summaryrefslogtreecommitdiffstats
path: root/arch/avr32/kernel/ptrace.c
blob: 1043fdc2df7ff476444fd845171640611247ec7b (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
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
/*
 * 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, SR=0x%08lx\n",
		 tsk->pid, tsk->thread.cpu_context.sr);
	if (!(tsk->thread.cpu_context.sr & SR_D)) {
		/*
		 * Set a breakpoint at the current pc to force the
		 * process into debug mode.  The syscall/exception
		 * exit code will set a breakpoint at the return
		 * address when this flag is set.
		 */
		pr_debug("ptrace_single_step: Setting TIF_BREAKPOINT\n");
		set_tsk_thread_flag(tsk, TIF_BREAKPOINT);
	}

	/* The monitor code will do the actual step for us */
	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);
}

/*
 * Handle hitting a breakpoint
 */
static void ptrace_break(struct task_struct *tsk, struct pt_regs *regs)
{
	siginfo_t info;

	info.si_signo = SIGTRAP;
	info.si_errno = 0;
	info.si_code  = TRAP_BRKPT;
	info.si_addr  = (void __user *)instruction_pointer(regs);

	pr_debug("ptrace_break: Sending SIGTRAP to PID %u (pc = 0x%p)\n",
		 tsk->pid, info.si_addr);
	force_sig_info(SIGTRAP, &info, tsk);
}

/*
 * 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;

	pr_debug("ptrace_read_user(%p, %#lx, %p)\n",
		 tsk, offset, data);

	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])];

	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;

	if (offset & 3 || offset >= sizeof(struct user)) {
		printk("ptrace_write_user: 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;

	pr_debug("arch_ptrace(%ld, %d, %#lx, %#lx)\n",
		 request, child->pid, addr, data);

	pr_debug("ptrace: Enabling monitor mode...\n");
	__mtdr(DBGREG_DC, __mfdr(DBGREG_DC) | DC_MM | DC_DBE);

	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 = access_process_vm(child, addr, &data, sizeof(data), 1);
		if (ret == sizeof(data))
			ret = 0;
		else
			ret = -EIO;
		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;

	/* Detach a process that was attached */
	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, (const void __user *)data);
		break;

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

	pr_debug("sys_ptrace returning %d (DC = 0x%08lx)\n", ret, __mfdr(DBGREG_DC));
	return ret;
}

asmlinkage void syscall_trace(void)
{
	pr_debug("syscall_trace called\n");
	if (!test_thread_flag(TIF_SYSCALL_TRACE))
		return;
	if (!(current->ptrace & PT_PTRACED))
		return;

	pr_debug("syscall_trace: notifying parent\n");
	/* 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;
	}
}

asmlinkage void do_debug_priv(struct pt_regs *regs)
{
	unsigned long dc, ds;
	unsigned long die_val;

	ds = __mfdr(DBGREG_DS);

	pr_debug("do_debug_priv: pc = %08lx, ds = %08lx\n", regs->pc, ds);

	if (ds & DS_SSS)
		die_val = DIE_SSTEP;
	else
		die_val = DIE_BREAKPOINT;

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

	if (likely(ds & DS_SSS)) {
		extern void itlb_miss(void);
		extern void tlb_miss_common(void);
		struct thread_info *ti;

		dc = __mfdr(DBGREG_DC);
		dc &= ~DC_SS;
		__mtdr(DBGREG_DC, dc);

		ti = current_thread_info();
		set_ti_thread_flag(ti, TIF_BREAKPOINT);

		/* The TLB miss handlers don't check thread flags */
		if ((regs->pc >= (unsigned long)&itlb_miss)
		    && (regs->pc <= (unsigned long)&tlb_miss_common)) {
			__mtdr(DBGREG_BWA2A, sysreg_read(RAR_EX));
			__mtdr(DBGREG_BWC2A, 0x40000001 | (get_asid() << 1));
		}

		/*
		 * If we're running in supervisor mode, the breakpoint
		 * will take us where we want directly, no need to
		 * single step.
		 */
		if ((regs->sr & MODE_MASK) != MODE_SUPERVISOR)
			set_ti_thread_flag(ti, TIF_SINGLE_STEP);
	} else {
		panic("Unable to handle debug trap at pc = %08lx\n",
		      regs->pc);
	}
}

/*
 * Handle breakpoints, single steps and other debuggy things. To keep
 * things simple initially, we run with interrupts and exceptions
 * disabled all the time.
 */
asmlinkage void do_debug(struct pt_regs *regs)
{
	unsigned long dc, ds;

	ds = __mfdr(DBGREG_DS);
	pr_debug("do_debug: pc = %08lx, ds = %08lx\n", regs->pc, ds);

	if (test_thread_flag(TIF_BREAKPOINT)) {
		pr_debug("TIF_BREAKPOINT set\n");
		/* We're taking care of it */
		clear_thread_flag(TIF_BREAKPOINT);
		__mtdr(DBGREG_BWC2A, 0);
	}

	if (test_thread_flag(TIF_SINGLE_STEP)) {
		pr_debug("TIF_SINGLE_STEP set, ds = 0x%08lx\n", ds);
		if (ds & DS_SSS) {
			dc = __mfdr(DBGREG_DC);
			dc &= ~DC_SS;
			__mtdr(DBGREG_DC, dc);

			clear_thread_flag(TIF_SINGLE_STEP);
			ptrace_break(current, regs);
		}
	} else {
		/* regular breakpoint */
		ptrace_break(current, regs);
	}
}