*THREAD_SIZE];
 154         irqctx->tinfo.task              = NULL;
 155         irqctx->tinfo.exec_domain       = NULL;
 156         irqctx->tinfo.cpu               = cpu;
 157         irqctx->tinfo.preempt_count     = HARDIRQ_OFFSET;
 158         irqctx->tinfo.addr_limit        = MAKE_MM_SEG(0);
 159
 160         hardirq_ctx[cpu] = irqctx;
 161
 162         irqctx = (union irq_ctx*) &softirq_stack[cpu*THREAD_SIZE];
 163         irqctx->tinfo.task              = NULL;
 164         irqctx->tinfo.exec_domain       = NULL;
 165         irqctx->tinfo.cpu               = cpu;
 166         irqctx->tinfo.preempt_count     = 0;
 167         irqctx->tinfo.addr_limit        = MAKE_MM_SEG(0);
 168
 169         softirq_ctx[cpu] = irqctx;
 170
 171         printk("CPU %u irqstacks, hard=%p soft=%p\n",
 172                 cpu,hardirq_ctx[cpu],softirq_ctx[cpu]);
 173 }
 174
 175 void irq_ctx_exit(int cpu)
 176 {
 177         hardirq_ctx[cpu] = NULL;
 178 }
 179
 180 extern asmlinkage void __do_softirq(void);
 181
 182 asmlinkage void do_softirq(void)
 183 {
 184         unsigned long flags;
 185         struct thread_info *curctx;
 186         union irq_ctx *irqctx;
 187         u32 *isp;
 188
 189         if (in_interrupt())
 190                 return;
 191
 192         local_irq_save(flags);
 193
 194         if (local_softirq_pending()) {
 195                 curctx = current_thread_info();
 196                 irqctx = softirq_ctx[smp_processor_id()];
 197                 irqctx->tinfo.task = curctx->task;
 198                 irqctx->tinfo.previous_esp = current_stack_pointer;
 199
 200                 /* build the stack frame on the softirq stack */
 201                 isp = (u32*) ((char*)irqctx + sizeof(*irqctx));
 202
 203                 asm volatile(
 204                         "       xchgl   %%ebx,%%esp     \n"
 205                         "       call    __do_softirq    \n"
 206                         "       movl    %%ebx,%%esp     \n"
 207                         : "=b"(isp)
 208                         : "0"(isp)
 209                         : "memory", "cc", "edx", "ecx", "eax"
 210                 );
 211                 /*
 212                  * Shouldnt happen, we returned above if in_interrupt():
 213                  */
 214                 WARN_ON_ONCE(softirq_count());
 215         }
 216
 217         local_irq_restore(flags);
 218 }
 219
 220 EXPORT_SYMBOL(do_softirq);
 221 #endif
 222
 223 /*
 224  * Interrupt statistics:
 225  */
 226
 227 atomic_t irq_err_count;
 228
 229 /*
 230  * /proc/interrupts printing:
 231  */
 232
 233 int show_interrupts(struct seq_file *p, void *v)
 234 {
 235         int i = *(loff_t *) v, j;
 236         struct irqaction * action;
 237         unsigned long flags;
 238
 239         if (i == 0) {
 240                 seq_printf(p, "           ");
 241                 for_each_online_cpu(j)
 242                         seq_printf(p, "CPU%-8d",j);
 243                 seq_putc(p, '\n');
 244         }
 245
 246         if (i < NR_IRQS) {
 247                 spin_lock_irqsave(&irq_desc[i].lock, flags);
 248                 action = irq_desc[i].action;
 249                 if (!action)
 250                         goto skip;
 251                 seq_printf(p, "%3d: ",i);
 252 #ifndef CONFIG_SMP
 253                 seq_printf(p, "%10u ", kstat_irqs(i));
 254 #else
 255                 for_each_online_cpu(j)
 256                         seq_printf(p, "%10u ", kstat_cpu(j).irqs[i]);
 257 #endif
 258                 seq_printf(p, " %8s", irq_desc[i].chip->name);
 259                 seq_printf(p, "-%s", handle_irq_name(irq_desc[i].handle_irq));
 260                 seq_printf(p, "  %s", action->name);
 261
 262                 for (action=action->next; action; action = action->next)
 263                         seq_printf(p, ", %s", action->name);
 264
 265                 seq_putc(p, '\n');
 266 skip:
 267                 spin_unlock_irqrestore(&irq_desc[i].lock, flags);
 268         } else if (i == NR_IRQS) {
 269                 seq_printf(p, "NMI: ");
 270                 for_each_online_cpu(j)
 271                         seq_printf(p, "%10u ", nmi_count(j));
 272                 seq_putc(p, '\n');
 273 #ifdef CONFIG_X86_LOCAL_APIC
 274                 seq_printf(p, "LOC: ");
 275                 for_each_online_cpu(j)
 276                         seq_printf(p, "%10u ",
 277                                 per_cpu(irq_stat,j).apic_timer_irqs);
 278                 seq_putc(p, '\n');
 279 #endif
 280                 seq_printf(p, "ERR: %10u\n", atomic_read(&irq_err_count));
 281 #if defined(CONFIG_X86_IO_APIC)
 282                 seq_printf(p, "MIS: %10u\n", atomic_read(&irq_mis_count));
 283 #endif
 284         }
 285         return 0;
 286 }
 287
 288 #ifdef CONFIG_HOTPLUG_CPU
 289 #include <mach_apic.h>
 290
 291 void fixup_irqs(cpumask_t map)
 292 {
 293         unsigned int irq;
 294         static int warned;
 295
 296         for (irq = 0; irq < NR_IRQS; irq++) {
 297                 cpumask_t mask;
 298                 if (irq == 2)
 299                         continue;
 300
 301                 cpus_and(mask, irq_desc[irq].affinity, map);
 302                 if (any_online_cpu(mask) == NR_CPUS) {
 303                         printk("Breaking affinity for irq %i\n", irq);
 304                         mask = map;
 305                 }
 306                 if (irq_desc[irq].chip->set_affinity)
 307                         irq_desc[irq].chip->set_affinity(irq, mask);
 308                 else if (irq_desc[irq].action && !(warned++))
 309                         printk("Cannot set affinity for irq %i\n", irq);
 310         }
 311
 312 #if 0
 313         barrier();
 314         /* Ingo Molnar says: "after the IO-APIC masks have been redirected
 315            [note the nop - the interrupt-enable boundary on x86 is two
 316            instructions from sti] - to flush out pending hardirqs and
 317            IPIs. After this point nothing is supposed to reach this CPU." */
 318         __asm__ __volatile__("sti; nop; cli");
 319         barrier();
 320 #else
 321         /* That doesn't seem sufficient.  Give it 1ms. */
 322         local_irq_enable();
 323         mdelay(1);
 324         local_irq_disable();
 325 #endif
 326 }
 327 #endif
 328