ptrace.c

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/* By Ross Biro 1/23/92 */
/*
 * Pentium III FXSR, SSE support
 *  Gareth Hughes <[email protected]>, May 2000
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/errno.h>
#include <linux/slab.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/perf_event.h>
#include <linux/hw_breakpoint.h>
#include <linux/rcupdate.h>
#include <linux/module.h>

#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/i387.h>
#include <asm/fpu-internal.h>
#include <asm/debugreg.h>
#include <asm/ldt.h>
#include <asm/desc.h>
#include <asm/prctl.h>
#include <asm/proto.h>
#include <asm/hw_breakpoint.h>
#include <asm/traps.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_XSTATE,
    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,
};

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;
}

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
};

/*
 * 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

/*
 * X86_32 CPUs don't save ss and esp if the CPU is already in kernel mode
 * when it traps.  The previous stack will be directly underneath the saved
 * registers, and 'sp/ss' won't even have been saved. Thus the '&regs->sp'.
 *
 * Now, if the stack is empty, '&regs->sp' is out of range. In this
 * case we try to take the previous stack. To always return a non-null
 * stack pointer we fall back to regs as stack if no previous stack
 * exists.
 *
 * This is valid only for kernel mode traps.
 */
unsigned long kernel_stack_pointer(struct pt_regs *regs)
{
    unsigned long context = (unsigned long)regs & ~(THREAD_SIZE - 1);
    unsigned long sp = (unsigned long)&regs->sp;
    struct thread_info *tinfo;

    if (context == (sp & ~(THREAD_SIZE - 1)))
        return sp;

    tinfo = (struct thread_info *)context;
    if (tinfo->previous_esp)
        return tinfo->previous_esp;

    return (unsigned long)regs;
}
EXPORT_SYMBOL_GPL(kernel_stack_pointer);

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 >= sizeof(*k)) {
            *k++ = getreg(target, pos);
            count -= sizeof(*k);
            pos += sizeof(*k);
        }
    } else {
        unsigned long __user *u = ubuf;
        while (count >= sizeof(*u)) {
            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 >= sizeof(*k) && !ret) {
            ret = putreg(target, pos, *k++);
            count -= sizeof(*k);
            pos += sizeof(*k);
        }
    } else {
        const unsigned long  __user *u = ubuf;
        while (count >= sizeof(*u) && !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,
                 struct perf_sample_data *data,
                 struct pt_regs *regs)
{
    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;
}

static int
ptrace_modify_breakpoint(struct perf_event *bp, int len, int type,
             struct task_struct *tsk, int disabled)
{
    int err;
    int gen_len, gen_type;
    struct perf_event_attr attr;

    /*
     * We should 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)
        return -EINVAL;

    err = arch_bp_generic_fields(len, type, &gen_len, &gen_type);
    if (err)
        return err;

    attr = bp->attr;
    attr.bp_len = gen_len;
    attr.bp_type = gen_type;
    attr.disabled = disabled;

    return modify_user_hw_breakpoint(bp, &attr);
}

/*
 * 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;
    struct perf_event *bp;

    if (ptrace_get_breakpoints(tsk) < 0)
        return -ESRCH;

    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;

                rc = ptrace_modify_breakpoint(bp, len, type,
                                  tsk, 1);
                if (rc)
                    break;
            }
            continue;
        }

        rc = ptrace_modify_breakpoint(bp, len, type, tsk, 0);
        if (rc)
            break;
    }
    /*
     * 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;
    }

    ptrace_put_breakpoints(tsk);

    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;

        if (ptrace_get_breakpoints(tsk) < 0)
            return -ESRCH;

        bp = thread->ptrace_bps[n];
        if (!bp)
            val = 0;
        else
            val = bp->hw.info.address;

        ptrace_put_breakpoints(tsk);
    } else if (n == 6) {
        val = thread->debugreg6;
     } else if (n == 7) {
        val = thread->ptrace_dr7;
    }
    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;
    struct perf_event_attr attr;
    int err = 0;

    if (ptrace_get_breakpoints(tsk) < 0)
        return -ESRCH;

    if (!t->ptrace_bps[nr]) {
        ptrace_breakpoint_init(&attr);
        /*
         * Put stub len and type to register (reserve) an inactive but
         * correct bp
         */
        attr.bp_addr = addr;
        attr.bp_len = HW_BREAKPOINT_LEN_1;
        attr.bp_type = HW_BREAKPOINT_W;
        attr.disabled = 1;

        bp = register_user_hw_breakpoint(&attr, ptrace_triggered,
                         NULL, tsk);

        /*
         * 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)) {
            err = PTR_ERR(bp);
            goto put;
        }

        t->ptrace_bps[nr] = bp;
    } else {
        bp = t->ptrace_bps[nr];

        attr = bp->attr;
        attr.bp_addr = addr;
        err = modify_user_hw_breakpoint(bp, &attr);
    }

put:
    ptrace_put_breakpoints(tsk);
    return err;
}

/*
 * Handle PTRACE_POKEUSR calls for the debug register area.
 */
static 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);
        if (!rc)
            thread->ptrace_dr7 = 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);
}

/*
 * 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,
         unsigned long addr, unsigned 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 >= 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 >= 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 ((int) addr < 0)
            return -EIO;
        ret = do_get_thread_area(child, addr,
                    (struct user_desc __user *)data);
        break;

    case PTRACE_SET_THREAD_AREA:
        if ((int) 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

    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 >= sizeof(*k)) {
            getreg32(target, pos, k++);
            count -= sizeof(*k);
            pos += sizeof(*k);
        }
    } else {
        compat_ulong_t __user *u = ubuf;
        while (count >= sizeof(*u)) {
            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 >= sizeof(*k) && !ret) {
            ret = putreg32(target, pos, *k++);
            count -= sizeof(*k);
            pos += sizeof(*k);
        }
    } else {
        const compat_ulong_t __user *u = ubuf;
        while (count >= sizeof(*u) && !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;
}

#ifdef CONFIG_X86_X32_ABI
static long x32_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;

    switch (request) {
    /* Read 32bits at location addr in the USER area.  Only allow
       to return the lower 32bits of segment and debug registers.  */
    case PTRACE_PEEKUSR: {
        u32 tmp;

        ret = -EIO;
        if ((addr & (sizeof(data) - 1)) || addr >= sizeof(struct user) ||
            addr < offsetof(struct user_regs_struct, cs))
            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, (__u32 __user *)datap);
        break;
    }

    /* Write the word at location addr in the USER area.  Only allow
       to update segment and debug registers with the upper 32bits
       zero-extended. */
    case PTRACE_POKEUSR:
        ret = -EIO;
        if ((addr & (sizeof(data) - 1)) || addr >= sizeof(struct user) ||
            addr < offsetof(struct user_regs_struct, cs))
            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);

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

    return ret;
}
#endif

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;

#ifdef CONFIG_X86_X32_ABI
    if (!is_ia32_task())
        return x32_arch_ptrace(child, request, caddr, cdata);
#endif

    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:
        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 struct user_regset x86_64_regsets[] __read_mostly = {
    [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_XSTATE] = {
        .core_note_type = NT_X86_XSTATE,
        .size = sizeof(u64), .align = sizeof(u64),
        .active = xstateregs_active, .get = xstateregs_get,
        .set = xstateregs_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

#endif  /* CONFIG_X86_64 */

#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
static struct user_regset x86_32_regsets[] __read_mostly = {
    [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_XSTATE] = {
        .core_note_type = NT_X86_XSTATE,
        .size = sizeof(u64), .align = sizeof(u64),
        .active = xstateregs_active, .get = xstateregs_get,
        .set = xstateregs_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

/*
 * This represents bytes 464..511 in the memory layout exported through
 * the REGSET_XSTATE interface.
 */
u64 xstate_fx_sw_bytes[USER_XSTATE_FX_SW_WORDS];

void update_regset_xstate_info(unsigned int size, u64 xstate_mask)
{
#ifdef CONFIG_X86_64
    x86_64_regsets[REGSET_XSTATE].n = size / sizeof(u64);
#endif
#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
    x86_32_regsets[REGSET_XSTATE].n = size / sizeof(u64);
#endif
    xstate_fx_sw_bytes[USER_XSTATE_XCR0_WORD] = xstate_mask;
}

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
}

static void fill_sigtrap_info(struct task_struct *tsk,
                struct pt_regs *regs,
                int error_code, int si_code,
                struct siginfo *info)
{
    tsk->thread.trap_nr = X86_TRAP_DB;
    tsk->thread.error_code = error_code;

    memset(info, 0, sizeof(*info));
    info->si_signo = SIGTRAP;
    info->si_code = si_code;
    info->si_addr = user_mode_vm(regs) ? (void __user *)regs->ip : NULL;
}

void user_single_step_siginfo(struct task_struct *tsk,
                struct pt_regs *regs,
                struct siginfo *info)
{
    fill_sigtrap_info(tsk, regs, 0, TRAP_BRKPT, info);
}

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

    fill_sigtrap_info(tsk, regs, error_code, si_code, &info);
    /* 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.
 */
long syscall_trace_enter(struct pt_regs *regs)
{
    long ret = 0;

    rcu_user_exit();

    /*
     * 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 */
    if (secure_computing(regs->orig_ax)) {
        /* seccomp failures shouldn't expose any additional code. */
        ret = -1L;
        goto out;
    }

    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 (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

out:
    return ret ?: regs->orig_ax;
}

void syscall_trace_leave(struct pt_regs *regs)
{
    bool step;

    /*
     * We may come here right after calling schedule_user()
     * or do_notify_resume(), in which case we can be in RCU
     * user mode.
     */
    rcu_user_exit();

    audit_syscall_exit(regs);

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

    /*
     * 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().
     */
    step = unlikely(test_thread_flag(TIF_SINGLESTEP)) &&
            !test_thread_flag(TIF_SYSCALL_EMU);
    if (step || test_thread_flag(TIF_SYSCALL_TRACE))
        tracehook_report_syscall_exit(regs, step);

    rcu_user_enter();
}