ptrace.c

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/*
 *  linux/arch/arm/kernel/ptrace.c
 *
 *  By Ross Biro 1/23/92
 * edited by Linus Torvalds
 * ARM modifications Copyright (C) 2000 Russell King
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/elf.h>
#include <linux/smp.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/security.h>
#include <linux/init.h>
#include <linux/signal.h>
#include <linux/uaccess.h>
#include <linux/perf_event.h>
#include <linux/hw_breakpoint.h>
#include <linux/regset.h>
#include <linux/audit.h>
#include <linux/tracehook.h>
#include <linux/unistd.h>

#include <asm/pgtable.h>
#include <asm/traps.h>

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

#define REG_PC  15
#define REG_PSR 16
/*
 * does not yet catch signals sent when the child dies.
 * in exit.c or in signal.c.
 */

#if 0
/*
 * Breakpoint SWI instruction: SWI &9F0001
 */
#define BREAKINST_ARM   0xef9f0001
#define BREAKINST_THUMB 0xdf00      /* fill this in later */
#else
/*
 * New breakpoints - use an undefined instruction.  The ARM architecture
 * reference manual guarantees that the following instruction space
 * will produce an undefined instruction exception on all CPUs:
 *
 *  ARM:   xxxx 0111 1111 xxxx xxxx xxxx 1111 xxxx
 *  Thumb: 1101 1110 xxxx xxxx
 */
#define BREAKINST_ARM   0xe7f001f0
#define BREAKINST_THUMB 0xde01
#endif

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

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

static const struct pt_regs_offset regoffset_table[] = {
    REG_OFFSET_NAME(r0),
    REG_OFFSET_NAME(r1),
    REG_OFFSET_NAME(r2),
    REG_OFFSET_NAME(r3),
    REG_OFFSET_NAME(r4),
    REG_OFFSET_NAME(r5),
    REG_OFFSET_NAME(r6),
    REG_OFFSET_NAME(r7),
    REG_OFFSET_NAME(r8),
    REG_OFFSET_NAME(r9),
    REG_OFFSET_NAME(r10),
    REG_OFFSET_NAME(fp),
    REG_OFFSET_NAME(ip),
    REG_OFFSET_NAME(sp),
    REG_OFFSET_NAME(lr),
    REG_OFFSET_NAME(pc),
    REG_OFFSET_NAME(cpsr),
    REG_OFFSET_NAME(ORIG_r0),
    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;
}

bool regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr)
{
    return ((addr & ~(THREAD_SIZE - 1))  ==
        (kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1)));
}

unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, unsigned int n)
{
    unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs);
    addr += n;
    if (regs_within_kernel_stack(regs, (unsigned long)addr))
        return *addr;
    else
        return 0;
}

/*
 * this routine will get a word off of the processes privileged stack.
 * the offset is how far from the base addr as stored in the THREAD.
 * this routine assumes that all the privileged stacks are in our
 * data space.
 */
static inline long get_user_reg(struct task_struct *task, int offset)
{
    return task_pt_regs(task)->uregs[offset];
}

/*
 * this routine will put a word on the processes privileged stack.
 * the offset is how far from the base addr as stored in the THREAD.
 * this routine assumes that all the privileged stacks are in our
 * data space.
 */
static inline int
put_user_reg(struct task_struct *task, int offset, long data)
{
    struct pt_regs newregs, *regs = task_pt_regs(task);
    int ret = -EINVAL;

    newregs = *regs;
    newregs.uregs[offset] = data;

    if (valid_user_regs(&newregs)) {
        regs->uregs[offset] = data;
        ret = 0;
    }

    return ret;
}

/*
 * Called by kernel/ptrace.c when detaching..
 */
void ptrace_disable(struct task_struct *child)
{
    /* Nothing to do. */
}

/*
 * Handle hitting a breakpoint.
 */
void ptrace_break(struct task_struct *tsk, struct pt_regs *regs)
{
    siginfo_t info;

    info.si_signo = SIGTRAP;
    info.si_errno = 0;
    info.si_code  = TRAP_BRKPT;
    info.si_addr  = (void __user *)instruction_pointer(regs);

    force_sig_info(SIGTRAP, &info, tsk);
}

static int break_trap(struct pt_regs *regs, unsigned int instr)
{
    ptrace_break(current, regs);
    return 0;
}

static struct undef_hook arm_break_hook = {
    .instr_mask = 0x0fffffff,
    .instr_val  = 0x07f001f0,
    .cpsr_mask  = PSR_T_BIT,
    .cpsr_val   = 0,
    .fn     = break_trap,
};

static struct undef_hook thumb_break_hook = {
    .instr_mask = 0xffff,
    .instr_val  = 0xde01,
    .cpsr_mask  = PSR_T_BIT,
    .cpsr_val   = PSR_T_BIT,
    .fn     = break_trap,
};

static struct undef_hook thumb2_break_hook = {
    .instr_mask = 0xffffffff,
    .instr_val  = 0xf7f0a000,
    .cpsr_mask  = PSR_T_BIT,
    .cpsr_val   = PSR_T_BIT,
    .fn     = break_trap,
};

static int __init ptrace_break_init(void)
{
    register_undef_hook(&arm_break_hook);
    register_undef_hook(&thumb_break_hook);
    register_undef_hook(&thumb2_break_hook);
    return 0;
}

core_initcall(ptrace_break_init);

/*
 * Read the word at offset "off" into the "struct user".  We
 * actually access the pt_regs stored on the kernel stack.
 */
static int ptrace_read_user(struct task_struct *tsk, unsigned long off,
                unsigned long __user *ret)
{
    unsigned long tmp;

    if (off & 3)
        return -EIO;

    tmp = 0;
    if (off == PT_TEXT_ADDR)
        tmp = tsk->mm->start_code;
    else if (off == PT_DATA_ADDR)
        tmp = tsk->mm->start_data;
    else if (off == PT_TEXT_END_ADDR)
        tmp = tsk->mm->end_code;
    else if (off < sizeof(struct pt_regs))
        tmp = get_user_reg(tsk, off >> 2);
    else if (off >= sizeof(struct user))
        return -EIO;

    return put_user(tmp, ret);
}

/*
 * Write the word at offset "off" into "struct user".  We
 * actually access the pt_regs stored on the kernel stack.
 */
static int ptrace_write_user(struct task_struct *tsk, unsigned long off,
                 unsigned long val)
{
    if (off & 3 || off >= sizeof(struct user))
        return -EIO;

    if (off >= sizeof(struct pt_regs))
        return 0;

    return put_user_reg(tsk, off >> 2, val);
}

#ifdef CONFIG_IWMMXT

/*
 * Get the child iWMMXt state.
 */
static int ptrace_getwmmxregs(struct task_struct *tsk, void __user *ufp)
{
    struct thread_info *thread = task_thread_info(tsk);

    if (!test_ti_thread_flag(thread, TIF_USING_IWMMXT))
        return -ENODATA;
    iwmmxt_task_disable(thread);  /* force it to ram */
    return copy_to_user(ufp, &thread->fpstate.iwmmxt, IWMMXT_SIZE)
        ? -EFAULT : 0;
}

/*
 * Set the child iWMMXt state.
 */
static int ptrace_setwmmxregs(struct task_struct *tsk, void __user *ufp)
{
    struct thread_info *thread = task_thread_info(tsk);

    if (!test_ti_thread_flag(thread, TIF_USING_IWMMXT))
        return -EACCES;
    iwmmxt_task_release(thread);  /* force a reload */
    return copy_from_user(&thread->fpstate.iwmmxt, ufp, IWMMXT_SIZE)
        ? -EFAULT : 0;
}

#endif

#ifdef CONFIG_CRUNCH
/*
 * Get the child Crunch state.
 */
static int ptrace_getcrunchregs(struct task_struct *tsk, void __user *ufp)
{
    struct thread_info *thread = task_thread_info(tsk);

    crunch_task_disable(thread);  /* force it to ram */
    return copy_to_user(ufp, &thread->crunchstate, CRUNCH_SIZE)
        ? -EFAULT : 0;
}

/*
 * Set the child Crunch state.
 */
static int ptrace_setcrunchregs(struct task_struct *tsk, void __user *ufp)
{
    struct thread_info *thread = task_thread_info(tsk);

    crunch_task_release(thread);  /* force a reload */
    return copy_from_user(&thread->crunchstate, ufp, CRUNCH_SIZE)
        ? -EFAULT : 0;
}
#endif

#ifdef CONFIG_HAVE_HW_BREAKPOINT
/*
 * Convert a virtual register number into an index for a thread_info
 * breakpoint array. Breakpoints are identified using positive numbers
 * whilst watchpoints are negative. The registers are laid out as pairs
 * of (address, control), each pair mapping to a unique hw_breakpoint struct.
 * Register 0 is reserved for describing resource information.
 */
static int ptrace_hbp_num_to_idx(long num)
{
    if (num < 0)
        num = (ARM_MAX_BRP << 1) - num;
    return (num - 1) >> 1;
}

/*
 * Returns the virtual register number for the address of the
 * breakpoint at index idx.
 */
static long ptrace_hbp_idx_to_num(int idx)
{
    long mid = ARM_MAX_BRP << 1;
    long num = (idx << 1) + 1;
    return num > mid ? mid - num : num;
}

/*
 * Handle hitting a HW-breakpoint.
 */
static void ptrace_hbptriggered(struct perf_event *bp,
                     struct perf_sample_data *data,
                     struct pt_regs *regs)
{
    struct arch_hw_breakpoint *bkpt = counter_arch_bp(bp);
    long num;
    int i;
    siginfo_t info;

    for (i = 0; i < ARM_MAX_HBP_SLOTS; ++i)
        if (current->thread.debug.hbp[i] == bp)
            break;

    num = (i == ARM_MAX_HBP_SLOTS) ? 0 : ptrace_hbp_idx_to_num(i);

    info.si_signo   = SIGTRAP;
    info.si_errno   = (int)num;
    info.si_code    = TRAP_HWBKPT;
    info.si_addr    = (void __user *)(bkpt->trigger);

    force_sig_info(SIGTRAP, &info, current);
}

/*
 * Set ptrace breakpoint pointers to zero for this task.
 * This is required in order to prevent child processes from unregistering
 * breakpoints held by their parent.
 */
void clear_ptrace_hw_breakpoint(struct task_struct *tsk)
{
    memset(tsk->thread.debug.hbp, 0, sizeof(tsk->thread.debug.hbp));
}

/*
 * Unregister breakpoints from this task and reset the pointers in
 * the thread_struct.
 */
void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
{
    int i;
    struct thread_struct *t = &tsk->thread;

    for (i = 0; i < ARM_MAX_HBP_SLOTS; i++) {
        if (t->debug.hbp[i]) {
            unregister_hw_breakpoint(t->debug.hbp[i]);
            t->debug.hbp[i] = NULL;
        }
    }
}

static u32 ptrace_get_hbp_resource_info(void)
{
    u8 num_brps, num_wrps, debug_arch, wp_len;
    u32 reg = 0;

    num_brps    = hw_breakpoint_slots(TYPE_INST);
    num_wrps    = hw_breakpoint_slots(TYPE_DATA);
    debug_arch  = arch_get_debug_arch();
    wp_len      = arch_get_max_wp_len();

    reg     |= debug_arch;
    reg     <<= 8;
    reg     |= wp_len;
    reg     <<= 8;
    reg     |= num_wrps;
    reg     <<= 8;
    reg     |= num_brps;

    return reg;
}

static struct perf_event *ptrace_hbp_create(struct task_struct *tsk, int type)
{
    struct perf_event_attr attr;

    ptrace_breakpoint_init(&attr);

    /* Initialise fields to sane defaults. */
    attr.bp_addr    = 0;
    attr.bp_len = HW_BREAKPOINT_LEN_4;
    attr.bp_type    = type;
    attr.disabled   = 1;

    return register_user_hw_breakpoint(&attr, ptrace_hbptriggered, NULL,
                       tsk);
}

static int ptrace_gethbpregs(struct task_struct *tsk, long num,
                 unsigned long  __user *data)
{
    u32 reg;
    int idx, ret = 0;
    struct perf_event *bp;
    struct arch_hw_breakpoint_ctrl arch_ctrl;

    if (num == 0) {
        reg = ptrace_get_hbp_resource_info();
    } else {
        idx = ptrace_hbp_num_to_idx(num);
        if (idx < 0 || idx >= ARM_MAX_HBP_SLOTS) {
            ret = -EINVAL;
            goto out;
        }

        bp = tsk->thread.debug.hbp[idx];
        if (!bp) {
            reg = 0;
            goto put;
        }

        arch_ctrl = counter_arch_bp(bp)->ctrl;

        /*
         * Fix up the len because we may have adjusted it
         * to compensate for an unaligned address.
         */
        while (!(arch_ctrl.len & 0x1))
            arch_ctrl.len >>= 1;

        if (num & 0x1)
            reg = bp->attr.bp_addr;
        else
            reg = encode_ctrl_reg(arch_ctrl);
    }

put:
    if (put_user(reg, data))
        ret = -EFAULT;

out:
    return ret;
}

static int ptrace_sethbpregs(struct task_struct *tsk, long num,
                 unsigned long __user *data)
{
    int idx, gen_len, gen_type, implied_type, ret = 0;
    u32 user_val;
    struct perf_event *bp;
    struct arch_hw_breakpoint_ctrl ctrl;
    struct perf_event_attr attr;

    if (num == 0)
        goto out;
    else if (num < 0)
        implied_type = HW_BREAKPOINT_RW;
    else
        implied_type = HW_BREAKPOINT_X;

    idx = ptrace_hbp_num_to_idx(num);
    if (idx < 0 || idx >= ARM_MAX_HBP_SLOTS) {
        ret = -EINVAL;
        goto out;
    }

    if (get_user(user_val, data)) {
        ret = -EFAULT;
        goto out;
    }

    bp = tsk->thread.debug.hbp[idx];
    if (!bp) {
        bp = ptrace_hbp_create(tsk, implied_type);
        if (IS_ERR(bp)) {
            ret = PTR_ERR(bp);
            goto out;
        }
        tsk->thread.debug.hbp[idx] = bp;
    }

    attr = bp->attr;

    if (num & 0x1) {
        /* Address */
        attr.bp_addr    = user_val;
    } else {
        /* Control */
        decode_ctrl_reg(user_val, &ctrl);
        ret = arch_bp_generic_fields(ctrl, &gen_len, &gen_type);
        if (ret)
            goto out;

        if ((gen_type & implied_type) != gen_type) {
            ret = -EINVAL;
            goto out;
        }

        attr.bp_len = gen_len;
        attr.bp_type    = gen_type;
        attr.disabled   = !ctrl.enabled;
    }

    ret = modify_user_hw_breakpoint(bp, &attr);
out:
    return ret;
}
#endif

/* regset get/set implementations */

static int gpr_get(struct task_struct *target,
           const struct user_regset *regset,
           unsigned int pos, unsigned int count,
           void *kbuf, void __user *ubuf)
{
    struct pt_regs *regs = task_pt_regs(target);

    return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
                   regs,
                   0, sizeof(*regs));
}

static int gpr_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;
    struct pt_regs newregs;

    ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
                 &newregs,
                 0, sizeof(newregs));
    if (ret)
        return ret;

    if (!valid_user_regs(&newregs))
        return -EINVAL;

    *task_pt_regs(target) = newregs;
    return 0;
}

static int fpa_get(struct task_struct *target,
           const struct user_regset *regset,
           unsigned int pos, unsigned int count,
           void *kbuf, void __user *ubuf)
{
    return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
                   &task_thread_info(target)->fpstate,
                   0, sizeof(struct user_fp));
}

static int fpa_set(struct task_struct *target,
           const struct user_regset *regset,
           unsigned int pos, unsigned int count,
           const void *kbuf, const void __user *ubuf)
{
    struct thread_info *thread = task_thread_info(target);

    thread->used_cp[1] = thread->used_cp[2] = 1;

    return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
        &thread->fpstate,
        0, sizeof(struct user_fp));
}

#ifdef CONFIG_VFP
/*
 * VFP register get/set implementations.
 *
 * With respect to the kernel, struct user_fp is divided into three chunks:
 * 16 or 32 real VFP registers (d0-d15 or d0-31)
 *  These are transferred to/from the real registers in the task's
 *  vfp_hard_struct.  The number of registers depends on the kernel
 *  configuration.
 *
 * 16 or 0 fake VFP registers (d16-d31 or empty)
 *  i.e., the user_vfp structure has space for 32 registers even if
 *  the kernel doesn't have them all.
 *
 *  vfp_get() reads this chunk as zero where applicable
 *  vfp_set() ignores this chunk
 *
 * 1 word for the FPSCR
 *
 * The bounds-checking logic built into user_regset_copyout and friends
 * means that we can make a simple sequence of calls to map the relevant data
 * to/from the specified slice of the user regset structure.
 */
static int vfp_get(struct task_struct *target,
           const struct user_regset *regset,
           unsigned int pos, unsigned int count,
           void *kbuf, void __user *ubuf)
{
    int ret;
    struct thread_info *thread = task_thread_info(target);
    struct vfp_hard_struct const *vfp = &thread->vfpstate.hard;
    const size_t user_fpregs_offset = offsetof(struct user_vfp, fpregs);
    const size_t user_fpscr_offset = offsetof(struct user_vfp, fpscr);

    vfp_sync_hwstate(thread);

    ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
                  &vfp->fpregs,
                  user_fpregs_offset,
                  user_fpregs_offset + sizeof(vfp->fpregs));
    if (ret)
        return ret;

    ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
                       user_fpregs_offset + sizeof(vfp->fpregs),
                       user_fpscr_offset);
    if (ret)
        return ret;

    return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
                   &vfp->fpscr,
                   user_fpscr_offset,
                   user_fpscr_offset + sizeof(vfp->fpscr));
}

/*
 * For vfp_set() a read-modify-write is done on the VFP registers,
 * in order to avoid writing back a half-modified set of registers on
 * failure.
 */
static int vfp_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;
    struct thread_info *thread = task_thread_info(target);
    struct vfp_hard_struct new_vfp;
    const size_t user_fpregs_offset = offsetof(struct user_vfp, fpregs);
    const size_t user_fpscr_offset = offsetof(struct user_vfp, fpscr);

    vfp_sync_hwstate(thread);
    new_vfp = thread->vfpstate.hard;

    ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
                  &new_vfp.fpregs,
                  user_fpregs_offset,
                  user_fpregs_offset + sizeof(new_vfp.fpregs));
    if (ret)
        return ret;

    ret = user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
                user_fpregs_offset + sizeof(new_vfp.fpregs),
                user_fpscr_offset);
    if (ret)
        return ret;

    ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
                 &new_vfp.fpscr,
                 user_fpscr_offset,
                 user_fpscr_offset + sizeof(new_vfp.fpscr));
    if (ret)
        return ret;

    vfp_flush_hwstate(thread);
    thread->vfpstate.hard = new_vfp;

    return 0;
}
#endif /* CONFIG_VFP */

enum arm_regset {
    REGSET_GPR,
    REGSET_FPR,
#ifdef CONFIG_VFP
    REGSET_VFP,
#endif
};

static const struct user_regset arm_regsets[] = {
    [REGSET_GPR] = {
        .core_note_type = NT_PRSTATUS,
        .n = ELF_NGREG,
        .size = sizeof(u32),
        .align = sizeof(u32),
        .get = gpr_get,
        .set = gpr_set
    },
    [REGSET_FPR] = {
        /*
         * For the FPA regs in fpstate, the real fields are a mixture
         * of sizes, so pretend that the registers are word-sized:
         */
        .core_note_type = NT_PRFPREG,
        .n = sizeof(struct user_fp) / sizeof(u32),
        .size = sizeof(u32),
        .align = sizeof(u32),
        .get = fpa_get,
        .set = fpa_set
    },
#ifdef CONFIG_VFP
    [REGSET_VFP] = {
        /*
         * Pretend that the VFP regs are word-sized, since the FPSCR is
         * a single word dangling at the end of struct user_vfp:
         */
        .core_note_type = NT_ARM_VFP,
        .n = ARM_VFPREGS_SIZE / sizeof(u32),
        .size = sizeof(u32),
        .align = sizeof(u32),
        .get = vfp_get,
        .set = vfp_set
    },
#endif /* CONFIG_VFP */
};

static const struct user_regset_view user_arm_view = {
    .name = "arm", .e_machine = ELF_ARCH, .ei_osabi = ELF_OSABI,
    .regsets = arm_regsets, .n = ARRAY_SIZE(arm_regsets)
};

const struct user_regset_view *task_user_regset_view(struct task_struct *task)
{
    return &user_arm_view;
}

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) {
        case PTRACE_PEEKUSR:
            ret = ptrace_read_user(child, addr, datap);
            break;

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

        case PTRACE_GETREGS:
            ret = copy_regset_to_user(child,
                          &user_arm_view, REGSET_GPR,
                          0, sizeof(struct pt_regs),
                          datap);
            break;

        case PTRACE_SETREGS:
            ret = copy_regset_from_user(child,
                            &user_arm_view, REGSET_GPR,
                            0, sizeof(struct pt_regs),
                            datap);
            break;

        case PTRACE_GETFPREGS:
            ret = copy_regset_to_user(child,
                          &user_arm_view, REGSET_FPR,
                          0, sizeof(union fp_state),
                          datap);
            break;

        case PTRACE_SETFPREGS:
            ret = copy_regset_from_user(child,
                            &user_arm_view, REGSET_FPR,
                            0, sizeof(union fp_state),
                            datap);
            break;

#ifdef CONFIG_IWMMXT
        case PTRACE_GETWMMXREGS:
            ret = ptrace_getwmmxregs(child, datap);
            break;

        case PTRACE_SETWMMXREGS:
            ret = ptrace_setwmmxregs(child, datap);
            break;
#endif

        case PTRACE_GET_THREAD_AREA:
            ret = put_user(task_thread_info(child)->tp_value,
                       datap);
            break;

        case PTRACE_SET_SYSCALL:
            task_thread_info(child)->syscall = data;
            ret = 0;
            break;

#ifdef CONFIG_CRUNCH
        case PTRACE_GETCRUNCHREGS:
            ret = ptrace_getcrunchregs(child, datap);
            break;

        case PTRACE_SETCRUNCHREGS:
            ret = ptrace_setcrunchregs(child, datap);
            break;
#endif

#ifdef CONFIG_VFP
        case PTRACE_GETVFPREGS:
            ret = copy_regset_to_user(child,
                          &user_arm_view, REGSET_VFP,
                          0, ARM_VFPREGS_SIZE,
                          datap);
            break;

        case PTRACE_SETVFPREGS:
            ret = copy_regset_from_user(child,
                            &user_arm_view, REGSET_VFP,
                            0, ARM_VFPREGS_SIZE,
                            datap);
            break;
#endif

#ifdef CONFIG_HAVE_HW_BREAKPOINT
        case PTRACE_GETHBPREGS:
            if (ptrace_get_breakpoints(child) < 0)
                return -ESRCH;

            ret = ptrace_gethbpregs(child, addr,
                        (unsigned long __user *)data);
            ptrace_put_breakpoints(child);
            break;
        case PTRACE_SETHBPREGS:
            if (ptrace_get_breakpoints(child) < 0)
                return -ESRCH;

            ret = ptrace_sethbpregs(child, addr,
                        (unsigned long __user *)data);
            ptrace_put_breakpoints(child);
            break;
#endif

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

    return ret;
}

enum ptrace_syscall_dir {
    PTRACE_SYSCALL_ENTER = 0,
    PTRACE_SYSCALL_EXIT,
};

static int ptrace_syscall_trace(struct pt_regs *regs, int scno,
                enum ptrace_syscall_dir dir)
{
    unsigned long ip;

    current_thread_info()->syscall = scno;

    if (!test_thread_flag(TIF_SYSCALL_TRACE))
        return scno;

    /*
     * IP is used to denote syscall entry/exit:
     * IP = 0 -> entry, =1 -> exit
     */
    ip = regs->ARM_ip;
    regs->ARM_ip = dir;

    if (dir == PTRACE_SYSCALL_EXIT)
        tracehook_report_syscall_exit(regs, 0);
    else if (tracehook_report_syscall_entry(regs))
        current_thread_info()->syscall = -1;

    regs->ARM_ip = ip;
    return current_thread_info()->syscall;
}

asmlinkage int syscall_trace_enter(struct pt_regs *regs, int scno)
{
    scno = ptrace_syscall_trace(regs, scno, PTRACE_SYSCALL_ENTER);
    if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
        trace_sys_enter(regs, scno);
    audit_syscall_entry(AUDIT_ARCH_ARM, scno, regs->ARM_r0, regs->ARM_r1,
                regs->ARM_r2, regs->ARM_r3);
    return scno;
}

asmlinkage int syscall_trace_exit(struct pt_regs *regs, int scno)
{
    scno = ptrace_syscall_trace(regs, scno, PTRACE_SYSCALL_EXIT);
    if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
        trace_sys_exit(regs, scno);
    audit_syscall_exit(regs);
    return scno;
}