summaryrefslogtreecommitdiffstats
path: root/arch/alpha/kernel/ptrace.c
blob: baa903602f6a03c86a8d841ba3ce751c3ece0cb9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
/* 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/errno.h>
#include <linux/ptrace.h>
#include <linux/user.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);
}

void user_enable_single_step(struct task_struct *child)
{
	/* Mark single stepping.  */
	task_thread_info(child)->bpt_nsaved = -1;
}

void user_disable_single_step(struct task_struct *child)
{
	ptrace_cancel_bpt(child);
}

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

long arch_ptrace(struct task_struct *child, long request, long addr, long data)
{
	unsigned long tmp;
	size_t copied;
	long ret;

	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;
		
		force_successful_syscall_return();
		ret = tmp;
		break;

	/* Read register number ADDR. */
	case PTRACE_PEEKUSR:
		force_successful_syscall_return();
		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;
	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) {
		send_sig(current->exit_code, current, 1);
		current->exit_code = 0;
	}
}