1 /* ptrace.c */
2 /* By Ross Biro 1/23/92 */
3 /*
4 * Pentium III FXSR, SSE support
5 * Gareth Hughes <gareth@valinux.com>, May 2000
6 */
7
8 #include <linux/kernel.h>
9 #include <linux/sched.h>
10 #include <linux/mm.h>
11 #include <linux/smp.h>
12 #include <linux/smp_lock.h>
13 #include <linux/errno.h>
14 #include <linux/ptrace.h>
15 #include <linux/user.h>
16
17 #include <asm/uaccess.h>
18 #include <asm/pgtable.h>
19 #include <asm/system.h>
20 #include <asm/processor.h>
21 #include <asm/i387.h>
22 #include <asm/debugreg.h>
23
24 /*
25 * does not yet catch signals sent when the child dies.
26 * in exit.c or in signal.c.
27 */
28
29 /* determines which flags the user has access to. */
30 /* 1 = access 0 = no access */
31 #define FLAG_MASK 0x00044dd5
32
33 /* set's the trap flag. */
34 #define TRAP_FLAG 0x100
35
36 /*
37 * Offset of eflags on child stack..
38 */
39 #define EFL_OFFSET ((EFL-2)*4-sizeof(struct pt_regs))
40
41 /*
42 * this routine will get a word off of the processes privileged stack.
43 * the offset is how far from the base addr as stored in the TSS.
44 * this routine assumes that all the privileged stacks are in our
45 * data space.
46 */
get_stack_long(struct task_struct * task,int offset)47 static inline int get_stack_long(struct task_struct *task, int offset)
48 {
49 unsigned char *stack;
50
51 stack = (unsigned char *)task->thread.esp0;
52 stack += offset;
53 return (*((int *)stack));
54 }
55
56 /*
57 * this routine will put a word on the processes privileged stack.
58 * the offset is how far from the base addr as stored in the TSS.
59 * this routine assumes that all the privileged stacks are in our
60 * data space.
61 */
put_stack_long(struct task_struct * task,int offset,unsigned long data)62 static inline int put_stack_long(struct task_struct *task, int offset,
63 unsigned long data)
64 {
65 unsigned char * stack;
66
67 stack = (unsigned char *) task->thread.esp0;
68 stack += offset;
69 *(unsigned long *) stack = data;
70 return 0;
71 }
72
putreg(struct task_struct * child,unsigned long regno,unsigned long value)73 static int putreg(struct task_struct *child,
74 unsigned long regno, unsigned long value)
75 {
76 switch (regno >> 2) {
77 case FS:
78 if (value && (value & 3) != 3)
79 return -EIO;
80 child->thread.fs = value;
81 return 0;
82 case GS:
83 if (value && (value & 3) != 3)
84 return -EIO;
85 child->thread.gs = value;
86 return 0;
87 case DS:
88 case ES:
89 if (value && (value & 3) != 3)
90 return -EIO;
91 value &= 0xffff;
92 break;
93 case SS:
94 case CS:
95 if ((value & 3) != 3)
96 return -EIO;
97 value &= 0xffff;
98 break;
99 case EFL:
100 value &= FLAG_MASK;
101 value |= get_stack_long(child, EFL_OFFSET) & ~FLAG_MASK;
102 break;
103 }
104 if (regno > GS*4)
105 regno -= 2*4;
106 put_stack_long(child, regno - sizeof(struct pt_regs), value);
107 return 0;
108 }
109
getreg(struct task_struct * child,unsigned long regno)110 static unsigned long getreg(struct task_struct *child,
111 unsigned long regno)
112 {
113 unsigned long retval = ~0UL;
114
115 switch (regno >> 2) {
116 case FS:
117 retval = child->thread.fs;
118 break;
119 case GS:
120 retval = child->thread.gs;
121 break;
122 case DS:
123 case ES:
124 case SS:
125 case CS:
126 retval = 0xffff;
127 /* fall through */
128 default:
129 if (regno > GS*4)
130 regno -= 2*4;
131 regno = regno - sizeof(struct pt_regs);
132 retval &= get_stack_long(child, regno);
133 }
134 return retval;
135 }
136
137 /*
138 * Called by kernel/ptrace.c when detaching..
139 *
140 * Make sure the single step bit is not set.
141 */
ptrace_disable(struct task_struct * child)142 void ptrace_disable(struct task_struct *child)
143 {
144 long tmp;
145
146 tmp = get_stack_long(child, EFL_OFFSET) & ~TRAP_FLAG;
147 put_stack_long(child, EFL_OFFSET, tmp);
148 }
149
sys_ptrace(long request,long pid,long addr,long data)150 asmlinkage int sys_ptrace(long request, long pid, long addr, long data)
151 {
152 struct task_struct *child;
153 struct user * dummy = NULL;
154 int i, ret;
155
156 lock_kernel();
157 ret = -EPERM;
158 if (request == PTRACE_TRACEME) {
159 /* are we already being traced? */
160 if (current->ptrace & PT_PTRACED)
161 goto out;
162 /* set the ptrace bit in the process flags. */
163 current->ptrace |= PT_PTRACED;
164 ret = 0;
165 goto out;
166 }
167 ret = -ESRCH;
168 read_lock(&tasklist_lock);
169 child = find_task_by_pid(pid);
170 if (child)
171 get_task_struct(child);
172 read_unlock(&tasklist_lock);
173 if (!child)
174 goto out;
175
176 ret = -EPERM;
177 if (pid == 1) /* you may not mess with init */
178 goto out_tsk;
179
180 if (request == PTRACE_ATTACH) {
181 ret = ptrace_attach(child);
182 goto out_tsk;
183 }
184
185 ret = ptrace_check_attach(child, request == PTRACE_KILL);
186 if (ret < 0)
187 goto out_tsk;
188
189 switch (request) {
190 /* when I and D space are separate, these will need to be fixed. */
191 case PTRACE_PEEKTEXT: /* read word at location addr. */
192 case PTRACE_PEEKDATA: {
193 unsigned long tmp;
194 int copied;
195
196 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
197 ret = -EIO;
198 if (copied != sizeof(tmp))
199 break;
200 ret = put_user(tmp,(unsigned long *) data);
201 break;
202 }
203
204 /* read the word at location addr in the USER area. */
205 case PTRACE_PEEKUSR: {
206 unsigned long tmp;
207
208 ret = -EIO;
209 if ((addr & 3) || addr < 0 ||
210 addr > sizeof(struct user) - 3)
211 break;
212
213 tmp = 0; /* Default return condition */
214 if(addr < FRAME_SIZE*sizeof(long))
215 tmp = getreg(child, addr);
216 if(addr >= (long) &dummy->u_debugreg[0] &&
217 addr <= (long) &dummy->u_debugreg[7]){
218 addr -= (long) &dummy->u_debugreg[0];
219 addr = addr >> 2;
220 tmp = child->thread.debugreg[addr];
221 }
222 ret = put_user(tmp,(unsigned long *) data);
223 break;
224 }
225
226 /* when I and D space are separate, this will have to be fixed. */
227 case PTRACE_POKETEXT: /* write the word at location addr. */
228 case PTRACE_POKEDATA:
229 ret = 0;
230 if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
231 break;
232 ret = -EIO;
233 break;
234
235 case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
236 ret = -EIO;
237 if ((addr & 3) || addr < 0 ||
238 addr > sizeof(struct user) - 3)
239 break;
240
241 if (addr < FRAME_SIZE*sizeof(long)) {
242 ret = putreg(child, addr, data);
243 break;
244 }
245 /* We need to be very careful here. We implicitly
246 want to modify a portion of the task_struct, and we
247 have to be selective about what portions we allow someone
248 to modify. */
249
250 ret = -EIO;
251 if(addr >= (long) &dummy->u_debugreg[0] &&
252 addr <= (long) &dummy->u_debugreg[7]){
253
254 if(addr == (long) &dummy->u_debugreg[4]) break;
255 if(addr == (long) &dummy->u_debugreg[5]) break;
256 if(addr < (long) &dummy->u_debugreg[4] &&
257 ((unsigned long) data) >= TASK_SIZE-3) break;
258
259 if(addr == (long) &dummy->u_debugreg[7]) {
260 data &= ~DR_CONTROL_RESERVED;
261 for(i=0; i<4; i++)
262 if ((0x5f54 >> ((data >> (16 + 4*i)) & 0xf)) & 1)
263 goto out_tsk;
264 }
265
266 addr -= (long) &dummy->u_debugreg;
267 addr = addr >> 2;
268 child->thread.debugreg[addr] = data;
269 ret = 0;
270 }
271 break;
272
273 case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
274 case PTRACE_CONT: { /* restart after signal. */
275 long tmp;
276
277 ret = -EIO;
278 if ((unsigned long) data > _NSIG)
279 break;
280 if (request == PTRACE_SYSCALL)
281 child->ptrace |= PT_TRACESYS;
282 else
283 child->ptrace &= ~PT_TRACESYS;
284 child->exit_code = data;
285 /* make sure the single step bit is not set. */
286 tmp = get_stack_long(child, EFL_OFFSET) & ~TRAP_FLAG;
287 put_stack_long(child, EFL_OFFSET,tmp);
288 wake_up_process(child);
289 ret = 0;
290 break;
291 }
292
293 /*
294 * make the child exit. Best I can do is send it a sigkill.
295 * perhaps it should be put in the status that it wants to
296 * exit.
297 */
298 case PTRACE_KILL: {
299 long tmp;
300
301 ret = 0;
302 if (child->state == TASK_ZOMBIE) /* already dead */
303 break;
304 child->exit_code = SIGKILL;
305 /* make sure the single step bit is not set. */
306 tmp = get_stack_long(child, EFL_OFFSET) & ~TRAP_FLAG;
307 put_stack_long(child, EFL_OFFSET, tmp);
308 wake_up_process(child);
309 break;
310 }
311
312 case PTRACE_SINGLESTEP: { /* set the trap flag. */
313 long tmp;
314
315 ret = -EIO;
316 if ((unsigned long) data > _NSIG)
317 break;
318 child->ptrace &= ~PT_TRACESYS;
319 if ((child->ptrace & PT_DTRACE) == 0) {
320 /* Spurious delayed TF traps may occur */
321 child->ptrace |= PT_DTRACE;
322 }
323 tmp = get_stack_long(child, EFL_OFFSET) | TRAP_FLAG;
324 put_stack_long(child, EFL_OFFSET, tmp);
325 child->exit_code = data;
326 /* give it a chance to run. */
327 wake_up_process(child);
328 ret = 0;
329 break;
330 }
331
332 case PTRACE_DETACH:
333 /* detach a process that was attached. */
334 ret = ptrace_detach(child, data);
335 break;
336
337 case PTRACE_GETREGS: { /* Get all gp regs from the child. */
338 if (!access_ok(VERIFY_WRITE, (unsigned *)data, FRAME_SIZE*sizeof(long))) {
339 ret = -EIO;
340 break;
341 }
342 for ( i = 0; i < FRAME_SIZE*sizeof(long); i += sizeof(long) ) {
343 __put_user(getreg(child, i),(unsigned long *) data);
344 data += sizeof(long);
345 }
346 ret = 0;
347 break;
348 }
349
350 case PTRACE_SETREGS: { /* Set all gp regs in the child. */
351 unsigned long tmp;
352 if (!access_ok(VERIFY_READ, (unsigned *)data, FRAME_SIZE*sizeof(long))) {
353 ret = -EIO;
354 break;
355 }
356 for ( i = 0; i < FRAME_SIZE*sizeof(long); i += sizeof(long) ) {
357 __get_user(tmp, (unsigned long *) data);
358 putreg(child, i, tmp);
359 data += sizeof(long);
360 }
361 ret = 0;
362 break;
363 }
364
365 case PTRACE_GETFPREGS: { /* Get the child FPU state. */
366 if (!access_ok(VERIFY_WRITE, (unsigned *)data,
367 sizeof(struct user_i387_struct))) {
368 ret = -EIO;
369 break;
370 }
371 ret = 0;
372 if ( !child->used_math )
373 load_empty_fpu(child);
374 get_fpregs((struct user_i387_struct *)data, child);
375 break;
376 }
377
378 case PTRACE_SETFPREGS: { /* Set the child FPU state. */
379 if (!access_ok(VERIFY_READ, (unsigned *)data,
380 sizeof(struct user_i387_struct))) {
381 ret = -EIO;
382 break;
383 }
384 child->used_math = 1;
385 set_fpregs(child, (struct user_i387_struct *)data);
386 ret = 0;
387 break;
388 }
389
390 case PTRACE_GETFPXREGS: { /* Get the child extended FPU state. */
391 if (!access_ok(VERIFY_WRITE, (unsigned *)data,
392 sizeof(struct user_fxsr_struct))) {
393 ret = -EIO;
394 break;
395 }
396 if ( !child->used_math )
397 load_empty_fpu(child);
398 ret = get_fpxregs((struct user_fxsr_struct *)data, child);
399 break;
400 }
401
402 case PTRACE_SETFPXREGS: { /* Set the child extended FPU state. */
403 if (!access_ok(VERIFY_READ, (unsigned *)data,
404 sizeof(struct user_fxsr_struct))) {
405 ret = -EIO;
406 break;
407 }
408 child->used_math = 1;
409 ret = set_fpxregs(child, (struct user_fxsr_struct *)data);
410 break;
411 }
412
413 case PTRACE_SETOPTIONS: {
414 if (data & PTRACE_O_TRACESYSGOOD)
415 child->ptrace |= PT_TRACESYSGOOD;
416 else
417 child->ptrace &= ~PT_TRACESYSGOOD;
418 ret = 0;
419 break;
420 }
421
422 default:
423 ret = -EIO;
424 break;
425 }
426 out_tsk:
427 free_task_struct(child);
428 out:
429 unlock_kernel();
430 return ret;
431 }
432
syscall_trace(void)433 asmlinkage void syscall_trace(void)
434 {
435 if ((current->ptrace & (PT_PTRACED|PT_TRACESYS)) !=
436 (PT_PTRACED|PT_TRACESYS))
437 return;
438 /* the 0x80 provides a way for the tracing parent to distinguish
439 between a syscall stop and SIGTRAP delivery */
440 current->exit_code = SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
441 ? 0x80 : 0);
442 current->state = TASK_STOPPED;
443 notify_parent(current, SIGCHLD);
444 schedule();
445 /*
446 * this isn't the same as continuing with a signal, but it will do
447 * for normal use. strace only continues with a signal if the
448 * stopping signal is not SIGTRAP. -brl
449 */
450 if (current->exit_code) {
451 send_sig(current->exit_code, current, 1);
452 current->exit_code = 0;
453 }
454 }
455