Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 738 insertions, 0 deletions

diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
new file mode 100644
index 000000000000..647233c02fc8
--- /dev/null
+++ b/arch/s390/kernel/ptrace.c
@@ -0,0 +1,738 @@
+/*
+ *  arch/s390/kernel/ptrace.c
+ *
+ *  S390 version
+ *    Copyright (C) 1999,2000 IBM Deutschland Entwicklung GmbH, IBM Corporation
+ *    Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com),
+ *               Martin Schwidefsky (schwidefsky@de.ibm.com)
+ *
+ *  Based on PowerPC version 
+ *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
+ *
+ *  Derived from "arch/m68k/kernel/ptrace.c"
+ *  Copyright (C) 1994 by Hamish Macdonald
+ *  Taken from linux/kernel/ptrace.c and modified for M680x0.
+ *  linux/kernel/ptrace.c is by Ross Biro 1/23/92, edited by Linus Torvalds
+ *
+ * Modified by Cort Dougan (cort@cs.nmt.edu) 
+ *
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License.  See the file README.legal in the main directory of
+ * this archive for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/smp.h>
+#include <linux/smp_lock.h>
+#include <linux/errno.h>
+#include <linux/ptrace.h>
+#include <linux/user.h>
+#include <linux/security.h>
+#include <linux/audit.h>
+
+#include <asm/segment.h>
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <asm/pgalloc.h>
+#include <asm/system.h>
+#include <asm/uaccess.h>
+
+#ifdef CONFIG_S390_SUPPORT
+#include "compat_ptrace.h"
+#endif
+
+static void
+FixPerRegisters(struct task_struct *task)
+{
+        struct pt_regs *regs;
+        per_struct *per_info;
+
+        regs = __KSTK_PTREGS(task);
+        per_info = (per_struct *) &task->thread.per_info;
+        per_info->control_regs.bits.em_instruction_fetch =
+                per_info->single_step | per_info->instruction_fetch;
+        
+        if (per_info->single_step) {
+                per_info->control_regs.bits.starting_addr = 0;
+#ifdef CONFIG_S390_SUPPORT
+                if (test_thread_flag(TIF_31BIT))
+                        per_info->control_regs.bits.ending_addr = 0x7fffffffUL;
+                else
+#endif
+                        per_info->control_regs.bits.ending_addr = PSW_ADDR_INSN;
+        } else {
+                per_info->control_regs.bits.starting_addr =
+                        per_info->starting_addr;
+                per_info->control_regs.bits.ending_addr =
+                        per_info->ending_addr;
+        }
+        /*
+         * if any of the control reg tracing bits are on 
+         * we switch on per in the psw
+         */
+        if (per_info->control_regs.words.cr[0] & PER_EM_MASK)
+                regs->psw.mask |= PSW_MASK_PER;
+        else
+                regs->psw.mask &= ~PSW_MASK_PER;
+
+        if (per_info->control_regs.bits.em_storage_alteration)
+                per_info->control_regs.bits.storage_alt_space_ctl = 1;
+        else
+                per_info->control_regs.bits.storage_alt_space_ctl = 0;
+}
+
+void
+set_single_step(struct task_struct *task)
+{
+        task->thread.per_info.single_step = 1;
+        FixPerRegisters(task);
+}
+
+void
+clear_single_step(struct task_struct *task)
+{
+        task->thread.per_info.single_step = 0;
+        FixPerRegisters(task);
+}
+
+/*
+ * Called by kernel/ptrace.c when detaching..
+ *
+ * Make sure single step bits etc are not set.
+ */
+void
+ptrace_disable(struct task_struct *child)
+{
+        /* make sure the single step bit is not set. */
+        clear_single_step(child);
+}
+
+#ifndef CONFIG_ARCH_S390X
+# define __ADDR_MASK 3
+#else
+# define __ADDR_MASK 7
+#endif
+
+/*
+ * 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 int
+peek_user(struct task_struct *child, addr_t addr, addr_t data)
+{
+        struct user *dummy = NULL;
+        addr_t offset, tmp;
+
+        /*
+         * Stupid gdb peeks/pokes the access registers in 64 bit with
+         * an alignment of 4. Programmers from hell...
+         */
+        if ((addr & 3) || addr > sizeof(struct user) - __ADDR_MASK)
+                return -EIO;
+
+        if (addr < (addr_t) &dummy->regs.acrs) {
+                /*
+                 * psw and gprs are stored on the stack
+                 */
+                tmp = *(addr_t *)((addr_t) &__KSTK_PTREGS(child)->psw + addr);
+                if (addr == (addr_t) &dummy->regs.psw.mask)
+                        /* Remove per bit from user psw. */
+                        tmp &= ~PSW_MASK_PER;
+
+        } else if (addr < (addr_t) &dummy->regs.orig_gpr2) {
+                /*
+                 * access registers are stored in the thread structure
+                 */
+                offset = addr - (addr_t) &dummy->regs.acrs;
+                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) __KSTK_PTREGS(child)->orig_gpr2;
+
+        } 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);
+
+        } else if (addr < (addr_t) (&dummy->regs.per_info + 1)) {
+                /*
+                 * per_info is found in the thread structure
+                 */
+                offset = addr - (addr_t) &dummy->regs.per_info;
+                tmp = *(addr_t *)((addr_t) &child->thread.per_info + offset);
+
+        } else
+                tmp = 0;
+
+        return put_user(tmp, (addr_t __user *) 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;
+
+        /*
+         * Stupid gdb peeks/pokes the access registers in 64 bit with
+         * an alignment of 4. Programmers from hell indeed...
+         */
+        if ((addr & 3) || addr > sizeof(struct user) - __ADDR_MASK)
+                return -EIO;
+
+        if (addr < (addr_t) &dummy->regs.acrs) {
+                /*
+                 * psw and gprs are stored on the stack
+                 */
+                if (addr == (addr_t) &dummy->regs.psw.mask &&
+#ifdef CONFIG_S390_SUPPORT
+                    data != PSW_MASK_MERGE(PSW_USER32_BITS, data) &&
+#endif
+                    data != PSW_MASK_MERGE(PSW_USER_BITS, data))
+                        /* Invalid psw mask. */
+                        return -EINVAL;
+#ifndef CONFIG_ARCH_S390X
+                if (addr == (addr_t) &dummy->regs.psw.addr)
+                        /* I'd like to reject addresses without the
+                           high order bit but older gdb's rely on it */
+                        data |= PSW_ADDR_AMODE;
+#endif
+                *(addr_t *)((addr_t) &__KSTK_PTREGS(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;
+                *(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
+                 */
+                __KSTK_PTREGS(child)->orig_gpr2 = data;
+
+        } 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 & ~FPC_VALID_MASK) != 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)) {
+                /*
+                 * per_info is found in the thread structure 
+                 */
+                offset = addr - (addr_t) &dummy->regs.per_info;
+                *(addr_t *)((addr_t) &child->thread.per_info + offset) = data;
+
+        }
+
+        FixPerRegisters(child);
+        return 0;
+}
+
+static int
+do_ptrace_normal(struct task_struct *child, long request, long addr, long data)
+{
+        unsigned long tmp;
+        ptrace_area parea; 
+        int copied, ret;
+
+        switch (request) {
+        case PTRACE_PEEKTEXT:
+        case PTRACE_PEEKDATA:
+                /* Remove high order bit from address (only for 31 bit). */
+                addr &= PSW_ADDR_INSN;
+                /* read word at location addr. */
+                copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
+                if (copied != sizeof(tmp))
+                        return -EIO;
+                return put_user(tmp, (unsigned long __user *) data);
+
+        case PTRACE_PEEKUSR:
+                /* read the word at location addr in the USER area. */
+                return peek_user(child, addr, data);
+
+        case PTRACE_POKETEXT:
+        case PTRACE_POKEDATA:
+                /* Remove high order bit from address (only for 31 bit). */
+                addr &= PSW_ADDR_INSN;
+                /* write the word at location addr. */
+                copied = access_process_vm(child, addr, &data, sizeof(data),1);
+                if (copied != sizeof(data))
+                        return -EIO;
+                return 0;
+
+        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 __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 tmp;
+                                if (get_user (tmp, (addr_t __user *) data))
+                                        return -EFAULT;
+                                ret = poke_user(child, addr, tmp);
+                        }
+                        if (ret)
+                                return ret;
+                        addr += sizeof(unsigned long);
+                        data += sizeof(unsigned long);
+                        copied += sizeof(unsigned long);
+                }
+                return 0;
+        }
+        return ptrace_request(child, request, addr, data);
+}
+
+#ifdef CONFIG_S390_SUPPORT
+/*
+ * 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 but for a 31 bit program.
+ */
+static int
+peek_user_emu31(struct task_struct *child, addr_t addr, addr_t data)
+{
+        struct user32 *dummy32 = NULL;
+        per_struct32 *dummy_per32 = NULL;
+        addr_t offset;
+        __u32 tmp;
+
+        if (!test_thread_flag(TIF_31BIT) ||
+            (addr & 3) || addr > sizeof(struct user) - 3)
+                return -EIO;
+
+        if (addr < (addr_t) &dummy32->regs.acrs) {
+                /*
+                 * psw and gprs are stored on the stack
+                 */
+                if (addr == (addr_t) &dummy32->regs.psw.mask) {
+                        /* Fake a 31 bit psw mask. */
+                        tmp = (__u32)(__KSTK_PTREGS(child)->psw.mask >> 32);
+                        tmp = PSW32_MASK_MERGE(PSW32_USER_BITS, tmp);
+                } else if (addr == (addr_t) &dummy32->regs.psw.addr) {
+                        /* Fake a 31 bit psw address. */
+                        tmp = (__u32) __KSTK_PTREGS(child)->psw.addr |
+                                PSW32_ADDR_AMODE31;
+                } else {
+                        /* gpr 0-15 */
+                        tmp = *(__u32 *)((addr_t) &__KSTK_PTREGS(child)->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) &__KSTK_PTREGS(child)->orig_gpr2 + 4);
+
+        } 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)) {
+                /*
+                 * per_info is found in the thread structure
+                 */
+                offset = addr - (addr_t) &dummy32->regs.per_info;
+                /* This is magic. See per_struct and per_struct32. */
+                if ((offset >= (addr_t) &dummy_per32->control_regs &&
+                     offset < (addr_t) (&dummy_per32->control_regs + 1)) ||
+                    (offset >= (addr_t) &dummy_per32->starting_addr &&
+                     offset <= (addr_t) &dummy_per32->ending_addr) ||
+                    offset == (addr_t) &dummy_per32->lowcore.words.address)
+                        offset = offset*2 + 4;
+                else
+                        offset = offset*2;
+                tmp = *(__u32 *)((addr_t) &child->thread.per_info + offset);
+
+        } else
+                tmp = 0;
+
+        return put_user(tmp, (__u32 __user *) data);
+}
+
+/*
+ * Same as poke_user but for a 31 bit program.
+ */
+static int
+poke_user_emu31(struct task_struct *child, addr_t addr, addr_t data)
+{
+        struct user32 *dummy32 = NULL;
+        per_struct32 *dummy_per32 = NULL;
+        addr_t offset;
+        __u32 tmp;
+
+        if (!test_thread_flag(TIF_31BIT) ||
+            (addr & 3) || addr > sizeof(struct user32) - 3)
+                return -EIO;
+
+        tmp = (__u32) data;
+
+        if (addr < (addr_t) &dummy32->regs.acrs) {
+                /*
+                 * 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_MERGE(PSW32_USER_BITS, tmp))
+                                /* Invalid psw mask. */
+                                return -EINVAL;
+                        __KSTK_PTREGS(child)->psw.mask =
+                                PSW_MASK_MERGE(PSW_USER32_BITS, (__u64) tmp << 32);
+                } else if (addr == (addr_t) &dummy32->regs.psw.addr) {
+                        /* Build a 64 bit psw address from 31 bit address. */
+                        __KSTK_PTREGS(child)->psw.addr = 
+                                (__u64) tmp & PSW32_ADDR_INSN;
+                } else {
+                        /* gpr 0-15 */
+                        *(__u32*)((addr_t) &__KSTK_PTREGS(child)->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) &__KSTK_PTREGS(child)->orig_gpr2 + 4) = tmp;
+
+        } 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)) {
+                /*
+                 * per_info is found in the thread structure.
+                 */
+                offset = addr - (addr_t) &dummy32->regs.per_info;
+                /*
+                 * This is magic. See per_struct and per_struct32.
+                 * By incident the offsets in per_struct are exactly
+                 * twice the offsets in per_struct32 for all fields.
+                 * The 8 byte fields need special handling though,
+                 * because the second half (bytes 4-7) is needed and
+                 * not the first half.
+                 */
+                if ((offset >= (addr_t) &dummy_per32->control_regs &&
+                     offset < (addr_t) (&dummy_per32->control_regs + 1)) ||
+                    (offset >= (addr_t) &dummy_per32->starting_addr &&
+                     offset <= (addr_t) &dummy_per32->ending_addr) ||
+                    offset == (addr_t) &dummy_per32->lowcore.words.address)
+                        offset = offset*2 + 4;
+                else
+                        offset = offset*2;
+                *(__u32 *)((addr_t) &child->thread.per_info + offset) = tmp;
+
+        }
+
+        FixPerRegisters(child);
+        return 0;
+}
+
+static int
+do_ptrace_emu31(struct task_struct *child, long request, long addr, long data)
+{
+        unsigned int tmp;  /* 4 bytes !! */
+        ptrace_area_emu31 parea; 
+        int copied, ret;
+
+        switch (request) {
+        case PTRACE_PEEKTEXT:
+        case PTRACE_PEEKDATA:
+                /* read word at location addr. */
+                copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
+                if (copied != sizeof(tmp))
+                        return -EIO;
+                return put_user(tmp, (unsigned int __user *) data);
+
+        case PTRACE_PEEKUSR:
+                /* read the word at location addr in the USER area. */
+                return peek_user_emu31(child, addr, data);
+
+        case PTRACE_POKETEXT:
+        case PTRACE_POKEDATA:
+                /* write the word at location addr. */
+                tmp = data;
+                copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 1);
+                if (copied != sizeof(tmp))
+                        return -EIO;
+                return 0;
+
+        case PTRACE_POKEUSR:
+                /* write the word at location addr in the USER area */
+                return poke_user_emu31(child, addr, data);
+
+        case PTRACE_PEEKUSR_AREA:
+        case PTRACE_POKEUSR_AREA:
+                if (copy_from_user(&parea, (void __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_emu31(child, addr, data);
+                        else {
+                                __u32 tmp;
+                                if (get_user (tmp, (__u32 __user *) data))
+                                        return -EFAULT;
+                                ret = poke_user_emu31(child, addr, tmp);
+                        }
+                        if (ret)
+                                return ret;
+                        addr += sizeof(unsigned int);
+                        data += sizeof(unsigned int);
+                        copied += sizeof(unsigned int);
+                }
+                return 0;
+        case PTRACE_GETEVENTMSG:
+                return put_user((__u32) child->ptrace_message,
+                                (unsigned int __user *) data);
+        case PTRACE_GETSIGINFO:
+                if (child->last_siginfo == NULL)
+                        return -EINVAL;
+                return copy_siginfo_to_user32((compat_siginfo_t __user *) data,
+                                              child->last_siginfo);
+        case PTRACE_SETSIGINFO:
+                if (child->last_siginfo == NULL)
+                        return -EINVAL;
+                return copy_siginfo_from_user32(child->last_siginfo,
+                                                (compat_siginfo_t __user *) data);
+        }
+        return ptrace_request(child, request, addr, data);
+}
+#endif
+
+#define PT32_IEEE_IP 0x13c
+
+static int
+do_ptrace(struct task_struct *child, long request, long addr, long data)
+{
+        int ret;
+
+        if (request == PTRACE_ATTACH)
+                return ptrace_attach(child);
+
+        /*
+         * Special cases to get/store the ieee instructions pointer.
+         */
+        if (child == current) {
+                if (request == PTRACE_PEEKUSR && addr == PT_IEEE_IP)
+                        return peek_user(child, addr, data);
+                if (request == PTRACE_POKEUSR && addr == PT_IEEE_IP)
+                        return poke_user(child, addr, data);
+#ifdef CONFIG_S390_SUPPORT
+                if (request == PTRACE_PEEKUSR &&
+                    addr == PT32_IEEE_IP && test_thread_flag(TIF_31BIT))
+                        return peek_user_emu31(child, addr, data);
+                if (request == PTRACE_POKEUSR &&
+                    addr == PT32_IEEE_IP && test_thread_flag(TIF_31BIT))
+                        return poke_user_emu31(child, addr, data);
+#endif
+        }
+
+        ret = ptrace_check_attach(child, request == PTRACE_KILL);
+        if (ret < 0)
+                return ret;
+
+        switch (request) {
+        case PTRACE_SYSCALL:
+                /* continue and stop at next (return from) syscall */
+        case PTRACE_CONT:
+                /* restart after signal. */
+                if ((unsigned long) data >= _NSIG)
+                        return -EIO;
+                if (request == PTRACE_SYSCALL)
+                        set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+                else
+                        clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+                child->exit_code = data;
+                /* make sure the single step bit is not set. */
+                clear_single_step(child);
+                wake_up_process(child);
+                return 0;
+
+        case PTRACE_KILL:
+                /*
+                 * make the child exit.  Best I can do is send it a sigkill. 
+                 * perhaps it should be put in the status that it wants to 
+                 * exit.
+                 */
+                if (child->exit_state == EXIT_ZOMBIE) /* already dead */
+                        return 0;
+                child->exit_code = SIGKILL;
+                /* make sure the single step bit is not set. */
+                clear_single_step(child);
+                wake_up_process(child);
+                return 0;
+
+        case PTRACE_SINGLESTEP:
+                /* set the trap flag. */
+                if ((unsigned long) data >= _NSIG)
+                        return -EIO;
+                clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+                child->exit_code = data;
+                if (data)
+                        set_tsk_thread_flag(child, TIF_SINGLE_STEP);
+                else
+                        set_single_step(child);
+                /* give it a chance to run. */
+                wake_up_process(child);
+                return 0;
+
+        case PTRACE_DETACH:
+                /* detach a process that was attached. */
+                return ptrace_detach(child, data);
+
+
+        /* Do requests that differ for 31/64 bit */
+        default:
+#ifdef CONFIG_S390_SUPPORT
+                if (test_thread_flag(TIF_31BIT))
+                        return do_ptrace_emu31(child, request, addr, data);
+#endif
+                return do_ptrace_normal(child, request, addr, data);
+        }
+        /* Not reached.  */
+        return -EIO;
+}
+
+asmlinkage long
+sys_ptrace(long request, long pid, long addr, long data)
+{
+        struct task_struct *child;
+        int ret;
+
+        lock_kernel();
+
+        if (request == PTRACE_TRACEME) {
+                /* are we already being traced? */
+                ret = -EPERM;
+                if (current->ptrace & PT_PTRACED)
+                        goto out;
+                ret = security_ptrace(current->parent, current);
+                if (ret)
+                        goto out;
+                /* set the ptrace bit in the process flags. */
+                current->ptrace |= PT_PTRACED;
+                goto out;
+        }
+
+        ret = -EPERM;
+        if (pid == 1)           /* you may not mess with init */
+                goto out;
+
+        ret = -ESRCH;
+        read_lock(&tasklist_lock);
+        child = find_task_by_pid(pid);
+        if (child)
+                get_task_struct(child);
+        read_unlock(&tasklist_lock);
+        if (!child)
+                goto out;
+
+        ret = do_ptrace(child, request, addr, data);
+
+        put_task_struct(child);
+out:
+        unlock_kernel();
+        return ret;
+}
+
+asmlinkage void
+syscall_trace(struct pt_regs *regs, int entryexit)
+{
+        if (unlikely(current->audit_context)) {
+                if (!entryexit)
+                        audit_syscall_entry(current, regs->gprs[2],
+                                            regs->orig_gpr2, regs->gprs[3],
+                                            regs->gprs[4], regs->gprs[5]);
+                else
+                        audit_syscall_exit(current, regs->gprs[2]);
+        }
+        if (!test_thread_flag(TIF_SYSCALL_TRACE))
+                return;
+        if (!(current->ptrace & PT_PTRACED))
+                return;
+        ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
+                                 ? 0x80 : 0));
+
+        /*
+         * this isn't the same as continuing with a signal, but it will do
+         * for normal use.  strace only continues with a signal if the
+         * stopping signal is not SIGTRAP.  -brl
+         */
+        if (current->exit_code) {
+                send_sig(current->exit_code, current, 1);
+                current->exit_code = 0;
+        }
+}