arch/x86/kernel/irq_32.c

   1 /*
   2  *      Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
   3  *
   4  * This file contains the lowest level x86-specific interrupt
   5  * entry, irq-stacks and irq statistics code. All the remaining
   6  * irq logic is done by the generic kernel/irq/ code and
   7  * by the x86-specific irq controller code. (e.g. i8259.c and
   8  * io_apic.c.)
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/seq_file.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/kernel_stat.h>
  15 #include <linux/notifier.h>
  16 #include <linux/cpu.h>
  17 #include <linux/delay.h>
  18
  19 #include <asm/apic.h>
  20 #include <asm/uaccess.h>
  21
  22 DEFINE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
  23 EXPORT_PER_CPU_SYMBOL(irq_stat);
  24
  25 DEFINE_PER_CPU(struct pt_regs *, irq_regs);
  26 EXPORT_PER_CPU_SYMBOL(irq_regs);
  27
  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(KERN_ERR "unexpected IRQ trap at vector %02x\n", irq);
  35
  36 #ifdef CONFIG_X86_LOCAL_APIC
  37         /*
  38          * Currently unexpected vectors happen only on SMP and APIC.
  39          * We _must_ ack these because every local APIC has only N
  40          * irq slots per priority level, and a 'hanging, unacked' IRQ
  41          * holds up an irq slot - in excessive cases (when multiple
  42          * unexpected vectors occur) that might lock up the APIC
  43          * completely.
  44          * But only ack when the APIC is enabled -AK
  45          */
  46         if (cpu_has_apic)
  47                 ack_APIC_irq();
  48 #endif
  49 }
  50
  51 #ifdef CONFIG_DEBUG_STACKOVERFLOW
  52 /* Debugging check for stack overflow: is there less than 1KB free? */
  53 static int check_stack_overflow(void)
  54 {
  55         long sp;
  56
  57         __asm__ __volatile__("andl %%esp,%0" :
  58                              "=r" (sp) : "0" (THREAD_SIZE - 1));
  59
  60         return sp < (sizeof(struct thread_info) + STACK_WARN);
  61 }
  62
  63 static void print_stack_overflow(void)
  64 {
  65         printk(KERN_WARNING "low stack detected by irq handler\n");
  66         dump_stack();
  67 }
  68
  69 #else
  70 static inline int check_stack_overflow(void) { return 0; }
  71 static inline void print_stack_overflow(void) { }
  72 #endif
  73
  74 #ifdef CONFIG_4KSTACKS
  75 /*
  76  * per-CPU IRQ handling contexts (thread information and stack)
  77  */
  78 union irq_ctx {
  79         struct thread_info      tinfo;
  80         u32                     stack[THREAD_SIZE/sizeof(u32)];
  81 };
  82
  83 static union irq_ctx *hardirq_ctx[NR_CPUS] __read_mostly;
  84 static union irq_ctx *softirq_ctx[NR_CPUS] __read_mostly;
  85
  86 static char softirq_stack[NR_CPUS * THREAD_SIZE] __page_aligned_bss;
  87 static char hardirq_stack[NR_CPUS * THREAD_SIZE] __page_aligned_bss;
  88
  89 static void call_on_stack(void *func, void *stack)
  90 {
  91         asm volatile("xchgl     %%ebx,%%esp     \n"
  92                      "call      *%%edi          \n"
  93                      "movl      %%ebx,%%esp     \n"
  94                      : "=b" (stack)
  95                      : "0" (stack),
  96                        "D"(func)
  97                      : "memory", "cc", "edx", "ecx", "eax");
  98 }
  99
 100 static inline int
 101 execute_on_irq_stack(int overflow, struct irq_desc *desc, int irq)
 102 {
 103         union irq_ctx *curctx, *irqctx;
 104         u32 *isp, arg1, arg2;
 105
 106         curctx = (union irq_ctx *) current_thread_info();
 107         irqctx = hardirq_ctx[smp_processor_id()];
 108
 109         /*
 110          * this is where we switch to the IRQ stack. However, if we are
 111          * already using the IRQ stack (because we interrupted a hardirq
 112          * handler) we can't do that and just have to keep using the
 113          * current stack (which is the irq stack already after all)
 114          */
 115         if (unlikely(curctx == irqctx))
 116                 return 0;
 117
 118         /* build the stack frame on the IRQ stack */
 119         isp = (u32 *) ((char*)irqctx + sizeof(*irqctx));
 120         irqctx->tinfo.task = curctx->tinfo.task;
 121         irqctx->tinfo.previous_esp = current_stack_pointer;
 122
 123         /*
 124          * Copy the softirq bits in preempt_count so that the
 125          * softirq checks work in the hardirq context.
 126          */
 127         irqctx->tinfo.preempt_count =
 128                 (irqctx->tinfo.preempt_count & ~SOFTIRQ_MASK) |
 129                 (curctx->tinfo.preempt_count & SOFTIRQ_MASK);
 130
 131         if (unlikely(overflow))
 132                 call_on_stack(print_stack_overflow, isp);
 133
 134         asm volatile("xchgl     %%ebx,%%esp     \n"
 135                      "call      *%%edi          \n"
 136                      "movl      %%ebx,%%esp     \n"
 137                      : "=a" (arg1), "=d" (arg2), "=b" (isp)
 138                      :  "0" (irq),   "1" (desc),  "2" (isp),
 139                         "D" (desc->handle_irq)
 140                      : "memory", "cc", "ecx");
 141         return 1;
 142 }
 143
 144 /*
 145  * allocate per-cpu stacks for hardirq and for softirq processing
 146  */
 147 void __cpuinit irq_ctx_init(int cpu)
 148 {
 149         union irq_ctx *irqctx;
 150
 151         if (hardirq_ctx[cpu])
 152                 return;
 153
 154         irqctx = (union irq_ctx*) &hardirq_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     = HARDIRQ_OFFSET;
 159         irqctx->tinfo.addr_limit        = MAKE_MM_SEG(0);
 160
 161         hardirq_ctx[cpu] = irqctx;
 162
 163         irqctx = (union irq_ctx*) &softirq_stack[cpu*THREAD_SIZE];
 164         irqctx->tinfo.task              = NULL;
 165         irqctx->tinfo.exec_domain       = NULL;
 166         irqctx->tinfo.cpu               = cpu;
 167         irqctx->tinfo.preempt_count     = 0;
 168         irqctx->tinfo.addr_limit        = MAKE_MM_SEG(0);
 169
 170         softirq_ctx[cpu] = irqctx;
 171
 172         printk(KERN_DEBUG "CPU %u irqstacks, hard=%p soft=%p\n",
 173                cpu,hardirq_ctx[cpu],softirq_ctx[cpu]);
 174 }
 175
 176 void irq_ctx_exit(int cpu)
 177 {
 178         hardirq_ctx[cpu] = NULL;
 179 }
 180
 181 asmlinkage void do_softirq(void)
 182 {
 183         unsigned long flags;
 184         struct thread_info *curctx;
 185         union irq_ctx *irqctx;
 186         u32 *isp;
 187
 188         if (in_interrupt())
 189                 return;
 190
 191         local_irq_save(flags);
 192
 193         if (local_softirq_pending()) {
 194                 curctx = current_thread_info();
 195                 irqctx = softirq_ctx[smp_processor_id()];
 196                 irqctx->tinfo.task = curctx->task;
 197                 irqctx->tinfo.previous_esp = current_stack_pointer;
 198
 199                 /* build the stack frame on the softirq stack */
 200                 isp = (u32*) ((char*)irqctx + sizeof(*irqctx));
 201
 202                 call_on_stack(__do_softirq, isp);
 203                 /*
 204                  * Shouldnt happen, we returned above if in_interrupt():
 205                  */
 206                 WARN_ON_ONCE(softirq_count());
 207         }
 208
 209         local_irq_restore(flags);
 210 }
 211
 212 #else
 213 static inline int
 214 execute_on_irq_stack(int overflow, struct irq_desc *desc, int irq) { return 0; }
 215 #endif
 216
 217 /*
 218  * do_IRQ handles all normal device IRQ's (the special
 219  * SMP cross-CPU interrupts have their own specific
 220  * handlers).
 221  */
 222 unsigned int do_IRQ(struct pt_regs *regs)
 223 {
 224         struct pt_regs *old_regs;
 225         /* high bit used in ret_from_ code */
 226         int overflow;
 227         unsigned vector = ~regs->orig_ax;
 228         struct irq_desc *desc;
 229         unsigned irq;
 230
 231
 232         old_regs = set_irq_regs(regs);
 233         irq_enter();
 234         irq = __get_cpu_var(vector_irq)[vector];
 235
 236         overflow = check_stack_overflow();
 237
 238         desc = irq_to_desc(irq);
 239         if (unlikely(!desc)) {
 240                 printk(KERN_EMERG "%s: cannot handle IRQ %d vector %#x cpu %d\n",
 241                                         __func__, irq, vector, smp_processor_id());
 242                 BUG();
 243         }
 244
 245         if (!execute_on_irq_stack(overflow, desc, irq)) {
 246                 if (unlikely(overflow))
 247                         print_stack_overflow();
 248                 desc->handle_irq(irq, desc);
 249         }
 250
 251         irq_exit();
 252         set_irq_regs(old_regs);
 253         return 1;
 254 }
 255
 256 #ifdef CONFIG_HOTPLUG_CPU
 257 #include <mach_apic.h>
 258
 259 void fixup_irqs(cpumask_t map)
 260 {
 261         unsigned int irq;
 262         static int warned;
 263         struct irq_desc *desc;
 264
 265         for_each_irq_desc(irq, desc) {
 266                 cpumask_t mask;
 267
 268                 if (irq == 2)
 269                         continue;
 270
 271                 cpus_and(mask, desc->affinity, map);
 272                 if (any_online_cpu(mask) == NR_CPUS) {
 273                         printk("Breaking affinity for irq %i\n", irq);
 274                         mask = map;
 275                 }
 276                 if (desc->chip->set_affinity)
 277                         desc->chip->set_affinity(irq, mask);
 278                 else if (desc->action && !(warned++))
 279                         printk("Cannot set affinity for irq %i\n", irq);
 280         }
 281
 282 #if 0
 283         barrier();
 284         /* Ingo Molnar says: "after the IO-APIC masks have been redirected
 285            [note the nop - the interrupt-enable boundary on x86 is two
 286            instructions from sti] - to flush out pending hardirqs and
 287            IPIs. After this point nothing is supposed to reach this CPU." */
 288         __asm__ __volatile__("sti; nop; cli");
 289         barrier();
 290 #else
 291         /* That doesn't seem sufficient.  Give it 1ms. */
 292         local_irq_enable();
 293         mdelay(1);
 294         local_irq_disable();
 295 #endif
 296 }
 297 #endif
 298