Linux-2.6.12-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;
+	}
+}