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, 861 insertions, 0 deletions

diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
new file mode 100644
index 000000000000..efd7a341614b
--- /dev/null
+++ b/arch/arm/kernel/ptrace.c
@@ -0,0 +1,861 @@
+/*
+ *  linux/arch/arm/kernel/ptrace.c
+ *
+ *  By Ross Biro 1/23/92
+ * edited by Linus Torvalds
+ * ARM modifications Copyright (C) 2000 Russell King
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/smp.h>
+#include <linux/smp_lock.h>
+#include <linux/ptrace.h>
+#include <linux/user.h>
+#include <linux/security.h>
+#include <linux/init.h>
+
+#include <asm/uaccess.h>
+#include <asm/pgtable.h>
+#include <asm/system.h>
+#include <asm/traps.h>
+
+#include "ptrace.h"
+
+#define REG_PC	15
+#define REG_PSR	16
+/*
+ * does not yet catch signals sent when the child dies.
+ * in exit.c or in signal.c.
+ */
+
+#if 0
+/*
+ * Breakpoint SWI instruction: SWI &9F0001
+ */
+#define BREAKINST_ARM	0xef9f0001
+#define BREAKINST_THUMB	0xdf00		/* fill this in later */
+#else
+/*
+ * New breakpoints - use an undefined instruction.  The ARM architecture
+ * reference manual guarantees that the following instruction space
+ * will produce an undefined instruction exception on all CPUs:
+ *
+ *  ARM:   xxxx 0111 1111 xxxx xxxx xxxx 1111 xxxx
+ *  Thumb: 1101 1110 xxxx xxxx
+ */
+#define BREAKINST_ARM	0xe7f001f0
+#define BREAKINST_THUMB	0xde01
+#endif
+
+/*
+ * Get the address of the live pt_regs for the specified task.
+ * These are saved onto the top kernel stack when the process
+ * is not running.
+ *
+ * Note: if a user thread is execve'd from kernel space, the
+ * kernel stack will not be empty on entry to the kernel, so
+ * ptracing these tasks will fail.
+ */
+static inline struct pt_regs *
+get_user_regs(struct task_struct *task)
+{
+	return (struct pt_regs *)
+		((unsigned long)task->thread_info + THREAD_SIZE -
+				 8 - sizeof(struct pt_regs));
+}
+
+/*
+ * this routine will get a word off of the processes privileged stack.
+ * the offset is how far from the base addr as stored in the THREAD.
+ * this routine assumes that all the privileged stacks are in our
+ * data space.
+ */
+static inline long get_user_reg(struct task_struct *task, int offset)
+{
+	return get_user_regs(task)->uregs[offset];
+}
+
+/*
+ * this routine will put a word on the processes privileged stack.
+ * the offset is how far from the base addr as stored in the THREAD.
+ * this routine assumes that all the privileged stacks are in our
+ * data space.
+ */
+static inline int
+put_user_reg(struct task_struct *task, int offset, long data)
+{
+	struct pt_regs newregs, *regs = get_user_regs(task);
+	int ret = -EINVAL;
+
+	newregs = *regs;
+	newregs.uregs[offset] = data;
+
+	if (valid_user_regs(&newregs)) {
+		regs->uregs[offset] = data;
+		ret = 0;
+	}
+
+	return ret;
+}
+
+static inline int
+read_u32(struct task_struct *task, unsigned long addr, u32 *res)
+{
+	int ret;
+
+	ret = access_process_vm(task, addr, res, sizeof(*res), 0);
+
+	return ret == sizeof(*res) ? 0 : -EIO;
+}
+
+static inline int
+read_instr(struct task_struct *task, unsigned long addr, u32 *res)
+{
+	int ret;
+
+	if (addr & 1) {
+		u16 val;
+		ret = access_process_vm(task, addr & ~1, &val, sizeof(val), 0);
+		ret = ret == sizeof(val) ? 0 : -EIO;
+		*res = val;
+	} else {
+		u32 val;
+		ret = access_process_vm(task, addr & ~3, &val, sizeof(val), 0);
+		ret = ret == sizeof(val) ? 0 : -EIO;
+		*res = val;
+	}
+	return ret;
+}
+
+/*
+ * Get value of register `rn' (in the instruction)
+ */
+static unsigned long
+ptrace_getrn(struct task_struct *child, unsigned long insn)
+{
+	unsigned int reg = (insn >> 16) & 15;
+	unsigned long val;
+
+	val = get_user_reg(child, reg);
+	if (reg == 15)
+		val = pc_pointer(val + 8);
+
+	return val;
+}
+
+/*
+ * Get value of operand 2 (in an ALU instruction)
+ */
+static unsigned long
+ptrace_getaluop2(struct task_struct *child, unsigned long insn)
+{
+	unsigned long val;
+	int shift;
+	int type;
+
+	if (insn & 1 << 25) {
+		val = insn & 255;
+		shift = (insn >> 8) & 15;
+		type = 3;
+	} else {
+		val = get_user_reg (child, insn & 15);
+
+		if (insn & (1 << 4))
+			shift = (int)get_user_reg (child, (insn >> 8) & 15);
+		else
+			shift = (insn >> 7) & 31;
+
+		type = (insn >> 5) & 3;
+	}
+
+	switch (type) {
+	case 0:	val <<= shift;	break;
+	case 1:	val >>= shift;	break;
+	case 2:
+		val = (((signed long)val) >> shift);
+		break;
+	case 3:
+ 		val = (val >> shift) | (val << (32 - shift));
+		break;
+	}
+	return val;
+}
+
+/*
+ * Get value of operand 2 (in a LDR instruction)
+ */
+static unsigned long
+ptrace_getldrop2(struct task_struct *child, unsigned long insn)
+{
+	unsigned long val;
+	int shift;
+	int type;
+
+	val = get_user_reg(child, insn & 15);
+	shift = (insn >> 7) & 31;
+	type = (insn >> 5) & 3;
+
+	switch (type) {
+	case 0:	val <<= shift;	break;
+	case 1:	val >>= shift;	break;
+	case 2:
+		val = (((signed long)val) >> shift);
+		break;
+	case 3:
+ 		val = (val >> shift) | (val << (32 - shift));
+		break;
+	}
+	return val;
+}
+
+#define OP_MASK	0x01e00000
+#define OP_AND	0x00000000
+#define OP_EOR	0x00200000
+#define OP_SUB	0x00400000
+#define OP_RSB	0x00600000
+#define OP_ADD	0x00800000
+#define OP_ADC	0x00a00000
+#define OP_SBC	0x00c00000
+#define OP_RSC	0x00e00000
+#define OP_ORR	0x01800000
+#define OP_MOV	0x01a00000
+#define OP_BIC	0x01c00000
+#define OP_MVN	0x01e00000
+
+static unsigned long
+get_branch_address(struct task_struct *child, unsigned long pc, unsigned long insn)
+{
+	u32 alt = 0;
+
+	switch (insn & 0x0e000000) {
+	case 0x00000000:
+	case 0x02000000: {
+		/*
+		 * data processing
+		 */
+		long aluop1, aluop2, ccbit;
+
+		if ((insn & 0xf000) != 0xf000)
+			break;
+
+		aluop1 = ptrace_getrn(child, insn);
+		aluop2 = ptrace_getaluop2(child, insn);
+		ccbit  = get_user_reg(child, REG_PSR) & PSR_C_BIT ? 1 : 0;
+
+		switch (insn & OP_MASK) {
+		case OP_AND: alt = aluop1 & aluop2;		break;
+		case OP_EOR: alt = aluop1 ^ aluop2;		break;
+		case OP_SUB: alt = aluop1 - aluop2;		break;
+		case OP_RSB: alt = aluop2 - aluop1;		break;
+		case OP_ADD: alt = aluop1 + aluop2;		break;
+		case OP_ADC: alt = aluop1 + aluop2 + ccbit;	break;
+		case OP_SBC: alt = aluop1 - aluop2 + ccbit;	break;
+		case OP_RSC: alt = aluop2 - aluop1 + ccbit;	break;
+		case OP_ORR: alt = aluop1 | aluop2;		break;
+		case OP_MOV: alt = aluop2;			break;
+		case OP_BIC: alt = aluop1 & ~aluop2;		break;
+		case OP_MVN: alt = ~aluop2;			break;
+		}
+		break;
+	}
+
+	case 0x04000000:
+	case 0x06000000:
+		/*
+		 * ldr
+		 */
+		if ((insn & 0x0010f000) == 0x0010f000) {
+			unsigned long base;
+
+			base = ptrace_getrn(child, insn);
+			if (insn & 1 << 24) {
+				long aluop2;
+
+				if (insn & 0x02000000)
+					aluop2 = ptrace_getldrop2(child, insn);
+				else
+					aluop2 = insn & 0xfff;
+
+				if (insn & 1 << 23)
+					base += aluop2;
+				else
+					base -= aluop2;
+			}
+			if (read_u32(child, base, &alt) == 0)
+				alt = pc_pointer(alt);
+		}
+		break;
+
+	case 0x08000000:
+		/*
+		 * ldm
+		 */
+		if ((insn & 0x00108000) == 0x00108000) {
+			unsigned long base;
+			unsigned int nr_regs;
+
+			if (insn & (1 << 23)) {
+				nr_regs = hweight16(insn & 65535) << 2;
+
+				if (!(insn & (1 << 24)))
+					nr_regs -= 4;
+			} else {
+				if (insn & (1 << 24))
+					nr_regs = -4;
+				else
+					nr_regs = 0;
+			}
+
+			base = ptrace_getrn(child, insn);
+
+			if (read_u32(child, base + nr_regs, &alt) == 0)
+				alt = pc_pointer(alt);
+			break;
+		}
+		break;
+
+	case 0x0a000000: {
+		/*
+		 * bl or b
+		 */
+		signed long displ;
+		/* It's a branch/branch link: instead of trying to
+		 * figure out whether the branch will be taken or not,
+		 * we'll put a breakpoint at both locations.  This is
+		 * simpler, more reliable, and probably not a whole lot
+		 * slower than the alternative approach of emulating the
+		 * branch.
+		 */
+		displ = (insn & 0x00ffffff) << 8;
+		displ = (displ >> 6) + 8;
+		if (displ != 0 && displ != 4)
+			alt = pc + displ;
+	    }
+	    break;
+	}
+
+	return alt;
+}
+
+static int
+swap_insn(struct task_struct *task, unsigned long addr,
+	  void *old_insn, void *new_insn, int size)
+{
+	int ret;
+
+	ret = access_process_vm(task, addr, old_insn, size, 0);
+	if (ret == size)
+		ret = access_process_vm(task, addr, new_insn, size, 1);
+	return ret;
+}
+
+static void
+add_breakpoint(struct task_struct *task, struct debug_info *dbg, unsigned long addr)
+{
+	int nr = dbg->nsaved;
+
+	if (nr < 2) {
+		u32 new_insn = BREAKINST_ARM;
+		int res;
+
+		res = swap_insn(task, addr, &dbg->bp[nr].insn, &new_insn, 4);
+
+		if (res == 4) {
+			dbg->bp[nr].address = addr;
+			dbg->nsaved += 1;
+		}
+	} else
+		printk(KERN_ERR "ptrace: too many breakpoints\n");
+}
+
+/*
+ * Clear one breakpoint in the user program.  We copy what the hardware
+ * does and use bit 0 of the address to indicate whether this is a Thumb
+ * breakpoint or an ARM breakpoint.
+ */
+static void clear_breakpoint(struct task_struct *task, struct debug_entry *bp)
+{
+	unsigned long addr = bp->address;
+	union debug_insn old_insn;
+	int ret;
+
+	if (addr & 1) {
+		ret = swap_insn(task, addr & ~1, &old_insn.thumb,
+				&bp->insn.thumb, 2);
+
+		if (ret != 2 || old_insn.thumb != BREAKINST_THUMB)
+			printk(KERN_ERR "%s:%d: corrupted Thumb breakpoint at "
+				"0x%08lx (0x%04x)\n", task->comm, task->pid,
+				addr, old_insn.thumb);
+	} else {
+		ret = swap_insn(task, addr & ~3, &old_insn.arm,
+				&bp->insn.arm, 4);
+
+		if (ret != 4 || old_insn.arm != BREAKINST_ARM)
+			printk(KERN_ERR "%s:%d: corrupted ARM breakpoint at "
+				"0x%08lx (0x%08x)\n", task->comm, task->pid,
+				addr, old_insn.arm);
+	}
+}
+
+void ptrace_set_bpt(struct task_struct *child)
+{
+	struct pt_regs *regs;
+	unsigned long pc;
+	u32 insn;
+	int res;
+
+	regs = get_user_regs(child);
+	pc = instruction_pointer(regs);
+
+	if (thumb_mode(regs)) {
+		printk(KERN_WARNING "ptrace: can't handle thumb mode\n");
+		return;
+	}
+
+	res = read_instr(child, pc, &insn);
+	if (!res) {
+		struct debug_info *dbg = &child->thread.debug;
+		unsigned long alt;
+
+		dbg->nsaved = 0;
+
+		alt = get_branch_address(child, pc, insn);
+		if (alt)
+			add_breakpoint(child, dbg, alt);
+
+		/*
+		 * Note that we ignore the result of setting the above
+		 * breakpoint since it may fail.  When it does, this is
+		 * not so much an error, but a forewarning that we may
+		 * be receiving a prefetch abort shortly.
+		 *
+		 * If we don't set this breakpoint here, then we can
+		 * lose control of the thread during single stepping.
+		 */
+		if (!alt || predicate(insn) != PREDICATE_ALWAYS)
+			add_breakpoint(child, dbg, pc + 4);
+	}
+}
+
+/*
+ * Ensure no single-step breakpoint is pending.  Returns non-zero
+ * value if child was being single-stepped.
+ */
+void ptrace_cancel_bpt(struct task_struct *child)
+{
+	int i, nsaved = child->thread.debug.nsaved;
+
+	child->thread.debug.nsaved = 0;
+
+	if (nsaved > 2) {
+		printk("ptrace_cancel_bpt: bogus nsaved: %d!\n", nsaved);
+		nsaved = 2;
+	}
+
+	for (i = 0; i < nsaved; i++)
+		clear_breakpoint(child, &child->thread.debug.bp[i]);
+}
+
+/*
+ * Called by kernel/ptrace.c when detaching..
+ *
+ * Make sure the single step bit is not set.
+ */
+void ptrace_disable(struct task_struct *child)
+{
+	child->ptrace &= ~PT_SINGLESTEP;
+	ptrace_cancel_bpt(child);
+}
+
+/*
+ * Handle hitting a breakpoint.
+ */
+void ptrace_break(struct task_struct *tsk, struct pt_regs *regs)
+{
+	siginfo_t info;
+
+	ptrace_cancel_bpt(tsk);
+
+	info.si_signo = SIGTRAP;
+	info.si_errno = 0;
+	info.si_code  = TRAP_BRKPT;
+	info.si_addr  = (void __user *)instruction_pointer(regs);
+
+	force_sig_info(SIGTRAP, &info, tsk);
+}
+
+static int break_trap(struct pt_regs *regs, unsigned int instr)
+{
+	ptrace_break(current, regs);
+	return 0;
+}
+
+static struct undef_hook arm_break_hook = {
+	.instr_mask	= 0x0fffffff,
+	.instr_val	= 0x07f001f0,
+	.cpsr_mask	= PSR_T_BIT,
+	.cpsr_val	= 0,
+	.fn		= break_trap,
+};
+
+static struct undef_hook thumb_break_hook = {
+	.instr_mask	= 0xffff,
+	.instr_val	= 0xde01,
+	.cpsr_mask	= PSR_T_BIT,
+	.cpsr_val	= PSR_T_BIT,
+	.fn		= break_trap,
+};
+
+static int __init ptrace_break_init(void)
+{
+	register_undef_hook(&arm_break_hook);
+	register_undef_hook(&thumb_break_hook);
+	return 0;
+}
+
+core_initcall(ptrace_break_init);
+
+/*
+ * Read the word at offset "off" into the "struct user".  We
+ * actually access the pt_regs stored on the kernel stack.
+ */
+static int ptrace_read_user(struct task_struct *tsk, unsigned long off,
+			    unsigned long __user *ret)
+{
+	unsigned long tmp;
+
+	if (off & 3 || off >= sizeof(struct user))
+		return -EIO;
+
+	tmp = 0;
+	if (off < sizeof(struct pt_regs))
+		tmp = get_user_reg(tsk, off >> 2);
+
+	return put_user(tmp, ret);
+}
+
+/*
+ * Write the word at offset "off" into "struct user".  We
+ * actually access the pt_regs stored on the kernel stack.
+ */
+static int ptrace_write_user(struct task_struct *tsk, unsigned long off,
+			     unsigned long val)
+{
+	if (off & 3 || off >= sizeof(struct user))
+		return -EIO;
+
+	if (off >= sizeof(struct pt_regs))
+		return 0;
+
+	return put_user_reg(tsk, off >> 2, val);
+}
+
+/*
+ * Get all user integer registers.
+ */
+static int ptrace_getregs(struct task_struct *tsk, void __user *uregs)
+{
+	struct pt_regs *regs = get_user_regs(tsk);
+
+	return copy_to_user(uregs, regs, sizeof(struct pt_regs)) ? -EFAULT : 0;
+}
+
+/*
+ * Set all user integer registers.
+ */
+static int ptrace_setregs(struct task_struct *tsk, void __user *uregs)
+{
+	struct pt_regs newregs;
+	int ret;
+
+	ret = -EFAULT;
+	if (copy_from_user(&newregs, uregs, sizeof(struct pt_regs)) == 0) {
+		struct pt_regs *regs = get_user_regs(tsk);
+
+		ret = -EINVAL;
+		if (valid_user_regs(&newregs)) {
+			*regs = newregs;
+			ret = 0;
+		}
+	}
+
+	return ret;
+}
+
+/*
+ * Get the child FPU state.
+ */
+static int ptrace_getfpregs(struct task_struct *tsk, void __user *ufp)
+{
+	return copy_to_user(ufp, &tsk->thread_info->fpstate,
+			    sizeof(struct user_fp)) ? -EFAULT : 0;
+}
+
+/*
+ * Set the child FPU state.
+ */
+static int ptrace_setfpregs(struct task_struct *tsk, void __user *ufp)
+{
+	struct thread_info *thread = tsk->thread_info;
+	thread->used_cp[1] = thread->used_cp[2] = 1;
+	return copy_from_user(&thread->fpstate, ufp,
+			      sizeof(struct user_fp)) ? -EFAULT : 0;
+}
+
+#ifdef CONFIG_IWMMXT
+
+/*
+ * Get the child iWMMXt state.
+ */
+static int ptrace_getwmmxregs(struct task_struct *tsk, void __user *ufp)
+{
+	struct thread_info *thread = tsk->thread_info;
+	void *ptr = &thread->fpstate;
+
+	if (!test_ti_thread_flag(thread, TIF_USING_IWMMXT))
+		return -ENODATA;
+	iwmmxt_task_disable(thread);  /* force it to ram */
+	/* The iWMMXt state is stored doubleword-aligned.  */
+	if (((long) ptr) & 4)
+		ptr += 4;
+	return copy_to_user(ufp, ptr, 0x98) ? -EFAULT : 0;
+}
+
+/*
+ * Set the child iWMMXt state.
+ */
+static int ptrace_setwmmxregs(struct task_struct *tsk, void __user *ufp)
+{
+	struct thread_info *thread = tsk->thread_info;
+	void *ptr = &thread->fpstate;
+
+	if (!test_ti_thread_flag(thread, TIF_USING_IWMMXT))
+		return -EACCES;
+	iwmmxt_task_release(thread);  /* force a reload */
+	/* The iWMMXt state is stored doubleword-aligned.  */
+	if (((long) ptr) & 4)
+		ptr += 4;
+	return copy_from_user(ptr, ufp, 0x98) ? -EFAULT : 0;
+}
+
+#endif
+
+static int do_ptrace(int request, struct task_struct *child, long addr, long data)
+{
+	unsigned long tmp;
+	int ret;
+
+	switch (request) {
+		/*
+		 * read word at location "addr" in the child process.
+		 */
+		case PTRACE_PEEKTEXT:
+		case PTRACE_PEEKDATA:
+			ret = access_process_vm(child, addr, &tmp,
+						sizeof(unsigned long), 0);
+			if (ret == sizeof(unsigned long))
+				ret = put_user(tmp, (unsigned long __user *) data);
+			else
+				ret = -EIO;
+			break;
+
+		case PTRACE_PEEKUSR:
+			ret = ptrace_read_user(child, addr, (unsigned long __user *)data);
+			break;
+
+		/*
+		 * write the word at location addr.
+		 */
+		case PTRACE_POKETEXT:
+		case PTRACE_POKEDATA:
+			ret = access_process_vm(child, addr, &data,
+						sizeof(unsigned long), 1);
+			if (ret == sizeof(unsigned long))
+				ret = 0;
+			else
+				ret = -EIO;
+			break;
+
+		case PTRACE_POKEUSR:
+			ret = ptrace_write_user(child, addr, data);
+			break;
+
+		/*
+		 * continue/restart and stop at next (return from) syscall
+		 */
+		case PTRACE_SYSCALL:
+		case PTRACE_CONT:
+			ret = -EIO;
+			if ((unsigned long) data > _NSIG)
+				break;
+			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 single-step breakpoint is gone. */
+			child->ptrace &= ~PT_SINGLESTEP;
+			ptrace_cancel_bpt(child);
+			wake_up_process(child);
+			ret = 0;
+			break;
+
+		/*
+		 * 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.
+		 */
+		case PTRACE_KILL:
+			/* make sure single-step breakpoint is gone. */
+			child->ptrace &= ~PT_SINGLESTEP;
+			ptrace_cancel_bpt(child);
+			if (child->exit_state != EXIT_ZOMBIE) {
+				child->exit_code = SIGKILL;
+				wake_up_process(child);
+			}
+			ret = 0;
+			break;
+
+		/*
+		 * execute single instruction.
+		 */
+		case PTRACE_SINGLESTEP:
+			ret = -EIO;
+			if ((unsigned long) data > _NSIG)
+				break;
+			child->ptrace |= PT_SINGLESTEP;
+			clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+			child->exit_code = data;
+			/* give it a chance to run. */
+			wake_up_process(child);
+			ret = 0;
+			break;
+
+		case PTRACE_DETACH:
+			ret = ptrace_detach(child, data);
+			break;
+
+		case PTRACE_GETREGS:
+			ret = ptrace_getregs(child, (void __user *)data);
+			break;
+
+		case PTRACE_SETREGS:
+			ret = ptrace_setregs(child, (void __user *)data);
+			break;
+
+		case PTRACE_GETFPREGS:
+			ret = ptrace_getfpregs(child, (void __user *)data);
+			break;
+		
+		case PTRACE_SETFPREGS:
+			ret = ptrace_setfpregs(child, (void __user *)data);
+			break;
+
+#ifdef CONFIG_IWMMXT
+		case PTRACE_GETWMMXREGS:
+			ret = ptrace_getwmmxregs(child, (void __user *)data);
+			break;
+
+		case PTRACE_SETWMMXREGS:
+			ret = ptrace_setwmmxregs(child, (void __user *)data);
+			break;
+#endif
+
+		case PTRACE_GET_THREAD_AREA:
+			ret = put_user(child->thread_info->tp_value,
+				       (unsigned long __user *) data);
+			break;
+
+		default:
+			ret = ptrace_request(child, request, addr, data);
+			break;
+	}
+
+	return ret;
+}
+
+asmlinkage int sys_ptrace(long request, long pid, long addr, long data)
+{
+	struct task_struct *child;
+	int ret;
+
+	lock_kernel();
+	ret = -EPERM;
+	if (request == PTRACE_TRACEME) {
+		/* are we already being traced? */
+		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;
+		ret = 0;
+		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 = -EPERM;
+	if (pid == 1)		/* you may not mess with init */
+		goto out_tsk;
+
+	if (request == PTRACE_ATTACH) {
+		ret = ptrace_attach(child);
+		goto out_tsk;
+	}
+	ret = ptrace_check_attach(child, request == PTRACE_KILL);
+	if (ret == 0)
+		ret = do_ptrace(request, child, addr, data);
+
+out_tsk:
+	put_task_struct(child);
+out:
+	unlock_kernel();
+	return ret;
+}
+
+asmlinkage void syscall_trace(int why, struct pt_regs *regs)
+{
+	unsigned long ip;
+
+	if (!test_thread_flag(TIF_SYSCALL_TRACE))
+		return;
+	if (!(current->ptrace & PT_PTRACED))
+		return;
+
+	/*
+	 * Save IP.  IP is used to denote syscall entry/exit:
+	 *  IP = 0 -> entry, = 1 -> exit
+	 */
+	ip = regs->ARM_ip;
+	regs->ARM_ip = why;
+
+	/* the 0x80 provides a way for the tracing parent to distinguish
+	   between a syscall stop and SIGTRAP delivery */
+	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;
+	}
+	regs->ARM_ip = ip;
+}