Message-Id: <1309641352-18714-7-git-send-email-jonas@southpole.se>
Date:	Sat,  2 Jul 2011 23:15:39 +0200
From:	Jonas Bonn <jonas@...thpole.se>
To:	linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org
Cc:	Jonas Bonn <jonas@...thpole.se>
Subject: [PATCH v2 06/19] OpenRISC: PTrace


Signed-off-by: Jonas Bonn <jonas@...thpole.se>
---
 arch/openrisc/include/asm/ptrace.h |  124 ++++++++
 arch/openrisc/kernel/ptrace.c      |  574 ++++++++++++++++++++++++++++++++++++
 arch/openrisc/kernel/ptrace.h      |   37 +++
 3 files changed, 735 insertions(+), 0 deletions(-)
 create mode 100644 arch/openrisc/include/asm/ptrace.h
 create mode 100644 arch/openrisc/kernel/ptrace.c
 create mode 100644 arch/openrisc/kernel/ptrace.h

diff --git a/arch/openrisc/include/asm/ptrace.h b/arch/openrisc/include/asm/ptrace.h
new file mode 100644
index 0000000..d3f620e
--- /dev/null
+++ b/arch/openrisc/include/asm/ptrace.h
@@ -0,0 +1,124 @@
+/*
+ * OpenRISC Linux
+ *
+ * Linux architectural port borrowing liberally from similar works of
+ * others.  All original copyrights apply as per the original source
+ * declaration.
+ *
+ * OpenRISC implementation:
+ * Copyright (C) 2003 Matjaz Breskvar <phoenix@...mi.com>
+ * Copyright (C) 2010-2011 Jonas Bonn <jonas@...thpole.se>
+ * et al.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef __ASM_OPENRISC_PTRACE_H
+#define __ASM_OPENRISC_PTRACE_H
+
+#include <asm/spr_defs.h>
+/*
+ * This struct defines the way the registers are stored on the
+ * kernel stack during a system call or other kernel entry.
+ *
+ * this should only contain volatile regs
+ * since we can keep non-volatile in the thread_struct
+ * should set this up when only volatiles are saved
+ * by intr code.
+ *
+ * Since this is going on the stack, *CARE MUST BE TAKEN* to insure
+ * that the overall structure is a multiple of 16 bytes in length.
+ *
+ * Note that the offsets of the fields in this struct correspond with
+ * the values below.
+ */
+
+/*
+ * These are 'magic' values for PTRACE_PEEKUSR that return info about where a
+ * process is located in memory.
+ */
+#define PT_TEXT_ADDR            0x10000
+#define PT_DATA_ADDR            0x10004
+#define PT_TEXT_END_ADDR        0x10008
+
+#ifndef __ASSEMBLY__
+
+struct pt_regs {
+	union {
+		struct {
+			/* Named registers */
+			long  sr;	/* Stored in place of r0 */
+			long  sp;	/* r1 */
+		};
+		struct {
+			/* Old style */
+			long offset[2];
+			long gprs[30];
+		};
+		struct {
+			/* New style */
+			long gpr[32];
+		};
+	};
+	long  pc;
+	long  orig_gpr11;  /* Used for restarting system calls */
+	long  syscallno;  /* Syscall no. (used by strace) */
+};
+#endif /* __ASSEMBLY__ */
+
+#ifdef __KERNEL__
+#define STACK_FRAME_OVERHEAD  128  /* size of minimum stack frame */
+//#define STACK_FRAME_OVERHEAD  0  /* size of minimum stack frame */
+
+#define instruction_pointer(regs)	((regs)->pc)
+#define user_mode(regs)			(((regs)->sr & SPR_SR_SM) == 0)
+#define user_stack_pointer(regs)	((unsigned long)(regs)->sp)
+#define profile_pc(regs)		instruction_pointer(regs)
+
+#define arch_has_single_step()  (1)
+
+#endif /* __KERNEL__ */
+
+/*
+ * Offsets used by 'ptrace' system call interface.
+ */
+#define PT_SR         0
+#define PT_SP         4
+#define PT_GPR2       8
+#define PT_GPR3       12
+#define PT_GPR4       16
+#define PT_GPR5       20
+#define PT_GPR6       24
+#define PT_GPR7       28
+#define PT_GPR8       32
+#define PT_GPR9       36
+#define PT_GPR10      40
+#define PT_GPR11      44
+#define PT_GPR12      48
+#define PT_GPR13      52
+#define PT_GPR14      56
+#define PT_GPR15      60
+#define PT_GPR16      64
+#define PT_GPR17      68
+#define PT_GPR18      72
+#define PT_GPR19      76
+#define PT_GPR20      80
+#define PT_GPR21      84
+#define PT_GPR22      88
+#define PT_GPR23      92
+#define PT_GPR24      96
+#define PT_GPR25      100
+#define PT_GPR26      104
+#define PT_GPR27      108
+#define PT_GPR28      112
+#define PT_GPR29      116
+#define PT_GPR30      120
+#define PT_GPR31      124
+#define PT_PC	      128
+#define PT_ORIG_GPR11 132
+#define PT_SYSCALLNO  136
+
+#endif /* __ASM_OPENRISC_PTRACE_H */
diff --git a/arch/openrisc/kernel/ptrace.c b/arch/openrisc/kernel/ptrace.c
new file mode 100644
index 0000000..a167a1e
--- /dev/null
+++ b/arch/openrisc/kernel/ptrace.c
@@ -0,0 +1,574 @@
+/*
+ * OpenRISC ptrace.c
+ *
+ * Linux architectural port borrowing liberally from similar works of
+ * others.  All original copyrights apply as per the original source
+ * declaration.
+ *
+ * Modifications for the OpenRISC architecture:
+ * Copyright (C) 2003 Matjaz Breskvar <phoenix@...mi.com>
+ * Copyright (C) 2005 Gyorgy Jeney <nog@...mi.com>
+ * Copyright (C) 2010 Julius Baxter <julius.baxter@...oc.se>
+ * Copyright (C) 2010-2011 Jonas Bonn <jonas@...thpole.se>
+ *
+ *      This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+
+#include <stddef.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/string.h>
+
+#include <linux/mm.h>
+#include <linux/errno.h>
+#include <linux/ptrace.h>
+#include <linux/audit.h>
+#include <linux/regset.h>
+#include <linux/tracehook.h>
+#include <linux/elf.h>
+
+#include <asm/thread_info.h>
+#include <asm/segment.h>
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <asm/system.h>
+
+#include "ptrace.h"
+
+/*
+ * retrieve the contents of OpenRISC userspace general registers
+ */
+static int genregs_get(struct task_struct *target,
+		       const struct user_regset *regset,
+		       unsigned int pos, unsigned int count,
+		       void *kbuf, void __user * ubuf)
+{
+	const struct pt_regs *regs = task_pt_regs(target);
+	int ret;
+
+#if 0
+	/* r0 */
+	ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
+				       0, offsetof(struct pt_regs, regs));
+#endif
+
+	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+				  regs, 0, sizeof(*regs));
+
+/* put PPC here */
+
+#if 0
+	/* fill out rest of elf_gregset_t structure with zeroes */
+	if (!ret)
+		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
+					       sizeof(struct pt_regs), -1);
+#endif
+
+	return ret;
+}
+
+/*
+ * update the contents of the OpenRISC userspace general registers
+ */
+static int genregs_set(struct task_struct *target,
+		       const struct user_regset *regset,
+		       unsigned int pos, unsigned int count,
+		       const void *kbuf, const void __user * ubuf)
+{
+	struct pt_regs *regs = task_pt_regs(target);
+	int ret;
+
+	/* PC */
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				 regs, 0, offsetof(struct pt_regs, sr));
+
+	/* skip SR */
+	ret = user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
+					offsetof(struct pt_regs, sr),
+					offsetof(struct pt_regs, sp));
+
+	/* SP, r2 - r31 */
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				 regs,
+				 offsetof(struct pt_regs, sp),
+				 sizeof(struct pt_regs));
+
+#if 0
+	/* read out the rest of the elf_gregset_t structure */
+	if (!ret)
+		ret = user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
+						sizeof(struct pt_regs), -1);
+#endif
+
+	return ret;
+}
+
+/*
+ * Define the register sets available on OpenRISC under Linux
+ */
+enum openrisc_regset {
+	REGSET_GENERAL,
+};
+
+static const struct user_regset openrisc_regsets[] = {
+	[REGSET_GENERAL] = {
+			    .core_note_type = NT_PRSTATUS,
+			    .n = ELF_NGREG,
+			    .size = sizeof(long),
+			    .align = sizeof(long),
+			    .get = genregs_get,
+			    .set = genregs_set,
+			    },
+};
+
+static const struct user_regset_view user_openrisc_native_view = {
+	.name = "OpenRISC",
+	.e_machine = EM_OPENRISC,
+	.regsets = openrisc_regsets,
+	.n = ARRAY_SIZE(openrisc_regsets),
+};
+
+const struct user_regset_view *task_user_regset_view(struct task_struct *task)
+{
+	return &user_openrisc_native_view;
+}
+
+void user_enable_single_step(struct task_struct *child)
+{
+	set_tsk_thread_flag(child, TIF_SINGLESTEP);
+}
+
+void user_disable_single_step(struct task_struct *child)
+{
+	clear_tsk_thread_flag(child, TIF_SINGLESTEP);
+}
+
+/*
+ * does not yet catch signals sent when the child dies.
+ * in exit.c or in signal.c.
+ */
+
+#define OPC_MASK 0x3f
+#define OPC_SHIFT 26
+#define OPC_J    0x00
+#define OPC_JAL  0x01
+#define OPC_BNF  0x03
+#define OPC_BF   0x04
+#define OPC_SYSC 0x08
+#define OPC_JR   0x11
+#define OPC_JALR 0x12
+
+#define JUMP_IMM_MASK 0x03ffffff
+#define JUMP_IMM_SIGN 0x02000000
+
+/* Trap instruction on bit 15 of SR, fixed one, unconditional */
+#define OR1K_TRAP 0x2100000f
+
+/* Macro to extract branch offset with sign extension of immediate. */
+#define BRANCH_OFFSET(insn) ((insn & JUMP_IMM_SIGN) ?			\
+			     ((insn & JUMP_IMM_MASK) << 2) | 0xf0000000 : \
+			     ((insn & JUMP_IMM_MASK) << 2))
+
+/* Get address of next instruction we can insert a breakpoint on */
+/* pc passed to function is address of instruction we've now just trapped on.
+   It is yet/next to be executed. We determine next instruction after PC to
+   place a l.trap on. If we should take a branch, we must remember this.
+*/
+static unsigned long
+get_next_address(struct task_struct *tsk, unsigned long pc, unsigned long insn)
+{
+	struct pt_regs *regs;
+	struct debug_info *dbg;
+	char opc;
+	unsigned long npc;
+	unsigned long rB;
+
+	dbg = &current_thread_info()->debug;
+
+	regs = task_pt_regs(tsk);
+	/* Extract opcode from instruction */
+	opc = (insn >> OPC_SHIFT) & OPC_MASK;
+
+	pr_debug(KERN_INFO
+		 "ptrace get_next_address: pc 0x%.8lx insn. 0x%.8lx opc. 0x%.2x\n",
+		 pc, insn, opc);
+
+	/*
+	   Will always proceed to next instruction if this function was called
+	   ie. we know we're not in a delay slot - the function calling this
+	   checks dbg->branch_taken.
+	 */
+	npc = pc + 4;
+
+	/* Check if we're to record a branch */
+	switch (opc) {
+	case OPC_BNF:
+		/* Check flag - we're branching if !flag */
+		if (!(((regs)->sr) & SPR_SR_F)) {
+			dbg->bp.branch = 1;
+			dbg->bp.branch_target = pc + BRANCH_OFFSET(insn);
+		}
+		break;
+	case OPC_BF:
+		/* Check flag - we're branching if flag */
+		if (((regs)->sr) & SPR_SR_F) {
+			dbg->bp.branch = 1;
+			dbg->bp.branch_target = pc + BRANCH_OFFSET(insn);
+		}
+		break;
+	case OPC_J:
+	case OPC_JAL:
+		/* PC-relative branch target encoded in instruction. Extract
+		   and add it. */
+		dbg->bp.branch = 1;
+		dbg->bp.branch_target = pc + BRANCH_OFFSET(insn);
+		break;
+	case OPC_JR:
+	case OPC_JALR:
+		/* Register number holding branch target is encoded in rB slot
+		   of instruction. Extract it. */
+		rB = (insn >> 11) & 0x1f;
+		pr_debug(KERN_INFO
+			 "ptrace get_next_address: jump reg from r%ld=0x%08lx\n",
+			 rB,
+			 /* *((unsigned long*)((char*)regs + (rB<<2) + 4)) */
+			 regs->gprs[rB - 2]);
+		if (rB < 2)
+			pr_debug(KERN_WARNING
+				 "ptrace get_next_address(): Warning, JR with GPR < 2");
+		dbg->bp.branch = 1;
+		dbg->bp.branch_target =
+		    /* *((unsigned long*)((char*)regs + (rB<<2) + 4)) */
+		    regs->gprs[rB - 2];
+		break;
+#if 0
+	case OPC_SYSC:
+		/* Not sure we want to do this */
+		/* Remember - l.sys has no delay slot. */
+		npc = 0x900;
+		break;
+#endif
+	default:
+		break;
+	}
+
+	/* If setting a branch target, remember where branch was */
+	if (dbg->bp.branch)
+		dbg->bp.branch_insn_address = pc;
+
+	if (dbg->bp.branch)
+		pr_debug(KERN_INFO
+			 "ptrace get_next_address: branch detected to 0x%.8lx\n",
+			 dbg->bp.branch_target);
+	pr_debug(KERN_INFO "ptrace get_next_address: returning 0x%.8lx\n", npc);
+
+	return npc;
+}
+
+static inline int
+read_instr(struct task_struct *tsk, unsigned long addr, u32 * res)
+{
+	int ret;
+	u32 val;
+	ret = access_process_vm(tsk, addr & ~3, &val, sizeof(val), 0);
+	ret = ret == sizeof(val) ? 0 : -EIO;
+	*res = val;
+	return ret;
+}
+
+static int
+swap_insn(struct task_struct *tsk, unsigned long addr,
+	  void *old_insn, void *new_insn, int size)
+{
+	int ret;
+
+	ret = access_process_vm(tsk, addr, old_insn, size, 0);
+	if (ret == size)
+		ret = access_process_vm(tsk, addr, new_insn, size, 1);
+	return ret;
+}
+
+static void
+add_breakpoint(struct task_struct *tsk, struct debug_info *dbg,
+	       unsigned long addr)
+{
+	u32 new_insn = OR1K_TRAP;
+	int res;
+
+	res = swap_insn(tsk, addr, &dbg->bp.insn, &new_insn, 4);
+
+	pr_debug(KERN_INFO
+		 "ptrace add_breakpoint: addr 0x%.8lx insn 0x%.8lx %d\n\n",
+		 addr, dbg->bp.insn, res);
+
+	if (res == 4) {
+		dbg->bp.address = addr;
+		dbg->bp.set = 1;
+	}
+}
+
+/*
+ * Clear the breakpoint in the user program.
+ */
+static void clear_breakpoint(struct task_struct *tsk, struct debug_entry *bp)
+{
+	u32 old_insn;
+	int ret;
+	struct pt_regs *regs;
+	unsigned long pc;
+
+	unsigned long addr = bp->address;
+
+	regs = task_pt_regs(tsk);
+	pc = instruction_pointer(regs);	/* This is NPC */
+
+	/* Either at the breakpoint, or in delay slot (pc will be at address of
+	 * branch instruction - OR1K exception handlers do that, for now.
+	 * Perhaps FIXME
+	 */
+	if ((pc == addr) || ((bp->branch_insn_address == pc) && bp->branch))
+		ret = swap_insn(tsk, addr & ~3, &old_insn, &bp->insn, 4);
+	else {
+		/* Trapped for some other reason. */
+		pr_debug(KERN_INFO
+			 "ptrace clear_breakpoint: not correct, pc 0x%.8lx bp 0x%.8lx\n",
+			 pc, addr);
+		pr_debug(KERN_INFO
+			 "ptrace clear_breakpoint: 0x%.8lx 0x%.8lx %ld\n",
+			 bp->branch_insn_address, bp->branch_target,
+			 bp->branch);
+		return;
+	}
+
+	pr_debug(KERN_INFO
+		 "ptrace clear_breakpoint: addr 0x%.8lx insn 0x%.8lx %d\n",
+		 addr, bp->insn, ret);
+
+	if (ret != 4 || old_insn != OR1K_TRAP)
+		pr_debug(KERN_ERR
+			 "%s:%d: corrupted breakpoint at 0x%08lx (0x%08x)\n",
+			 tsk->comm, task_pid_nr(tsk), addr, old_insn);
+
+	bp->set = 0;
+}
+
+void ptrace_set_bpt(struct task_struct *tsk)
+{
+	struct pt_regs *regs;
+	unsigned long pc;
+	u32 insn;
+	int res;
+
+	regs = task_pt_regs(tsk);
+	pc = instruction_pointer(regs);	/* This is NPC */
+
+	res = read_instr(tsk, pc, &insn);
+	if (!res) {
+		struct debug_info *dbg = &current_thread_info()->debug;
+		unsigned long npc;
+
+		/* First check if breakpoint is still set, if so, probably
+		   just let us run until we hit it.
+		   This can occur because perhaps we caused an exception before
+		   a jump or in a delay slot, and the OR1K exception handlers
+		   will rewind us to the branch before the delay slot or jump
+		   target.
+		   This way we skip everything that goes on during an exception
+		   and can hopefully just track the program's execution.
+		 */
+		if (dbg->bp.set)
+			return;
+
+		/* Are we in delay slot of branch we should take? */
+		if (dbg->bp.branch == 1) {
+			/* Branch target is already determined. Set l.trap. */
+			npc = dbg->bp.branch_target;
+
+			/* Reset NPC to branch instruction - should be one
+			 * before this one.
+			 */
+			instruction_pointer(regs) = dbg->bp.branch_insn_address;
+
+			/* Now mark this as no longer needing to be taken */
+			dbg->bp.branch = 0;
+		} else {
+			npc = get_next_address(tsk, pc, insn);
+		}
+
+		add_breakpoint(tsk, dbg, npc);
+	}
+}
+
+/*
+ * Ensure no single-step breakpoint is pending.  Returns non-zero
+ * value if child was being single-stepped.
+ */
+void ptrace_cancel_bpt(struct task_struct *tsk)
+{
+	clear_breakpoint(tsk,
+			 (struct debug_entry *)&current_thread_info()->debug);
+}
+
+/*
+ * Called by kernel/ptrace.c when detaching..
+ *
+ * Make sure the single step bit is not set.
+ */
+void ptrace_disable(struct task_struct *child)
+{
+	pr_debug(KERN_WARNING "ptrace_disable(): TODO\n");
+
+	user_disable_single_step(child);
+	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+}
+
+/*
+ * 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)
+{
+	struct pt_regs *regs;
+	unsigned long tmp;
+
+	/*    if (off & 3 || off >= sizeof(struct user))
+	   return -EIO; */
+
+	regs = task_pt_regs(tsk);
+
+	tmp = 0;
+	if (off == PT_TEXT_ADDR)
+		tmp = tsk->mm->start_code;
+	else if (off == PT_DATA_ADDR)
+		tmp = tsk->mm->start_data;
+	else if (off == PT_TEXT_END_ADDR)
+		tmp = tsk->mm->end_code;
+	else if (off < sizeof(struct pt_regs))
+		tmp = *((unsigned long *)((char *)regs + off));
+
+	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)
+{
+	struct pt_regs *regs;
+
+	/*if (off & 3 || off >= sizeof(struct user))
+	   return -EIO; */
+
+	if (off >= sizeof(struct pt_regs))
+		return 0;
+
+	regs = task_pt_regs(tsk);
+
+	if (off != offsetof(struct pt_regs, sr)) {
+		*((unsigned long *)((char *)regs + off)) = val;
+	} else {
+		/* Prevent any process from setting the SR flags and
+		 * thus elevating privileges
+		 */
+	}
+
+	return 0;
+}
+
+long arch_ptrace(struct task_struct *child, long request, unsigned long addr,
+		 unsigned long data)
+{
+	int ret;
+	unsigned long __user *datap = (unsigned long __user *)data;
+
+	switch (request) {
+		/* read the word at location addr in the USER area. */
+	case PTRACE_PEEKUSR:
+		ret = ptrace_read_user(child, addr, datap);
+		break;
+	case PTRACE_POKEUSR:
+		ret = ptrace_write_user(child, addr, data);
+		break;
+	default:
+		ret = ptrace_request(child, request, addr, data);
+		break;
+	}
+
+	single_step_set(current);
+
+	return ret;
+}
+
+/* notification of system call entry/exit
+ * - triggered by current->work.syscall_trace
+ */
+asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
+{
+	long ret = 0;
+
+	if (test_thread_flag(TIF_SYSCALL_TRACE) &&
+	    tracehook_report_syscall_entry(regs))
+		/*
+		 * Tracing decided this syscall should not happen.
+		 * We'll return a bogus call number to get an ENOSYS
+		 * error, but leave the original number in <something>.
+		 */
+		ret = -1L;
+
+/*	if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
+		trace_sys_enter(regs, regs->syscallno);
+*/
+
+	/* Are these regs right??? */
+	if (unlikely(current->audit_context))
+		audit_syscall_entry(audit_arch(), regs->syscallno,
+				    regs->gpr[3], regs->gpr[4],
+				    regs->gpr[5], regs->gpr[6]);
+
+	return ret ? : regs->syscallno;
+
+#if 0
+/*FIXME : audit the rest of this */
+
+	/*
+	 * 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;
+	}
+out:
+	/*FIXME: audit_arch isn't even defined for openrisc */
+	/*FIXME:  What's with the register numbers here... makes no sense */
+	if (unlikely(current->audit_context) && !entryexit)
+		audit_syscall_entry(audit_arch(), regs->regs[2],
+				    regs->regs[4], regs->regs[5],
+				    regs->regs[6], regs->regs[7]);
+	/*RGD*/
+#endif
+}
+
+asmlinkage void do_syscall_trace_leave(struct pt_regs *regs)
+{
+	int step;
+
+	if (unlikely(current->audit_context))
+		audit_syscall_exit(AUDITSC_RESULT(regs->gpr[11]),
+				   regs->gpr[11]);
+
+/*	if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
+		trace_sys_exit(regs, regs->gprs[9]);
+*/
+
+	step = test_thread_flag(TIF_SINGLESTEP);
+	if (step || test_thread_flag(TIF_SYSCALL_TRACE))
+		tracehook_report_syscall_exit(regs, step);
+}
diff --git a/arch/openrisc/kernel/ptrace.h b/arch/openrisc/kernel/ptrace.h
new file mode 100644
index 0000000..157d6ea
--- /dev/null
+++ b/arch/openrisc/kernel/ptrace.h
@@ -0,0 +1,37 @@
+/*
+ *  linux/arch/openrisc/kernel/ptrace.h
+ *
+ *  Copyright (C) 2000-2003 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/ptrace.h>
+
+extern void ptrace_cancel_bpt(struct task_struct *);
+extern void ptrace_set_bpt(struct task_struct *);
+extern void ptrace_break(struct task_struct *, struct pt_regs *);
+
+/*
+ * Send SIGTRAP if we're single-stepping
+ */
+static inline void single_step_trap(struct task_struct *task)
+{
+	if (test_tsk_thread_flag (task, TIF_SINGLESTEP)){
+		ptrace_cancel_bpt(task);
+		send_sig(SIGTRAP, task, 1);
+	}
+}
+
+static inline void single_step_clear(struct task_struct *task)
+{
+	if (test_tsk_thread_flag(task, TIF_SINGLESTEP))
+		ptrace_cancel_bpt(task);
+}
+
+static inline void single_step_set(struct task_struct *task)
+{
+	if (test_tsk_thread_flag(task, TIF_SINGLESTEP))
+		ptrace_set_bpt(task);
+}
-- 
1.7.4.1

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