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 bits used in ret_from_ code */
  57         int irq = regs->orig_eax & 0xff;
  58 #ifdef CONFIG_4KSTACKS
  59         union irq_ctx *curctx, *irqctx;
  60         u32 *isp;
  61 #endif
  62
  63         irq_enter();
  64 #ifdef CONFIG_DEBUG_STACKOVERFLOW
  65         /* Debugging check for stack overflow: is there less than 1KB free? */
  66         {
  67                 long esp;
  68
  69                 __asm__ __volatile__("andl %%esp,%0" :
  70                                         "=r" (esp) : "0" (THREAD_SIZE - 1));
  71                 if (unlikely(esp < (sizeof(struct thread_info) + STACK_WARN))) {
  72                         printk("do_IRQ: stack overflow: %ld\n",
  73                                 esp - sizeof(struct thread_info));
  74                         dump_stack();
  75                 }
  76         }
  77 #endif
  78
  79 #ifdef CONFIG_4KSTACKS
  80
  81         curctx = (union irq_ctx *) current_thread_info();
  82         irqctx = hardirq_ctx[smp_processor_id()];
  83
  84         /*
  85          * this is where we switch to the IRQ stack. However, if we are
  86          * already using the IRQ stack (because we interrupted a hardirq
  87          * handler) we can't do that and just have to keep using the
  88          * current stack (which is the irq stack already after all)
  89          */
  90         if (curctx != irqctx) {
  91                 int arg1, arg2, ebx;
  92
  93                 /* build the stack frame on the IRQ stack */
  94                 isp = (u32*) ((char*)irqctx + sizeof(*irqctx));
  95                 irqctx->tinfo.task = curctx->tinfo.task;
  96                 irqctx->tinfo.previous_esp = current_stack_pointer;
  97
  98                 /*
  99                  * Copy the softirq bits in preempt_count so that the
 100                  * softirq checks work in the hardirq context.
 101                  */
 102                 irqctx->tinfo.preempt_count =
 103                         irqctx->tinfo.preempt_count & ~SOFTIRQ_MASK |
 104                         curctx->tinfo.preempt_count & SOFTIRQ_MASK;
 105
 106                 asm volatile(
 107                         "       xchgl   %%ebx,%%esp      \n"
 108                         "       call    __do_IRQ         \n"
 109                         "       movl   %%ebx,%%esp      \n"
 110                         : "=a" (arg1), "=d" (arg2), "=b" (ebx)
 111                         :  "0" (irq),   "1" (regs),  "2" (isp)
 112                         : "memory", "cc", "ecx"
 113                 );
 114         } else
 115 #endif
 116                 __do_IRQ(irq, regs);
 117
 118         irq_exit();
 119
 120         return 1;
 121 }
 122
 123 #ifdef CONFIG_4KSTACKS
 124
 125 /*
 126  * These should really be __section__(".bss.page_aligned") as well, but
 127  * gcc's 3.0 and earlier don't handle that correctly.
 128  */
 129 static char softirq_stack[NR_CPUS * THREAD_SIZE]
 130                 __attribute__((__aligned__(THREAD_SIZE)));
 131
 132 static char hardirq_stack[NR_CPUS * THREAD_SIZE]
 133                 __attribute__((__aligned__(THREAD_SIZE)));
 134
 135 /*
 136  * allocate per-cpu stacks for hardirq and for softirq processing
 137  */
 138 void irq_ctx_init(int cpu)
 139 {
 140         union irq_ctx *irqctx;
 141
 142         if (hardirq_ctx[cpu])
 143                 return;
 144
 145         irqctx = (union irq_ctx*) &hardirq_stack[cpu*THREAD_SIZE];
 146         irqctx->tinfo.task              = NULL;
 147         irqctx->tinfo.exec_domain       = NULL;
 148         irqctx->tinfo.cpu               = cpu;
 149         irqctx->tinfo.preempt_count     = HARDIRQ_OFFSET;
 150         irqctx->tinfo.addr_limit        = MAKE_MM_SEG(0);
 151
 152         hardirq_ctx[cpu] = irqctx;
 153
 154         irqctx = (union irq_ctx*) &softirq_stack[cpu*THREAD_SIZE];
 155         irqctx->tinfo.task              = NULL;
 156         irqctx->tinfo.exec_domain       = NULL;
 157         irqctx->tinfo.cpu               = cpu;
 158         irqctx->tinfo.preempt_count     = SOFTIRQ_OFFSET;
 159         irqctx->tinfo.addr_limit        = MAKE_MM_SEG(0);
 160
 161         softirq_ctx[cpu] = irqctx;
 162
 163         printk("CPU %u irqstacks, hard=%p soft=%p\n",
 164                 cpu,hardirq_ctx[cpu],softirq_ctx[cpu]);
 165 }
 166
 167 void irq_ctx_exit(int cpu)
 168 {
 169         hardirq_ctx[cpu] = NULL;
 170 }
 171
 172 extern asmlinkage void __do_softirq(void);
 173
 174 asmlinkage void do_softirq(void)
 175 {
 176         unsigned long flags;
 177         struct thread_info *curctx;
 178         union irq_ctx *irqctx;
 179         u32 *isp;
 180
 181         if (in_interrupt())
 182                 return;
 183
 184         local_irq_save(flags);
 185
 186         if (local_softirq_pending()) {
 187                 curctx = current_thread_info();
 188                 irqctx = softirq_ctx[smp_processor_id()];
 189                 irqctx->tinfo.task = curctx->task;
 190                 irqctx->tinfo.previous_esp = current_stack_pointer;
 191
 192                 /* build the stack frame on the softirq stack */
 193                 isp = (u32*) ((char*)irqctx + sizeof(*irqctx));
 194
 195                 asm volatile(
 196                         "       xchgl   %%ebx,%%esp     \n"
 197                         "       call    __do_softirq    \n"
 198                         "       movl    %%ebx,%%esp     \n"
 199                         : "=b"(isp)
 200                         : "0"(isp)
 201                         : "memory", "cc", "edx", "ecx", "eax"
 202                 );
 203         }
 204
 205         local_irq_restore(flags);
 206 }
 207
 208 EXPORT_SYMBOL(do_softirq);
 209 #endif
 210
 211 /*
 212  * Interrupt statistics:
 213  */
 214
 215 atomic_t irq_err_count;
 216
 217 /*
 218  * /proc/interrupts printing:
 219  */
 220
 221 int show_interrupts(struct seq_file *p, void *v)
 222 {
 223         int i = *(loff_t *) v, j;
 224         struct irqaction * action;
 225         unsigned long flags;
 226
 227         if (i == 0) {
 228                 seq_printf(p, "           ");
 229                 for_each_online_cpu(j)
 230                         seq_printf(p, "CPU%d       ",j);
 231                 seq_putc(p, '\n');
 232         }
 233
 234         if (i < NR_IRQS) {
 235                 spin_lock_irqsave(&irq_desc[i].lock, flags);
 236                 action = irq_desc[i].action;
 237                 if (!action)
 238                         goto skip;
 239                 seq_printf(p, "%3d: ",i);
 240 #ifndef CONFIG_SMP
 241                 seq_printf(p, "%10u ", kstat_irqs(i));
 242 #else
 243                 for_each_online_cpu(j)
 244                         seq_printf(p, "%10u ", kstat_cpu(j).irqs[i]);
 245 #endif
 246                 seq_printf(p, " %14s", irq_desc[i].handler->typename);
 247                 seq_printf(p, "  %s", action->name);
 248
 249                 for (action=action->next; action; action = action->next)
 250                         seq_printf(p, ", %s", action->name);
 251
 252                 seq_putc(p, '\n');
 253 skip:
 254                 spin_unlock_irqrestore(&irq_desc[i].lock, flags);
 255         } else if (i == NR_IRQS) {
 256                 seq_printf(p, "NMI: ");
 257                 for_each_online_cpu(j)
 258                         seq_printf(p, "%10u ", nmi_count(j));
 259                 seq_putc(p, '\n');
 260 #ifdef CONFIG_X86_LOCAL_APIC
 261                 seq_printf(p, "LOC: ");
 262                 for_each_online_cpu(j)
 263                         seq_printf(p, "%10u ",
 264                                 per_cpu(irq_stat,j).apic_timer_irqs);
 265                 seq_putc(p, '\n');
 266 #endif
 267                 seq_printf(p, "ERR: %10u\n", atomic_read(&irq_err_count));
 268 #if defined(CONFIG_X86_IO_APIC)
 269                 seq_printf(p, "MIS: %10u\n", atomic_read(&irq_mis_count));
 270 #endif
 271         }
 272         return 0;
 273 }
 274
 275 #ifdef CONFIG_HOTPLUG_CPU
 276 #include <mach_apic.h>
 277
 278 void fixup_irqs(cpumask_t map)
 279 {
 280         unsigned int irq;
 281         static int warned;
 282
 283         for (irq = 0; irq < NR_IRQS; irq++) {
 284                 cpumask_t mask;
 285                 if (irq == 2)
 286                         continue;
 287
 288                 cpus_and(mask, irq_affinity[irq], map);
 289                 if (any_online_cpu(mask) == NR_CPUS) {
 290                         printk("Breaking affinity for irq %i\n", irq);
 291                         mask = map;
 292                 }
 293                 if (irq_desc[irq].handler->set_affinity)
 294                         irq_desc[irq].handler->set_affinity(irq, mask);
 295                 else if (irq_desc[irq].action && !(warned++))
 296                         printk("Cannot set affinity for irq %i\n", irq);
 297         }
 298
 299 #if 0
 300         barrier();
 301         /* Ingo Molnar says: "after the IO-APIC masks have been redirected
 302            [note the nop - the interrupt-enable boundary on x86 is two
 303            instructions from sti] - to flush out pending hardirqs and
 304            IPIs. After this point nothing is supposed to reach this CPU." */
 305         __asm__ __volatile__("sti; nop; cli");
 306         barrier();
 307 #else
 308         /* That doesn't seem sufficient.  Give it 1ms. */
 309         local_irq_enable();
 310         mdelay(1);
 311         local_irq_disable();
 312 #endif
 313 }
 314 #endif
 315