Merge branch 'tracing/hw-breakpoints' into perf/core

[linux-2.6/linux-2.6-openrd.git] / arch / x86 / kernel / ptrace.c

/* By Ross Biro 1/23/92 */
/*
 * Pentium III FXSR, SSE support
 *      Gareth Hughes <gareth@valinux.com>, May 2000
 *
 * BTS tracing
 *      Markus Metzger <markus.t.metzger@intel.com>, Dec 2007
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/regset.h>
#include <linux/tracehook.h>
#include <linux/user.h>
#include <linux/elf.h>
#include <linux/security.h>
#include <linux/audit.h>
#include <linux/seccomp.h>
#include <linux/signal.h>
#include <linux/workqueue.h>
#include <linux/perf_event.h>
#include <linux/hw_breakpoint.h>

#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/processor.h>
#include <asm/i387.h>
#include <asm/debugreg.h>
#include <asm/ldt.h>
#include <asm/desc.h>
#include <asm/prctl.h>
#include <asm/proto.h>
#include <asm/ds.h>
#include <asm/hw_breakpoint.h>

#include "tls.h"

#define CREATE_TRACE_POINTS
#include <trace/events/syscalls.h>

enum x86_regset {
        REGSET_GENERAL,
        REGSET_FP,
        REGSET_XFP,
        REGSET_IOPERM64 = REGSET_XFP,
        REGSET_TLS,
        REGSET_IOPERM32,
};

struct pt_regs_offset {
        const char *name;
        int offset;
};

#define REG_OFFSET_NAME(r) {.name = #r, .offset = offsetof(struct pt_regs, r)}
#define REG_OFFSET_END {.name = NULL, .offset = 0}

static const struct pt_regs_offset regoffset_table[] = {
#ifdef CONFIG_X86_64
        REG_OFFSET_NAME(r15),
        REG_OFFSET_NAME(r14),
        REG_OFFSET_NAME(r13),
        REG_OFFSET_NAME(r12),
        REG_OFFSET_NAME(r11),
        REG_OFFSET_NAME(r10),
        REG_OFFSET_NAME(r9),
        REG_OFFSET_NAME(r8),
#endif
        REG_OFFSET_NAME(bx),
        REG_OFFSET_NAME(cx),
        REG_OFFSET_NAME(dx),
        REG_OFFSET_NAME(si),
        REG_OFFSET_NAME(di),
        REG_OFFSET_NAME(bp),
        REG_OFFSET_NAME(ax),
#ifdef CONFIG_X86_32
        REG_OFFSET_NAME(ds),
        REG_OFFSET_NAME(es),
        REG_OFFSET_NAME(fs),
        REG_OFFSET_NAME(gs),
#endif
        REG_OFFSET_NAME(orig_ax),
        REG_OFFSET_NAME(ip),
        REG_OFFSET_NAME(cs),
        REG_OFFSET_NAME(flags),
        REG_OFFSET_NAME(sp),
        REG_OFFSET_NAME(ss),
        REG_OFFSET_END,
};

/**
 * regs_query_register_offset() - query register offset from its name
 * @name:       the name of a register
 *
 * regs_query_register_offset() returns the offset of a register in struct
 * pt_regs from its name. If the name is invalid, this returns -EINVAL;
 */
int regs_query_register_offset(const char *name)
{
        const struct pt_regs_offset *roff;
        for (roff = regoffset_table; roff->name != NULL; roff++)
                if (!strcmp(roff->name, name))
                        return roff->offset;
        return -EINVAL;
}

/**
 * regs_query_register_name() - query register name from its offset
 * @offset:     the offset of a register in struct pt_regs.
 *
 * regs_query_register_name() returns the name of a register from its
 * offset in struct pt_regs. If the @offset is invalid, this returns NULL;
 */
const char *regs_query_register_name(unsigned int offset)
{
        const struct pt_regs_offset *roff;
        for (roff = regoffset_table; roff->name != NULL; roff++)
                if (roff->offset == offset)
                        return roff->name;
        return NULL;
}

static const int arg_offs_table[] = {
#ifdef CONFIG_X86_32
        [0] = offsetof(struct pt_regs, ax),
        [1] = offsetof(struct pt_regs, dx),
        [2] = offsetof(struct pt_regs, cx)
#else /* CONFIG_X86_64 */
        [0] = offsetof(struct pt_regs, di),
        [1] = offsetof(struct pt_regs, si),
        [2] = offsetof(struct pt_regs, dx),
        [3] = offsetof(struct pt_regs, cx),
        [4] = offsetof(struct pt_regs, r8),
        [5] = offsetof(struct pt_regs, r9)
#endif
};

/**
 * regs_get_argument_nth() - get Nth argument at function call
 * @regs:       pt_regs which contains registers at function entry.
 * @n:          argument number.
 *
 * regs_get_argument_nth() returns @n th argument of a function call.
 * Since usually the kernel stack will be changed right after function entry,
 * you must use this at function entry. If the @n th entry is NOT in the
 * kernel stack or pt_regs, this returns 0.
 */
unsigned long regs_get_argument_nth(struct pt_regs *regs, unsigned int n)
{
        if (n < ARRAY_SIZE(arg_offs_table))
                return *(unsigned long *)((char *)regs + arg_offs_table[n]);
        else {
                /*
                 * The typical case: arg n is on the stack.
                 * (Note: stack[0] = return address, so skip it)
                 */
                n -= ARRAY_SIZE(arg_offs_table);
                return regs_get_kernel_stack_nth(regs, 1 + n);
        }
}

/*
 * does not yet catch signals sent when the child dies.
 * in exit.c or in signal.c.
 */

/*
 * Determines which flags the user has access to [1 = access, 0 = no access].
 */
#define FLAG_MASK_32            ((unsigned long)                        \
                                 (X86_EFLAGS_CF | X86_EFLAGS_PF |       \
                                  X86_EFLAGS_AF | X86_EFLAGS_ZF |       \
                                  X86_EFLAGS_SF | X86_EFLAGS_TF |       \
                                  X86_EFLAGS_DF | X86_EFLAGS_OF |       \
                                  X86_EFLAGS_RF | X86_EFLAGS_AC))

/*
 * Determines whether a value may be installed in a segment register.
 */
static inline bool invalid_selector(u16 value)
{
        return unlikely(value != 0 && (value & SEGMENT_RPL_MASK) != USER_RPL);
}

#ifdef CONFIG_X86_32

#define FLAG_MASK               FLAG_MASK_32

static unsigned long *pt_regs_access(struct pt_regs *regs, unsigned long regno)
{
        BUILD_BUG_ON(offsetof(struct pt_regs, bx) != 0);
        return &regs->bx + (regno >> 2);
}

static u16 get_segment_reg(struct task_struct *task, unsigned long offset)
{
        /*
         * Returning the value truncates it to 16 bits.
         */
        unsigned int retval;
        if (offset != offsetof(struct user_regs_struct, gs))
                retval = *pt_regs_access(task_pt_regs(task), offset);
        else {
                if (task == current)
                        retval = get_user_gs(task_pt_regs(task));
                else
                        retval = task_user_gs(task);
        }
        return retval;
}

static int set_segment_reg(struct task_struct *task,
                           unsigned long offset, u16 value)
{
        /*
         * The value argument was already truncated to 16 bits.
         */
        if (invalid_selector(value))
                return -EIO;

        /*
         * For %cs and %ss we cannot permit a null selector.
         * We can permit a bogus selector as long as it has USER_RPL.
         * Null selectors are fine for other segment registers, but
         * we will never get back to user mode with invalid %cs or %ss
         * and will take the trap in iret instead.  Much code relies
         * on user_mode() to distinguish a user trap frame (which can
         * safely use invalid selectors) from a kernel trap frame.
         */
        switch (offset) {
        case offsetof(struct user_regs_struct, cs):
        case offsetof(struct user_regs_struct, ss):
                if (unlikely(value == 0))
                        return -EIO;

        default:
                *pt_regs_access(task_pt_regs(task), offset) = value;
                break;

        case offsetof(struct user_regs_struct, gs):
                if (task == current)
                        set_user_gs(task_pt_regs(task), value);
                else
                        task_user_gs(task) = value;
        }

        return 0;
}

#else  /* CONFIG_X86_64 */

#define FLAG_MASK               (FLAG_MASK_32 | X86_EFLAGS_NT)

static unsigned long *pt_regs_access(struct pt_regs *regs, unsigned long offset)
{
        BUILD_BUG_ON(offsetof(struct pt_regs, r15) != 0);
        return &regs->r15 + (offset / sizeof(regs->r15));
}

static u16 get_segment_reg(struct task_struct *task, unsigned long offset)
{
        /*
         * Returning the value truncates it to 16 bits.
         */
        unsigned int seg;

        switch (offset) {
        case offsetof(struct user_regs_struct, fs):
                if (task == current) {
                        /* Older gas can't assemble movq %?s,%r?? */
                        asm("movl %%fs,%0" : "=r" (seg));
                        return seg;
                }
                return task->thread.fsindex;
        case offsetof(struct user_regs_struct, gs):
                if (task == current) {
                        asm("movl %%gs,%0" : "=r" (seg));
                        return seg;
                }
                return task->thread.gsindex;
        case offsetof(struct user_regs_struct, ds):
                if (task == current) {
                        asm("movl %%ds,%0" : "=r" (seg));
                        return seg;
                }
                return task->thread.ds;
        case offsetof(struct user_regs_struct, es):
                if (task == current) {
                        asm("movl %%es,%0" : "=r" (seg));
                        return seg;
                }
                return task->thread.es;

        case offsetof(struct user_regs_struct, cs):
        case offsetof(struct user_regs_struct, ss):
                break;
        }
        return *pt_regs_access(task_pt_regs(task), offset);
}

static int set_segment_reg(struct task_struct *task,
                           unsigned long offset, u16 value)
{
        /*
         * The value argument was already truncated to 16 bits.
         */
        if (invalid_selector(value))
                return -EIO;

        switch (offset) {
        case offsetof(struct user_regs_struct,fs):
                /*
                 * If this is setting fs as for normal 64-bit use but
                 * setting fs_base has implicitly changed it, leave it.
                 */
                if ((value == FS_TLS_SEL && task->thread.fsindex == 0 &&
                     task->thread.fs != 0) ||
                    (value == 0 && task->thread.fsindex == FS_TLS_SEL &&
                     task->thread.fs == 0))
                        break;
                task->thread.fsindex = value;
                if (task == current)
                        loadsegment(fs, task->thread.fsindex);
                break;
        case offsetof(struct user_regs_struct,gs):
                /*
                 * If this is setting gs as for normal 64-bit use but
                 * setting gs_base has implicitly changed it, leave it.
                 */
                if ((value == GS_TLS_SEL && task->thread.gsindex == 0 &&
                     task->thread.gs != 0) ||
                    (value == 0 && task->thread.gsindex == GS_TLS_SEL &&
                     task->thread.gs == 0))
                        break;
                task->thread.gsindex = value;
                if (task == current)
                        load_gs_index(task->thread.gsindex);
                break;
        case offsetof(struct user_regs_struct,ds):
                task->thread.ds = value;
                if (task == current)
                        loadsegment(ds, task->thread.ds);
                break;
        case offsetof(struct user_regs_struct,es):
                task->thread.es = value;
                if (task == current)
                        loadsegment(es, task->thread.es);
                break;

                /*
                 * Can't actually change these in 64-bit mode.
                 */
        case offsetof(struct user_regs_struct,cs):
                if (unlikely(value == 0))
                        return -EIO;
#ifdef CONFIG_IA32_EMULATION
                if (test_tsk_thread_flag(task, TIF_IA32))
                        task_pt_regs(task)->cs = value;
#endif
                break;
        case offsetof(struct user_regs_struct,ss):
                if (unlikely(value == 0))
                        return -EIO;
#ifdef CONFIG_IA32_EMULATION
                if (test_tsk_thread_flag(task, TIF_IA32))
                        task_pt_regs(task)->ss = value;
#endif
                break;
        }

        return 0;
}

#endif  /* CONFIG_X86_32 */

static unsigned long get_flags(struct task_struct *task)
{
        unsigned long retval = task_pt_regs(task)->flags;

        /*
         * If the debugger set TF, hide it from the readout.
         */
        if (test_tsk_thread_flag(task, TIF_FORCED_TF))
                retval &= ~X86_EFLAGS_TF;

        return retval;
}

static int set_flags(struct task_struct *task, unsigned long value)
{
        struct pt_regs *regs = task_pt_regs(task);

        /*
         * If the user value contains TF, mark that
         * it was not "us" (the debugger) that set it.
         * If not, make sure it stays set if we had.
         */
        if (value & X86_EFLAGS_TF)
                clear_tsk_thread_flag(task, TIF_FORCED_TF);
        else if (test_tsk_thread_flag(task, TIF_FORCED_TF))
                value |= X86_EFLAGS_TF;

        regs->flags = (regs->flags & ~FLAG_MASK) | (value & FLAG_MASK);

        return 0;
}

static int putreg(struct task_struct *child,
                  unsigned long offset, unsigned long value)
{
        switch (offset) {
        case offsetof(struct user_regs_struct, cs):
        case offsetof(struct user_regs_struct, ds):
        case offsetof(struct user_regs_struct, es):
        case offsetof(struct user_regs_struct, fs):
        case offsetof(struct user_regs_struct, gs):
        case offsetof(struct user_regs_struct, ss):
                return set_segment_reg(child, offset, value);

        case offsetof(struct user_regs_struct, flags):
                return set_flags(child, value);

#ifdef CONFIG_X86_64
        case offsetof(struct user_regs_struct,fs_base):
                if (value >= TASK_SIZE_OF(child))
                        return -EIO;
                /*
                 * When changing the segment base, use do_arch_prctl
                 * to set either thread.fs or thread.fsindex and the
                 * corresponding GDT slot.
                 */
                if (child->thread.fs != value)
                        return do_arch_prctl(child, ARCH_SET_FS, value);
                return 0;
        case offsetof(struct user_regs_struct,gs_base):
                /*
                 * Exactly the same here as the %fs handling above.
                 */
                if (value >= TASK_SIZE_OF(child))
                        return -EIO;
                if (child->thread.gs != value)
                        return do_arch_prctl(child, ARCH_SET_GS, value);
                return 0;
#endif
        }

        *pt_regs_access(task_pt_regs(child), offset) = value;
        return 0;
}

static unsigned long getreg(struct task_struct *task, unsigned long offset)
{
        switch (offset) {
        case offsetof(struct user_regs_struct, cs):
        case offsetof(struct user_regs_struct, ds):
        case offsetof(struct user_regs_struct, es):
        case offsetof(struct user_regs_struct, fs):
        case offsetof(struct user_regs_struct, gs):
        case offsetof(struct user_regs_struct, ss):
                return get_segment_reg(task, offset);

        case offsetof(struct user_regs_struct, flags):
                return get_flags(task);

#ifdef CONFIG_X86_64
        case offsetof(struct user_regs_struct, fs_base): {
                /*
                 * do_arch_prctl may have used a GDT slot instead of
                 * the MSR.  To userland, it appears the same either
                 * way, except the %fs segment selector might not be 0.
                 */
                unsigned int seg = task->thread.fsindex;
                if (task->thread.fs != 0)
                        return task->thread.fs;
                if (task == current)
                        asm("movl %%fs,%0" : "=r" (seg));
                if (seg != FS_TLS_SEL)
                        return 0;
                return get_desc_base(&task->thread.tls_array[FS_TLS]);
        }
        case offsetof(struct user_regs_struct, gs_base): {
                /*
                 * Exactly the same here as the %fs handling above.
                 */
                unsigned int seg = task->thread.gsindex;
                if (task->thread.gs != 0)
                        return task->thread.gs;
                if (task == current)
                        asm("movl %%gs,%0" : "=r" (seg));
                if (seg != GS_TLS_SEL)
                        return 0;
                return get_desc_base(&task->thread.tls_array[GS_TLS]);
        }
#endif
        }

        return *pt_regs_access(task_pt_regs(task), offset);
}

static int genregs_get(struct task_struct *target,
                       const struct user_regset *regset,
                       unsigned int pos, unsigned int count,
                       void *kbuf, void __user *ubuf)
{
        if (kbuf) {
                unsigned long *k = kbuf;
                while (count > 0) {
                        *k++ = getreg(target, pos);
                        count -= sizeof(*k);
                        pos += sizeof(*k);
                }
        } else {
                unsigned long __user *u = ubuf;
                while (count > 0) {
                        if (__put_user(getreg(target, pos), u++))
                                return -EFAULT;
                        count -= sizeof(*u);
                        pos += sizeof(*u);
                }
        }

        return 0;
}

static int genregs_set(struct task_struct *target,
                       const struct user_regset *regset,
                       unsigned int pos, unsigned int count,
                       const void *kbuf, const void __user *ubuf)
{
        int ret = 0;
        if (kbuf) {
                const unsigned long *k = kbuf;
                while (count > 0 && !ret) {
                        ret = putreg(target, pos, *k++);
                        count -= sizeof(*k);
                        pos += sizeof(*k);
                }
        } else {
                const unsigned long  __user *u = ubuf;
                while (count > 0 && !ret) {
                        unsigned long word;
                        ret = __get_user(word, u++);
                        if (ret)
                                break;
                        ret = putreg(target, pos, word);
                        count -= sizeof(*u);
                        pos += sizeof(*u);
                }
        }
        return ret;
}

static void ptrace_triggered(struct perf_event *bp, void *data)
{
        int i;
        struct thread_struct *thread = &(current->thread);

        /*
         * Store in the virtual DR6 register the fact that the breakpoint
         * was hit so the thread's debugger will see it.
         */
        for (i = 0; i < HBP_NUM; i++) {
                if (thread->ptrace_bps[i] == bp)
                        break;
        }

        thread->debugreg6 |= (DR_TRAP0 << i);
}

/*
 * Walk through every ptrace breakpoints for this thread and
 * build the dr7 value on top of their attributes.
 *
 */
static unsigned long ptrace_get_dr7(struct perf_event *bp[])
{
        int i;
        int dr7 = 0;
        struct arch_hw_breakpoint *info;

        for (i = 0; i < HBP_NUM; i++) {
                if (bp[i] && !bp[i]->attr.disabled) {
                        info = counter_arch_bp(bp[i]);
                        dr7 |= encode_dr7(i, info->len, info->type);
                }
        }

        return dr7;
}

/*
 * Handle ptrace writes to debug register 7.
 */
static int ptrace_write_dr7(struct task_struct *tsk, unsigned long data)
{
        struct thread_struct *thread = &(tsk->thread);
        unsigned long old_dr7;
        int i, orig_ret = 0, rc = 0;
        int enabled, second_pass = 0;
        unsigned len, type;
        int gen_len, gen_type;
        struct perf_event *bp;

        data &= ~DR_CONTROL_RESERVED;
        old_dr7 = ptrace_get_dr7(thread->ptrace_bps);
restore:
        /*
         * Loop through all the hardware breakpoints, making the
         * appropriate changes to each.
         */
        for (i = 0; i < HBP_NUM; i++) {
                enabled = decode_dr7(data, i, &len, &type);
                bp = thread->ptrace_bps[i];

                if (!enabled) {
                        if (bp) {
                                /*
                                 * Don't unregister the breakpoints right-away,
                                 * unless all register_user_hw_breakpoint()
                                 * requests have succeeded. This prevents
                                 * any window of opportunity for debug
                                 * register grabbing by other users.
                                 */
                                if (!second_pass)
                                        continue;
                                thread->ptrace_bps[i] = NULL;
                                unregister_hw_breakpoint(bp);
                        }
                        continue;
                }

                /*
                 * We shoud have at least an inactive breakpoint at this
                 * slot. It means the user is writing dr7 without having
                 * written the address register first
                 */
                if (!bp) {
                        rc = -EINVAL;
                        break;
                }

                rc = arch_bp_generic_fields(len, type, &gen_len, &gen_type);
                if (rc)
                        break;

                /*
                 * This is a temporary thing as bp is unregistered/registered
                 * to simulate modification
                 */
                bp = modify_user_hw_breakpoint(bp, bp->attr.bp_addr, gen_len,
                                               gen_type, bp->callback,
                                               tsk, true);
                thread->ptrace_bps[i] = NULL;

                if (!bp) { /* incorrect bp, or we have a bug in bp API */
                        rc = -EINVAL;
                        break;
                }
                if (IS_ERR(bp)) {
                        rc = PTR_ERR(bp);
                        bp = NULL;
                        break;
                }
                thread->ptrace_bps[i] = bp;
        }
        /*
         * Make a second pass to free the remaining unused breakpoints
         * or to restore the original breakpoints if an error occurred.
         */
        if (!second_pass) {
                second_pass = 1;
                if (rc < 0) {
                        orig_ret = rc;
                        data = old_dr7;
                }
                goto restore;
        }
        return ((orig_ret < 0) ? orig_ret : rc);
}

/*
 * Handle PTRACE_PEEKUSR calls for the debug register area.
 */
static unsigned long ptrace_get_debugreg(struct task_struct *tsk, int n)
{
        struct thread_struct *thread = &(tsk->thread);
        unsigned long val = 0;

        if (n < HBP_NUM) {
                struct perf_event *bp;
                bp = thread->ptrace_bps[n];
                if (!bp)
                        return 0;
                val = bp->hw.info.address;
        } else if (n == 6) {
                val = thread->debugreg6;
         } else if (n == 7) {
                val = ptrace_get_dr7(thread->ptrace_bps);
        }
        return val;
}

static int ptrace_set_breakpoint_addr(struct task_struct *tsk, int nr,
                                      unsigned long addr)
{
        struct perf_event *bp;
        struct thread_struct *t = &tsk->thread;

        if (!t->ptrace_bps[nr]) {
                /*
                 * Put stub len and type to register (reserve) an inactive but
                 * correct bp
                 */
                bp = register_user_hw_breakpoint(addr, HW_BREAKPOINT_LEN_1,
                                                 HW_BREAKPOINT_W,
                                                 ptrace_triggered, tsk,
                                                 false);
        } else {
                bp = t->ptrace_bps[nr];
                t->ptrace_bps[nr] = NULL;
                bp = modify_user_hw_breakpoint(bp, addr, bp->attr.bp_len,
                                               bp->attr.bp_type,
                                               bp->callback,
                                               tsk,
                                               bp->attr.disabled);
        }

        if (!bp)
                return -EIO;
        /*
         * CHECKME: the previous code returned -EIO if the addr wasn't a
         * valid task virtual addr. The new one will return -EINVAL in this
         * case.
         * -EINVAL may be what we want for in-kernel breakpoints users, but
         * -EIO looks better for ptrace, since we refuse a register writing
         * for the user. And anyway this is the previous behaviour.
         */
        if (IS_ERR(bp))
                return PTR_ERR(bp);

        t->ptrace_bps[nr] = bp;

        return 0;
}

/*
 * Handle PTRACE_POKEUSR calls for the debug register area.
 */
int ptrace_set_debugreg(struct task_struct *tsk, int n, unsigned long val)
{
        struct thread_struct *thread = &(tsk->thread);
        int rc = 0;

        /* There are no DR4 or DR5 registers */
        if (n == 4 || n == 5)
                return -EIO;

        if (n == 6) {
                thread->debugreg6 = val;
                goto ret_path;
        }
        if (n < HBP_NUM) {
                rc = ptrace_set_breakpoint_addr(tsk, n, val);
                if (rc)
                        return rc;
        }
        /* All that's left is DR7 */
        if (n == 7)
                rc = ptrace_write_dr7(tsk, val);

ret_path:
        return rc;
}

/*
 * These access the current or another (stopped) task's io permission
 * bitmap for debugging or core dump.
 */
static int ioperm_active(struct task_struct *target,
                         const struct user_regset *regset)
{
        return target->thread.io_bitmap_max / regset->size;
}

static int ioperm_get(struct task_struct *target,
                      const struct user_regset *regset,
                      unsigned int pos, unsigned int count,
                      void *kbuf, void __user *ubuf)
{
        if (!target->thread.io_bitmap_ptr)
                return -ENXIO;

        return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
                                   target->thread.io_bitmap_ptr,
                                   0, IO_BITMAP_BYTES);
}

#ifdef CONFIG_X86_PTRACE_BTS
/*
 * A branch trace store context.
 *
 * Contexts may only be installed by ptrace_bts_config() and only for
 * ptraced tasks.
 *
 * Contexts are destroyed when the tracee is detached from the tracer.
 * The actual destruction work requires interrupts enabled, so the
 * work is deferred and will be scheduled during __ptrace_unlink().
 *
 * Contexts hold an additional task_struct reference on the traced
 * task, as well as a reference on the tracer's mm.
 *
 * Ptrace already holds a task_struct for the duration of ptrace operations,
 * but since destruction is deferred, it may be executed after both
 * tracer and tracee exited.
 */
struct bts_context {
        /* The branch trace handle. */
        struct bts_tracer       *tracer;

        /* The buffer used to store the branch trace and its size. */
        void                    *buffer;
        unsigned int            size;

        /* The mm that paid for the above buffer. */
        struct mm_struct        *mm;

        /* The task this context belongs to. */
        struct task_struct      *task;

        /* The signal to send on a bts buffer overflow. */
        unsigned int            bts_ovfl_signal;

        /* The work struct to destroy a context. */
        struct work_struct      work;
};

static int alloc_bts_buffer(struct bts_context *context, unsigned int size)
{
        void *buffer = NULL;
        int err = -ENOMEM;

        err = account_locked_memory(current->mm, current->signal->rlim, size);
        if (err < 0)
                return err;

        buffer = kzalloc(size, GFP_KERNEL);
        if (!buffer)
                goto out_refund;

        context->buffer = buffer;
        context->size = size;
        context->mm = get_task_mm(current);

        return 0;

 out_refund:
        refund_locked_memory(current->mm, size);
        return err;
}

static inline void free_bts_buffer(struct bts_context *context)
{
        if (!context->buffer)
                return;

        kfree(context->buffer);
        context->buffer = NULL;

        refund_locked_memory(context->mm, context->size);
        context->size = 0;

        mmput(context->mm);
        context->mm = NULL;
}

static void free_bts_context_work(struct work_struct *w)
{
        struct bts_context *context;

        context = container_of(w, struct bts_context, work);

        ds_release_bts(context->tracer);
        put_task_struct(context->task);
        free_bts_buffer(context);
        kfree(context);
}

static inline void free_bts_context(struct bts_context *context)
{
        INIT_WORK(&context->work, free_bts_context_work);
        schedule_work(&context->work);
}

static inline struct bts_context *alloc_bts_context(struct task_struct *task)
{
        struct bts_context *context = kzalloc(sizeof(*context), GFP_KERNEL);
        if (context) {
                context->task = task;
                task->bts = context;

                get_task_struct(task);
        }

        return context;
}

static int ptrace_bts_read_record(struct task_struct *child, size_t index,
                                  struct bts_struct __user *out)
{
        struct bts_context *context;
        const struct bts_trace *trace;
        struct bts_struct bts;
        const unsigned char *at;
        int error;

        context = child->bts;
        if (!context)
                return -ESRCH;

        trace = ds_read_bts(context->tracer);
        if (!trace)
                return -ESRCH;

        at = trace->ds.top - ((index + 1) * trace->ds.size);
        if ((void *)at < trace->ds.begin)
                at += (trace->ds.n * trace->ds.size);

        if (!trace->read)
                return -EOPNOTSUPP;

        error = trace->read(context->tracer, at, &bts);
        if (error < 0)
                return error;

        if (copy_to_user(out, &bts, sizeof(bts)))
                return -EFAULT;

        return sizeof(bts);
}

static int ptrace_bts_drain(struct task_struct *child,
                            long size,
                            struct bts_struct __user *out)
{
        struct bts_context *context;
        const struct bts_trace *trace;
        const unsigned char *at;
        int error, drained = 0;

        context = child->bts;
        if (!context)
                return -ESRCH;

        trace = ds_read_bts(context->tracer);
        if (!trace)
                return -ESRCH;

        if (!trace->read)
                return -EOPNOTSUPP;

        if (size < (trace->ds.top - trace->ds.begin))
                return -EIO;

        for (at = trace->ds.begin; (void *)at < trace->ds.top;
             out++, drained++, at += trace->ds.size) {
                struct bts_struct bts;

                error = trace->read(context->tracer, at, &bts);
                if (error < 0)
                        return error;

                if (copy_to_user(out, &bts, sizeof(bts)))
                        return -EFAULT;
        }

        memset(trace->ds.begin, 0, trace->ds.n * trace->ds.size);

        error = ds_reset_bts(context->tracer);
        if (error < 0)
                return error;

        return drained;
}

static int ptrace_bts_config(struct task_struct *child,
                             long cfg_size,
                             const struct ptrace_bts_config __user *ucfg)
{
        struct bts_context *context;
        struct ptrace_bts_config cfg;
        unsigned int flags = 0;

        if (cfg_size < sizeof(cfg))
                return -EIO;

        if (copy_from_user(&cfg, ucfg, sizeof(cfg)))
                return -EFAULT;

        context = child->bts;
        if (!context)
                context = alloc_bts_context(child);
        if (!context)
                return -ENOMEM;

        if (cfg.flags & PTRACE_BTS_O_SIGNAL) {
                if (!cfg.signal)
                        return -EINVAL;

                return -EOPNOTSUPP;
                context->bts_ovfl_signal = cfg.signal;
        }

        ds_release_bts(context->tracer);
        context->tracer = NULL;

        if ((cfg.flags & PTRACE_BTS_O_ALLOC) && (cfg.size != context->size)) {
                int err;

                free_bts_buffer(context);
                if (!cfg.size)
                        return 0;

                err = alloc_bts_buffer(context, cfg.size);
                if (err < 0)
                        return err;
        }

        if (cfg.flags & PTRACE_BTS_O_TRACE)
                flags |= BTS_USER;

        if (cfg.flags & PTRACE_BTS_O_SCHED)
                flags |= BTS_TIMESTAMPS;

        context->tracer =
                ds_request_bts_task(child, context->buffer, context->size,
                                    NULL, (size_t)-1, flags);
        if (unlikely(IS_ERR(context->tracer))) {
                int error = PTR_ERR(context->tracer);

                free_bts_buffer(context);
                context->tracer = NULL;
                return error;
        }

        return sizeof(cfg);
}

static int ptrace_bts_status(struct task_struct *child,
                             long cfg_size,
                             struct ptrace_bts_config __user *ucfg)
{
        struct bts_context *context;
        const struct bts_trace *trace;
        struct ptrace_bts_config cfg;

        context = child->bts;
        if (!context)
                return -ESRCH;

        if (cfg_size < sizeof(cfg))
                return -EIO;

        trace = ds_read_bts(context->tracer);
        if (!trace)
                return -ESRCH;

        memset(&cfg, 0, sizeof(cfg));
        cfg.size        = trace->ds.end - trace->ds.begin;
        cfg.signal      = context->bts_ovfl_signal;
        cfg.bts_size    = sizeof(struct bts_struct);

        if (cfg.signal)
                cfg.flags |= PTRACE_BTS_O_SIGNAL;

        if (trace->ds.flags & BTS_USER)
                cfg.flags |= PTRACE_BTS_O_TRACE;

        if (trace->ds.flags & BTS_TIMESTAMPS)
                cfg.flags |= PTRACE_BTS_O_SCHED;

        if (copy_to_user(ucfg, &cfg, sizeof(cfg)))
                return -EFAULT;

        return sizeof(cfg);
}

static int ptrace_bts_clear(struct task_struct *child)
{
        struct bts_context *context;
        const struct bts_trace *trace;

        context = child->bts;
        if (!context)
                return -ESRCH;

        trace = ds_read_bts(context->tracer);
        if (!trace)
                return -ESRCH;

        memset(trace->ds.begin, 0, trace->ds.n * trace->ds.size);

        return ds_reset_bts(context->tracer);
}

static int ptrace_bts_size(struct task_struct *child)
{
        struct bts_context *context;
        const struct bts_trace *trace;

        context = child->bts;
        if (!context)
                return -ESRCH;

        trace = ds_read_bts(context->tracer);
        if (!trace)
                return -ESRCH;

        return (trace->ds.top - trace->ds.begin) / trace->ds.size;
}

/*
 * Called from __ptrace_unlink() after the child has been moved back
 * to its original parent.
 */
void ptrace_bts_untrace(struct task_struct *child)
{
        if (unlikely(child->bts)) {
                free_bts_context(child->bts);
                child->bts = NULL;
        }
}
#endif /* CONFIG_X86_PTRACE_BTS */

/*
 * Called by kernel/ptrace.c when detaching..
 *
 * Make sure the single step bit is not set.
 */
void ptrace_disable(struct task_struct *child)
{
        user_disable_single_step(child);
#ifdef TIF_SYSCALL_EMU
        clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
#endif
}

#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
static const struct user_regset_view user_x86_32_view; /* Initialized below. */
#endif

long arch_ptrace(struct task_struct *child, long request, long addr, long data)
{
        int ret;
        unsigned long __user *datap = (unsigned long __user *)data;

        switch (request) {
        /* read the word at location addr in the USER area. */
        case PTRACE_PEEKUSR: {
                unsigned long tmp;

                ret = -EIO;
                if ((addr & (sizeof(data) - 1)) || addr < 0 ||
                    addr >= sizeof(struct user))
                        break;

                tmp = 0;  /* Default return condition */
                if (addr < sizeof(struct user_regs_struct))
                        tmp = getreg(child, addr);
                else if (addr >= offsetof(struct user, u_debugreg[0]) &&
                         addr <= offsetof(struct user, u_debugreg[7])) {
                        addr -= offsetof(struct user, u_debugreg[0]);
                        tmp = ptrace_get_debugreg(child, addr / sizeof(data));
                }
                ret = put_user(tmp, datap);
                break;
        }

        case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
                ret = -EIO;
                if ((addr & (sizeof(data) - 1)) || addr < 0 ||
                    addr >= sizeof(struct user))
                        break;

                if (addr < sizeof(struct user_regs_struct))
                        ret = putreg(child, addr, data);
                else if (addr >= offsetof(struct user, u_debugreg[0]) &&
                         addr <= offsetof(struct user, u_debugreg[7])) {
                        addr -= offsetof(struct user, u_debugreg[0]);
                        ret = ptrace_set_debugreg(child,
                                                  addr / sizeof(data), data);
                }
                break;

        case PTRACE_GETREGS:    /* Get all gp regs from the child. */
                return copy_regset_to_user(child,
                                           task_user_regset_view(current),
                                           REGSET_GENERAL,
                                           0, sizeof(struct user_regs_struct),
                                           datap);

        case PTRACE_SETREGS:    /* Set all gp regs in the child. */
                return copy_regset_from_user(child,
                                             task_user_regset_view(current),
                                             REGSET_GENERAL,
                                             0, sizeof(struct user_regs_struct),
                                             datap);

        case PTRACE_GETFPREGS:  /* Get the child FPU state. */
                return copy_regset_to_user(child,
                                           task_user_regset_view(current),
                                           REGSET_FP,
                                           0, sizeof(struct user_i387_struct),
                                           datap);

        case PTRACE_SETFPREGS:  /* Set the child FPU state. */
                return copy_regset_from_user(child,
                                             task_user_regset_view(current),
                                             REGSET_FP,
                                             0, sizeof(struct user_i387_struct),
                                             datap);

#ifdef CONFIG_X86_32
        case PTRACE_GETFPXREGS: /* Get the child extended FPU state. */
                return copy_regset_to_user(child, &user_x86_32_view,
                                           REGSET_XFP,
                                           0, sizeof(struct user_fxsr_struct),
                                           datap) ? -EIO : 0;

        case PTRACE_SETFPXREGS: /* Set the child extended FPU state. */
                return copy_regset_from_user(child, &user_x86_32_view,
                                             REGSET_XFP,
                                             0, sizeof(struct user_fxsr_struct),
                                             datap) ? -EIO : 0;
#endif

#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
        case PTRACE_GET_THREAD_AREA:
                if (addr < 0)
                        return -EIO;
                ret = do_get_thread_area(child, addr,
                                         (struct user_desc __user *) data);
                break;

        case PTRACE_SET_THREAD_AREA:
                if (addr < 0)
                        return -EIO;
                ret = do_set_thread_area(child, addr,
                                         (struct user_desc __user *) data, 0);
                break;
#endif

#ifdef CONFIG_X86_64
                /* normal 64bit interface to access TLS data.
                   Works just like arch_prctl, except that the arguments
                   are reversed. */
        case PTRACE_ARCH_PRCTL:
                ret = do_arch_prctl(child, data, addr);
                break;
#endif

        /*
         * These bits need more cooking - not enabled yet:
         */
#ifdef CONFIG_X86_PTRACE_BTS
        case PTRACE_BTS_CONFIG:
                ret = ptrace_bts_config
                        (child, data, (struct ptrace_bts_config __user *)addr);
                break;

        case PTRACE_BTS_STATUS:
                ret = ptrace_bts_status
                        (child, data, (struct ptrace_bts_config __user *)addr);
                break;

        case PTRACE_BTS_SIZE:
                ret = ptrace_bts_size(child);
                break;

        case PTRACE_BTS_GET:
                ret = ptrace_bts_read_record
                        (child, data, (struct bts_struct __user *) addr);
                break;

        case PTRACE_BTS_CLEAR:
                ret = ptrace_bts_clear(child);
                break;

        case PTRACE_BTS_DRAIN:
                ret = ptrace_bts_drain
                        (child, data, (struct bts_struct __user *) addr);
                break;
#endif /* CONFIG_X86_PTRACE_BTS */

        default:
                ret = ptrace_request(child, request, addr, data);
                break;
        }

        return ret;
}

#ifdef CONFIG_IA32_EMULATION

#include <linux/compat.h>
#include <linux/syscalls.h>
#include <asm/ia32.h>
#include <asm/user32.h>

#define R32(l,q)                                                        \
        case offsetof(struct user32, regs.l):                           \
                regs->q = value; break

#define SEG32(rs)                                                       \
        case offsetof(struct user32, regs.rs):                          \
                return set_segment_reg(child,                           \
                                       offsetof(struct user_regs_struct, rs), \
                                       value);                          \
                break

static int putreg32(struct task_struct *child, unsigned regno, u32 value)
{
        struct pt_regs *regs = task_pt_regs(child);

        switch (regno) {

        SEG32(cs);
        SEG32(ds);
        SEG32(es);
        SEG32(fs);
        SEG32(gs);
        SEG32(ss);

        R32(ebx, bx);
        R32(ecx, cx);
        R32(edx, dx);
        R32(edi, di);
        R32(esi, si);
        R32(ebp, bp);
        R32(eax, ax);
        R32(eip, ip);
        R32(esp, sp);

        case offsetof(struct user32, regs.orig_eax):
                /*
                 * A 32-bit debugger setting orig_eax means to restore
                 * the state of the task restarting a 32-bit syscall.
                 * Make sure we interpret the -ERESTART* codes correctly
                 * in case the task is not actually still sitting at the
                 * exit from a 32-bit syscall with TS_COMPAT still set.
                 */
                regs->orig_ax = value;
                if (syscall_get_nr(child, regs) >= 0)
                        task_thread_info(child)->status |= TS_COMPAT;
                break;

        case offsetof(struct user32, regs.eflags):
                return set_flags(child, value);

        case offsetof(struct user32, u_debugreg[0]) ...
                offsetof(struct user32, u_debugreg[7]):
                regno -= offsetof(struct user32, u_debugreg[0]);
                return ptrace_set_debugreg(child, regno / 4, value);

        default:
                if (regno > sizeof(struct user32) || (regno & 3))
                        return -EIO;

                /*
                 * Other dummy fields in the virtual user structure
                 * are ignored
                 */
                break;
        }
        return 0;
}

#undef R32
#undef SEG32

#define R32(l,q)                                                        \
        case offsetof(struct user32, regs.l):                           \
                *val = regs->q; break

#define SEG32(rs)                                                       \
        case offsetof(struct user32, regs.rs):                          \
                *val = get_segment_reg(child,                           \
                                       offsetof(struct user_regs_struct, rs)); \
                break

static int getreg32(struct task_struct *child, unsigned regno, u32 *val)
{
        struct pt_regs *regs = task_pt_regs(child);

        switch (regno) {

        SEG32(ds);
        SEG32(es);
        SEG32(fs);
        SEG32(gs);

        R32(cs, cs);
        R32(ss, ss);
        R32(ebx, bx);
        R32(ecx, cx);
        R32(edx, dx);
        R32(edi, di);
        R32(esi, si);
        R32(ebp, bp);
        R32(eax, ax);
        R32(orig_eax, orig_ax);
        R32(eip, ip);
        R32(esp, sp);

        case offsetof(struct user32, regs.eflags):
                *val = get_flags(child);
                break;

        case offsetof(struct user32, u_debugreg[0]) ...
                offsetof(struct user32, u_debugreg[7]):
                regno -= offsetof(struct user32, u_debugreg[0]);
                *val = ptrace_get_debugreg(child, regno / 4);
                break;

        default:
                if (regno > sizeof(struct user32) || (regno & 3))
                        return -EIO;

                /*
                 * Other dummy fields in the virtual user structure
                 * are ignored
                 */
                *val = 0;
                break;
        }
        return 0;
}

#undef R32
#undef SEG32

static int genregs32_get(struct task_struct *target,
                         const struct user_regset *regset,
                         unsigned int pos, unsigned int count,
                         void *kbuf, void __user *ubuf)
{
        if (kbuf) {
                compat_ulong_t *k = kbuf;
                while (count > 0) {
                        getreg32(target, pos, k++);
                        count -= sizeof(*k);
                        pos += sizeof(*k);
                }
        } else {
                compat_ulong_t __user *u = ubuf;
                while (count > 0) {
                        compat_ulong_t word;
                        getreg32(target, pos, &word);
                        if (__put_user(word, u++))
                                return -EFAULT;
                        count -= sizeof(*u);
                        pos += sizeof(*u);
                }
        }

        return 0;
}

static int genregs32_set(struct task_struct *target,
                         const struct user_regset *regset,
                         unsigned int pos, unsigned int count,
                         const void *kbuf, const void __user *ubuf)
{
        int ret = 0;
        if (kbuf) {
                const compat_ulong_t *k = kbuf;
                while (count > 0 && !ret) {
                        ret = putreg32(target, pos, *k++);
                        count -= sizeof(*k);
                        pos += sizeof(*k);
                }
        } else {
                const compat_ulong_t __user *u = ubuf;
                while (count > 0 && !ret) {
                        compat_ulong_t word;
                        ret = __get_user(word, u++);
                        if (ret)
                                break;
                        ret = putreg32(target, pos, word);
                        count -= sizeof(*u);
                        pos += sizeof(*u);
                }
        }
        return ret;
}

long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
                        compat_ulong_t caddr, compat_ulong_t cdata)
{
        unsigned long addr = caddr;
        unsigned long data = cdata;
        void __user *datap = compat_ptr(data);
        int ret;
        __u32 val;

        switch (request) {
        case PTRACE_PEEKUSR:
                ret = getreg32(child, addr, &val);
                if (ret == 0)
                        ret = put_user(val, (__u32 __user *)datap);
                break;

        case PTRACE_POKEUSR:
                ret = putreg32(child, addr, data);
                break;

        case PTRACE_GETREGS:    /* Get all gp regs from the child. */
                return copy_regset_to_user(child, &user_x86_32_view,
                                           REGSET_GENERAL,
                                           0, sizeof(struct user_regs_struct32),
                                           datap);

        case PTRACE_SETREGS:    /* Set all gp regs in the child. */
                return copy_regset_from_user(child, &user_x86_32_view,
                                             REGSET_GENERAL, 0,
                                             sizeof(struct user_regs_struct32),
                                             datap);

        case PTRACE_GETFPREGS:  /* Get the child FPU state. */
                return copy_regset_to_user(child, &user_x86_32_view,
                                           REGSET_FP, 0,
                                           sizeof(struct user_i387_ia32_struct),
                                           datap);

        case PTRACE_SETFPREGS:  /* Set the child FPU state. */
                return copy_regset_from_user(
                        child, &user_x86_32_view, REGSET_FP,
                        0, sizeof(struct user_i387_ia32_struct), datap);

        case PTRACE_GETFPXREGS: /* Get the child extended FPU state. */
                return copy_regset_to_user(child, &user_x86_32_view,
                                           REGSET_XFP, 0,
                                           sizeof(struct user32_fxsr_struct),
                                           datap);

        case PTRACE_SETFPXREGS: /* Set the child extended FPU state. */
                return copy_regset_from_user(child, &user_x86_32_view,
                                             REGSET_XFP, 0,
                                             sizeof(struct user32_fxsr_struct),
                                             datap);

        case PTRACE_GET_THREAD_AREA:
        case PTRACE_SET_THREAD_AREA:
#ifdef CONFIG_X86_PTRACE_BTS
        case PTRACE_BTS_CONFIG:
        case PTRACE_BTS_STATUS:
        case PTRACE_BTS_SIZE:
        case PTRACE_BTS_GET:
        case PTRACE_BTS_CLEAR:
        case PTRACE_BTS_DRAIN:
#endif /* CONFIG_X86_PTRACE_BTS */
                return arch_ptrace(child, request, addr, data);

        default:
                return compat_ptrace_request(child, request, addr, data);
        }

        return ret;
}

#endif  /* CONFIG_IA32_EMULATION */

#ifdef CONFIG_X86_64

static const struct user_regset x86_64_regsets[] = {
        [REGSET_GENERAL] = {
                .core_note_type = NT_PRSTATUS,
                .n = sizeof(struct user_regs_struct) / sizeof(long),
                .size = sizeof(long), .align = sizeof(long),
                .get = genregs_get, .set = genregs_set
        },
        [REGSET_FP] = {
                .core_note_type = NT_PRFPREG,
                .n = sizeof(struct user_i387_struct) / sizeof(long),
                .size = sizeof(long), .align = sizeof(long),
                .active = xfpregs_active, .get = xfpregs_get, .set = xfpregs_set
        },
        [REGSET_IOPERM64] = {
                .core_note_type = NT_386_IOPERM,
                .n = IO_BITMAP_LONGS,
                .size = sizeof(long), .align = sizeof(long),
                .active = ioperm_active, .get = ioperm_get
        },
};

static const struct user_regset_view user_x86_64_view = {
        .name = "x86_64", .e_machine = EM_X86_64,
        .regsets = x86_64_regsets, .n = ARRAY_SIZE(x86_64_regsets)
};

#else  /* CONFIG_X86_32 */

#define user_regs_struct32      user_regs_struct
#define genregs32_get           genregs_get
#define genregs32_set           genregs_set

#define user_i387_ia32_struct   user_i387_struct
#define user32_fxsr_struct      user_fxsr_struct

#endif  /* CONFIG_X86_64 */

#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
static const struct user_regset x86_32_regsets[] = {
        [REGSET_GENERAL] = {
                .core_note_type = NT_PRSTATUS,
                .n = sizeof(struct user_regs_struct32) / sizeof(u32),
                .size = sizeof(u32), .align = sizeof(u32),
                .get = genregs32_get, .set = genregs32_set
        },
        [REGSET_FP] = {
                .core_note_type = NT_PRFPREG,
                .n = sizeof(struct user_i387_ia32_struct) / sizeof(u32),
                .size = sizeof(u32), .align = sizeof(u32),
                .active = fpregs_active, .get = fpregs_get, .set = fpregs_set
        },
        [REGSET_XFP] = {
                .core_note_type = NT_PRXFPREG,
                .n = sizeof(struct user32_fxsr_struct) / sizeof(u32),
                .size = sizeof(u32), .align = sizeof(u32),
                .active = xfpregs_active, .get = xfpregs_get, .set = xfpregs_set
        },
        [REGSET_TLS] = {
                .core_note_type = NT_386_TLS,
                .n = GDT_ENTRY_TLS_ENTRIES, .bias = GDT_ENTRY_TLS_MIN,
                .size = sizeof(struct user_desc),
                .align = sizeof(struct user_desc),
                .active = regset_tls_active,
                .get = regset_tls_get, .set = regset_tls_set
        },
        [REGSET_IOPERM32] = {
                .core_note_type = NT_386_IOPERM,
                .n = IO_BITMAP_BYTES / sizeof(u32),
                .size = sizeof(u32), .align = sizeof(u32),
                .active = ioperm_active, .get = ioperm_get
        },
};

static const struct user_regset_view user_x86_32_view = {
        .name = "i386", .e_machine = EM_386,
        .regsets = x86_32_regsets, .n = ARRAY_SIZE(x86_32_regsets)
};
#endif

const struct user_regset_view *task_user_regset_view(struct task_struct *task)
{
#ifdef CONFIG_IA32_EMULATION
        if (test_tsk_thread_flag(task, TIF_IA32))
#endif
#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
                return &user_x86_32_view;
#endif
#ifdef CONFIG_X86_64
        return &user_x86_64_view;
#endif
}

void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs,
                                         int error_code, int si_code)
{
        struct siginfo info;

        tsk->thread.trap_no = 1;
        tsk->thread.error_code = error_code;

        memset(&info, 0, sizeof(info));
        info.si_signo = SIGTRAP;
        info.si_code = si_code;

        /* User-mode ip? */
        info.si_addr = user_mode_vm(regs) ? (void __user *) regs->ip : NULL;

        /* Send us the fake SIGTRAP */
        force_sig_info(SIGTRAP, &info, tsk);
}


#ifdef CONFIG_X86_32
# define IS_IA32        1
#elif defined CONFIG_IA32_EMULATION
# define IS_IA32        is_compat_task()
#else
# define IS_IA32        0
#endif

/*
 * We must return the syscall number to actually look up in the table.
 * This can be -1L to skip running any syscall at all.
 */
asmregparm long syscall_trace_enter(struct pt_regs *regs)
{
        long ret = 0;

        /*
         * If we stepped into a sysenter/syscall insn, it trapped in
         * kernel mode; do_debug() cleared TF and set TIF_SINGLESTEP.
         * If user-mode had set TF itself, then it's still clear from
         * do_debug() and we need to set it again to restore the user
         * state.  If we entered on the slow path, TF was already set.
         */
        if (test_thread_flag(TIF_SINGLESTEP))
                regs->flags |= X86_EFLAGS_TF;

        /* do the secure computing check first */
        secure_computing(regs->orig_ax);

        if (unlikely(test_thread_flag(TIF_SYSCALL_EMU)))
                ret = -1L;

        if ((ret || test_thread_flag(TIF_SYSCALL_TRACE)) &&
            tracehook_report_syscall_entry(regs))
                ret = -1L;

        if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
                trace_sys_enter(regs, regs->orig_ax);

        if (unlikely(current->audit_context)) {
                if (IS_IA32)
                        audit_syscall_entry(AUDIT_ARCH_I386,
                                            regs->orig_ax,
                                            regs->bx, regs->cx,
                                            regs->dx, regs->si);
#ifdef CONFIG_X86_64
                else
                        audit_syscall_entry(AUDIT_ARCH_X86_64,
                                            regs->orig_ax,
                                            regs->di, regs->si,
                                            regs->dx, regs->r10);
#endif
        }

        return ret ?: regs->orig_ax;
}

asmregparm void syscall_trace_leave(struct pt_regs *regs)
{
        if (unlikely(current->audit_context))
                audit_syscall_exit(AUDITSC_RESULT(regs->ax), regs->ax);

        if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
                trace_sys_exit(regs, regs->ax);

        if (test_thread_flag(TIF_SYSCALL_TRACE))
                tracehook_report_syscall_exit(regs, 0);

        /*
         * If TIF_SYSCALL_EMU is set, we only get here because of
         * TIF_SINGLESTEP (i.e. this is PTRACE_SYSEMU_SINGLESTEP).
         * We already reported this syscall instruction in
         * syscall_trace_enter(), so don't do any more now.
         */
        if (unlikely(test_thread_flag(TIF_SYSCALL_EMU)))
                return;

        /*
         * If we are single-stepping, synthesize a trap to follow the
         * system call instruction.
         */
        if (test_thread_flag(TIF_SINGLESTEP) &&
            tracehook_consider_fatal_signal(current, SIGTRAP))
                send_sigtrap(current, regs, 0, TRAP_BRKPT);
}