Logo Search packages:      
Sourcecode: linux version File versions  Download package

traps_32.c

/*
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  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 'asm.s'.
 */
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.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/highmem.h>
#include <linux/kallsyms.h>
#include <linux/ptrace.h>
#include <linux/utsname.h>
#include <linux/kprobes.h>
#include <linux/kexec.h>
#include <linux/unwind.h>
#include <linux/uaccess.h>
#include <linux/nmi.h>
#include <linux/bug.h>

#ifdef CONFIG_EISA
#include <linux/ioport.h>
#include <linux/eisa.h>
#endif

#ifdef CONFIG_MCA
#include <linux/mca.h>
#endif

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

#include <asm/processor.h>
#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/nmi.h>
#include <asm/unwind.h>
#include <asm/smp.h>
#include <asm/arch_hooks.h>
#include <linux/kdebug.h>
#include <asm/stacktrace.h>

#include <linux/module.h>

#include "mach_traps.h"

int panic_on_unrecovered_nmi;

DECLARE_BITMAP(used_vectors, NR_VECTORS);
EXPORT_SYMBOL_GPL(used_vectors);

asmlinkage int system_call(void);

/* Do we ignore FPU interrupts ? */
char ignore_fpu_irq = 0;

/*
 * The IDT has to be page-aligned to simplify the Pentium
 * F0 0F bug workaround.. We have a special link segment
 * for this.
 */
struct desc_struct idt_table[256] __attribute__((__section__(".data.idt"))) = { {0, 0}, };

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 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 alignment_check(void);
asmlinkage void spurious_interrupt_bug(void);
asmlinkage void machine_check(void);

int kstack_depth_to_print = 24;
static unsigned int code_bytes = 64;

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

/* The form of the top of the frame on the stack */
struct stack_frame {
      struct stack_frame *next_frame;
      unsigned long return_address;
};

static inline unsigned long print_context_stack(struct thread_info *tinfo,
                        unsigned long *stack, unsigned long ebp,
                        const struct stacktrace_ops *ops, void *data)
{
#ifdef      CONFIG_FRAME_POINTER
      struct stack_frame *frame = (struct stack_frame *)ebp;
      while (valid_stack_ptr(tinfo, frame, sizeof(*frame))) {
            struct stack_frame *next;
            unsigned long addr;

            addr = frame->return_address;
            ops->address(data, addr);
            /*
             * break out of recursive entries (such as
             * end_of_stack_stop_unwind_function). Also,
             * we can never allow a frame pointer to
             * move downwards!
             */
            next = frame->next_frame;
            if (next <= frame)
                  break;
            frame = next;
      }
#else
      while (valid_stack_ptr(tinfo, stack, sizeof(*stack))) {
            unsigned long addr;

            addr = *stack++;
            if (__kernel_text_address(addr))
                  ops->address(data, addr);
      }
#endif
      return ebp;
}

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

void dump_trace(struct task_struct *task, struct pt_regs *regs,
              unsigned long *stack,
            const struct stacktrace_ops *ops, void *data)
{
      unsigned long ebp = 0;

      if (!task)
            task = current;

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

#ifdef CONFIG_FRAME_POINTER
      if (!ebp) {
            if (task == current) {
                  /* Grab ebp right from our regs */
                  asm ("movl %%ebp, %0" : "=r" (ebp) : );
            } else {
                  /* ebp is the last reg pushed by switch_to */
                  ebp = *(unsigned long *) task->thread.esp;
            }
      }
#endif

      while (1) {
            struct thread_info *context;
            context = (struct thread_info *)
                  ((unsigned long)stack & (~(THREAD_SIZE - 1)));
            ebp = print_context_stack(context, stack, ebp, ops, data);
            /* Should be after the line below, but somewhere
               in early boot context comes out corrupted and we
               can't reference it -AK */
            if (ops->stack(data, "IRQ") < 0)
                  break;
            stack = (unsigned long*)context->previous_esp;
            if (!stack)
                  break;
            touch_nmi_watchdog();
      }
}
EXPORT_SYMBOL(dump_trace);

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

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

static int print_trace_stack(void *data, char *name)
{
      return 0;
}

/*
 * Print one address/symbol entries per line.
 */
static void print_trace_address(void *data, unsigned long addr)
{
      printk("%s [<%08lx>] ", (char *)data, addr);
      print_symbol("%s\n", addr);
      touch_nmi_watchdog();
}

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,
};

static void
show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
               unsigned long * stack, char *log_lvl)
{
      dump_trace(task, regs, stack, &print_trace_ops, log_lvl);
      printk("%s =======================\n", log_lvl);
}

void show_trace(struct task_struct *task, struct pt_regs *regs,
            unsigned long * stack)
{
      show_trace_log_lvl(task, regs, stack, "");
}

static void show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
                         unsigned long *esp, char *log_lvl)
{
      unsigned long *stack;
      int i;

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

      stack = esp;
      for(i = 0; i < kstack_depth_to_print; i++) {
            if (kstack_end(stack))
                  break;
            if (i && ((i % 8) == 0))
                  printk("\n%s       ", log_lvl);
            printk("%08lx ", *stack++);
      }
      printk("\n%sCall Trace:\n", log_lvl);
      show_trace_log_lvl(task, regs, esp, log_lvl);
}

void show_stack(struct task_struct *task, unsigned long *esp)
{
      printk("       ");
      show_stack_log_lvl(task, NULL, esp, "");
}

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

      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(current, NULL, &stack);
}

EXPORT_SYMBOL(dump_stack);

void show_registers(struct pt_regs *regs)
{
      int i;

      print_modules();
      __show_registers(regs, 0);
      printk(KERN_EMERG "Process %.*s (pid: %d, ti=%p task=%p task.ti=%p)",
            TASK_COMM_LEN, current->comm, task_pid_nr(current),
            current_thread_info(), current, task_thread_info(current));
      /*
       * When in-kernel, we also print out the stack and code at the
       * time of the fault..
       */
      if (!user_mode_vm(regs)) {
            u8 *eip;
            unsigned int code_prologue = code_bytes * 43 / 64;
            unsigned int code_len = code_bytes;
            unsigned char c;

            printk("\n" KERN_EMERG "Stack: ");
            show_stack_log_lvl(NULL, regs, &regs->esp, KERN_EMERG);

            printk(KERN_EMERG "Code: ");

            eip = (u8 *)regs->eip - code_prologue;
            if (eip < (u8 *)PAGE_OFFSET ||
                  probe_kernel_address(eip, c)) {
                  /* try starting at EIP */
                  eip = (u8 *)regs->eip;
                  code_len = code_len - code_prologue + 1;
            }
            for (i = 0; i < code_len; i++, eip++) {
                  if (eip < (u8 *)PAGE_OFFSET ||
                        probe_kernel_address(eip, c)) {
                        printk(" Bad EIP value.");
                        break;
                  }
                  if (eip == (u8 *)regs->eip)
                        printk("<%02x> ", c);
                  else
                        printk("%02x ", c);
            }
      }
      printk("\n");
}     

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

      if (eip < PAGE_OFFSET)
            return 0;
      if (probe_kernel_address((unsigned short *)eip, ud2))
            return 0;

      return ud2 == 0x0b0f;
}

/*
 * This is gone through when something in the kernel has done something bad and
 * is about to be terminated.
 */
void die(const char * str, struct pt_regs * regs, long err)
{
      static struct {
            raw_spinlock_t lock;
            u32 lock_owner;
            int lock_owner_depth;
      } die = {
            .lock =                 __RAW_SPIN_LOCK_UNLOCKED,
            .lock_owner =           -1,
            .lock_owner_depth =     0
      };
      static int die_counter;
      unsigned long flags;

      oops_enter();

      if (die.lock_owner != raw_smp_processor_id()) {
            console_verbose();
            raw_local_irq_save(flags);
            __raw_spin_lock(&die.lock);
            die.lock_owner = smp_processor_id();
            die.lock_owner_depth = 0;
            bust_spinlocks(1);
      } else
            raw_local_irq_save(flags);

      if (++die.lock_owner_depth < 3) {
            unsigned long esp;
            unsigned short ss;

            report_bug(regs->eip, regs);

            printk(KERN_EMERG "%s: %04lx [#%d] ", 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");

            if (notify_die(DIE_OOPS, str, regs, err,
                              current->thread.trap_no, SIGSEGV) !=
                        NOTIFY_STOP) {
                  show_registers(regs);
                  /* Executive summary in case the oops scrolled away */
                  esp = (unsigned long) (&regs->esp);
                  savesegment(ss, ss);
                  if (user_mode(regs)) {
                        esp = regs->esp;
                        ss = regs->xss & 0xffff;
                  }
                  printk(KERN_EMERG "EIP: [<%08lx>] ", regs->eip);
                  print_symbol("%s", regs->eip);
                  printk(" SS:ESP %04x:%08lx\n", ss, esp);
            }
            else
                  regs = NULL;
      } else
            printk(KERN_EMERG "Recursive die() failure, output suppressed\n");

      bust_spinlocks(0);
      die.lock_owner = -1;
      add_taint(TAINT_DIE);
      __raw_spin_unlock(&die.lock);
      raw_local_irq_restore(flags);

      if (!regs)
            return;

      if (kexec_should_crash(current))
            crash_kexec(regs);

      if (in_interrupt())
            panic("Fatal exception in interrupt");

      if (panic_on_oops)
            panic("Fatal exception");

      oops_exit();
      do_exit(SIGSEGV);
}

static inline void die_if_kernel(const char * str, struct pt_regs * regs, long err)
{
      if (!user_mode_vm(regs))
            die(str, regs, err);
}

static void __kprobes do_trap(int trapnr, int signr, char *str, int vm86,
                        struct pt_regs * regs, long error_code,
                        siginfo_t *info)
{
      struct task_struct *tsk = current;

      if (regs->eflags & VM_MASK) {
            if (vm86)
                  goto vm86_trap;
            goto trap_signal;
      }

      if (!user_mode(regs))
            goto kernel_trap;

      trap_signal: {
            /*
             * 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 (info)
                  force_sig_info(signr, info, tsk);
            else
                  force_sig(signr, tsk);
            return;
      }

      kernel_trap: {
            if (!fixup_exception(regs)) {
                  tsk->thread.error_code = error_code;
                  tsk->thread.trap_no = trapnr;
                  die(str, regs, error_code);
            }
            return;
      }

      vm86_trap: {
            int ret = handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code, trapnr);
            if (ret) goto trap_signal;
            return;
      }
}

#define DO_ERROR(trapnr, signr, str, name) \
fastcall void do_##name(struct pt_regs * regs, long error_code) \
{ \
      if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
                                    == NOTIFY_STOP) \
            return; \
      do_trap(trapnr, signr, str, 0, regs, error_code, NULL); \
}

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

#define DO_VM86_ERROR(trapnr, signr, str, name) \
fastcall void do_##name(struct pt_regs * regs, long error_code) \
{ \
      if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
                                    == NOTIFY_STOP) \
            return; \
      do_trap(trapnr, signr, str, 1, regs, error_code, NULL); \
}

#define DO_VM86_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr) \
fastcall 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; \
      do_trap(trapnr, signr, str, 1, regs, error_code, &info); \
}

DO_VM86_ERROR_INFO( 0, SIGFPE,  "divide error", divide_error, FPE_INTDIV, regs->eip)
#ifndef CONFIG_KPROBES
DO_VM86_ERROR( 3, SIGTRAP, "int3", int3)
#endif
DO_VM86_ERROR( 4, SIGSEGV, "overflow", overflow)
DO_VM86_ERROR( 5, SIGSEGV, "bounds", bounds)
DO_ERROR_INFO( 6, SIGILL,  "invalid opcode", invalid_op, ILL_ILLOPN, regs->eip, 0)
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(12, SIGBUS,  "stack segment", stack_segment)
DO_ERROR_INFO(17, SIGBUS, "alignment check", alignment_check, BUS_ADRALN, 0, 0)
DO_ERROR_INFO(32, SIGSEGV, "iret exception", iret_error, ILL_BADSTK, 0, 1)

fastcall void __kprobes do_general_protection(struct pt_regs * regs,
                                    long error_code)
{
      int cpu = get_cpu();
      struct tss_struct *tss = &per_cpu(init_tss, cpu);
      struct thread_struct *thread = &current->thread;

      /*
       * Perform the lazy TSS's I/O bitmap copy. If the TSS has an
       * invalid offset set (the LAZY one) and the faulting thread has
       * a valid I/O bitmap pointer, we copy the I/O bitmap in the TSS
       * and we set the offset field correctly. Then we let the CPU to
       * restart the faulting instruction.
       */
      if (tss->x86_tss.io_bitmap_base == INVALID_IO_BITMAP_OFFSET_LAZY &&
          thread->io_bitmap_ptr) {
            memcpy(tss->io_bitmap, thread->io_bitmap_ptr,
                   thread->io_bitmap_max);
            /*
             * If the previously set map was extending to higher ports
             * than the current one, pad extra space with 0xff (no access).
             */
            if (thread->io_bitmap_max < tss->io_bitmap_max)
                  memset((char *) tss->io_bitmap +
                        thread->io_bitmap_max, 0xff,
                        tss->io_bitmap_max - thread->io_bitmap_max);
            tss->io_bitmap_max = thread->io_bitmap_max;
            tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET;
            tss->io_bitmap_owner = thread;
            put_cpu();
            return;
      }
      put_cpu();

      if (regs->eflags & VM_MASK)
            goto gp_in_vm86;

      if (!user_mode(regs))
            goto gp_in_kernel;

      current->thread.error_code = error_code;
      current->thread.trap_no = 13;
      if (show_unhandled_signals && unhandled_signal(current, SIGSEGV) &&
          printk_ratelimit())
            printk(KERN_INFO
                "%s[%d] general protection eip:%lx esp:%lx error:%lx\n",
                current->comm, task_pid_nr(current),
                regs->eip, regs->esp, error_code);

      force_sig(SIGSEGV, current);
      return;

gp_in_vm86:
      local_irq_enable();
      handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
      return;

gp_in_kernel:
      if (!fixup_exception(regs)) {
            current->thread.error_code = error_code;
            current->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 on "
            "CPU %d.\n", reason, smp_processor_id());
      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. */
      clear_mem_error(reason);
}

static __kprobes void
io_check_error(unsigned char reason, struct pt_regs * regs)
{
      unsigned long i;

      printk(KERN_EMERG "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);
      i = 2000;
      while (--i) udelay(1000);
      reason &= ~8;
      outb(reason, 0x61);
}

static __kprobes void
unknown_nmi_error(unsigned char reason, struct pt_regs * regs)
{
#ifdef CONFIG_MCA
      /* Might actually be able to figure out what the guilty party
      * is. */
      if( MCA_bus ) {
            mca_handle_nmi();
            return;
      }
#endif
      printk(KERN_EMERG "Uhhuh. NMI received for unknown reason %02x on "
            "CPU %d.\n", reason, smp_processor_id());
      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");
}

static DEFINE_SPINLOCK(nmi_print_lock);

void __kprobes die_nmi(struct pt_regs *regs, const char *msg)
{
      if (notify_die(DIE_NMIWATCHDOG, msg, regs, 0, 2, SIGINT) ==
          NOTIFY_STOP)
            return;

      spin_lock(&nmi_print_lock);
      /*
      * We are in trouble anyway, lets at least try
      * to get a message out.
      */
      bust_spinlocks(1);
      printk(KERN_EMERG "%s", msg);
      printk(" on CPU%d, eip %08lx, registers:\n",
            smp_processor_id(), regs->eip);
      show_registers(regs);
      console_silent();
      spin_unlock(&nmi_print_lock);
      bust_spinlocks(0);

      /* If we are in kernel we are probably nested up pretty bad
       * and might aswell get out now while we still can.
      */
      if (!user_mode_vm(regs)) {
            current->thread.trap_no = 2;
            crash_kexec(regs);
      }

      do_exit(SIGSEGV);
}

static __kprobes void default_do_nmi(struct pt_regs * regs)
{
      unsigned char reason = 0;

      /* Only the BSP gets external NMIs from the system.  */
      if (!smp_processor_id())
            reason = get_nmi_reason();
 
      if (!(reason & 0xc0)) {
            if (notify_die(DIE_NMI_IPI, "nmi_ipi", regs, reason, 2, SIGINT)
                                          == NOTIFY_STOP)
                  return;
#ifdef CONFIG_X86_LOCAL_APIC
            /*
             * 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, smp_processor_id()))
#endif
                  unknown_nmi_error(reason, regs);

            return;
      }
      if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT) == NOTIFY_STOP)
            return;
      if (reason & 0x80)
            mem_parity_error(reason, regs);
      if (reason & 0x40)
            io_check_error(reason, regs);
      /*
       * Reassert NMI in case it became active meanwhile
       * as it's edge-triggered.
       */
      reassert_nmi();
}

static int ignore_nmis;

fastcall __kprobes void do_nmi(struct pt_regs * regs, long error_code)
{
      int cpu;

      nmi_enter();

      cpu = smp_processor_id();

      ++nmi_count(cpu);

      if (!ignore_nmis)
            default_do_nmi(regs);

      nmi_exit();
}

void stop_nmi(void)
{
      acpi_nmi_disable();
      ignore_nmis++;
}

void restart_nmi(void)
{
      ignore_nmis--;
      acpi_nmi_enable();
}

#ifdef CONFIG_KPROBES
fastcall 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;
      /* This is an interrupt gate, because kprobes wants interrupts
      disabled.  Normal trap handlers don't. */
      restore_interrupts(regs);
      do_trap(3, SIGTRAP, "int3", 1, regs, error_code, NULL);
}
#endif

/*
 * Our handling of the processor debug registers is non-trivial.
 * We do not clear them on entry and exit from the kernel. Therefore
 * it is possible to get a watchpoint trap here from inside the kernel.
 * However, the code in ./ptrace.c has ensured that the user can
 * only set watchpoints on userspace addresses. Therefore the in-kernel
 * watchpoint trap can only occur in code which is reading/writing
 * from user space. Such code must not hold kernel locks (since it
 * can equally take a page fault), therefore it is safe to call
 * force_sig_info even though that claims and releases locks.
 * 
 * Code in ./signal.c ensures that the debug control register
 * is restored before we deliver any signal, and therefore that
 * user code runs with the correct debug control register even though
 * we clear it here.
 *
 * Being careful here means that we don't have to be as careful in a
 * lot of more complicated places (task switching can be a bit lazy
 * about restoring all the debug state, and ptrace doesn't have to
 * find every occurrence of the TF bit that could be saved away even
 * by user code)
 */
fastcall void __kprobes do_debug(struct pt_regs * regs, long error_code)
{
      unsigned int condition;
      struct task_struct *tsk = current;

      trace_hardirqs_fixup();

      get_debugreg(condition, 6);

      if (notify_die(DIE_DEBUG, "debug", regs, condition, error_code,
                              SIGTRAP) == NOTIFY_STOP)
            return;
      /* It's safe to allow irq's after DR6 has been saved */
      if (regs->eflags & X86_EFLAGS_IF)
            local_irq_enable();

      /* Mask out spurious debug traps due to lazy DR7 setting */
      if (condition & (DR_TRAP0|DR_TRAP1|DR_TRAP2|DR_TRAP3)) {
            if (!tsk->thread.debugreg[7])
                  goto clear_dr7;
      }

      if (regs->eflags & VM_MASK)
            goto debug_vm86;

      /* Save debug status register where ptrace can see it */
      tsk->thread.debugreg[6] = condition;

      /*
       * Single-stepping through TF: make sure we ignore any events in
       * kernel space (but re-enable TF when returning to user mode).
       */
      if (condition & DR_STEP) {
            /*
             * We already checked v86 mode above, so we can
             * check for kernel mode by just checking the CPL
             * of CS.
             */
            if (!user_mode(regs))
                  goto clear_TF_reenable;
      }

      /* Ok, finally something we can handle */
      send_sigtrap(tsk, regs, error_code);

      /* Disable additional traps. They'll be re-enabled when
       * the signal is delivered.
       */
clear_dr7:
      set_debugreg(0, 7);
      return;

debug_vm86:
      handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code, 1);
      return;

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

/*
 * 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
 */
void math_error(void __user *eip)
{
      struct task_struct * task;
      siginfo_t info;
      unsigned short cwd, swd;

      /*
       * 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 = eip;
      /*
       * (~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 syncronizing 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: /* No unmasked exception */
                  return;
            default:    /* Multiple exceptions */
                  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);
}

fastcall void do_coprocessor_error(struct pt_regs * regs, long error_code)
{
      ignore_fpu_irq = 1;
      math_error((void __user *)regs->eip);
}

static void simd_math_error(void __user *eip)
{
      struct task_struct * task;
      siginfo_t info;
      unsigned short mxcsr;

      /*
       * 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 = eip;
      /*
       * 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);
}

fastcall void do_simd_coprocessor_error(struct pt_regs * regs,
                                long error_code)
{
      if (cpu_has_xmm) {
            /* Handle SIMD FPU exceptions on PIII+ processors. */
            ignore_fpu_irq = 1;
            simd_math_error((void __user *)regs->eip);
      } else {
            /*
             * Handle strange cache flush from user space exception
             * in all other cases.  This is undocumented behaviour.
             */
            if (regs->eflags & VM_MASK) {
                  handle_vm86_fault((struct kernel_vm86_regs *)regs,
                                error_code);
                  return;
            }
            current->thread.trap_no = 19;
            current->thread.error_code = error_code;
            die_if_kernel("cache flush denied", regs, error_code);
            force_sig(SIGSEGV, current);
      }
}

fastcall void do_spurious_interrupt_bug(struct pt_regs * regs,
                                long error_code)
{
#if 0
      /* No need to warn about this any longer. */
      printk("Ignoring P6 Local APIC Spurious Interrupt Bug...\n");
#endif
}

fastcall unsigned long patch_espfix_desc(unsigned long uesp,
                                unsigned long kesp)
{
      struct desc_struct *gdt = __get_cpu_var(gdt_page).gdt;
      unsigned long base = (kesp - uesp) & -THREAD_SIZE;
      unsigned long new_kesp = kesp - base;
      unsigned long lim_pages = (new_kesp | (THREAD_SIZE - 1)) >> PAGE_SHIFT;
      __u64 desc = *(__u64 *)&gdt[GDT_ENTRY_ESPFIX_SS];
      /* Set up base for espfix segment */
      desc &= 0x00f0ff0000000000ULL;
      desc |=     ((((__u64)base) << 16) & 0x000000ffffff0000ULL) |
            ((((__u64)base) << 32) & 0xff00000000000000ULL) |
            ((((__u64)lim_pages) << 32) & 0x000f000000000000ULL) |
            (lim_pages & 0xffff);
      *(__u64 *)&gdt[GDT_ENTRY_ESPFIX_SS] = desc;
      return new_kesp;
}

/*
 *  '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.
 *
 * Must be called with kernel preemption disabled (in this case,
 * local interrupts are disabled at the call-site in entry.S).
 */
asmlinkage void math_state_restore(void)
{
      struct thread_info *thread = current_thread_info();
      struct task_struct *tsk = thread->task;

      clts();           /* Allow maths ops (or we recurse) */
      if (!tsk_used_math(tsk))
            init_fpu(tsk);
      restore_fpu(tsk);
      thread->status |= TS_USEDFPU; /* So we fnsave on switch_to() */
      tsk->fpu_counter++;
}
EXPORT_SYMBOL_GPL(math_state_restore);

#ifndef CONFIG_MATH_EMULATION

asmlinkage void math_emulate(long arg)
{
      printk(KERN_EMERG "math-emulation not enabled and no coprocessor found.\n");
      printk(KERN_EMERG "killing %s.\n",current->comm);
      force_sig(SIGFPE,current);
      schedule();
}

#endif /* CONFIG_MATH_EMULATION */

/*
 * This needs to use 'idt_table' rather than 'idt', and
 * thus use the _nonmapped_ version of the IDT, as the
 * Pentium F0 0F bugfix can have resulted in the mapped
 * IDT being write-protected.
 */
void set_intr_gate(unsigned int n, void *addr)
{
      _set_gate(n, DESCTYPE_INT, addr, __KERNEL_CS);
}

/*
 * This routine sets up an interrupt gate at directory privilege level 3.
 */
static inline void set_system_intr_gate(unsigned int n, void *addr)
{
      _set_gate(n, DESCTYPE_INT | DESCTYPE_DPL3, addr, __KERNEL_CS);
}

static void __init set_trap_gate(unsigned int n, void *addr)
{
      _set_gate(n, DESCTYPE_TRAP, addr, __KERNEL_CS);
}

static void __init set_system_gate(unsigned int n, void *addr)
{
      _set_gate(n, DESCTYPE_TRAP | DESCTYPE_DPL3, addr, __KERNEL_CS);
}

static void __init set_task_gate(unsigned int n, unsigned int gdt_entry)
{
      _set_gate(n, DESCTYPE_TASK, (void *)0, (gdt_entry<<3));
}


void __init trap_init(void)
{
      int i;

#ifdef CONFIG_EISA
      void __iomem *p = ioremap(0x0FFFD9, 4);
      if (readl(p) == 'E'+('I'<<8)+('S'<<16)+('A'<<24)) {
            EISA_bus = 1;
      }
      iounmap(p);
#endif

#ifdef CONFIG_X86_LOCAL_APIC
      init_apic_mappings();
#endif

      set_trap_gate(0,&divide_error);
      set_intr_gate(1,&debug);
      set_intr_gate(2,&nmi);
      set_system_intr_gate(3, &int3); /* int3/4 can be called from all */
      set_system_gate(4,&overflow);
      set_trap_gate(5,&bounds);
      set_trap_gate(6,&invalid_op);
      set_trap_gate(7,&device_not_available);
      set_task_gate(8,GDT_ENTRY_DOUBLEFAULT_TSS);
      set_trap_gate(9,&coprocessor_segment_overrun);
      set_trap_gate(10,&invalid_TSS);
      set_trap_gate(11,&segment_not_present);
      set_trap_gate(12,&stack_segment);
      set_trap_gate(13,&general_protection);
      set_intr_gate(14,&page_fault);
      set_trap_gate(15,&spurious_interrupt_bug);
      set_trap_gate(16,&coprocessor_error);
      set_trap_gate(17,&alignment_check);
#ifdef CONFIG_X86_MCE
      set_trap_gate(18,&machine_check);
#endif
      set_trap_gate(19,&simd_coprocessor_error);

      if (cpu_has_fxsr) {
            /*
             * Verify that the FXSAVE/FXRSTOR data will be 16-byte aligned.
             * Generates a compile-time "error: zero width for bit-field" if
             * the alignment is wrong.
             */
            struct fxsrAlignAssert {
                  int _:!(offsetof(struct task_struct,
                              thread.i387.fxsave) & 15);
            };

            printk(KERN_INFO "Enabling fast FPU save and restore... ");
            set_in_cr4(X86_CR4_OSFXSR);
            printk("done.\n");
      }
      if (cpu_has_xmm) {
            printk(KERN_INFO "Enabling unmasked SIMD FPU exception "
                        "support... ");
            set_in_cr4(X86_CR4_OSXMMEXCPT);
            printk("done.\n");
      }

      set_system_gate(SYSCALL_VECTOR,&system_call);

      /* Reserve all the builtin and the syscall vector. */
      for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++)
            set_bit(i, used_vectors);
      set_bit(SYSCALL_VECTOR, used_vectors);

      /*
       * Should be a barrier for any external CPU state.
       */
      cpu_init();

      trap_init_hook();
}

static int __init kstack_setup(char *s)
{
      kstack_depth_to_print = simple_strtoul(s, NULL, 0);
      return 1;
}
__setup("kstack=", kstack_setup);

static int __init code_bytes_setup(char *s)
{
      code_bytes = simple_strtoul(s, NULL, 0);
      if (code_bytes > 8192)
            code_bytes = 8192;

      return 1;
}
__setup("code_bytes=", code_bytes_setup);

Generated by  Doxygen 1.6.0   Back to index