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traps_64.c

/*
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *  Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
 *
 *  Pentium III FXSR, SSE support
 *    Gareth Hughes <gareth@valinux.com>, May 2000
 */

/*
 * 'Traps.c' handles hardware traps and faults after we have saved some
 * state in 'entry.S'.
 */
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/timer.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/kallsyms.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/nmi.h>
#include <linux/kprobes.h>
#include <linux/kexec.h>
#include <linux/unwind.h>
#include <linux/uaccess.h>
#include <linux/bug.h>
#include <linux/kdebug.h>
#include <linux/utsname.h>

#if defined(CONFIG_EDAC)
#include <linux/edac.h>
#endif

#include <asm/system.h>
#include <asm/io.h>
#include <asm/atomic.h>
#include <asm/debugreg.h>
#include <asm/desc.h>
#include <asm/i387.h>
#include <asm/processor.h>
#include <asm/unwind.h>
#include <asm/smp.h>
#include <asm/pgalloc.h>
#include <asm/pda.h>
#include <asm/proto.h>
#include <asm/nmi.h>
#include <asm/stacktrace.h>

asmlinkage void divide_error(void);
asmlinkage void debug(void);
asmlinkage void nmi(void);
asmlinkage void int3(void);
asmlinkage void overflow(void);
asmlinkage void bounds(void);
asmlinkage void invalid_op(void);
asmlinkage void device_not_available(void);
asmlinkage void double_fault(void);
asmlinkage void coprocessor_segment_overrun(void);
asmlinkage void invalid_TSS(void);
asmlinkage void segment_not_present(void);
asmlinkage void stack_segment(void);
asmlinkage void general_protection(void);
asmlinkage void page_fault(void);
asmlinkage void coprocessor_error(void);
asmlinkage void simd_coprocessor_error(void);
asmlinkage void reserved(void);
asmlinkage void alignment_check(void);
asmlinkage void machine_check(void);
asmlinkage void spurious_interrupt_bug(void);

static inline void conditional_sti(struct pt_regs *regs)
{
      if (regs->eflags & X86_EFLAGS_IF)
            local_irq_enable();
}

static inline void preempt_conditional_sti(struct pt_regs *regs)
{
      preempt_disable();
      if (regs->eflags & X86_EFLAGS_IF)
            local_irq_enable();
}

static inline void preempt_conditional_cli(struct pt_regs *regs)
{
      if (regs->eflags & X86_EFLAGS_IF)
            local_irq_disable();
      /* Make sure to not schedule here because we could be running
         on an exception stack. */
      preempt_enable_no_resched();
}

int kstack_depth_to_print = 12;

#ifdef CONFIG_KALLSYMS
void printk_address(unsigned long address)
{
      unsigned long offset = 0, symsize;
      const char *symname;
      char *modname;
      char *delim = ":";
      char namebuf[128];

      symname = kallsyms_lookup(address, &symsize, &offset,
                              &modname, namebuf);
      if (!symname) {
            printk(" [<%016lx>]\n", address);
            return;
      }
      if (!modname)
            modname = delim = "";         
      printk(" [<%016lx>] %s%s%s%s+0x%lx/0x%lx\n",
            address, delim, modname, delim, symname, offset, symsize);
}
#else
void printk_address(unsigned long address)
{
      printk(" [<%016lx>]\n", address);
}
#endif

static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
                              unsigned *usedp, char **idp)
{
      static char ids[][8] = {
            [DEBUG_STACK - 1] = "#DB",
            [NMI_STACK - 1] = "NMI",
            [DOUBLEFAULT_STACK - 1] = "#DF",
            [STACKFAULT_STACK - 1] = "#SS",
            [MCE_STACK - 1] = "#MC",
#if DEBUG_STKSZ > EXCEPTION_STKSZ
            [N_EXCEPTION_STACKS ... N_EXCEPTION_STACKS + DEBUG_STKSZ / EXCEPTION_STKSZ - 2] = "#DB[?]"
#endif
      };
      unsigned k;

      /*
       * Iterate over all exception stacks, and figure out whether
       * 'stack' is in one of them:
       */
      for (k = 0; k < N_EXCEPTION_STACKS; k++) {
            unsigned long end = per_cpu(orig_ist, cpu).ist[k];
            /*
             * Is 'stack' above this exception frame's end?
             * If yes then skip to the next frame.
             */
            if (stack >= end)
                  continue;
            /*
             * Is 'stack' above this exception frame's start address?
             * If yes then we found the right frame.
             */
            if (stack >= end - EXCEPTION_STKSZ) {
                  /*
                   * Make sure we only iterate through an exception
                   * stack once. If it comes up for the second time
                   * then there's something wrong going on - just
                   * break out and return NULL:
                   */
                  if (*usedp & (1U << k))
                        break;
                  *usedp |= 1U << k;
                  *idp = ids[k];
                  return (unsigned long *)end;
            }
            /*
             * If this is a debug stack, and if it has a larger size than
             * the usual exception stacks, then 'stack' might still
             * be within the lower portion of the debug stack:
             */
#if DEBUG_STKSZ > EXCEPTION_STKSZ
            if (k == DEBUG_STACK - 1 && stack >= end - DEBUG_STKSZ) {
                  unsigned j = N_EXCEPTION_STACKS - 1;

                  /*
                   * Black magic. A large debug stack is composed of
                   * multiple exception stack entries, which we
                   * iterate through now. Dont look:
                   */
                  do {
                        ++j;
                        end -= EXCEPTION_STKSZ;
                        ids[j][4] = '1' + (j - N_EXCEPTION_STACKS);
                  } while (stack < end - EXCEPTION_STKSZ);
                  if (*usedp & (1U << j))
                        break;
                  *usedp |= 1U << j;
                  *idp = ids[j];
                  return (unsigned long *)end;
            }
#endif
      }
      return NULL;
}

#define MSG(txt) ops->warning(data, txt)

/*
 * x86-64 can have up to three kernel stacks: 
 * process stack
 * interrupt stack
 * severe exception (double fault, nmi, stack fault, debug, mce) hardware stack
 */

static inline int valid_stack_ptr(struct thread_info *tinfo, void *p)
{
      void *t = (void *)tinfo;
        return p > t && p < t + THREAD_SIZE - 3;
}

void dump_trace(struct task_struct *tsk, struct pt_regs *regs,
            unsigned long *stack,
            const struct stacktrace_ops *ops, void *data)
{
      const unsigned cpu = get_cpu();
      unsigned long *irqstack_end = (unsigned long*)cpu_pda(cpu)->irqstackptr;
      unsigned used = 0;
      struct thread_info *tinfo;

      if (!tsk)
            tsk = current;

      if (!stack) {
            unsigned long dummy;
            stack = &dummy;
            if (tsk && tsk != current)
                  stack = (unsigned long *)tsk->thread.rsp;
      }

      /*
       * Print function call entries within a stack. 'cond' is the
       * "end of stackframe" condition, that the 'stack++'
       * iteration will eventually trigger.
       */
#define HANDLE_STACK(cond) \
      do while (cond) { \
            unsigned long addr = *stack++; \
            /* Use unlocked access here because except for NMIs   \
               we should be already protected against module unloads */ \
            if (__kernel_text_address(addr)) { \
                  /* \
                   * If the address is either in the text segment of the \
                   * kernel, or in the region which contains vmalloc'ed \
                   * memory, it *may* be the address of a calling \
                   * routine; if so, print it so that someone tracing \
                   * down the cause of the crash will be able to figure \
                   * out the call path that was taken. \
                   */ \
                  ops->address(data, addr);   \
            } \
      } while (0)

      /*
       * Print function call entries in all stacks, starting at the
       * current stack address. If the stacks consist of nested
       * exceptions
       */
      for (;;) {
            char *id;
            unsigned long *estack_end;
            estack_end = in_exception_stack(cpu, (unsigned long)stack,
                                    &used, &id);

            if (estack_end) {
                  if (ops->stack(data, id) < 0)
                        break;
                  HANDLE_STACK (stack < estack_end);
                  ops->stack(data, "<EOE>");
                  /*
                   * We link to the next stack via the
                   * second-to-last pointer (index -2 to end) in the
                   * exception stack:
                   */
                  stack = (unsigned long *) estack_end[-2];
                  continue;
            }
            if (irqstack_end) {
                  unsigned long *irqstack;
                  irqstack = irqstack_end -
                        (IRQSTACKSIZE - 64) / sizeof(*irqstack);

                  if (stack >= irqstack && stack < irqstack_end) {
                        if (ops->stack(data, "IRQ") < 0)
                              break;
                        HANDLE_STACK (stack < irqstack_end);
                        /*
                         * We link to the next stack (which would be
                         * the process stack normally) the last
                         * pointer (index -1 to end) in the IRQ stack:
                         */
                        stack = (unsigned long *) (irqstack_end[-1]);
                        irqstack_end = NULL;
                        ops->stack(data, "EOI");
                        continue;
                  }
            }
            break;
      }

      /*
       * This handles the process stack:
       */
      tinfo = task_thread_info(tsk);
      HANDLE_STACK (valid_stack_ptr(tinfo, stack));
#undef HANDLE_STACK
      put_cpu();
}
EXPORT_SYMBOL(dump_trace);

static void
print_trace_warning_symbol(void *data, char *msg, unsigned long symbol)
{
      print_symbol(msg, symbol);
      printk("\n");
}

static void print_trace_warning(void *data, char *msg)
{
      printk("%s\n", msg);
}

static int print_trace_stack(void *data, char *name)
{
      printk(" <%s> ", name);
      return 0;
}

static void print_trace_address(void *data, unsigned long addr)
{
      touch_nmi_watchdog();
      printk_address(addr);
}

static const struct stacktrace_ops print_trace_ops = {
      .warning = print_trace_warning,
      .warning_symbol = print_trace_warning_symbol,
      .stack = print_trace_stack,
      .address = print_trace_address,
};

void
show_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long *stack)
{
      printk("\nCall Trace:\n");
      dump_trace(tsk, regs, stack, &print_trace_ops, NULL);
      printk("\n");
}

static void
_show_stack(struct task_struct *tsk, struct pt_regs *regs, unsigned long *rsp)
{
      unsigned long *stack;
      int i;
      const int cpu = smp_processor_id();
      unsigned long *irqstack_end = (unsigned long *) (cpu_pda(cpu)->irqstackptr);
      unsigned long *irqstack = (unsigned long *) (cpu_pda(cpu)->irqstackptr - IRQSTACKSIZE);

      // debugging aid: "show_stack(NULL, NULL);" prints the
      // back trace for this cpu.

      if (rsp == NULL) {
            if (tsk)
                  rsp = (unsigned long *)tsk->thread.rsp;
            else
                  rsp = (unsigned long *)&rsp;
      }

      stack = rsp;
      for(i=0; i < kstack_depth_to_print; i++) {
            if (stack >= irqstack && stack <= irqstack_end) {
                  if (stack == irqstack_end) {
                        stack = (unsigned long *) (irqstack_end[-1]);
                        printk(" <EOI> ");
                  }
            } else {
            if (((long) stack & (THREAD_SIZE-1)) == 0)
                  break;
            }
            if (i && ((i % 4) == 0))
                  printk("\n");
            printk(" %016lx", *stack++);
            touch_nmi_watchdog();
      }
      show_trace(tsk, regs, rsp);
}

void show_stack(struct task_struct *tsk, unsigned long * rsp)
{
      _show_stack(tsk, NULL, rsp);
}

/*
 * The architecture-independent dump_stack generator
 */
void dump_stack(void)
{
      unsigned long dummy;

      printk("Pid: %d, comm: %.20s %s %s %.*s\n",
            current->pid, current->comm, print_tainted(),
            init_utsname()->release,
            (int)strcspn(init_utsname()->version, " "),
            init_utsname()->version);
      show_trace(NULL, NULL, &dummy);
}

EXPORT_SYMBOL(dump_stack);

void show_registers(struct pt_regs *regs)
{
      int i;
      int in_kernel = !user_mode(regs);
      unsigned long rsp;
      const int cpu = smp_processor_id();
      struct task_struct *cur = cpu_pda(cpu)->pcurrent;

      rsp = regs->rsp;
      printk("CPU %d ", cpu);
      __show_regs(regs);
      printk("Process %s (pid: %d, threadinfo %p, task %p)\n",
            cur->comm, cur->pid, task_thread_info(cur), cur);

      /*
       * When in-kernel, we also print out the stack and code at the
       * time of the fault..
       */
      if (in_kernel) {
            printk("Stack: ");
            _show_stack(NULL, regs, (unsigned long*)rsp);

            printk("\nCode: ");
            if (regs->rip < PAGE_OFFSET)
                  goto bad;

            for (i=0; i<20; i++) {
                  unsigned char c;
                  if (__get_user(c, &((unsigned char*)regs->rip)[i])) {
bad:
                        printk(" Bad RIP value.");
                        break;
                  }
                  printk("%02x ", c);
            }
      }
      printk("\n");
}     

int is_valid_bugaddr(unsigned long rip)
{
      unsigned short ud2;

      if (__copy_from_user(&ud2, (const void __user *) rip, sizeof(ud2)))
            return 0;

      return ud2 == 0x0b0f;
}

#ifdef CONFIG_BUG
void out_of_line_bug(void)
{ 
      BUG(); 
} 
EXPORT_SYMBOL(out_of_line_bug);
#endif

static raw_spinlock_t die_lock = __RAW_SPIN_LOCK_UNLOCKED;
static int die_owner = -1;
static unsigned int die_nest_count;

unsigned __kprobes long oops_begin(void)
{
      int cpu;
      unsigned long flags;

      oops_enter();

      /* racy, but better than risking deadlock. */
      raw_local_irq_save(flags);
      cpu = smp_processor_id();
      if (!__raw_spin_trylock(&die_lock)) {
            if (cpu == die_owner) 
                  /* nested oops. should stop eventually */;
            else
                  __raw_spin_lock(&die_lock);
      }
      die_nest_count++;
      die_owner = cpu;
      console_verbose();
      bust_spinlocks(1);
      return flags;
}

void __kprobes oops_end(unsigned long flags)
{ 
      die_owner = -1;
      bust_spinlocks(0);
      die_nest_count--;
      if (!die_nest_count)
            /* Nest count reaches zero, release the lock. */
            __raw_spin_unlock(&die_lock);
      raw_local_irq_restore(flags);
      if (panic_on_oops)
            panic("Fatal exception");
      oops_exit();
}

void __kprobes __die(const char * str, struct pt_regs * regs, long err)
{
      static int die_counter;
      printk(KERN_EMERG "%s: %04lx [%u] ", str, err & 0xffff,++die_counter);
#ifdef CONFIG_PREEMPT
      printk("PREEMPT ");
#endif
#ifdef CONFIG_SMP
      printk("SMP ");
#endif
#ifdef CONFIG_DEBUG_PAGEALLOC
      printk("DEBUG_PAGEALLOC");
#endif
      printk("\n");
      notify_die(DIE_OOPS, str, regs, err, current->thread.trap_no, SIGSEGV);
      show_registers(regs);
      add_taint(TAINT_DIE);
      /* Executive summary in case the oops scrolled away */
      printk(KERN_ALERT "RIP ");
      printk_address(regs->rip); 
      printk(" RSP <%016lx>\n", regs->rsp); 
      if (kexec_should_crash(current))
            crash_kexec(regs);
}

void die(const char * str, struct pt_regs * regs, long err)
{
      unsigned long flags = oops_begin();

      if (!user_mode(regs))
            report_bug(regs->rip, regs);

      __die(str, regs, err);
      oops_end(flags);
      do_exit(SIGSEGV); 
}

void __kprobes die_nmi(char *str, struct pt_regs *regs, int do_panic)
{
      unsigned long flags = oops_begin();

      /*
       * We are in trouble anyway, lets at least try
       * to get a message out.
       */
      printk(str, smp_processor_id());
      show_registers(regs);
      if (kexec_should_crash(current))
            crash_kexec(regs);
      if (do_panic || panic_on_oops)
            panic("Non maskable interrupt");
      oops_end(flags);
      nmi_exit();
      local_irq_enable();
      do_exit(SIGSEGV);
}

static void __kprobes do_trap(int trapnr, int signr, char *str,
                        struct pt_regs * regs, long error_code,
                        siginfo_t *info)
{
      struct task_struct *tsk = current;

      if (user_mode(regs)) {
            /*
             * We want error_code and trap_no set for userspace
             * faults and kernelspace faults which result in
             * die(), but not kernelspace faults which are fixed
             * up.  die() gives the process no chance to handle
             * the signal and notice the kernel fault information,
             * so that won't result in polluting the information
             * about previously queued, but not yet delivered,
             * faults.  See also do_general_protection below.
             */
            tsk->thread.error_code = error_code;
            tsk->thread.trap_no = trapnr;

            if (show_unhandled_signals && unhandled_signal(tsk, signr) &&
                printk_ratelimit())
                  printk(KERN_INFO
                         "%s[%d] trap %s rip:%lx rsp:%lx error:%lx\n",
                         tsk->comm, tsk->pid, str,
                         regs->rip, regs->rsp, error_code); 

            if (info)
                  force_sig_info(signr, info, tsk);
            else
                  force_sig(signr, tsk);
            return;
      }


      /* kernel trap */ 
      {          
            const struct exception_table_entry *fixup;
            fixup = search_exception_tables(regs->rip);
            if (fixup)
                  regs->rip = fixup->fixup;
            else {
                  tsk->thread.error_code = error_code;
                  tsk->thread.trap_no = trapnr;
                  die(str, regs, error_code);
            }
            return;
      }
}

#define DO_ERROR(trapnr, signr, str, name) \
asmlinkage void do_##name(struct pt_regs * regs, long error_code) \
{ \
      if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
                                          == NOTIFY_STOP) \
            return; \
      conditional_sti(regs);                                \
      do_trap(trapnr, signr, str, regs, error_code, NULL); \
}

#define DO_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr) \
asmlinkage void do_##name(struct pt_regs * regs, long error_code) \
{ \
      siginfo_t info; \
      info.si_signo = signr; \
      info.si_errno = 0; \
      info.si_code = sicode; \
      info.si_addr = (void __user *)siaddr; \
      trace_hardirqs_fixup(); \
      if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
                                          == NOTIFY_STOP) \
            return; \
      conditional_sti(regs);                                \
      do_trap(trapnr, signr, str, regs, error_code, &info); \
}

DO_ERROR_INFO( 0, SIGFPE,  "divide error", divide_error, FPE_INTDIV, regs->rip)
DO_ERROR( 4, SIGSEGV, "overflow", overflow)
DO_ERROR( 5, SIGSEGV, "bounds", bounds)
DO_ERROR_INFO( 6, SIGILL,  "invalid opcode", invalid_op, ILL_ILLOPN, regs->rip)
DO_ERROR( 7, SIGSEGV, "device not available", device_not_available)
DO_ERROR( 9, SIGFPE,  "coprocessor segment overrun", coprocessor_segment_overrun)
DO_ERROR(10, SIGSEGV, "invalid TSS", invalid_TSS)
DO_ERROR(11, SIGBUS,  "segment not present", segment_not_present)
DO_ERROR_INFO(17, SIGBUS, "alignment check", alignment_check, BUS_ADRALN, 0)
DO_ERROR(18, SIGSEGV, "reserved", reserved)

/* Runs on IST stack */
asmlinkage void do_stack_segment(struct pt_regs *regs, long error_code)
{
      if (notify_die(DIE_TRAP, "stack segment", regs, error_code,
                  12, SIGBUS) == NOTIFY_STOP)
            return;
      preempt_conditional_sti(regs);
      do_trap(12, SIGBUS, "stack segment", regs, error_code, NULL);
      preempt_conditional_cli(regs);
}

asmlinkage void do_double_fault(struct pt_regs * regs, long error_code)
{
      static const char str[] = "double fault";
      struct task_struct *tsk = current;

      /* Return not checked because double check cannot be ignored */
      notify_die(DIE_TRAP, str, regs, error_code, 8, SIGSEGV);

      tsk->thread.error_code = error_code;
      tsk->thread.trap_no = 8;

      /* This is always a kernel trap and never fixable (and thus must
         never return). */
      for (;;)
            die(str, regs, error_code);
}

asmlinkage void __kprobes do_general_protection(struct pt_regs * regs,
                                    long error_code)
{
      struct task_struct *tsk = current;

      conditional_sti(regs);

      if (user_mode(regs)) {
            tsk->thread.error_code = error_code;
            tsk->thread.trap_no = 13;

            if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
                printk_ratelimit())
                  printk(KERN_INFO
                   "%s[%d] general protection rip:%lx rsp:%lx error:%lx\n",
                         tsk->comm, tsk->pid,
                         regs->rip, regs->rsp, error_code); 

            force_sig(SIGSEGV, tsk);
            return;
      } 

      /* kernel gp */
      {
            const struct exception_table_entry *fixup;
            fixup = search_exception_tables(regs->rip);
            if (fixup) {
                  regs->rip = fixup->fixup;
                  return;
            }

            tsk->thread.error_code = error_code;
            tsk->thread.trap_no = 13;
            if (notify_die(DIE_GPF, "general protection fault", regs,
                              error_code, 13, SIGSEGV) == NOTIFY_STOP)
                  return;
            die("general protection fault", regs, error_code);
      }
}

static __kprobes void
mem_parity_error(unsigned char reason, struct pt_regs * regs)
{
      printk(KERN_EMERG "Uhhuh. NMI received for unknown reason %02x.\n",
            reason);
      printk(KERN_EMERG "You have some hardware problem, likely on the PCI bus.\n");

#if defined(CONFIG_EDAC)
      if(edac_handler_set()) {
            edac_atomic_assert_error();
            return;
      }
#endif

      if (panic_on_unrecovered_nmi)
            panic("NMI: Not continuing");

      printk(KERN_EMERG "Dazed and confused, but trying to continue\n");

      /* Clear and disable the memory parity error line. */
      reason = (reason & 0xf) | 4;
      outb(reason, 0x61);
}

static __kprobes void
io_check_error(unsigned char reason, struct pt_regs * regs)
{
      printk("NMI: IOCK error (debug interrupt?)\n");
      show_registers(regs);

      /* Re-enable the IOCK line, wait for a few seconds */
      reason = (reason & 0xf) | 8;
      outb(reason, 0x61);
      mdelay(2000);
      reason &= ~8;
      outb(reason, 0x61);
}

static __kprobes void
unknown_nmi_error(unsigned char reason, struct pt_regs * regs)
{
      printk(KERN_EMERG "Uhhuh. NMI received for unknown reason %02x.\n",
            reason);
      printk(KERN_EMERG "Do you have a strange power saving mode enabled?\n");

      if (panic_on_unrecovered_nmi)
            panic("NMI: Not continuing");

      printk(KERN_EMERG "Dazed and confused, but trying to continue\n");
}

/* Runs on IST stack. This code must keep interrupts off all the time.
   Nested NMIs are prevented by the CPU. */
asmlinkage __kprobes void default_do_nmi(struct pt_regs *regs)
{
      unsigned char reason = 0;
      int cpu;

      cpu = smp_processor_id();

      /* Only the BSP gets external NMIs from the system.  */
      if (!cpu)
            reason = get_nmi_reason();

      if (!(reason & 0xc0)) {
            if (notify_die(DIE_NMI_IPI, "nmi_ipi", regs, reason, 2, SIGINT)
                                                == NOTIFY_STOP)
                  return;
            /*
             * Ok, so this is none of the documented NMI sources,
             * so it must be the NMI watchdog.
             */
            if (nmi_watchdog_tick(regs,reason))
                  return;
            if (!do_nmi_callback(regs,cpu))
                  unknown_nmi_error(reason, regs);

            return;
      }
      if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT) == NOTIFY_STOP)
            return; 

      /* AK: following checks seem to be broken on modern chipsets. FIXME */

      if (reason & 0x80)
            mem_parity_error(reason, regs);
      if (reason & 0x40)
            io_check_error(reason, regs);
}

/* runs on IST stack. */
asmlinkage void __kprobes do_int3(struct pt_regs * regs, long error_code)
{
      trace_hardirqs_fixup();

      if (notify_die(DIE_INT3, "int3", regs, error_code, 3, SIGTRAP) == NOTIFY_STOP) {
            return;
      }
      preempt_conditional_sti(regs);
      do_trap(3, SIGTRAP, "int3", regs, error_code, NULL);
      preempt_conditional_cli(regs);
}

/* Help handler running on IST stack to switch back to user stack
   for scheduling or signal handling. The actual stack switch is done in
   entry.S */
asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
{
      struct pt_regs *regs = eregs;
      /* Did already sync */
      if (eregs == (struct pt_regs *)eregs->rsp)
            ;
      /* Exception from user space */
      else if (user_mode(eregs))
            regs = task_pt_regs(current);
      /* Exception from kernel and interrupts are enabled. Move to
         kernel process stack. */
      else if (eregs->eflags & X86_EFLAGS_IF)
            regs = (struct pt_regs *)(eregs->rsp -= sizeof(struct pt_regs));
      if (eregs != regs)
            *regs = *eregs;
      return regs;
}

/* runs on IST stack. */
asmlinkage void __kprobes do_debug(struct pt_regs * regs,
                           unsigned long error_code)
{
      unsigned long condition;
      struct task_struct *tsk = current;
      siginfo_t info;

      trace_hardirqs_fixup();

      get_debugreg(condition, 6);

      if (notify_die(DIE_DEBUG, "debug", regs, condition, error_code,
                                    SIGTRAP) == NOTIFY_STOP)
            return;

      preempt_conditional_sti(regs);

      /* Mask out spurious debug traps due to lazy DR7 setting */
      if (condition & (DR_TRAP0|DR_TRAP1|DR_TRAP2|DR_TRAP3)) {
            if (!tsk->thread.debugreg7) { 
                  goto clear_dr7;
            }
      }

      tsk->thread.debugreg6 = condition;

      /* Mask out spurious TF errors due to lazy TF clearing */
      if (condition & DR_STEP) {
            /*
             * The TF error should be masked out only if the current
             * process is not traced and if the TRAP flag has been set
             * previously by a tracing process (condition detected by
             * the PT_DTRACE flag); remember that the i386 TRAP flag
             * can be modified by the process itself in user mode,
             * allowing programs to debug themselves without the ptrace()
             * interface.
             */
                if (!user_mode(regs))
                       goto clear_TF_reenable;
            /*
             * Was the TF flag set by a debugger? If so, clear it now,
             * so that register information is correct.
             */
            if (tsk->ptrace & PT_DTRACE) {
                  regs->eflags &= ~TF_MASK;
                  tsk->ptrace &= ~PT_DTRACE;
            }
      }

      /* Ok, finally something we can handle */
      tsk->thread.trap_no = 1;
      tsk->thread.error_code = error_code;
      info.si_signo = SIGTRAP;
      info.si_errno = 0;
      info.si_code = TRAP_BRKPT;
      info.si_addr = user_mode(regs) ? (void __user *)regs->rip : NULL;
      force_sig_info(SIGTRAP, &info, tsk);

clear_dr7:
      set_debugreg(0UL, 7);
      preempt_conditional_cli(regs);
      return;

clear_TF_reenable:
      set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
      regs->eflags &= ~TF_MASK;
      preempt_conditional_cli(regs);
}

static int kernel_math_error(struct pt_regs *regs, const char *str, int trapnr)
{
      const struct exception_table_entry *fixup;
      fixup = search_exception_tables(regs->rip);
      if (fixup) {
            regs->rip = fixup->fixup;
            return 1;
      }
      notify_die(DIE_GPF, str, regs, 0, trapnr, SIGFPE);
      /* Illegal floating point operation in the kernel */
      current->thread.trap_no = trapnr;
      die(str, regs, 0);
      return 0;
}

/*
 * Note that we play around with the 'TS' bit in an attempt to get
 * the correct behaviour even in the presence of the asynchronous
 * IRQ13 behaviour
 */
asmlinkage void do_coprocessor_error(struct pt_regs *regs)
{
      void __user *rip = (void __user *)(regs->rip);
      struct task_struct * task;
      siginfo_t info;
      unsigned short cwd, swd;

      conditional_sti(regs);
      if (!user_mode(regs) &&
          kernel_math_error(regs, "kernel x87 math error", 16))
            return;

      /*
       * Save the info for the exception handler and clear the error.
       */
      task = current;
      save_init_fpu(task);
      task->thread.trap_no = 16;
      task->thread.error_code = 0;
      info.si_signo = SIGFPE;
      info.si_errno = 0;
      info.si_code = __SI_FAULT;
      info.si_addr = rip;
      /*
       * (~cwd & swd) will mask out exceptions that are not set to unmasked
       * status.  0x3f is the exception bits in these regs, 0x200 is the
       * C1 reg you need in case of a stack fault, 0x040 is the stack
       * fault bit.  We should only be taking one exception at a time,
       * so if this combination doesn't produce any single exception,
       * then we have a bad program that isn't synchronizing its FPU usage
       * and it will suffer the consequences since we won't be able to
       * fully reproduce the context of the exception
       */
      cwd = get_fpu_cwd(task);
      swd = get_fpu_swd(task);
      switch (swd & ~cwd & 0x3f) {
            case 0x000:
            default:
                  break;
            case 0x001: /* Invalid Op */
                  /*
                   * swd & 0x240 == 0x040: Stack Underflow
                   * swd & 0x240 == 0x240: Stack Overflow
                   * User must clear the SF bit (0x40) if set
                   */
                  info.si_code = FPE_FLTINV;
                  break;
            case 0x002: /* Denormalize */
            case 0x010: /* Underflow */
                  info.si_code = FPE_FLTUND;
                  break;
            case 0x004: /* Zero Divide */
                  info.si_code = FPE_FLTDIV;
                  break;
            case 0x008: /* Overflow */
                  info.si_code = FPE_FLTOVF;
                  break;
            case 0x020: /* Precision */
                  info.si_code = FPE_FLTRES;
                  break;
      }
      force_sig_info(SIGFPE, &info, task);
}

asmlinkage void bad_intr(void)
{
      printk("bad interrupt"); 
}

asmlinkage void do_simd_coprocessor_error(struct pt_regs *regs)
{
      void __user *rip = (void __user *)(regs->rip);
      struct task_struct * task;
      siginfo_t info;
      unsigned short mxcsr;

      conditional_sti(regs);
      if (!user_mode(regs) &&
            kernel_math_error(regs, "kernel simd math error", 19))
            return;

      /*
       * Save the info for the exception handler and clear the error.
       */
      task = current;
      save_init_fpu(task);
      task->thread.trap_no = 19;
      task->thread.error_code = 0;
      info.si_signo = SIGFPE;
      info.si_errno = 0;
      info.si_code = __SI_FAULT;
      info.si_addr = rip;
      /*
       * The SIMD FPU exceptions are handled a little differently, as there
       * is only a single status/control register.  Thus, to determine which
       * unmasked exception was caught we must mask the exception mask bits
       * at 0x1f80, and then use these to mask the exception bits at 0x3f.
       */
      mxcsr = get_fpu_mxcsr(task);
      switch (~((mxcsr & 0x1f80) >> 7) & (mxcsr & 0x3f)) {
            case 0x000:
            default:
                  break;
            case 0x001: /* Invalid Op */
                  info.si_code = FPE_FLTINV;
                  break;
            case 0x002: /* Denormalize */
            case 0x010: /* Underflow */
                  info.si_code = FPE_FLTUND;
                  break;
            case 0x004: /* Zero Divide */
                  info.si_code = FPE_FLTDIV;
                  break;
            case 0x008: /* Overflow */
                  info.si_code = FPE_FLTOVF;
                  break;
            case 0x020: /* Precision */
                  info.si_code = FPE_FLTRES;
                  break;
      }
      force_sig_info(SIGFPE, &info, task);
}

asmlinkage void do_spurious_interrupt_bug(struct pt_regs * regs)
{
}

asmlinkage void __attribute__((weak)) smp_thermal_interrupt(void)
{
}

asmlinkage void __attribute__((weak)) mce_threshold_interrupt(void)
{
}

/*
 *  'math_state_restore()' saves the current math information in the
 * old math state array, and gets the new ones from the current task
 *
 * Careful.. There are problems with IBM-designed IRQ13 behaviour.
 * Don't touch unless you *really* know how it works.
 */
asmlinkage void math_state_restore(void)
{
      struct task_struct *me = current;
      clts();                 /* Allow maths ops (or we recurse) */

      if (!used_math())
            init_fpu(me);
      restore_fpu_checking(&me->thread.i387.fxsave);
      task_thread_info(me)->status |= TS_USEDFPU;
      me->fpu_counter++;
}

void __init trap_init(void)
{
      set_intr_gate(0,&divide_error);
      set_intr_gate_ist(1,&debug,DEBUG_STACK);
      set_intr_gate_ist(2,&nmi,NMI_STACK);
      set_system_gate_ist(3,&int3,DEBUG_STACK); /* int3 can be called from all */
      set_system_gate(4,&overflow); /* int4 can be called from all */
      set_intr_gate(5,&bounds);
      set_intr_gate(6,&invalid_op);
      set_intr_gate(7,&device_not_available);
      set_intr_gate_ist(8,&double_fault, DOUBLEFAULT_STACK);
      set_intr_gate(9,&coprocessor_segment_overrun);
      set_intr_gate(10,&invalid_TSS);
      set_intr_gate(11,&segment_not_present);
      set_intr_gate_ist(12,&stack_segment,STACKFAULT_STACK);
      set_intr_gate(13,&general_protection);
      set_intr_gate(14,&page_fault);
      set_intr_gate(15,&spurious_interrupt_bug);
      set_intr_gate(16,&coprocessor_error);
      set_intr_gate(17,&alignment_check);
#ifdef CONFIG_X86_MCE
      set_intr_gate_ist(18,&machine_check, MCE_STACK); 
#endif
      set_intr_gate(19,&simd_coprocessor_error);

#ifdef CONFIG_IA32_EMULATION
      set_system_gate(IA32_SYSCALL_VECTOR, ia32_syscall);
#endif
       
      /*
       * Should be a barrier for any external CPU state.
       */
      cpu_init();
}


static int __init oops_setup(char *s)
{ 
      if (!s)
            return -EINVAL;
      if (!strcmp(s, "panic"))
            panic_on_oops = 1;
      return 0;
} 
early_param("oops", oops_setup);

static int __init kstack_setup(char *s)
{
      if (!s)
            return -EINVAL;
      kstack_depth_to_print = simple_strtoul(s,NULL,0);
      return 0;
}
early_param("kstack", kstack_setup);

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