i387: Split up <asm/i387.h> into exported and internal interfaces

[mirror_ubuntu-artful-kernel.git] / arch / x86 / kernel / ptrace.c

/* By Ross Biro 1/23/92 */
/*
 * Pentium III FXSR, SSE support
 *      Gareth Hughes <gareth@valinux.com>, 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 <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/system.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 "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,
};

/**
 * 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
};

/*
 * 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 >= 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;
}

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:
                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

#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 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_no = 1;
        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;

        /*
         * 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 (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;
}

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

        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);
}