aboutsummaryrefslogtreecommitdiff
path: root/src/libmach/Linux.c
blob: eb01a6e64b00ac20ac8b55389d219baa56622863 (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
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
/*
 * process interface for Linux.
 * 
 * Uses ptrace for registers and data,
 * /proc for some process status.
 * There's not much point to worrying about
 * byte order here -- using ptrace means
 * we're running on the architecture we're debugging,
 * unless truly weird stuff is going on.
 *
 * It is tempting to use /proc/%d/mem along with
 * the sp and pc in the stat file to get a stack trace
 * without attaching to the program, but unfortunately
 * you can't read the mem file unless you've attached.
 */

#include <u.h>
#include <sys/ptrace.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/procfs.h>
#include <signal.h>
#include <errno.h>
#include <libc.h>
#include <mach.h>
#include <elf.h>
#include "ureg386.h"

Mach *machcpu = &mach386;

typedef struct PtraceRegs PtraceRegs;

struct PtraceRegs
{
	Regs r;
	int pid;
};

static int ptracesegrw(Map*, Seg*, ulong, void*, uint, int);
static int ptraceregrw(Regs*, char*, ulong*, int);

static int attachedpids[1000];
static int nattached;

static int
ptraceattach(int pid)
{
	int i;

	for(i=0; i<nattached; i++)
		if(attachedpids[i]==pid)
			return 0;
	if(nattached == nelem(attachedpids)){
		werrstr("attached to too many processes");
		return -1;
	}

	if(ptrace(PTRACE_ATTACH, pid, 0, 0) < 0){
		werrstr("ptrace attach %d: %r", pid);
		return -1;
	}
	
	if(ctlproc(pid, "waitstop") < 0){
		fprint(2, "waitstop: %r");
		ptrace(PTRACE_DETACH, pid, 0, 0);
		return -1;
	}
	attachedpids[nattached++] = pid;
	return 0;
}

void
unmapproc(Map *map)
{
	int i;

	if(map == nil)
		return;
	for(i=0; i<map->nseg; i++)
		while(i<map->nseg && map->seg[i].pid){
			map->nseg--;
			memmove(&map->seg[i], &map->seg[i+1], 
				(map->nseg-i)*sizeof(map->seg[0]));
		}
}

int
mapproc(int pid, Map *map, Regs **rp)
{
	Seg s;
	PtraceRegs *r;

	if(ptraceattach(pid) < 0)
		return -1;

	memset(&s, 0, sizeof s);
	s.base = 0;
	s.size = 0xFFFFFFFF;
	s.offset = 0;
	s.name = "data";
	s.file = nil;
	s.rw = ptracesegrw;
	s.pid = pid;
	if(addseg(map, s) < 0){
		fprint(2, "addseg: %r\n");
		return -1;
	}

	if((r = mallocz(sizeof(PtraceRegs), 1)) == nil){
		fprint(2, "mallocz: %r\n");
		return -1;
	}
	r->r.rw = ptraceregrw;
	r->pid = pid;
	*rp = (Regs*)r;
	return 0;
}

int
detachproc(int pid)
{
	int i;

	for(i=0; i<nattached; i++){
		if(attachedpids[i] == pid){
			attachedpids[i] = attachedpids[--nattached];
			break;
		}
	}
	return ptrace(PTRACE_DETACH, pid, 0, 0);
}

static int
ptracerw(int type, int xtype, int isr, int pid, ulong addr, void *v, uint n)
{
	int i;
	u32int u;
	uchar buf[4];

	for(i=0; i<n; i+=4){
		if(isr){
			errno = 0;
			u = ptrace(type, pid, addr+i, 0);
			if(errno)
				goto ptraceerr;
			if(n-i >= 4)
				*(u32int*)((char*)v+i) = u;
			else{
				*(u32int*)buf = u;
				memmove((char*)v+i, buf, n-i);
			}
		}else{
			if(n-i >= 4)
				u = *(u32int*)((char*)v+i);
			else{
				errno = 0;
				u = ptrace(xtype, pid, addr+i, 0);
				if(errno)
					return -1;
				*(u32int*)buf = u;
				memmove(buf, (char*)v+i, n-i);
				u = *(u32int*)buf;
			}
			if(ptrace(type, pid, addr+i, u) < 0)
				goto ptraceerr;
		}
	}
	return 0;

ptraceerr:
	werrstr("ptrace: %r");
	return -1;
}

static int
ptracesegrw(Map *map, Seg *seg, ulong addr, void *v, uint n, int isr)
{
	addr += seg->base;
	return ptracerw(isr ? PTRACE_PEEKDATA : PTRACE_POKEDATA, PTRACE_PEEKDATA,
		isr, seg->pid, addr, v, n);
}

static char* linuxregs[] = {
	"BX",
	"CX",
	"DX",
	"SI",
	"DI",
	"BP",
	"AX",
	"DS",
	"ES",
	"FS",
	"GS",
	"OAX",
	"PC",
	"CS",
	"EFLAGS",
	"SP",
	"SS",
};

static ulong
reg2linux(char *reg)
{
	int i;

	for(i=0; i<nelem(linuxregs); i++)
		if(strcmp(linuxregs[i], reg) == 0)
			return 4*i;
	return ~(ulong)0;
}

static int
ptraceregrw(Regs *regs, char *name, ulong *val, int isr)
{
	int pid;
	ulong addr;
	u32int u;

	pid = ((PtraceRegs*)regs)->pid;
	addr = reg2linux(name);
	if(~addr == 0){
		if(isr){
			*val = ~(ulong)0;
			return 0;
		}
		werrstr("register not available");
		return -1;
	}
	if(isr){
		errno = 0;
		u = ptrace(PTRACE_PEEKUSER, pid, addr, 0);
		if(errno)
			goto ptraceerr;
		*val = u;
	}else{
		u = *val;
		if(ptrace(PTRACE_POKEUSER, pid, addr, (void*)(uintptr)u) < 0)
			goto ptraceerr;
	}
	return 0;

ptraceerr:
	werrstr("ptrace: %r");
	return -1;
}

static int
isstopped(int pid)
{
	char buf[1024];
	int fd, n;
	char *p;

	snprint(buf, sizeof buf, "/proc/%d/stat", pid);
	if((fd = open(buf, OREAD)) < 0)
		return 0;
	n = read(fd, buf, sizeof buf-1);
	close(fd);
	if(n <= 0)
		return 0;
	buf[n] = 0;

	/* command name is in parens, no parens afterward */
	p = strrchr(buf, ')');
	if(p == nil || *++p != ' ')
		return 0;
	++p;

	/* next is state - T is stopped for tracing */
	return *p == 'T';
}

/* /proc/pid/stat contains 
	pid
	command in parens
	0. state
	1. ppid
	2. pgrp
	3. session
	4. tty_nr
	5. tpgid
	6. flags (math=4, traced=10)
	7. minflt
	8. cminflt
	9. majflt
	10. cmajflt
	11. utime
	12. stime
	13. cutime
	14. cstime
	15. priority
	16. nice
	17. 0
	18. itrealvalue
	19. starttime
	20. vsize
	21. rss
	22. rlim
	23. startcode
	24. endcode
	25. startstack
	26. kstkesp
	27. kstkeip
	28. pending signal bitmap
	29. blocked signal bitmap
	30. ignored signal bitmap
	31. caught signal bitmap
	32. wchan
	33. nswap
	34. cnswap
	35. exit_signal
	36. processor
*/

int
procnotes(int pid, char ***pnotes)
{
	char buf[1024], *f[40];
	int fd, i, n, nf;
	char *p, *s, **notes;
	ulong sigs;
	extern char *_p9sigstr(int, char*);

	*pnotes = nil;
	snprint(buf, sizeof buf, "/proc/%d/stat", pid);
	if((fd = open(buf, OREAD)) < 0){
		fprint(2, "open %s: %r\n", buf);
		return -1;
	}
	n = read(fd, buf, sizeof buf-1);
	close(fd);
	if(n <= 0){
		fprint(2, "read %s: %r\n", buf);
		return -1;
	}
	buf[n] = 0;

	/* command name is in parens, no parens afterward */
	p = strrchr(buf, ')');
	if(p == nil || *++p != ' '){
		fprint(2, "bad format in /proc/%d/stat\n", pid);
		return -1;
	}
	++p;

	nf = tokenize(p, f, nelem(f));
	if(0) print("code 0x%lux-0x%lux stack 0x%lux kstk 0x%lux keip 0x%lux pending 0x%lux\n",
		strtoul(f[23], 0, 0), strtoul(f[24], 0, 0), strtoul(f[25], 0, 0),
		strtoul(f[26], 0, 0), strtoul(f[27], 0, 0), strtoul(f[28], 0, 0));
	if(nf <= 28)
		return -1;

	sigs = strtoul(f[28], 0, 0) & ~(1<<SIGCONT);
	if(sigs == 0){
		*pnotes = nil;
		return 0;
	}

	notes = mallocz(32*sizeof(char*), 0);
	if(notes == nil)
		return -1;
	n = 0;
	for(i=0; i<32; i++){
		if((sigs&(1<<i)) == 0)
			continue;
		if((s = _p9sigstr(i, nil)) == nil)
			continue;
		notes[n++] = s;
	}
	*pnotes = notes;
	return n;
}

#undef waitpid

int
ctlproc(int pid, char *msg)
{
	int i, p, status;

	if(strcmp(msg, "attached") == 0){
		for(i=0; i<nattached; i++)
			if(attachedpids[i]==pid)
				return 0;
		if(nattached == nelem(attachedpids)){
			werrstr("attached to too many processes");
			return -1;
		}
		attachedpids[nattached++] = pid;
		return 0;
	}

	if(strcmp(msg, "hang") == 0){
		if(pid == getpid())
			return ptrace(PTRACE_TRACEME, 0, 0, 0);
		werrstr("can only hang self");
		return -1;
	}
	if(strcmp(msg, "kill") == 0)
		return ptrace(PTRACE_KILL, pid, 0, 0);
	if(strcmp(msg, "startstop") == 0){
		if(ptrace(PTRACE_CONT, pid, 0, 0) < 0)
			return -1;
		goto waitstop;
	}
	if(strcmp(msg, "sysstop") == 0){
		if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
			return -1;
		goto waitstop;
	}
	if(strcmp(msg, "stop") == 0){
		if(kill(pid, SIGSTOP) < 0)
			return -1;
		goto waitstop;
	}
	if(strcmp(msg, "step") == 0){
		if(ptrace(PTRACE_SINGLESTEP, pid, 0, 0) < 0)
			return -1;
		goto waitstop;
	}
	if(strcmp(msg, "waitstop") == 0){
	waitstop:
		if(isstopped(pid))
			return 0;
		for(;;){
			p = waitpid(pid, &status, WUNTRACED|__WALL);
			if(p <= 0){
				if(errno == ECHILD){
					if(isstopped(pid))
						return 0;
				}
				return -1;
			}
/*fprint(2, "got pid %d status %x\n", pid, status); */
			if(WIFEXITED(status) || WIFSTOPPED(status))
				return 0;
		}
	}
	if(strcmp(msg, "start") == 0)
		return ptrace(PTRACE_CONT, pid, 0, 0);
	werrstr("unknown control message '%s'", msg);
	return -1;
}

char*
proctextfile(int pid)
{
	static char buf[1024], pbuf[128];

	snprint(pbuf, sizeof pbuf, "/proc/%d/exe", pid);
	if(readlink(pbuf, buf, sizeof buf) >= 0)
		return buf;
	if(access(pbuf, AEXIST) >= 0)
		return pbuf;
	return nil;
}