[linux-2.6-block.git] / arch / alpha / kernel / ptrace.c

/* ptrace.c */
/* By Ross Biro 1/23/92 */
/* edited by Linus Torvalds */
/* mangled further by Bob Manson (manson@santafe.edu) */
/* more mutilation by David Mosberger (davidm@azstarnet.com) */

#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/slab.h>
#include <linux/security.h>
#include <linux/signal.h>

#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/fpu.h>

#include "proto.h"

#define DEBUG	DBG_MEM
#undef DEBUG

#ifdef DEBUG
enum {
	DBG_MEM		= (1<<0),
	DBG_BPT		= (1<<1),
	DBG_MEM_ALL	= (1<<2)
};
#define DBG(fac,args)	{if ((fac) & DEBUG) printk args;}
#else
#define DBG(fac,args)
#endif

#define BREAKINST	0x00000080	/* call_pal bpt */

/*
 * does not yet catch signals sent when the child dies.
 * in exit.c or in signal.c.
 */

/*
 * Processes always block with the following stack-layout:
 *
 *  +================================+ <---- task + 2*PAGE_SIZE
 *  | PALcode saved frame (ps, pc,   | ^
 *  | gp, a0, a1, a2)		     | |
 *  +================================+ | struct pt_regs
 *  |	        		     | |
 *  | frame generated by SAVE_ALL    | |
 *  |	        		     | v
 *  +================================+
 *  |	        		     | ^
 *  | frame saved by do_switch_stack | | struct switch_stack
 *  |	        		     | v
 *  +================================+
 */

/* 
 * The following table maps a register index into the stack offset at
 * which the register is saved.  Register indices are 0-31 for integer
 * regs, 32-63 for fp regs, and 64 for the pc.  Notice that sp and
 * zero have no stack-slot and need to be treated specially (see
 * get_reg/put_reg below).
 */
enum {
	REG_R0 = 0, REG_F0 = 32, REG_FPCR = 63, REG_PC = 64
};

#define PT_REG(reg) \
  (PAGE_SIZE*2 - sizeof(struct pt_regs) + offsetof(struct pt_regs, reg))

#define SW_REG(reg) \
 (PAGE_SIZE*2 - sizeof(struct pt_regs) - sizeof(struct switch_stack) \
  + offsetof(struct switch_stack, reg))

static int regoff[] = {
	PT_REG(	   r0), PT_REG(	   r1), PT_REG(	   r2), PT_REG(	  r3),
	PT_REG(	   r4), PT_REG(	   r5), PT_REG(	   r6), PT_REG(	  r7),
	PT_REG(	   r8), SW_REG(	   r9), SW_REG(	  r10), SW_REG(	 r11),
	SW_REG(	  r12), SW_REG(	  r13), SW_REG(	  r14), SW_REG(	 r15),
	PT_REG(	  r16), PT_REG(	  r17), PT_REG(	  r18), PT_REG(	 r19),
	PT_REG(	  r20), PT_REG(	  r21), PT_REG(	  r22), PT_REG(	 r23),
	PT_REG(	  r24), PT_REG(	  r25), PT_REG(	  r26), PT_REG(	 r27),
	PT_REG(	  r28), PT_REG(	   gp),		   -1,		   -1,
	SW_REG(fp[ 0]), SW_REG(fp[ 1]), SW_REG(fp[ 2]), SW_REG(fp[ 3]),
	SW_REG(fp[ 4]), SW_REG(fp[ 5]), SW_REG(fp[ 6]), SW_REG(fp[ 7]),
	SW_REG(fp[ 8]), SW_REG(fp[ 9]), SW_REG(fp[10]), SW_REG(fp[11]),
	SW_REG(fp[12]), SW_REG(fp[13]), SW_REG(fp[14]), SW_REG(fp[15]),
	SW_REG(fp[16]), SW_REG(fp[17]), SW_REG(fp[18]), SW_REG(fp[19]),
	SW_REG(fp[20]), SW_REG(fp[21]), SW_REG(fp[22]), SW_REG(fp[23]),
	SW_REG(fp[24]), SW_REG(fp[25]), SW_REG(fp[26]), SW_REG(fp[27]),
	SW_REG(fp[28]), SW_REG(fp[29]), SW_REG(fp[30]), SW_REG(fp[31]),
	PT_REG(	   pc)
};

static unsigned long zero;

/*
 * Get address of register REGNO in task TASK.
 */
static unsigned long *
get_reg_addr(struct task_struct * task, unsigned long regno)
{
	unsigned long *addr;

	if (regno == 30) {
		addr = &task_thread_info(task)->pcb.usp;
	} else if (regno == 65) {
		addr = &task_thread_info(task)->pcb.unique;
	} else if (regno == 31 || regno > 65) {
		zero = 0;
		addr = &zero;
	} else {
		addr = task_stack_page(task) + regoff[regno];
	}
	return addr;
}

/*
 * Get contents of register REGNO in task TASK.
 */
static unsigned long
get_reg(struct task_struct * task, unsigned long regno)
{
	/* Special hack for fpcr -- combine hardware and software bits.  */
	if (regno == 63) {
		unsigned long fpcr = *get_reg_addr(task, regno);
		unsigned long swcr
		  = task_thread_info(task)->ieee_state & IEEE_SW_MASK;
		swcr = swcr_update_status(swcr, fpcr);
		return fpcr | swcr;
	}
	return *get_reg_addr(task, regno);
}

/*
 * Write contents of register REGNO in task TASK.
 */
static int
put_reg(struct task_struct *task, unsigned long regno, unsigned long data)
{
	if (regno == 63) {
		task_thread_info(task)->ieee_state
		  = ((task_thread_info(task)->ieee_state & ~IEEE_SW_MASK)
		     | (data & IEEE_SW_MASK));
		data = (data & FPCR_DYN_MASK) | ieee_swcr_to_fpcr(data);
	}
	*get_reg_addr(task, regno) = data;
	return 0;
}

static inline int
read_int(struct task_struct *task, unsigned long addr, int * data)
{
	int copied = access_process_vm(task, addr, data, sizeof(int), 0);
	return (copied == sizeof(int)) ? 0 : -EIO;
}

static inline int
write_int(struct task_struct *task, unsigned long addr, int data)
{
	int copied = access_process_vm(task, addr, &data, sizeof(int), 1);
	return (copied == sizeof(int)) ? 0 : -EIO;
}

/*
 * Set breakpoint.
 */
int
ptrace_set_bpt(struct task_struct * child)
{
	int displ, i, res, reg_b, nsaved = 0;
	unsigned int insn, op_code;
	unsigned long pc;

	pc  = get_reg(child, REG_PC);
	res = read_int(child, pc, (int *) &insn);
	if (res < 0)
		return res;

	op_code = insn >> 26;
	if (op_code >= 0x30) {
		/*
		 * It's a branch: instead of trying to figure out
		 * whether the branch will be taken or not, we'll put
		 * a breakpoint at either location.  This is simpler,
		 * more reliable, and probably not a whole lot slower
		 * than the alternative approach of emulating the
		 * branch (emulation can be tricky for fp branches).
		 */
		displ = ((s32)(insn << 11)) >> 9;
		task_thread_info(child)->bpt_addr[nsaved++] = pc + 4;
		if (displ)		/* guard against unoptimized code */
			task_thread_info(child)->bpt_addr[nsaved++]
			  = pc + 4 + displ;
		DBG(DBG_BPT, ("execing branch\n"));
	} else if (op_code == 0x1a) {
		reg_b = (insn >> 16) & 0x1f;
		task_thread_info(child)->bpt_addr[nsaved++] = get_reg(child, reg_b);
		DBG(DBG_BPT, ("execing jump\n"));
	} else {
		task_thread_info(child)->bpt_addr[nsaved++] = pc + 4;
		DBG(DBG_BPT, ("execing normal insn\n"));
	}

	/* install breakpoints: */
	for (i = 0; i < nsaved; ++i) {
		res = read_int(child, task_thread_info(child)->bpt_addr[i],
			       (int *) &insn);
		if (res < 0)
			return res;
		task_thread_info(child)->bpt_insn[i] = insn;
		DBG(DBG_BPT, ("    -> next_pc=%lx\n",
			      task_thread_info(child)->bpt_addr[i]));
		res = write_int(child, task_thread_info(child)->bpt_addr[i],
				BREAKINST);
		if (res < 0)
			return res;
	}
	task_thread_info(child)->bpt_nsaved = nsaved;
	return 0;
}

/*
 * Ensure no single-step breakpoint is pending.  Returns non-zero
 * value if child was being single-stepped.
 */
int
ptrace_cancel_bpt(struct task_struct * child)
{
	int i, nsaved = task_thread_info(child)->bpt_nsaved;

	task_thread_info(child)->bpt_nsaved = 0;

	if (nsaved > 2) {
		printk("ptrace_cancel_bpt: bogus nsaved: %d!\n", nsaved);
		nsaved = 2;
	}

	for (i = 0; i < nsaved; ++i) {
		write_int(child, task_thread_info(child)->bpt_addr[i],
			  task_thread_info(child)->bpt_insn[i]);
	}
	return (nsaved != 0);
}

/*
 * Called by kernel/ptrace.c when detaching..
 *
 * Make sure the single step bit is not set.
 */
void ptrace_disable(struct task_struct *child)
{ 
	ptrace_cancel_bpt(child);
}

asmlinkage long
do_sys_ptrace(long request, long pid, long addr, long data,
	      struct pt_regs *regs)
{
	struct task_struct *child;
	unsigned long tmp;
	size_t copied;
	long ret;

	lock_kernel();
	DBG(DBG_MEM, ("request=%ld pid=%ld addr=0x%lx data=0x%lx\n",
		      request, pid, addr, data));
	if (request == PTRACE_TRACEME) {
		ret = ptrace_traceme();
		goto out_notsk;
	}

	child = ptrace_get_task_struct(pid);
	if (IS_ERR(child)) {
		ret = PTR_ERR(child);
		goto out_notsk;
	}

	if (request == PTRACE_ATTACH) {
		ret = ptrace_attach(child);
		goto out;
	}

	ret = ptrace_check_attach(child, request == PTRACE_KILL);
	if (ret < 0)
		goto out;

	switch (request) {
	/* When I and D space are separate, these will need to be fixed.  */
	case PTRACE_PEEKTEXT: /* read word at location addr. */
	case PTRACE_PEEKDATA:
		copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
		ret = -EIO;
		if (copied != sizeof(tmp))
			break;
		
		regs->r0 = 0;	/* special return: no errors */
		ret = tmp;
		break;

	/* Read register number ADDR. */
	case PTRACE_PEEKUSR:
		regs->r0 = 0;	/* special return: no errors */
		ret = get_reg(child, addr);
		DBG(DBG_MEM, ("peek $%ld->%#lx\n", addr, ret));
		break;

	/* When I and D space are separate, this will have to be fixed.  */
	case PTRACE_POKETEXT: /* write the word at location addr. */
	case PTRACE_POKEDATA:
		ret = generic_ptrace_pokedata(child, addr, data);
		break;

	case PTRACE_POKEUSR: /* write the specified register */
		DBG(DBG_MEM, ("poke $%ld<-%#lx\n", addr, data));
		ret = put_reg(child, addr, data);
		break;

	case PTRACE_SYSCALL:
		/* continue and stop at next (return from) syscall */
	case PTRACE_CONT:    /* restart after signal. */
		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;
		/* make sure single-step breakpoint is gone. */
		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:
		ret = 0;
		if (child->exit_state == EXIT_ZOMBIE)
			break;
		child->exit_code = SIGKILL;
		/* make sure single-step breakpoint is gone. */
		ptrace_cancel_bpt(child);
		wake_up_process(child);
		goto out;

	case PTRACE_SINGLESTEP:  /* execute single instruction. */
		ret = -EIO;
		if (!valid_signal(data))
			break;
		/* Mark single stepping.  */
		task_thread_info(child)->bpt_nsaved = -1;
		clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
		child->exit_code = data;
		wake_up_process(child);
		/* give it a chance to run. */
		ret = 0;
		goto out;

	case PTRACE_DETACH:	 /* detach a process that was attached. */
		ret = ptrace_detach(child, data);
		goto out;

	default:
		ret = ptrace_request(child, request, addr, data);
		goto out;
	}
 out:
	put_task_struct(child);
 out_notsk:
	unlock_kernel();
	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) {
		send_sig(current->exit_code, current, 1);
		current->exit_code = 0;
	}
}
Commit	Line	Data
1da177e4 LT	1	/* ptrace.c */
	2	/* By Ross Biro 1/23/92 */
	3	/* edited by Linus Torvalds */
	4	/* mangled further by Bob Manson (manson@santafe.edu) */
	5	/* more mutilation by David Mosberger (davidm@azstarnet.com) */
	6
	7	#include <linux/kernel.h>
	8	#include <linux/sched.h>
	9	#include <linux/mm.h>
	10	#include <linux/smp.h>
	11	#include <linux/smp_lock.h>
	12	#include <linux/errno.h>
	13	#include <linux/ptrace.h>
	14	#include <linux/user.h>
	15	#include <linux/slab.h>
	16	#include <linux/security.h>
7ed20e1a	17	#include <linux/signal.h>
1da177e4 LT	18
	19	#include <asm/uaccess.h>
	20	#include <asm/pgtable.h>
	21	#include <asm/system.h>
	22	#include <asm/fpu.h>
	23
	24	#include "proto.h"
	25
	26	#define DEBUG DBG_MEM
	27	#undef DEBUG
	28
	29	#ifdef DEBUG
	30	enum {
	31	DBG_MEM = (1<<0),
	32	DBG_BPT = (1<<1),
	33	DBG_MEM_ALL = (1<<2)
	34	};
	35	#define DBG(fac,args) {if ((fac) & DEBUG) printk args;}
	36	#else
	37	#define DBG(fac,args)
	38	#endif
	39
	40	#define BREAKINST 0x00000080 /* call_pal bpt */
	41
	42	/*
	43	* does not yet catch signals sent when the child dies.
	44	* in exit.c or in signal.c.
	45	*/
	46
	47	/*
	48	* Processes always block with the following stack-layout:
	49	*
	50	* +================================+ <---- task + 2*PAGE_SIZE
	51	* \| PALcode saved frame (ps, pc, \| ^
	52	* \| gp, a0, a1, a2) \| \|
	53	* +================================+ \| struct pt_regs
	54	* \| \| \|
	55	* \| frame generated by SAVE_ALL \| \|
	56	* \| \| v
	57	* +================================+
	58	* \| \| ^
	59	* \| frame saved by do_switch_stack \| \| struct switch_stack
	60	* \| \| v
	61	* +================================+
	62	*/
	63
	64	/*
	65	* The following table maps a register index into the stack offset at
	66	* which the register is saved. Register indices are 0-31 for integer
	67	* regs, 32-63 for fp regs, and 64 for the pc. Notice that sp and
	68	* zero have no stack-slot and need to be treated specially (see
	69	* get_reg/put_reg below).
	70	*/
	71	enum {
	72	REG_R0 = 0, REG_F0 = 32, REG_FPCR = 63, REG_PC = 64
	73	};
	74
e52f4ca2	75	#define PT_REG(reg) \
	76	(PAGE_SIZE*2 - sizeof(struct pt_regs) + offsetof(struct pt_regs, reg))
	77
	78	#define SW_REG(reg) \
	79	(PAGE_SIZE*2 - sizeof(struct pt_regs) - sizeof(struct switch_stack) \
	80	+ offsetof(struct switch_stack, reg))
	81
1da177e4 LT	82	static int regoff[] = {
	83	PT_REG( r0), PT_REG( r1), PT_REG( r2), PT_REG( r3),
	84	PT_REG( r4), PT_REG( r5), PT_REG( r6), PT_REG( r7),
	85	PT_REG( r8), SW_REG( r9), SW_REG( r10), SW_REG( r11),
	86	SW_REG( r12), SW_REG( r13), SW_REG( r14), SW_REG( r15),
	87	PT_REG( r16), PT_REG( r17), PT_REG( r18), PT_REG( r19),
	88	PT_REG( r20), PT_REG( r21), PT_REG( r22), PT_REG( r23),
	89	PT_REG( r24), PT_REG( r25), PT_REG( r26), PT_REG( r27),
	90	PT_REG( r28), PT_REG( gp), -1, -1,
	91	SW_REG(fp[ 0]), SW_REG(fp[ 1]), SW_REG(fp[ 2]), SW_REG(fp[ 3]),
	92	SW_REG(fp[ 4]), SW_REG(fp[ 5]), SW_REG(fp[ 6]), SW_REG(fp[ 7]),
	93	SW_REG(fp[ 8]), SW_REG(fp[ 9]), SW_REG(fp[10]), SW_REG(fp[11]),
	94	SW_REG(fp[12]), SW_REG(fp[13]), SW_REG(fp[14]), SW_REG(fp[15]),
	95	SW_REG(fp[16]), SW_REG(fp[17]), SW_REG(fp[18]), SW_REG(fp[19]),
	96	SW_REG(fp[20]), SW_REG(fp[21]), SW_REG(fp[22]), SW_REG(fp[23]),
	97	SW_REG(fp[24]), SW_REG(fp[25]), SW_REG(fp[26]), SW_REG(fp[27]),
	98	SW_REG(fp[28]), SW_REG(fp[29]), SW_REG(fp[30]), SW_REG(fp[31]),
	99	PT_REG( pc)
	100	};
	101
	102	static unsigned long zero;
	103
	104	/*
	105	* Get address of register REGNO in task TASK.
	106	*/
	107	static unsigned long *
	108	get_reg_addr(struct task_struct * task, unsigned long regno)
	109	{
	110	unsigned long *addr;
	111
	112	if (regno == 30) {
37bfbaf9	113	addr = &task_thread_info(task)->pcb.usp;
1da177e4	114	} else if (regno == 65) {
37bfbaf9	115	addr = &task_thread_info(task)->pcb.unique;
1da177e4 LT	116	} else if (regno == 31 \|\| regno > 65) {
	117	zero = 0;
	118	addr = &zero;
	119	} else {
27f45130	120	addr = task_stack_page(task) + regoff[regno];
1da177e4 LT	121	}
	122	return addr;
	123	}
	124
	125	/*
	126	* Get contents of register REGNO in task TASK.
	127	*/
	128	static unsigned long
	129	get_reg(struct task_struct * task, unsigned long regno)
	130	{
	131	/* Special hack for fpcr -- combine hardware and software bits. */
	132	if (regno == 63) {
	133	unsigned long fpcr = *get_reg_addr(task, regno);
	134	unsigned long swcr
37bfbaf9	135	= task_thread_info(task)->ieee_state & IEEE_SW_MASK;
1da177e4 LT	136	swcr = swcr_update_status(swcr, fpcr);
	137	return fpcr \| swcr;
	138	}
	139	return *get_reg_addr(task, regno);
	140	}
	141
	142	/*
	143	* Write contents of register REGNO in task TASK.
	144	*/
	145	static int
	146	put_reg(struct task_struct *task, unsigned long regno, unsigned long data)
	147	{
	148	if (regno == 63) {
37bfbaf9 AV	149	task_thread_info(task)->ieee_state
37bfbaf9 AV	150	= ((task_thread_info(task)->ieee_state & ~IEEE_SW_MASK)
1da177e4 LT	151	\| (data & IEEE_SW_MASK));
	152	data = (data & FPCR_DYN_MASK) \| ieee_swcr_to_fpcr(data);
	153	}
	154	*get_reg_addr(task, regno) = data;
	155	return 0;
	156	}
	157
	158	static inline int
	159	read_int(struct task_struct task, unsigned long addr, int data)
	160	{
	161	int copied = access_process_vm(task, addr, data, sizeof(int), 0);
	162	return (copied == sizeof(int)) ? 0 : -EIO;
	163	}
	164
	165	static inline int
	166	write_int(struct task_struct *task, unsigned long addr, int data)
	167	{
	168	int copied = access_process_vm(task, addr, &data, sizeof(int), 1);
	169	return (copied == sizeof(int)) ? 0 : -EIO;
	170	}
	171
	172	/*
	173	* Set breakpoint.
	174	*/
	175	int
	176	ptrace_set_bpt(struct task_struct * child)
	177	{
	178	int displ, i, res, reg_b, nsaved = 0;
	179	unsigned int insn, op_code;
	180	unsigned long pc;
	181
	182	pc = get_reg(child, REG_PC);
	183	res = read_int(child, pc, (int *) &insn);
	184	if (res < 0)
	185	return res;
	186
	187	op_code = insn >> 26;
	188	if (op_code >= 0x30) {
	189	/*
	190	* It's a branch: instead of trying to figure out
	191	* whether the branch will be taken or not, we'll put
	192	* a breakpoint at either location. This is simpler,
	193	* more reliable, and probably not a whole lot slower
	194	* than the alternative approach of emulating the
	195	* branch (emulation can be tricky for fp branches).
	196	*/
	197	displ = ((s32)(insn << 11)) >> 9;
37bfbaf9	198	task_thread_info(child)->bpt_addr[nsaved++] = pc + 4;
1da177e4	199	if (displ) /* guard against unoptimized code */
37bfbaf9	200	task_thread_info(child)->bpt_addr[nsaved++]
1da177e4 LT	201	= pc + 4 + displ;
	202	DBG(DBG_BPT, ("execing branch\n"));
	203	} else if (op_code == 0x1a) {
	204	reg_b = (insn >> 16) & 0x1f;
37bfbaf9	205	task_thread_info(child)->bpt_addr[nsaved++] = get_reg(child, reg_b);
1da177e4 LT	206	DBG(DBG_BPT, ("execing jump\n"));
1da177e4 LT	207	} else {
37bfbaf9	208	task_thread_info(child)->bpt_addr[nsaved++] = pc + 4;
1da177e4 LT	209	DBG(DBG_BPT, ("execing normal insn\n"));
	210	}
	211
	212	/* install breakpoints: */
	213	for (i = 0; i < nsaved; ++i) {
37bfbaf9	214	res = read_int(child, task_thread_info(child)->bpt_addr[i],
1da177e4 LT	215	(int *) &insn);
	216	if (res < 0)
	217	return res;
37bfbaf9	218	task_thread_info(child)->bpt_insn[i] = insn;
1da177e4	219	DBG(DBG_BPT, (" -> next_pc=%lx\n",
37bfbaf9 AV	220	task_thread_info(child)->bpt_addr[i]));
37bfbaf9 AV	221	res = write_int(child, task_thread_info(child)->bpt_addr[i],
1da177e4 LT	222	BREAKINST);
	223	if (res < 0)
	224	return res;
	225	}
37bfbaf9	226	task_thread_info(child)->bpt_nsaved = nsaved;
1da177e4 LT	227	return 0;
	228	}
	229
	230	/*
	231	* Ensure no single-step breakpoint is pending. Returns non-zero
	232	* value if child was being single-stepped.
	233	*/
	234	int
	235	ptrace_cancel_bpt(struct task_struct * child)
	236	{
37bfbaf9	237	int i, nsaved = task_thread_info(child)->bpt_nsaved;
1da177e4	238
37bfbaf9	239	task_thread_info(child)->bpt_nsaved = 0;
1da177e4 LT	240
	241	if (nsaved > 2) {
	242	printk("ptrace_cancel_bpt: bogus nsaved: %d!\n", nsaved);
	243	nsaved = 2;
	244	}
	245
	246	for (i = 0; i < nsaved; ++i) {
37bfbaf9 AV	247	write_int(child, task_thread_info(child)->bpt_addr[i],
37bfbaf9 AV	248	task_thread_info(child)->bpt_insn[i]);
1da177e4 LT	249	}
	250	return (nsaved != 0);
	251	}
	252
	253	/*
	254	* Called by kernel/ptrace.c when detaching..
	255	*
	256	* Make sure the single step bit is not set.
	257	*/
	258	void ptrace_disable(struct task_struct *child)
	259	{
	260	ptrace_cancel_bpt(child);
	261	}
	262
	263	asmlinkage long
	264	do_sys_ptrace(long request, long pid, long addr, long data,
	265	struct pt_regs *regs)
	266	{
	267	struct task_struct *child;
	268	unsigned long tmp;
	269	size_t copied;
	270	long ret;
	271
	272	lock_kernel();
	273	DBG(DBG_MEM, ("request=%ld pid=%ld addr=0x%lx data=0x%lx\n",
	274	request, pid, addr, data));
1da177e4	275	if (request == PTRACE_TRACEME) {
6b9c7ed8	276	ret = ptrace_traceme();
1da177e4 LT	277	goto out_notsk;
1da177e4 LT	278	}
1da177e4	279
6b9c7ed8 CH	280	child = ptrace_get_task_struct(pid);
	281	if (IS_ERR(child)) {
	282	ret = PTR_ERR(child);
1da177e4	283	goto out_notsk;
6b9c7ed8	284	}
1da177e4 LT	285
	286	if (request == PTRACE_ATTACH) {
	287	ret = ptrace_attach(child);
	288	goto out;
	289	}
	290
	291	ret = ptrace_check_attach(child, request == PTRACE_KILL);
	292	if (ret < 0)
	293	goto out;
	294
	295	switch (request) {
	296	/* When I and D space are separate, these will need to be fixed. */
	297	case PTRACE_PEEKTEXT: /* read word at location addr. */
	298	case PTRACE_PEEKDATA:
	299	copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
	300	ret = -EIO;
	301	if (copied != sizeof(tmp))
	302	break;
	303
	304	regs->r0 = 0; /* special return: no errors */
	305	ret = tmp;
	306	break;
	307
	308	/* Read register number ADDR. */
	309	case PTRACE_PEEKUSR:
	310	regs->r0 = 0; /* special return: no errors */
	311	ret = get_reg(child, addr);
	312	DBG(DBG_MEM, ("peek $%ld->%#lx\n", addr, ret));
	313	break;
	314
	315	/* When I and D space are separate, this will have to be fixed. */
	316	case PTRACE_POKETEXT: /* write the word at location addr. */
	317	case PTRACE_POKEDATA:
f284ce72	318	ret = generic_ptrace_pokedata(child, addr, data);
1da177e4 LT	319	break;
	320
	321	case PTRACE_POKEUSR: /* write the specified register */
	322	DBG(DBG_MEM, ("poke $%ld<-%#lx\n", addr, data));
	323	ret = put_reg(child, addr, data);
	324	break;
	325
	326	case PTRACE_SYSCALL:
	327	/* continue and stop at next (return from) syscall */
	328	case PTRACE_CONT: /* restart after signal. */
	329	ret = -EIO;
7ed20e1a	330	if (!valid_signal(data))
1da177e4 LT	331	break;
	332	if (request == PTRACE_SYSCALL)
	333	set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
	334	else
	335	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
	336	child->exit_code = data;
	337	/* make sure single-step breakpoint is gone. */
	338	ptrace_cancel_bpt(child);
	339	wake_up_process(child);
	340	ret = 0;
	341	break;
	342
	343	/*
	344	* Make the child exit. Best I can do is send it a sigkill.
	345	* perhaps it should be put in the status that it wants to
	346	* exit.
	347	*/
	348	case PTRACE_KILL:
	349	ret = 0;
	350	if (child->exit_state == EXIT_ZOMBIE)
	351	break;
	352	child->exit_code = SIGKILL;
	353	/* make sure single-step breakpoint is gone. */
	354	ptrace_cancel_bpt(child);
	355	wake_up_process(child);
	356	goto out;
	357
	358	case PTRACE_SINGLESTEP: /* execute single instruction. */
	359	ret = -EIO;
7ed20e1a	360	if (!valid_signal(data))
1da177e4 LT	361	break;
1da177e4 LT	362	/* Mark single stepping. */
37bfbaf9	363	task_thread_info(child)->bpt_nsaved = -1;
1da177e4 LT	364	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
	365	child->exit_code = data;
	366	wake_up_process(child);
	367	/* give it a chance to run. */
	368	ret = 0;
	369	goto out;
	370
	371	case PTRACE_DETACH: /* detach a process that was attached. */
	372	ret = ptrace_detach(child, data);
	373	goto out;
	374
	375	default:
	376	ret = ptrace_request(child, request, addr, data);
	377	goto out;
	378	}
	379	out:
	380	put_task_struct(child);
	381	out_notsk:
	382	unlock_kernel();
	383	return ret;
	384	}
	385
	386	asmlinkage void
	387	syscall_trace(void)
	388	{
	389	if (!test_thread_flag(TIF_SYSCALL_TRACE))
	390	return;
	391	if (!(current->ptrace & PT_PTRACED))
	392	return;
	393	/* The 0x80 provides a way for the tracing parent to distinguish
	394	between a syscall stop and SIGTRAP delivery */
	395	ptrace_notify(SIGTRAP \| ((current->ptrace & PT_TRACESYSGOOD)
	396	? 0x80 : 0));
	397
	398	/*
	399	* This isn't the same as continuing with a signal, but it will do
	400	* for normal use. strace only continues with a signal if the
	401	* stopping signal is not SIGTRAP. -brl
	402	*/
	403	if (current->exit_code) {
	404	send_sig(current->exit_code, current, 1);
	405	current->exit_code = 0;
	406	}
	407	}