ptrace.c

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/*
 *  Ptrace user space interface.
 *
 *    Copyright IBM Corp. 1999, 2010
 *    Author(s): Denis Joseph Barrow
 *               Martin Schwidefsky ([email protected])
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/security.h>
#include <linux/audit.h>
#include <linux/signal.h>
#include <linux/elf.h>
#include <linux/regset.h>
#include <linux/tracehook.h>
#include <linux/seccomp.h>
#include <linux/compat.h>
#include <trace/syscall.h>
#include <asm/segment.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>
#include <asm/switch_to.h>
#include "entry.h"

#ifdef CONFIG_COMPAT
#include "compat_ptrace.h"
#endif

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

enum s390_regset {
    REGSET_GENERAL,
    REGSET_FP,
    REGSET_LAST_BREAK,
    REGSET_TDB,
    REGSET_SYSTEM_CALL,
    REGSET_GENERAL_EXTENDED,
};

void update_per_regs(struct task_struct *task)
{
    struct pt_regs *regs = task_pt_regs(task);
    struct thread_struct *thread = &task->thread;
    struct per_regs old, new;

#ifdef CONFIG_64BIT
    /* Take care of the enable/disable of transactional execution. */
    if (MACHINE_HAS_TE) {
        unsigned long cr0, cr0_new;

        __ctl_store(cr0, 0, 0);
        /* set or clear transaction execution bits 8 and 9. */
        if (task->thread.per_flags & PER_FLAG_NO_TE)
            cr0_new = cr0 & ~(3UL << 54);
        else
            cr0_new = cr0 | (3UL << 54);
        /* Only load control register 0 if necessary. */
        if (cr0 != cr0_new)
            __ctl_load(cr0_new, 0, 0);
    }
#endif
    /* Copy user specified PER registers */
    new.control = thread->per_user.control;
    new.start = thread->per_user.start;
    new.end = thread->per_user.end;

    /* merge TIF_SINGLE_STEP into user specified PER registers. */
    if (test_tsk_thread_flag(task, TIF_SINGLE_STEP)) {
        new.control |= PER_EVENT_IFETCH;
#ifdef CONFIG_64BIT
        new.control |= PER_CONTROL_SUSPENSION;
        new.control |= PER_EVENT_TRANSACTION_END;
#endif
        new.start = 0;
        new.end = PSW_ADDR_INSN;
    }

    /* Take care of the PER enablement bit in the PSW. */
    if (!(new.control & PER_EVENT_MASK)) {
        regs->psw.mask &= ~PSW_MASK_PER;
        return;
    }
    regs->psw.mask |= PSW_MASK_PER;
    __ctl_store(old, 9, 11);
    if (memcmp(&new, &old, sizeof(struct per_regs)) != 0)
        __ctl_load(new, 9, 11);
}

void user_enable_single_step(struct task_struct *task)
{
    set_tsk_thread_flag(task, TIF_SINGLE_STEP);
    if (task == current)
        update_per_regs(task);
}

void user_disable_single_step(struct task_struct *task)
{
    clear_tsk_thread_flag(task, TIF_SINGLE_STEP);
    if (task == current)
        update_per_regs(task);
}

/*
 * Called by kernel/ptrace.c when detaching..
 *
 * Clear all debugging related fields.
 */
void ptrace_disable(struct task_struct *task)
{
    memset(&task->thread.per_user, 0, sizeof(task->thread.per_user));
    memset(&task->thread.per_event, 0, sizeof(task->thread.per_event));
    clear_tsk_thread_flag(task, TIF_SINGLE_STEP);
    clear_tsk_thread_flag(task, TIF_PER_TRAP);
    task->thread.per_flags = 0;
}

#ifndef CONFIG_64BIT
# define __ADDR_MASK 3
#else
# define __ADDR_MASK 7
#endif

static inline unsigned long __peek_user_per(struct task_struct *child,
                        addr_t addr)
{
    struct per_struct_kernel *dummy = NULL;

    if (addr == (addr_t) &dummy->cr9)
        /* Control bits of the active per set. */
        return test_thread_flag(TIF_SINGLE_STEP) ?
            PER_EVENT_IFETCH : child->thread.per_user.control;
    else if (addr == (addr_t) &dummy->cr10)
        /* Start address of the active per set. */
        return test_thread_flag(TIF_SINGLE_STEP) ?
            0 : child->thread.per_user.start;
    else if (addr == (addr_t) &dummy->cr11)
        /* End address of the active per set. */
        return test_thread_flag(TIF_SINGLE_STEP) ?
            PSW_ADDR_INSN : child->thread.per_user.end;
    else if (addr == (addr_t) &dummy->bits)
        /* Single-step bit. */
        return test_thread_flag(TIF_SINGLE_STEP) ?
            (1UL << (BITS_PER_LONG - 1)) : 0;
    else if (addr == (addr_t) &dummy->starting_addr)
        /* Start address of the user specified per set. */
        return child->thread.per_user.start;
    else if (addr == (addr_t) &dummy->ending_addr)
        /* End address of the user specified per set. */
        return child->thread.per_user.end;
    else if (addr == (addr_t) &dummy->perc_atmid)
        /* PER code, ATMID and AI of the last PER trap */
        return (unsigned long)
            child->thread.per_event.cause << (BITS_PER_LONG - 16);
    else if (addr == (addr_t) &dummy->address)
        /* Address of the last PER trap */
        return child->thread.per_event.address;
    else if (addr == (addr_t) &dummy->access_id)
        /* Access id of the last PER trap */
        return (unsigned long)
            child->thread.per_event.paid << (BITS_PER_LONG - 8);
    return 0;
}

/*
 * Read the word at offset addr from the user area of a process. The
 * trouble here is that the information is littered over different
 * locations. The process registers are found on the kernel stack,
 * the floating point stuff and the trace settings are stored in
 * the task structure. In addition the different structures in
 * struct user contain pad bytes that should be read as zeroes.
 * Lovely...
 */
static unsigned long __peek_user(struct task_struct *child, addr_t addr)
{
    struct user *dummy = NULL;
    addr_t offset, tmp;

    if (addr < (addr_t) &dummy->regs.acrs) {
        /*
         * psw and gprs are stored on the stack
         */
        tmp = *(addr_t *)((addr_t) &task_pt_regs(child)->psw + addr);
        if (addr == (addr_t) &dummy->regs.psw.mask)
            /* Return a clean psw mask. */
            tmp = psw_user_bits | (tmp & PSW_MASK_USER);

    } else if (addr < (addr_t) &dummy->regs.orig_gpr2) {
        /*
         * access registers are stored in the thread structure
         */
        offset = addr - (addr_t) &dummy->regs.acrs;
#ifdef CONFIG_64BIT
        /*
         * Very special case: old & broken 64 bit gdb reading
         * from acrs[15]. Result is a 64 bit value. Read the
         * 32 bit acrs[15] value and shift it by 32. Sick...
         */
        if (addr == (addr_t) &dummy->regs.acrs[15])
            tmp = ((unsigned long) child->thread.acrs[15]) << 32;
        else
#endif
        tmp = *(addr_t *)((addr_t) &child->thread.acrs + offset);

    } else if (addr == (addr_t) &dummy->regs.orig_gpr2) {
        /*
         * orig_gpr2 is stored on the kernel stack
         */
        tmp = (addr_t) task_pt_regs(child)->orig_gpr2;

    } else if (addr < (addr_t) &dummy->regs.fp_regs) {
        /*
         * prevent reads of padding hole between
         * orig_gpr2 and fp_regs on s390.
         */
        tmp = 0;

    } else if (addr < (addr_t) (&dummy->regs.fp_regs + 1)) {
        /* 
         * floating point regs. are stored in the thread structure
         */
        offset = addr - (addr_t) &dummy->regs.fp_regs;
        tmp = *(addr_t *)((addr_t) &child->thread.fp_regs + offset);
        if (addr == (addr_t) &dummy->regs.fp_regs.fpc)
            tmp &= (unsigned long) FPC_VALID_MASK
                << (BITS_PER_LONG - 32);

    } else if (addr < (addr_t) (&dummy->regs.per_info + 1)) {
        /*
         * Handle access to the per_info structure.
         */
        addr -= (addr_t) &dummy->regs.per_info;
        tmp = __peek_user_per(child, addr);

    } else
        tmp = 0;

    return tmp;
}

static int
peek_user(struct task_struct *child, addr_t addr, addr_t data)
{
    addr_t tmp, mask;

    /*
     * Stupid gdb peeks/pokes the access registers in 64 bit with
     * an alignment of 4. Programmers from hell...
     */
    mask = __ADDR_MASK;
#ifdef CONFIG_64BIT
    if (addr >= (addr_t) &((struct user *) NULL)->regs.acrs &&
        addr < (addr_t) &((struct user *) NULL)->regs.orig_gpr2)
        mask = 3;
#endif
    if ((addr & mask) || addr > sizeof(struct user) - __ADDR_MASK)
        return -EIO;

    tmp = __peek_user(child, addr);
    return put_user(tmp, (addr_t __user *) data);
}

static inline void __poke_user_per(struct task_struct *child,
                   addr_t addr, addr_t data)
{
    struct per_struct_kernel *dummy = NULL;

    /*
     * There are only three fields in the per_info struct that the
     * debugger user can write to.
     * 1) cr9: the debugger wants to set a new PER event mask
     * 2) starting_addr: the debugger wants to set a new starting
     *    address to use with the PER event mask.
     * 3) ending_addr: the debugger wants to set a new ending
     *    address to use with the PER event mask.
     * The user specified PER event mask and the start and end
     * addresses are used only if single stepping is not in effect.
     * Writes to any other field in per_info are ignored.
     */
    if (addr == (addr_t) &dummy->cr9)
        /* PER event mask of the user specified per set. */
        child->thread.per_user.control =
            data & (PER_EVENT_MASK | PER_CONTROL_MASK);
    else if (addr == (addr_t) &dummy->starting_addr)
        /* Starting address of the user specified per set. */
        child->thread.per_user.start = data;
    else if (addr == (addr_t) &dummy->ending_addr)
        /* Ending address of the user specified per set. */
        child->thread.per_user.end = data;
}

/*
 * Write a word to the user area of a process at location addr. This
 * operation does have an additional problem compared to peek_user.
 * Stores to the program status word and on the floating point
 * control register needs to get checked for validity.
 */
static int __poke_user(struct task_struct *child, addr_t addr, addr_t data)
{
    struct user *dummy = NULL;
    addr_t offset;

    if (addr < (addr_t) &dummy->regs.acrs) {
        /*
         * psw and gprs are stored on the stack
         */
        if (addr == (addr_t) &dummy->regs.psw.mask &&
            ((data & ~PSW_MASK_USER) != psw_user_bits ||
             ((data & PSW_MASK_EA) && !(data & PSW_MASK_BA))))
            /* Invalid psw mask. */
            return -EINVAL;
        *(addr_t *)((addr_t) &task_pt_regs(child)->psw + addr) = data;

    } else if (addr < (addr_t) (&dummy->regs.orig_gpr2)) {
        /*
         * access registers are stored in the thread structure
         */
        offset = addr - (addr_t) &dummy->regs.acrs;
#ifdef CONFIG_64BIT
        /*
         * Very special case: old & broken 64 bit gdb writing
         * to acrs[15] with a 64 bit value. Ignore the lower
         * half of the value and write the upper 32 bit to
         * acrs[15]. Sick...
         */
        if (addr == (addr_t) &dummy->regs.acrs[15])
            child->thread.acrs[15] = (unsigned int) (data >> 32);
        else
#endif
        *(addr_t *)((addr_t) &child->thread.acrs + offset) = data;

    } else if (addr == (addr_t) &dummy->regs.orig_gpr2) {
        /*
         * orig_gpr2 is stored on the kernel stack
         */
        task_pt_regs(child)->orig_gpr2 = data;

    } else if (addr < (addr_t) &dummy->regs.fp_regs) {
        /*
         * prevent writes of padding hole between
         * orig_gpr2 and fp_regs on s390.
         */
        return 0;

    } else if (addr < (addr_t) (&dummy->regs.fp_regs + 1)) {
        /*
         * floating point regs. are stored in the thread structure
         */
        if (addr == (addr_t) &dummy->regs.fp_regs.fpc &&
            (data & ~((unsigned long) FPC_VALID_MASK
                  << (BITS_PER_LONG - 32))) != 0)
            return -EINVAL;
        offset = addr - (addr_t) &dummy->regs.fp_regs;
        *(addr_t *)((addr_t) &child->thread.fp_regs + offset) = data;

    } else if (addr < (addr_t) (&dummy->regs.per_info + 1)) {
        /*
         * Handle access to the per_info structure.
         */
        addr -= (addr_t) &dummy->regs.per_info;
        __poke_user_per(child, addr, data);

    }

    return 0;
}

static int poke_user(struct task_struct *child, addr_t addr, addr_t data)
{
    addr_t mask;

    /*
     * Stupid gdb peeks/pokes the access registers in 64 bit with
     * an alignment of 4. Programmers from hell indeed...
     */
    mask = __ADDR_MASK;
#ifdef CONFIG_64BIT
    if (addr >= (addr_t) &((struct user *) NULL)->regs.acrs &&
        addr < (addr_t) &((struct user *) NULL)->regs.orig_gpr2)
        mask = 3;
#endif
    if ((addr & mask) || addr > sizeof(struct user) - __ADDR_MASK)
        return -EIO;

    return __poke_user(child, addr, data);
}

long arch_ptrace(struct task_struct *child, long request,
         unsigned long addr, unsigned long data)
{
    ptrace_area parea; 
    int copied, ret;

    switch (request) {
    case PTRACE_PEEKUSR:
        /* read the word at location addr in the USER area. */
        return peek_user(child, addr, data);

    case PTRACE_POKEUSR:
        /* write the word at location addr in the USER area */
        return poke_user(child, addr, data);

    case PTRACE_PEEKUSR_AREA:
    case PTRACE_POKEUSR_AREA:
        if (copy_from_user(&parea, (void __force __user *) addr,
                            sizeof(parea)))
            return -EFAULT;
        addr = parea.kernel_addr;
        data = parea.process_addr;
        copied = 0;
        while (copied < parea.len) {
            if (request == PTRACE_PEEKUSR_AREA)
                ret = peek_user(child, addr, data);
            else {
                addr_t utmp;
                if (get_user(utmp,
                         (addr_t __force __user *) data))
                    return -EFAULT;
                ret = poke_user(child, addr, utmp);
            }
            if (ret)
                return ret;
            addr += sizeof(unsigned long);
            data += sizeof(unsigned long);
            copied += sizeof(unsigned long);
        }
        return 0;
    case PTRACE_GET_LAST_BREAK:
        put_user(task_thread_info(child)->last_break,
             (unsigned long __user *) data);
        return 0;
    case PTRACE_ENABLE_TE:
        if (!MACHINE_HAS_TE)
            return -EIO;
        child->thread.per_flags &= ~PER_FLAG_NO_TE;
        return 0;
    case PTRACE_DISABLE_TE:
        if (!MACHINE_HAS_TE)
            return -EIO;
        child->thread.per_flags |= PER_FLAG_NO_TE;
        return 0;
    default:
        /* Removing high order bit from addr (only for 31 bit). */
        addr &= PSW_ADDR_INSN;
        return ptrace_request(child, request, addr, data);
    }
}

#ifdef CONFIG_COMPAT
/*
 * Now the fun part starts... a 31 bit program running in the
 * 31 bit emulation tracing another program. PTRACE_PEEKTEXT,
 * PTRACE_PEEKDATA, PTRACE_POKETEXT and PTRACE_POKEDATA are easy
 * to handle, the difference to the 64 bit versions of the requests
 * is that the access is done in multiples of 4 byte instead of
 * 8 bytes (sizeof(unsigned long) on 31/64 bit).
 * The ugly part are PTRACE_PEEKUSR, PTRACE_PEEKUSR_AREA,
 * PTRACE_POKEUSR and PTRACE_POKEUSR_AREA. If the traced program
 * is a 31 bit program too, the content of struct user can be
 * emulated. A 31 bit program peeking into the struct user of
 * a 64 bit program is a no-no.
 */

/*
 * Same as peek_user_per but for a 31 bit program.
 */
static inline __u32 __peek_user_per_compat(struct task_struct *child,
                       addr_t addr)
{
    struct compat_per_struct_kernel *dummy32 = NULL;

    if (addr == (addr_t) &dummy32->cr9)
        /* Control bits of the active per set. */
        return (__u32) test_thread_flag(TIF_SINGLE_STEP) ?
            PER_EVENT_IFETCH : child->thread.per_user.control;
    else if (addr == (addr_t) &dummy32->cr10)
        /* Start address of the active per set. */
        return (__u32) test_thread_flag(TIF_SINGLE_STEP) ?
            0 : child->thread.per_user.start;
    else if (addr == (addr_t) &dummy32->cr11)
        /* End address of the active per set. */
        return test_thread_flag(TIF_SINGLE_STEP) ?
            PSW32_ADDR_INSN : child->thread.per_user.end;
    else if (addr == (addr_t) &dummy32->bits)
        /* Single-step bit. */
        return (__u32) test_thread_flag(TIF_SINGLE_STEP) ?
            0x80000000 : 0;
    else if (addr == (addr_t) &dummy32->starting_addr)
        /* Start address of the user specified per set. */
        return (__u32) child->thread.per_user.start;
    else if (addr == (addr_t) &dummy32->ending_addr)
        /* End address of the user specified per set. */
        return (__u32) child->thread.per_user.end;
    else if (addr == (addr_t) &dummy32->perc_atmid)
        /* PER code, ATMID and AI of the last PER trap */
        return (__u32) child->thread.per_event.cause << 16;
    else if (addr == (addr_t) &dummy32->address)
        /* Address of the last PER trap */
        return (__u32) child->thread.per_event.address;
    else if (addr == (addr_t) &dummy32->access_id)
        /* Access id of the last PER trap */
        return (__u32) child->thread.per_event.paid << 24;
    return 0;
}

/*
 * Same as peek_user but for a 31 bit program.
 */
static u32 __peek_user_compat(struct task_struct *child, addr_t addr)
{
    struct compat_user *dummy32 = NULL;
    addr_t offset;
    __u32 tmp;

    if (addr < (addr_t) &dummy32->regs.acrs) {
        struct pt_regs *regs = task_pt_regs(child);
        /*
         * psw and gprs are stored on the stack
         */
        if (addr == (addr_t) &dummy32->regs.psw.mask) {
            /* Fake a 31 bit psw mask. */
            tmp = (__u32)(regs->psw.mask >> 32);
            tmp = psw32_user_bits | (tmp & PSW32_MASK_USER);
        } else if (addr == (addr_t) &dummy32->regs.psw.addr) {
            /* Fake a 31 bit psw address. */
            tmp = (__u32) regs->psw.addr |
                (__u32)(regs->psw.mask & PSW_MASK_BA);
        } else {
            /* gpr 0-15 */
            tmp = *(__u32 *)((addr_t) &regs->psw + addr*2 + 4);
        }
    } else if (addr < (addr_t) (&dummy32->regs.orig_gpr2)) {
        /*
         * access registers are stored in the thread structure
         */
        offset = addr - (addr_t) &dummy32->regs.acrs;
        tmp = *(__u32*)((addr_t) &child->thread.acrs + offset);

    } else if (addr == (addr_t) (&dummy32->regs.orig_gpr2)) {
        /*
         * orig_gpr2 is stored on the kernel stack
         */
        tmp = *(__u32*)((addr_t) &task_pt_regs(child)->orig_gpr2 + 4);

    } else if (addr < (addr_t) &dummy32->regs.fp_regs) {
        /*
         * prevent reads of padding hole between
         * orig_gpr2 and fp_regs on s390.
         */
        tmp = 0;

    } else if (addr < (addr_t) (&dummy32->regs.fp_regs + 1)) {
        /*
         * floating point regs. are stored in the thread structure 
         */
            offset = addr - (addr_t) &dummy32->regs.fp_regs;
        tmp = *(__u32 *)((addr_t) &child->thread.fp_regs + offset);

    } else if (addr < (addr_t) (&dummy32->regs.per_info + 1)) {
        /*
         * Handle access to the per_info structure.
         */
        addr -= (addr_t) &dummy32->regs.per_info;
        tmp = __peek_user_per_compat(child, addr);

    } else
        tmp = 0;

    return tmp;
}

static int peek_user_compat(struct task_struct *child,
                addr_t addr, addr_t data)
{
    __u32 tmp;

    if (!is_compat_task() || (addr & 3) || addr > sizeof(struct user) - 3)
        return -EIO;

    tmp = __peek_user_compat(child, addr);
    return put_user(tmp, (__u32 __user *) data);
}

/*
 * Same as poke_user_per but for a 31 bit program.
 */
static inline void __poke_user_per_compat(struct task_struct *child,
                      addr_t addr, __u32 data)
{
    struct compat_per_struct_kernel *dummy32 = NULL;

    if (addr == (addr_t) &dummy32->cr9)
        /* PER event mask of the user specified per set. */
        child->thread.per_user.control =
            data & (PER_EVENT_MASK | PER_CONTROL_MASK);
    else if (addr == (addr_t) &dummy32->starting_addr)
        /* Starting address of the user specified per set. */
        child->thread.per_user.start = data;
    else if (addr == (addr_t) &dummy32->ending_addr)
        /* Ending address of the user specified per set. */
        child->thread.per_user.end = data;
}

/*
 * Same as poke_user but for a 31 bit program.
 */
static int __poke_user_compat(struct task_struct *child,
                  addr_t addr, addr_t data)
{
    struct compat_user *dummy32 = NULL;
    __u32 tmp = (__u32) data;
    addr_t offset;

    if (addr < (addr_t) &dummy32->regs.acrs) {
        struct pt_regs *regs = task_pt_regs(child);
        /*
         * psw, gprs, acrs and orig_gpr2 are stored on the stack
         */
        if (addr == (addr_t) &dummy32->regs.psw.mask) {
            /* Build a 64 bit psw mask from 31 bit mask. */
            if ((tmp & ~PSW32_MASK_USER) != psw32_user_bits)
                /* Invalid psw mask. */
                return -EINVAL;
            regs->psw.mask = (regs->psw.mask & ~PSW_MASK_USER) |
                (regs->psw.mask & PSW_MASK_BA) |
                (__u64)(tmp & PSW32_MASK_USER) << 32;
        } else if (addr == (addr_t) &dummy32->regs.psw.addr) {
            /* Build a 64 bit psw address from 31 bit address. */
            regs->psw.addr = (__u64) tmp & PSW32_ADDR_INSN;
            /* Transfer 31 bit amode bit to psw mask. */
            regs->psw.mask = (regs->psw.mask & ~PSW_MASK_BA) |
                (__u64)(tmp & PSW32_ADDR_AMODE);
        } else {
            /* gpr 0-15 */
            *(__u32*)((addr_t) &regs->psw + addr*2 + 4) = tmp;
        }
    } else if (addr < (addr_t) (&dummy32->regs.orig_gpr2)) {
        /*
         * access registers are stored in the thread structure
         */
        offset = addr - (addr_t) &dummy32->regs.acrs;
        *(__u32*)((addr_t) &child->thread.acrs + offset) = tmp;

    } else if (addr == (addr_t) (&dummy32->regs.orig_gpr2)) {
        /*
         * orig_gpr2 is stored on the kernel stack
         */
        *(__u32*)((addr_t) &task_pt_regs(child)->orig_gpr2 + 4) = tmp;

    } else if (addr < (addr_t) &dummy32->regs.fp_regs) {
        /*
         * prevent writess of padding hole between
         * orig_gpr2 and fp_regs on s390.
         */
        return 0;

    } else if (addr < (addr_t) (&dummy32->regs.fp_regs + 1)) {
        /*
         * floating point regs. are stored in the thread structure 
         */
        if (addr == (addr_t) &dummy32->regs.fp_regs.fpc &&
            (tmp & ~FPC_VALID_MASK) != 0)
            /* Invalid floating point control. */
            return -EINVAL;
            offset = addr - (addr_t) &dummy32->regs.fp_regs;
        *(__u32 *)((addr_t) &child->thread.fp_regs + offset) = tmp;

    } else if (addr < (addr_t) (&dummy32->regs.per_info + 1)) {
        /*
         * Handle access to the per_info structure.
         */
        addr -= (addr_t) &dummy32->regs.per_info;
        __poke_user_per_compat(child, addr, data);
    }

    return 0;
}

static int poke_user_compat(struct task_struct *child,
                addr_t addr, addr_t data)
{
    if (!is_compat_task() || (addr & 3) ||
        addr > sizeof(struct compat_user) - 3)
        return -EIO;

    return __poke_user_compat(child, addr, data);
}

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;
    compat_ptrace_area parea;
    int copied, ret;

    switch (request) {
    case PTRACE_PEEKUSR:
        /* read the word at location addr in the USER area. */
        return peek_user_compat(child, addr, data);

    case PTRACE_POKEUSR:
        /* write the word at location addr in the USER area */
        return poke_user_compat(child, addr, data);

    case PTRACE_PEEKUSR_AREA:
    case PTRACE_POKEUSR_AREA:
        if (copy_from_user(&parea, (void __force __user *) addr,
                            sizeof(parea)))
            return -EFAULT;
        addr = parea.kernel_addr;
        data = parea.process_addr;
        copied = 0;
        while (copied < parea.len) {
            if (request == PTRACE_PEEKUSR_AREA)
                ret = peek_user_compat(child, addr, data);
            else {
                __u32 utmp;
                if (get_user(utmp,
                         (__u32 __force __user *) data))
                    return -EFAULT;
                ret = poke_user_compat(child, addr, utmp);
            }
            if (ret)
                return ret;
            addr += sizeof(unsigned int);
            data += sizeof(unsigned int);
            copied += sizeof(unsigned int);
        }
        return 0;
    case PTRACE_GET_LAST_BREAK:
        put_user(task_thread_info(child)->last_break,
             (unsigned int __user *) data);
        return 0;
    }
    return compat_ptrace_request(child, request, addr, data);
}
#endif

asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
{
    long ret = 0;

    /* Do the secure computing check first. */
    if (secure_computing(regs->gprs[2])) {
        /* seccomp failures shouldn't expose any additional code. */
        ret = -1;
        goto out;
    }

    /*
     * The sysc_tracesys code in entry.S stored the system
     * call number to gprs[2].
     */
    if (test_thread_flag(TIF_SYSCALL_TRACE) &&
        (tracehook_report_syscall_entry(regs) ||
         regs->gprs[2] >= NR_syscalls)) {
        /*
         * Tracing decided this syscall should not happen or the
         * debugger stored an invalid system call number. Skip
         * the system call and the system call restart handling.
         */
        clear_thread_flag(TIF_SYSCALL);
        ret = -1;
    }

    if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
        trace_sys_enter(regs, regs->gprs[2]);

    audit_syscall_entry(is_compat_task() ?
                AUDIT_ARCH_S390 : AUDIT_ARCH_S390X,
                regs->gprs[2], regs->orig_gpr2,
                regs->gprs[3], regs->gprs[4],
                regs->gprs[5]);
out:
    return ret ?: regs->gprs[2];
}

asmlinkage void do_syscall_trace_exit(struct pt_regs *regs)
{
    audit_syscall_exit(regs);

    if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
        trace_sys_exit(regs, regs->gprs[2]);

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

/*
 * user_regset definitions.
 */

static int s390_regs_get(struct task_struct *target,
             const struct user_regset *regset,
             unsigned int pos, unsigned int count,
             void *kbuf, void __user *ubuf)
{
    if (target == current)
        save_access_regs(target->thread.acrs);

    if (kbuf) {
        unsigned long *k = kbuf;
        while (count > 0) {
            *k++ = __peek_user(target, pos);
            count -= sizeof(*k);
            pos += sizeof(*k);
        }
    } else {
        unsigned long __user *u = ubuf;
        while (count > 0) {
            if (__put_user(__peek_user(target, pos), u++))
                return -EFAULT;
            count -= sizeof(*u);
            pos += sizeof(*u);
        }
    }
    return 0;
}

static int s390_regs_set(struct task_struct *target,
             const struct user_regset *regset,
             unsigned int pos, unsigned int count,
             const void *kbuf, const void __user *ubuf)
{
    int rc = 0;

    if (target == current)
        save_access_regs(target->thread.acrs);

    if (kbuf) {
        const unsigned long *k = kbuf;
        while (count > 0 && !rc) {
            rc = __poke_user(target, pos, *k++);
            count -= sizeof(*k);
            pos += sizeof(*k);
        }
    } else {
        const unsigned long  __user *u = ubuf;
        while (count > 0 && !rc) {
            unsigned long word;
            rc = __get_user(word, u++);
            if (rc)
                break;
            rc = __poke_user(target, pos, word);
            count -= sizeof(*u);
            pos += sizeof(*u);
        }
    }

    if (rc == 0 && target == current)
        restore_access_regs(target->thread.acrs);

    return rc;
}

static int s390_fpregs_get(struct task_struct *target,
               const struct user_regset *regset, unsigned int pos,
               unsigned int count, void *kbuf, void __user *ubuf)
{
    if (target == current)
        save_fp_regs(&target->thread.fp_regs);

    return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
                   &target->thread.fp_regs, 0, -1);
}

static int s390_fpregs_set(struct task_struct *target,
               const struct user_regset *regset, unsigned int pos,
               unsigned int count, const void *kbuf,
               const void __user *ubuf)
{
    int rc = 0;

    if (target == current)
        save_fp_regs(&target->thread.fp_regs);

    /* If setting FPC, must validate it first. */
    if (count > 0 && pos < offsetof(s390_fp_regs, fprs)) {
        u32 fpc[2] = { target->thread.fp_regs.fpc, 0 };
        rc = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &fpc,
                    0, offsetof(s390_fp_regs, fprs));
        if (rc)
            return rc;
        if ((fpc[0] & ~FPC_VALID_MASK) != 0 || fpc[1] != 0)
            return -EINVAL;
        target->thread.fp_regs.fpc = fpc[0];
    }

    if (rc == 0 && count > 0)
        rc = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
                    target->thread.fp_regs.fprs,
                    offsetof(s390_fp_regs, fprs), -1);

    if (rc == 0 && target == current)
        restore_fp_regs(&target->thread.fp_regs);

    return rc;
}

#ifdef CONFIG_64BIT

static int s390_last_break_get(struct task_struct *target,
                   const struct user_regset *regset,
                   unsigned int pos, unsigned int count,
                   void *kbuf, void __user *ubuf)
{
    if (count > 0) {
        if (kbuf) {
            unsigned long *k = kbuf;
            *k = task_thread_info(target)->last_break;
        } else {
            unsigned long  __user *u = ubuf;
            if (__put_user(task_thread_info(target)->last_break, u))
                return -EFAULT;
        }
    }
    return 0;
}

static int s390_last_break_set(struct task_struct *target,
                   const struct user_regset *regset,
                   unsigned int pos, unsigned int count,
                   const void *kbuf, const void __user *ubuf)
{
    return 0;
}

static int s390_tdb_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);
    unsigned char *data;

    if (!(regs->int_code & 0x200))
        return -ENODATA;
    data = target->thread.trap_tdb;
    return user_regset_copyout(&pos, &count, &kbuf, &ubuf, data, 0, 256);
}

static int s390_tdb_set(struct task_struct *target,
            const struct user_regset *regset,
            unsigned int pos, unsigned int count,
            const void *kbuf, const void __user *ubuf)
{
    return 0;
}

#endif

static int s390_system_call_get(struct task_struct *target,
                const struct user_regset *regset,
                unsigned int pos, unsigned int count,
                void *kbuf, void __user *ubuf)
{
    unsigned int *data = &task_thread_info(target)->system_call;
    return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
                   data, 0, sizeof(unsigned int));
}

static int s390_system_call_set(struct task_struct *target,
                const struct user_regset *regset,
                unsigned int pos, unsigned int count,
                const void *kbuf, const void __user *ubuf)
{
    unsigned int *data = &task_thread_info(target)->system_call;
    return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
                  data, 0, sizeof(unsigned int));
}

static const struct user_regset s390_regsets[] = {
    [REGSET_GENERAL] = {
        .core_note_type = NT_PRSTATUS,
        .n = sizeof(s390_regs) / sizeof(long),
        .size = sizeof(long),
        .align = sizeof(long),
        .get = s390_regs_get,
        .set = s390_regs_set,
    },
    [REGSET_FP] = {
        .core_note_type = NT_PRFPREG,
        .n = sizeof(s390_fp_regs) / sizeof(long),
        .size = sizeof(long),
        .align = sizeof(long),
        .get = s390_fpregs_get,
        .set = s390_fpregs_set,
    },
#ifdef CONFIG_64BIT
    [REGSET_LAST_BREAK] = {
        .core_note_type = NT_S390_LAST_BREAK,
        .n = 1,
        .size = sizeof(long),
        .align = sizeof(long),
        .get = s390_last_break_get,
        .set = s390_last_break_set,
    },
    [REGSET_TDB] = {
        .core_note_type = NT_S390_TDB,
        .n = 1,
        .size = 256,
        .align = 1,
        .get = s390_tdb_get,
        .set = s390_tdb_set,
    },
#endif
    [REGSET_SYSTEM_CALL] = {
        .core_note_type = NT_S390_SYSTEM_CALL,
        .n = 1,
        .size = sizeof(unsigned int),
        .align = sizeof(unsigned int),
        .get = s390_system_call_get,
        .set = s390_system_call_set,
    },
};

static const struct user_regset_view user_s390_view = {
    .name = UTS_MACHINE,
    .e_machine = EM_S390,
    .regsets = s390_regsets,
    .n = ARRAY_SIZE(s390_regsets)
};

#ifdef CONFIG_COMPAT
static int s390_compat_regs_get(struct task_struct *target,
                const struct user_regset *regset,
                unsigned int pos, unsigned int count,
                void *kbuf, void __user *ubuf)
{
    if (target == current)
        save_access_regs(target->thread.acrs);

    if (kbuf) {
        compat_ulong_t *k = kbuf;
        while (count > 0) {
            *k++ = __peek_user_compat(target, pos);
            count -= sizeof(*k);
            pos += sizeof(*k);
        }
    } else {
        compat_ulong_t __user *u = ubuf;
        while (count > 0) {
            if (__put_user(__peek_user_compat(target, pos), u++))
                return -EFAULT;
            count -= sizeof(*u);
            pos += sizeof(*u);
        }
    }
    return 0;
}

static int s390_compat_regs_set(struct task_struct *target,
                const struct user_regset *regset,
                unsigned int pos, unsigned int count,
                const void *kbuf, const void __user *ubuf)
{
    int rc = 0;

    if (target == current)
        save_access_regs(target->thread.acrs);

    if (kbuf) {
        const compat_ulong_t *k = kbuf;
        while (count > 0 && !rc) {
            rc = __poke_user_compat(target, pos, *k++);
            count -= sizeof(*k);
            pos += sizeof(*k);
        }
    } else {
        const compat_ulong_t  __user *u = ubuf;
        while (count > 0 && !rc) {
            compat_ulong_t word;
            rc = __get_user(word, u++);
            if (rc)
                break;
            rc = __poke_user_compat(target, pos, word);
            count -= sizeof(*u);
            pos += sizeof(*u);
        }
    }

    if (rc == 0 && target == current)
        restore_access_regs(target->thread.acrs);

    return rc;
}

static int s390_compat_regs_high_get(struct task_struct *target,
                     const struct user_regset *regset,
                     unsigned int pos, unsigned int count,
                     void *kbuf, void __user *ubuf)
{
    compat_ulong_t *gprs_high;

    gprs_high = (compat_ulong_t *)
        &task_pt_regs(target)->gprs[pos / sizeof(compat_ulong_t)];
    if (kbuf) {
        compat_ulong_t *k = kbuf;
        while (count > 0) {
            *k++ = *gprs_high;
            gprs_high += 2;
            count -= sizeof(*k);
        }
    } else {
        compat_ulong_t __user *u = ubuf;
        while (count > 0) {
            if (__put_user(*gprs_high, u++))
                return -EFAULT;
            gprs_high += 2;
            count -= sizeof(*u);
        }
    }
    return 0;
}

static int s390_compat_regs_high_set(struct task_struct *target,
                     const struct user_regset *regset,
                     unsigned int pos, unsigned int count,
                     const void *kbuf, const void __user *ubuf)
{
    compat_ulong_t *gprs_high;
    int rc = 0;

    gprs_high = (compat_ulong_t *)
        &task_pt_regs(target)->gprs[pos / sizeof(compat_ulong_t)];
    if (kbuf) {
        const compat_ulong_t *k = kbuf;
        while (count > 0) {
            *gprs_high = *k++;
            *gprs_high += 2;
            count -= sizeof(*k);
        }
    } else {
        const compat_ulong_t  __user *u = ubuf;
        while (count > 0 && !rc) {
            unsigned long word;
            rc = __get_user(word, u++);
            if (rc)
                break;
            *gprs_high = word;
            *gprs_high += 2;
            count -= sizeof(*u);
        }
    }

    return rc;
}

static int s390_compat_last_break_get(struct task_struct *target,
                      const struct user_regset *regset,
                      unsigned int pos, unsigned int count,
                      void *kbuf, void __user *ubuf)
{
    compat_ulong_t last_break;

    if (count > 0) {
        last_break = task_thread_info(target)->last_break;
        if (kbuf) {
            unsigned long *k = kbuf;
            *k = last_break;
        } else {
            unsigned long  __user *u = ubuf;
            if (__put_user(last_break, u))
                return -EFAULT;
        }
    }
    return 0;
}

static int s390_compat_last_break_set(struct task_struct *target,
                      const struct user_regset *regset,
                      unsigned int pos, unsigned int count,
                      const void *kbuf, const void __user *ubuf)
{
    return 0;
}

static const struct user_regset s390_compat_regsets[] = {
    [REGSET_GENERAL] = {
        .core_note_type = NT_PRSTATUS,
        .n = sizeof(s390_compat_regs) / sizeof(compat_long_t),
        .size = sizeof(compat_long_t),
        .align = sizeof(compat_long_t),
        .get = s390_compat_regs_get,
        .set = s390_compat_regs_set,
    },
    [REGSET_FP] = {
        .core_note_type = NT_PRFPREG,
        .n = sizeof(s390_fp_regs) / sizeof(compat_long_t),
        .size = sizeof(compat_long_t),
        .align = sizeof(compat_long_t),
        .get = s390_fpregs_get,
        .set = s390_fpregs_set,
    },
    [REGSET_LAST_BREAK] = {
        .core_note_type = NT_S390_LAST_BREAK,
        .n = 1,
        .size = sizeof(long),
        .align = sizeof(long),
        .get = s390_compat_last_break_get,
        .set = s390_compat_last_break_set,
    },
    [REGSET_TDB] = {
        .core_note_type = NT_S390_TDB,
        .n = 1,
        .size = 256,
        .align = 1,
        .get = s390_tdb_get,
        .set = s390_tdb_set,
    },
    [REGSET_SYSTEM_CALL] = {
        .core_note_type = NT_S390_SYSTEM_CALL,
        .n = 1,
        .size = sizeof(compat_uint_t),
        .align = sizeof(compat_uint_t),
        .get = s390_system_call_get,
        .set = s390_system_call_set,
    },
    [REGSET_GENERAL_EXTENDED] = {
        .core_note_type = NT_S390_HIGH_GPRS,
        .n = sizeof(s390_compat_regs_high) / sizeof(compat_long_t),
        .size = sizeof(compat_long_t),
        .align = sizeof(compat_long_t),
        .get = s390_compat_regs_high_get,
        .set = s390_compat_regs_high_set,
    },
};

static const struct user_regset_view user_s390_compat_view = {
    .name = "s390",
    .e_machine = EM_S390,
    .regsets = s390_compat_regsets,
    .n = ARRAY_SIZE(s390_compat_regsets)
};
#endif

const struct user_regset_view *task_user_regset_view(struct task_struct *task)
{
#ifdef CONFIG_COMPAT
    if (test_tsk_thread_flag(task, TIF_31BIT))
        return &user_s390_compat_view;
#endif
    return &user_s390_view;
}

static const char *gpr_names[NUM_GPRS] = {
    "r0", "r1",  "r2",  "r3",  "r4",  "r5",  "r6",  "r7",
    "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15",
};

unsigned long regs_get_register(struct pt_regs *regs, unsigned int offset)
{
    if (offset >= NUM_GPRS)
        return 0;
    return regs->gprs[offset];
}

int regs_query_register_offset(const char *name)
{
    unsigned long offset;

    if (!name || *name != 'r')
        return -EINVAL;
    if (strict_strtoul(name + 1, 10, &offset))
        return -EINVAL;
    if (offset >= NUM_GPRS)
        return -EINVAL;
    return offset;
}

const char *regs_query_register_name(unsigned int offset)
{
    if (offset >= NUM_GPRS)
        return NULL;
    return gpr_names[offset];
}

static int regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr)
{
    unsigned long ksp = kernel_stack_pointer(regs);

    return (addr & ~(THREAD_SIZE - 1)) == (ksp & ~(THREAD_SIZE - 1));
}

unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, unsigned int n)
{
    unsigned long addr;

    addr = kernel_stack_pointer(regs) + n * sizeof(long);
    if (!regs_within_kernel_stack(regs, addr))
        return 0;
    return *(unsigned long *)addr;
}