[GitHub/mt8127/android_kernel_alcatel_ttab.git] / arch / avr32 / kernel / ptrace.c

/*
 * Copyright (C) 2004-2006 Atmel Corporation
 *
 * 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.
 */
#undef DEBUG
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/ptrace.h>
#include <linux/errno.h>
#include <linux/user.h>
#include <linux/security.h>
#include <linux/unistd.h>
#include <linux/notifier.h>

#include <asm/traps.h>
#include <asm/uaccess.h>
#include <asm/ocd.h>
#include <asm/mmu_context.h>
#include <linux/kdebug.h>

static struct pt_regs *get_user_regs(struct task_struct *tsk)
{
	return (struct pt_regs *)((unsigned long)task_stack_page(tsk) +
				  THREAD_SIZE - sizeof(struct pt_regs));
}

static void ptrace_single_step(struct task_struct *tsk)
{
	pr_debug("ptrace_single_step: pid=%u, PC=0x%08lx, SR=0x%08lx\n",
		 tsk->pid, task_pt_regs(tsk)->pc, task_pt_regs(tsk)->sr);

	/*
	 * We can't schedule in Debug mode, so when TIF_BREAKPOINT is
	 * set, the system call or exception handler will do a
	 * breakpoint to enter monitor mode before returning to
	 * userspace.
	 *
	 * The monitor code will then notice that TIF_SINGLE_STEP is
	 * set and return to userspace with single stepping enabled.
	 * The CPU will then enter monitor mode again after exactly
	 * one instruction has been executed, and the monitor code
	 * will then send a SIGTRAP to the process.
	 */
	set_tsk_thread_flag(tsk, TIF_BREAKPOINT);
	set_tsk_thread_flag(tsk, TIF_SINGLE_STEP);
}

/*
 * Called by kernel/ptrace.c when detaching
 *
 * Make sure any single step bits, etc. are not set
 */
void ptrace_disable(struct task_struct *child)
{
	clear_tsk_thread_flag(child, TIF_SINGLE_STEP);
	clear_tsk_thread_flag(child, TIF_BREAKPOINT);
	ocd_disable(child);
}

/*
 * Read the word at offset "offset" into the task's "struct user". We
 * actually access the pt_regs struct stored on the kernel stack.
 */
static int ptrace_read_user(struct task_struct *tsk, unsigned long offset,
			    unsigned long __user *data)
{
	unsigned long *regs;
	unsigned long value;

	if (offset & 3 || offset >= sizeof(struct user)) {
		printk("ptrace_read_user: invalid offset 0x%08lx\n", offset);
		return -EIO;
	}

	regs = (unsigned long *)get_user_regs(tsk);

	value = 0;
	if (offset < sizeof(struct pt_regs))
		value = regs[offset / sizeof(regs[0])];

	pr_debug("ptrace_read_user(%s[%u], %#lx, %p) -> %#lx\n",
		 tsk->comm, tsk->pid, offset, data, value);

	return put_user(value, data);
}

/*
 * Write the word "value" to offset "offset" into the task's "struct
 * user". We actually access the pt_regs struct stored on the kernel
 * stack.
 */
static int ptrace_write_user(struct task_struct *tsk, unsigned long offset,
			     unsigned long value)
{
	unsigned long *regs;

	pr_debug("ptrace_write_user(%s[%u], %#lx, %#lx)\n",
			tsk->comm, tsk->pid, offset, value);

	if (offset & 3 || offset >= sizeof(struct user)) {
		pr_debug("  invalid offset 0x%08lx\n", offset);
		return -EIO;
	}

	if (offset >= sizeof(struct pt_regs))
		return 0;

	regs = (unsigned long *)get_user_regs(tsk);
	regs[offset / sizeof(regs[0])] = value;

	return 0;
}

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(*regs)) ? -EFAULT : 0;
}

static int ptrace_setregs(struct task_struct *tsk, const void __user *uregs)
{
	struct pt_regs newregs;
	int ret;

	ret = -EFAULT;
	if (copy_from_user(&newregs, uregs, sizeof(newregs)) == 0) {
		struct pt_regs *regs = get_user_regs(tsk);

		ret = -EINVAL;
		if (valid_user_regs(&newregs)) {
			*regs = newregs;
			ret = 0;
		}
	}

	return ret;
}

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

	switch (request) {
	/* Read the word at location addr in the child process */
	case PTRACE_PEEKTEXT:
	case PTRACE_PEEKDATA:
		ret = generic_ptrace_peekdata(child, addr, data);
		break;

	case PTRACE_PEEKUSR:
		ret = ptrace_read_user(child, addr,
				       (unsigned long __user *)data);
		break;

	/* Write the word in data at location addr */
	case PTRACE_POKETEXT:
	case PTRACE_POKEDATA:
		ret = generic_ptrace_pokedata(child, addr, data);
		break;

	case PTRACE_POKEUSR:
		ret = ptrace_write_user(child, addr, data);
		break;

	/* continue and stop at next (return from) syscall */
	case PTRACE_SYSCALL:
	/* restart after signal */
	case PTRACE_CONT:
		ret = -EIO;
		if (!valid_signal(data))
			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;
		/* XXX: Are we sure no breakpoints are active here? */
		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:
		ret = 0;
		if (child->exit_state == EXIT_ZOMBIE)
			break;
		child->exit_code = SIGKILL;
		wake_up_process(child);
		break;

	/*
	 * execute single instruction.
	 */
	case PTRACE_SINGLESTEP:
		ret = -EIO;
		if (!valid_signal(data))
			break;
		clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
		ptrace_single_step(child);
		child->exit_code = data;
		wake_up_process(child);
		ret = 0;
		break;

	case PTRACE_GETREGS:
		ret = ptrace_getregs(child, (void __user *)data);
		break;

	case PTRACE_SETREGS:
		ret = ptrace_setregs(child, (const void __user *)data);
		break;

	default:
		ret = ptrace_request(child, request, addr, data);
		break;
	}

	return ret;
}

asmlinkage void syscall_trace(void)
{
	if (!test_thread_flag(TIF_SYSCALL_TRACE))
		return;
	if (!(current->ptrace & PT_PTRACED))
		return;

	/* 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) {
		pr_debug("syscall_trace: sending signal %d to PID %u\n",
			 current->exit_code, current->pid);
		send_sig(current->exit_code, current, 1);
		current->exit_code = 0;
	}
}

/*
 * debug_trampoline() is an assembly stub which will store all user
 * registers on the stack and execute a breakpoint instruction.
 *
 * If we single-step into an exception handler which runs with
 * interrupts disabled the whole time so it doesn't have to check for
 * pending work, its return address will be modified so that it ends
 * up returning to debug_trampoline.
 *
 * If the exception handler decides to store the user context and
 * enable interrupts after all, it will restore the original return
 * address and status register value. Before it returns, it will
 * notice that TIF_BREAKPOINT is set and execute a breakpoint
 * instruction.
 */
extern void debug_trampoline(void);

asmlinkage struct pt_regs *do_debug(struct pt_regs *regs)
{
	struct thread_info	*ti;
	unsigned long		trampoline_addr;
	u32			status;
	u32			ctrl;
	int			code;

	status = ocd_read(DS);
	ti = current_thread_info();
	code = TRAP_BRKPT;

	pr_debug("do_debug: status=0x%08x PC=0x%08lx SR=0x%08lx tif=0x%08lx\n",
			status, regs->pc, regs->sr, ti->flags);

	if (!user_mode(regs)) {
		unsigned long	die_val = DIE_BREAKPOINT;

		if (status & (1 << OCD_DS_SSS_BIT))
			die_val = DIE_SSTEP;

		if (notify_die(die_val, "ptrace", regs, 0, 0, SIGTRAP)
				== NOTIFY_STOP)
			return regs;

		if ((status & (1 << OCD_DS_SWB_BIT))
				&& test_and_clear_ti_thread_flag(
					ti, TIF_BREAKPOINT)) {
			/*
			 * Explicit breakpoint from trampoline or
			 * exception/syscall/interrupt handler.
			 *
			 * The real saved regs are on the stack right
			 * after the ones we saved on entry.
			 */
			regs++;
			pr_debug("  -> TIF_BREAKPOINT done, adjusted regs:"
					"PC=0x%08lx SR=0x%08lx\n",
					regs->pc, regs->sr);
			BUG_ON(!user_mode(regs));

			if (test_thread_flag(TIF_SINGLE_STEP)) {
				pr_debug("Going to do single step...\n");
				return regs;
			}

			/*
			 * No TIF_SINGLE_STEP means we're done
			 * stepping over a syscall. Do the trap now.
			 */
			code = TRAP_TRACE;
		} else if ((status & (1 << OCD_DS_SSS_BIT))
				&& test_ti_thread_flag(ti, TIF_SINGLE_STEP)) {

			pr_debug("Stepped into something, "
					"setting TIF_BREAKPOINT...\n");
			set_ti_thread_flag(ti, TIF_BREAKPOINT);

			/*
			 * We stepped into an exception, interrupt or
			 * syscall handler. Some exception handlers
			 * don't check for pending work, so we need to
			 * set up a trampoline just in case.
			 *
			 * The exception entry code will undo the
			 * trampoline stuff if it does a full context
			 * save (which also means that it'll check for
			 * pending work later.)
			 */
			if ((regs->sr & MODE_MASK) == MODE_EXCEPTION) {
				trampoline_addr
					= (unsigned long)&debug_trampoline;

				pr_debug("Setting up trampoline...\n");
				ti->rar_saved = sysreg_read(RAR_EX);
				ti->rsr_saved = sysreg_read(RSR_EX);
				sysreg_write(RAR_EX, trampoline_addr);
				sysreg_write(RSR_EX, (MODE_EXCEPTION
							| SR_EM | SR_GM));
				BUG_ON(ti->rsr_saved & MODE_MASK);
			}

			/*
			 * If we stepped into a system call, we
			 * shouldn't do a single step after we return
			 * since the return address is right after the
			 * "scall" instruction we were told to step
			 * over.
			 */
			if ((regs->sr & MODE_MASK) == MODE_SUPERVISOR) {
				pr_debug("Supervisor; no single step\n");
				clear_ti_thread_flag(ti, TIF_SINGLE_STEP);
			}

			ctrl = ocd_read(DC);
			ctrl &= ~(1 << OCD_DC_SS_BIT);
			ocd_write(DC, ctrl);

			return regs;
		} else {
			printk(KERN_ERR "Unexpected OCD_DS value: 0x%08x\n",
					status);
			printk(KERN_ERR "Thread flags: 0x%08lx\n", ti->flags);
			die("Unhandled debug trap in kernel mode",
					regs, SIGTRAP);
		}
	} else if (status & (1 << OCD_DS_SSS_BIT)) {
		/* Single step in user mode */
		code = TRAP_TRACE;

		ctrl = ocd_read(DC);
		ctrl &= ~(1 << OCD_DC_SS_BIT);
		ocd_write(DC, ctrl);
	}

	pr_debug("Sending SIGTRAP: code=%d PC=0x%08lx SR=0x%08lx\n",
			code, regs->pc, regs->sr);

	clear_thread_flag(TIF_SINGLE_STEP);
	_exception(SIGTRAP, regs, code, instruction_pointer(regs));

	return regs;
}
Commit	Line	Data
5f97f7f9 HS	1	/*
	2	* Copyright (C) 2004-2006 Atmel Corporation
	3	*
	4	* This program is free software; you can redistribute it and/or modify
	5	* it under the terms of the GNU General Public License version 2 as
	6	* published by the Free Software Foundation.
	7	*/
	8	#undef DEBUG
	9	#include <linux/kernel.h>
	10	#include <linux/sched.h>
	11	#include <linux/mm.h>
5f97f7f9 HS	12	#include <linux/ptrace.h>
	13	#include <linux/errno.h>
	14	#include <linux/user.h>
	15	#include <linux/security.h>
	16	#include <linux/unistd.h>
	17	#include <linux/notifier.h>
	18
	19	#include <asm/traps.h>
	20	#include <asm/uaccess.h>
	21	#include <asm/ocd.h>
	22	#include <asm/mmu_context.h>
1eeb66a1	23	#include <linux/kdebug.h>
5f97f7f9 HS	24
	25	static struct pt_regs get_user_regs(struct task_struct tsk)
	26	{
c9f4f06d	27	return (struct pt_regs *)((unsigned long)task_stack_page(tsk) +
5f97f7f9 HS	28	THREAD_SIZE - sizeof(struct pt_regs));
	29	}
	30
	31	static void ptrace_single_step(struct task_struct *tsk)
	32	{
2507bc13 HS	33	pr_debug("ptrace_single_step: pid=%u, PC=0x%08lx, SR=0x%08lx\n",
2507bc13 HS	34	tsk->pid, task_pt_regs(tsk)->pc, task_pt_regs(tsk)->sr);
5f97f7f9	35
2507bc13 HS	36	/*
	37	* We can't schedule in Debug mode, so when TIF_BREAKPOINT is
	38	* set, the system call or exception handler will do a
	39	* breakpoint to enter monitor mode before returning to
	40	* userspace.
	41	*
	42	* The monitor code will then notice that TIF_SINGLE_STEP is
	43	* set and return to userspace with single stepping enabled.
	44	* The CPU will then enter monitor mode again after exactly
	45	* one instruction has been executed, and the monitor code
	46	* will then send a SIGTRAP to the process.
	47	*/
	48	set_tsk_thread_flag(tsk, TIF_BREAKPOINT);
5f97f7f9 HS	49	set_tsk_thread_flag(tsk, TIF_SINGLE_STEP);
	50	}
	51
	52	/*
	53	* Called by kernel/ptrace.c when detaching
	54	*
	55	* Make sure any single step bits, etc. are not set
	56	*/
	57	void ptrace_disable(struct task_struct *child)
	58	{
	59	clear_tsk_thread_flag(child, TIF_SINGLE_STEP);
2507bc13	60	clear_tsk_thread_flag(child, TIF_BREAKPOINT);
13b54a50	61	ocd_disable(child);
5f97f7f9 HS	62	}
	63
	64	/*
	65	* Read the word at offset "offset" into the task's "struct user". We
	66	* actually access the pt_regs struct stored on the kernel stack.
	67	*/
	68	static int ptrace_read_user(struct task_struct *tsk, unsigned long offset,
	69	unsigned long __user *data)
	70	{
	71	unsigned long *regs;
	72	unsigned long value;
	73
5f97f7f9 HS	74	if (offset & 3 \|\| offset >= sizeof(struct user)) {
	75	printk("ptrace_read_user: invalid offset 0x%08lx\n", offset);
	76	return -EIO;
	77	}
	78
	79	regs = (unsigned long *)get_user_regs(tsk);
	80
	81	value = 0;
	82	if (offset < sizeof(struct pt_regs))
	83	value = regs[offset / sizeof(regs[0])];
	84
2507bc13 HS	85	pr_debug("ptrace_read_user(%s[%u], %#lx, %p) -> %#lx\n",
	86	tsk->comm, tsk->pid, offset, data, value);
	87
5f97f7f9 HS	88	return put_user(value, data);
	89	}
	90
	91	/*
	92	* Write the word "value" to offset "offset" into the task's "struct
	93	* user". We actually access the pt_regs struct stored on the kernel
	94	* stack.
	95	*/
	96	static int ptrace_write_user(struct task_struct *tsk, unsigned long offset,
	97	unsigned long value)
	98	{
	99	unsigned long *regs;
	100
2507bc13 HS	101	pr_debug("ptrace_write_user(%s[%u], %#lx, %#lx)\n",
	102	tsk->comm, tsk->pid, offset, value);
	103
5f97f7f9	104	if (offset & 3 \|\| offset >= sizeof(struct user)) {
2507bc13	105	pr_debug(" invalid offset 0x%08lx\n", offset);
5f97f7f9 HS	106	return -EIO;
	107	}
	108
	109	if (offset >= sizeof(struct pt_regs))
	110	return 0;
	111
	112	regs = (unsigned long *)get_user_regs(tsk);
	113	regs[offset / sizeof(regs[0])] = value;
	114
	115	return 0;
	116	}
	117
	118	static int ptrace_getregs(struct task_struct tsk, void __user uregs)
	119	{
	120	struct pt_regs *regs = get_user_regs(tsk);
	121
	122	return copy_to_user(uregs, regs, sizeof(*regs)) ? -EFAULT : 0;
	123	}
	124
	125	static int ptrace_setregs(struct task_struct tsk, const void __user uregs)
	126	{
	127	struct pt_regs newregs;
	128	int ret;
	129
	130	ret = -EFAULT;
	131	if (copy_from_user(&newregs, uregs, sizeof(newregs)) == 0) {
	132	struct pt_regs *regs = get_user_regs(tsk);
	133
	134	ret = -EINVAL;
	135	if (valid_user_regs(&newregs)) {
	136	*regs = newregs;
	137	ret = 0;
	138	}
	139	}
	140
	141	return ret;
	142	}
	143
	144	long arch_ptrace(struct task_struct *child, long request, long addr, long data)
	145	{
5f97f7f9 HS	146	int ret;
5f97f7f9 HS	147
5f97f7f9 HS	148	switch (request) {
	149	/* Read the word at location addr in the child process */
	150	case PTRACE_PEEKTEXT:
	151	case PTRACE_PEEKDATA:
76647323	152	ret = generic_ptrace_peekdata(child, addr, data);
5f97f7f9 HS	153	break;
	154
	155	case PTRACE_PEEKUSR:
	156	ret = ptrace_read_user(child, addr,
	157	(unsigned long __user *)data);
	158	break;
	159
	160	/* Write the word in data at location addr */
	161	case PTRACE_POKETEXT:
	162	case PTRACE_POKEDATA:
f284ce72	163	ret = generic_ptrace_pokedata(child, addr, data);
5f97f7f9 HS	164	break;
	165
	166	case PTRACE_POKEUSR:
	167	ret = ptrace_write_user(child, addr, data);
	168	break;
	169
	170	/* continue and stop at next (return from) syscall */
	171	case PTRACE_SYSCALL:
	172	/* restart after signal */
	173	case PTRACE_CONT:
	174	ret = -EIO;
	175	if (!valid_signal(data))
	176	break;
	177	if (request == PTRACE_SYSCALL)
	178	set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
	179	else
	180	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
	181	child->exit_code = data;
	182	/* XXX: Are we sure no breakpoints are active here? */
	183	wake_up_process(child);
	184	ret = 0;
	185	break;
	186
	187	/*
	188	* Make the child exit. Best I can do is send it a
	189	* SIGKILL. Perhaps it should be put in the status that it
	190	* wants to exit.
	191	*/
	192	case PTRACE_KILL:
	193	ret = 0;
	194	if (child->exit_state == EXIT_ZOMBIE)
	195	break;
	196	child->exit_code = SIGKILL;
	197	wake_up_process(child);
	198	break;
	199
	200	/*
	201	* execute single instruction.
	202	*/
	203	case PTRACE_SINGLESTEP:
	204	ret = -EIO;
	205	if (!valid_signal(data))
	206	break;
	207	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
	208	ptrace_single_step(child);
	209	child->exit_code = data;
	210	wake_up_process(child);
	211	ret = 0;
	212	break;
	213
5f97f7f9 HS	214	case PTRACE_GETREGS:
	215	ret = ptrace_getregs(child, (void __user *)data);
	216	break;
	217
	218	case PTRACE_SETREGS:
	219	ret = ptrace_setregs(child, (const void __user *)data);
	220	break;
	221
	222	default:
	223	ret = ptrace_request(child, request, addr, data);
	224	break;
	225	}
	226
5f97f7f9 HS	227	return ret;
	228	}
	229
	230	asmlinkage void syscall_trace(void)
	231	{
5f97f7f9 HS	232	if (!test_thread_flag(TIF_SYSCALL_TRACE))
	233	return;
	234	if (!(current->ptrace & PT_PTRACED))
	235	return;
	236
5f97f7f9 HS	237	/* The 0x80 provides a way for the tracing parent to
	238	* distinguish between a syscall stop and SIGTRAP delivery */
	239	ptrace_notify(SIGTRAP \| ((current->ptrace & PT_TRACESYSGOOD)
	240	? 0x80 : 0));
	241
	242	/*
	243	* this isn't the same as continuing with a signal, but it
	244	* will do for normal use. strace only continues with a
	245	* signal if the stopping signal is not SIGTRAP. -brl
	246	*/
	247	if (current->exit_code) {
	248	pr_debug("syscall_trace: sending signal %d to PID %u\n",
	249	current->exit_code, current->pid);
	250	send_sig(current->exit_code, current, 1);
	251	current->exit_code = 0;
	252	}
	253	}
	254
5f97f7f9	255	/*
2507bc13 HS	256	* debug_trampoline() is an assembly stub which will store all user
	257	* registers on the stack and execute a breakpoint instruction.
	258	*
	259	* If we single-step into an exception handler which runs with
	260	* interrupts disabled the whole time so it doesn't have to check for
	261	* pending work, its return address will be modified so that it ends
	262	* up returning to debug_trampoline.
	263	*
	264	* If the exception handler decides to store the user context and
	265	* enable interrupts after all, it will restore the original return
	266	* address and status register value. Before it returns, it will
	267	* notice that TIF_BREAKPOINT is set and execute a breakpoint
	268	* instruction.
5f97f7f9	269	*/
2507bc13	270	extern void debug_trampoline(void);
5f97f7f9	271
2507bc13 HS	272	asmlinkage struct pt_regs do_debug(struct pt_regs regs)
	273	{
	274	struct thread_info *ti;
	275	unsigned long trampoline_addr;
	276	u32 status;
	277	u32 ctrl;
	278	int code;
	279
	280	status = ocd_read(DS);
	281	ti = current_thread_info();
	282	code = TRAP_BRKPT;
	283
	284	pr_debug("do_debug: status=0x%08x PC=0x%08lx SR=0x%08lx tif=0x%08lx\n",
	285	status, regs->pc, regs->sr, ti->flags);
	286
	287	if (!user_mode(regs)) {
	288	unsigned long die_val = DIE_BREAKPOINT;
	289
	290	if (status & (1 << OCD_DS_SSS_BIT))
	291	die_val = DIE_SSTEP;
	292
	293	if (notify_die(die_val, "ptrace", regs, 0, 0, SIGTRAP)
	294	== NOTIFY_STOP)
	295	return regs;
	296
	297	if ((status & (1 << OCD_DS_SWB_BIT))
	298	&& test_and_clear_ti_thread_flag(
	299	ti, TIF_BREAKPOINT)) {
	300	/*
	301	* Explicit breakpoint from trampoline or
	302	* exception/syscall/interrupt handler.
	303	*
	304	* The real saved regs are on the stack right
	305	* after the ones we saved on entry.
	306	*/
	307	regs++;
	308	pr_debug(" -> TIF_BREAKPOINT done, adjusted regs:"
	309	"PC=0x%08lx SR=0x%08lx\n",
	310	regs->pc, regs->sr);
	311	BUG_ON(!user_mode(regs));
	312
	313	if (test_thread_flag(TIF_SINGLE_STEP)) {
	314	pr_debug("Going to do single step...\n");
	315	return regs;
	316	}
	317
	318	/*
	319	* No TIF_SINGLE_STEP means we're done
	320	* stepping over a syscall. Do the trap now.
	321	*/
	322	code = TRAP_TRACE;
	323	} else if ((status & (1 << OCD_DS_SSS_BIT))
	324	&& test_ti_thread_flag(ti, TIF_SINGLE_STEP)) {
	325
	326	pr_debug("Stepped into something, "
	327	"setting TIF_BREAKPOINT...\n");
	328	set_ti_thread_flag(ti, TIF_BREAKPOINT);
	329
	330	/*
	331	* We stepped into an exception, interrupt or
	332	* syscall handler. Some exception handlers
	333	* don't check for pending work, so we need to
	334	* set up a trampoline just in case.
	335	*
336	* The exception entry code will undo the
337	* trampoline stuff if it does a full context
338	* save (which also means that it'll check for
339	* pending work later.)
340	*/
341	if ((regs->sr & MODE_MASK) == MODE_EXCEPTION) {
342	trampoline_addr
343	= (unsigned long)&debug_trampoline;
344
345	pr_debug("Setting up trampoline...\n");
346	ti->rar_saved = sysreg_read(RAR_EX);
347	ti->rsr_saved = sysreg_read(RSR_EX);
348	sysreg_write(RAR_EX, trampoline_addr);
349	sysreg_write(RSR_EX, (MODE_EXCEPTION
350	\| SR_EM \| SR_GM));
351	BUG_ON(ti->rsr_saved & MODE_MASK);
352	}
353
354	/*
355	* If we stepped into a system call, we
356	* shouldn't do a single step after we return
357	* since the return address is right after the
358	* "scall" instruction we were told to step
359	* over.
360	*/
361	if ((regs->sr & MODE_MASK) == MODE_SUPERVISOR) {
362	pr_debug("Supervisor; no single step\n");
363	clear_ti_thread_flag(ti, TIF_SINGLE_STEP);
364	}
365
366	ctrl = ocd_read(DC);
367	ctrl &= ~(1 << OCD_DC_SS_BIT);
368	ocd_write(DC, ctrl);
369
370	return regs;
371	} else {
372	printk(KERN_ERR "Unexpected OCD_DS value: 0x%08x\n",
373	status);
374	printk(KERN_ERR "Thread flags: 0x%08lx\n", ti->flags);
375	die("Unhandled debug trap in kernel mode",
376	regs, SIGTRAP);
377	}
378	} else if (status & (1 << OCD_DS_SSS_BIT)) {
379	/* Single step in user mode */
380	code = TRAP_TRACE;
5f97f7f9	381
2507bc13 HS	382	ctrl = ocd_read(DC);
	383	ctrl &= ~(1 << OCD_DC_SS_BIT);
	384	ocd_write(DC, ctrl);
5f97f7f9 HS	385	}
5f97f7f9 HS	386
2507bc13 HS	387	pr_debug("Sending SIGTRAP: code=%d PC=0x%08lx SR=0x%08lx\n",
2507bc13 HS	388	code, regs->pc, regs->sr);
5f97f7f9	389
2507bc13 HS	390	clear_thread_flag(TIF_SINGLE_STEP);
	391	_exception(SIGTRAP, regs, code, instruction_pointer(regs));
	392
	393	return regs;
5f97f7f9	394	}