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 * x86-64 port 2000-2002 Andi Kleen
8 */
9
10 #include <linux/kernel.h>
11 #include <linux/sched.h>
12 #include <linux/mm.h>
13 #include <linux/smp.h>
14 #include <linux/smp_lock.h>
15 #include <linux/errno.h>
16 #include <linux/ptrace.h>
17 #include <linux/user.h>
18
19 #include <asm/uaccess.h>
20 #include <asm/pgtable.h>
21 #include <asm/system.h>
22 #include <asm/processor.h>
23 #include <asm/i387.h>
24 #include <asm/debugreg.h>
25
26 /*
27 * does not yet catch signals sent when the child dies.
28 * in exit.c or in signal.c.
29 */
30
31 /* determines which flags the user has access to. */
32 /* 1 = access 0 = no access */
33 #define FLAG_MASK 0x44dd5UL
34
35 /* set's the trap flag. */
36 #define TRAP_FLAG 0x100UL
37
38 /*
39 * eflags and offset of eflags on child stack..
40 */
41 #define EFLAGS offsetof(struct pt_regs, eflags)
42 #define EFL_OFFSET ((int)(EFLAGS-sizeof(struct pt_regs)))
43
44 /*
45 * this routine will get a word off of the processes privileged stack.
46 * the offset is how far from the base addr as stored in the TSS.
47 * this routine assumes that all the privileged stacks are in our
48 * data space.
49 */
get_stack_long(struct task_struct * task,int offset)50 static inline unsigned long get_stack_long(struct task_struct *task, int offset)
51 {
52 unsigned char *stack;
53
54 stack = (unsigned char *)task->thread.rsp0;
55 stack += offset;
56 return (*((unsigned long *)stack));
57 }
58
59 /*
60 * this routine will put a word on the processes privileged stack.
61 * the offset is how far from the base addr as stored in the TSS.
62 * this routine assumes that all the privileged stacks are in our
63 * data space.
64 */
put_stack_long(struct task_struct * task,int offset,unsigned long data)65 static inline long put_stack_long(struct task_struct *task, int offset,
66 unsigned long data)
67 {
68 unsigned char * stack;
69
70 stack = (unsigned char *) task->thread.rsp0;
71 stack += offset;
72 *(unsigned long *) stack = data;
73 return 0;
74 }
75
76 /*
77 * Called by kernel/ptrace.c when detaching..
78 *
79 * Make sure the single step bit is not set.
80 */
ptrace_disable(struct task_struct * child)81 void ptrace_disable(struct task_struct *child)
82 {
83 long tmp;
84
85 tmp = get_stack_long(child, EFL_OFFSET) & ~TRAP_FLAG;
86 put_stack_long(child, EFL_OFFSET, tmp);
87 }
88
putreg(struct task_struct * child,unsigned long regno,unsigned long value)89 static int putreg(struct task_struct *child,
90 unsigned long regno, unsigned long value)
91 {
92 unsigned long tmp;
93 if (child->thread.flags & THREAD_IA32)
94 value &= 0xffffffff;
95 switch (regno) {
96 case offsetof(struct user_regs_struct,fs):
97 if (value && (value & 3) != 3)
98 return -EIO;
99 child->thread.fsindex = value & 0xffff;
100 return 0;
101 case offsetof(struct user_regs_struct,gs):
102 if (value && (value & 3) != 3)
103 return -EIO;
104 child->thread.gsindex = value & 0xffff;
105 return 0;
106 case offsetof(struct user_regs_struct,ds):
107 if (value && (value & 3) != 3)
108 return -EIO;
109 child->thread.ds = value & 0xffff;
110 return 0;
111 case offsetof(struct user_regs_struct,es):
112 if (value && (value & 3) != 3)
113 return -EIO;
114 child->thread.es = value & 0xffff;
115 return 0;
116 case offsetof(struct user_regs_struct,fs_base):
117 if (value >= TASK_SIZE)
118 return -EIO;
119 child->thread.fs = value;
120 return 0;
121 case offsetof(struct user_regs_struct,gs_base):
122 if (value >= TASK_SIZE)
123 return -EIO;
124 child->thread.gs = value;
125 return 0;
126 case offsetof(struct user_regs_struct, eflags):
127 value &= FLAG_MASK;
128 tmp = get_stack_long(child, EFL_OFFSET);
129 tmp &= ~FLAG_MASK;
130 value |= tmp;
131 break;
132 case offsetof(struct user_regs_struct,cs):
133 if ((value & 3) != 3)
134 return -EIO;
135 value &= 0xffff;
136 break;
137 case offsetof(struct user_regs_struct,ss):
138 if ((value & 3) != 3)
139 return -EIO;
140 value &= 0xffff;
141 break;
142 case offsetof(struct user_regs_struct, rip):
143 /* Check if the new RIP address is canonical */
144 if (value >= TASK_SIZE)
145 return -EIO;
146 break;
147 }
148 put_stack_long(child, regno - sizeof(struct pt_regs), value);
149 return 0;
150 }
151
getreg(struct task_struct * child,unsigned long regno)152 static unsigned long getreg(struct task_struct *child, unsigned long regno)
153 {
154 unsigned long val;
155 switch (regno) {
156 case offsetof(struct user_regs_struct, fs):
157 return child->thread.fsindex;
158 case offsetof(struct user_regs_struct, gs):
159 return child->thread.gsindex;
160 case offsetof(struct user_regs_struct, ds):
161 return child->thread.ds;
162 case offsetof(struct user_regs_struct, es):
163 return child->thread.es;
164 case offsetof(struct user_regs_struct, fs_base):
165 return child->thread.fs;
166 case offsetof(struct user_regs_struct, gs_base):
167 return child->thread.gs;
168 default:
169 regno = regno - sizeof(struct pt_regs);
170 val = get_stack_long(child, regno);
171 if (child->thread.flags & THREAD_IA32)
172 val &= 0xffffffff;
173 return val;
174 }
175
176 }
177
sys_ptrace(long request,long pid,long addr,long data)178 asmlinkage long sys_ptrace(long request, long pid, long addr, long data)
179 {
180 struct task_struct *child;
181 struct user * dummy = NULL;
182 long i, ret;
183
184 /* This lock_kernel fixes a subtle race with suid exec */
185 lock_kernel();
186 ret = -EPERM;
187 if (request == PTRACE_TRACEME) {
188 /* are we already being traced? */
189 if (current->ptrace & PT_PTRACED)
190 goto out;
191 /* set the ptrace bit in the process flags. */
192 current->ptrace |= PT_PTRACED;
193 ret = 0;
194 goto out;
195 }
196 ret = -ESRCH;
197 read_lock(&tasklist_lock);
198 child = find_task_by_pid(pid);
199 if (child)
200 get_task_struct(child);
201 read_unlock(&tasklist_lock);
202 if (!child)
203 goto out;
204
205 ret = -EPERM;
206 if (pid == 1) /* you may not mess with init */
207 goto out_tsk;
208
209 if (request == PTRACE_ATTACH) {
210 ret = ptrace_attach(child);
211 goto out_tsk;
212 }
213 ret = ptrace_check_attach(child, request == PTRACE_KILL);
214 if (ret < 0)
215 goto out_tsk;
216
217 switch (request) {
218 /* when I and D space are separate, these will need to be fixed. */
219 case PTRACE_PEEKTEXT: /* read word at location addr. */
220 case PTRACE_PEEKDATA: {
221 unsigned long tmp;
222 int copied;
223
224 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
225 ret = -EIO;
226 if (copied != sizeof(tmp))
227 break;
228 ret = put_user(tmp,(unsigned long *) data);
229 break;
230 }
231
232 /* read the word at location addr in the USER area. */
233 case PTRACE_PEEKUSR: {
234 unsigned long tmp;
235
236 ret = -EIO;
237 if ((addr & 7) || addr < 0 ||
238 addr > sizeof(struct user) - 7)
239 break;
240
241 tmp = 0; /* Default return condition */
242 if(addr < sizeof(struct user_regs_struct))
243 tmp = getreg(child, addr);
244 if(addr >= (long) &dummy->u_debugreg[0] &&
245 addr <= (long) &dummy->u_debugreg[7]){
246 addr -= (long) &dummy->u_debugreg[0];
247 addr = addr >> 3;
248 tmp = child->thread.debugreg[addr];
249 }
250 ret = put_user(tmp,(unsigned long *) data);
251 break;
252 }
253
254 /* when I and D space are separate, this will have to be fixed. */
255 case PTRACE_POKETEXT: /* write the word at location addr. */
256 case PTRACE_POKEDATA:
257 ret = 0;
258 if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
259 break;
260 ret = -EIO;
261 break;
262
263 case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
264 ret = -EIO;
265 if ((addr & 7) || addr < 0 ||
266 addr > sizeof(struct user) - 7)
267 break;
268
269 if (addr < sizeof(struct user_regs_struct)) {
270 ret = putreg(child, addr, data);
271 break;
272 }
273 /* We need to be very careful here. We implicitly
274 want to modify a portion of the task_struct, and we
275 have to be selective about what portions we allow someone
276 to modify. */
277
278 ret = -EIO;
279 if(addr >= (long) &dummy->u_debugreg[0] &&
280 addr <= (long) &dummy->u_debugreg[7]){
281
282 if(addr == (long) &dummy->u_debugreg[4]) break;
283 if(addr == (long) &dummy->u_debugreg[5]) break;
284 if(addr < (long) &dummy->u_debugreg[4] &&
285 ((unsigned long) data) >= TASK_SIZE-3) break;
286
287 if (addr == (long) &dummy->u_debugreg[6]) {
288 if (data >> 32)
289 goto out_tsk;
290 }
291
292 if(addr == (long) &dummy->u_debugreg[7]) {
293 data &= ~DR_CONTROL_RESERVED;
294 for(i=0; i<4; i++)
295 if ((0x5454 >> ((data >> (16 + 4*i)) & 0xf)) & 1)
296 goto out_tsk;
297 }
298
299 addr -= (long) &dummy->u_debugreg;
300 addr = addr >> 3;
301 child->thread.debugreg[addr] = data;
302 ret = 0;
303 }
304 break;
305
306 case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
307 case PTRACE_CONT: { /* restart after signal. */
308 long tmp;
309
310 ret = -EIO;
311 if ((unsigned long) data > _NSIG)
312 break;
313 if (request == PTRACE_SYSCALL)
314 child->ptrace |= PT_TRACESYS;
315 else
316 child->ptrace &= ~PT_TRACESYS;
317 child->exit_code = data;
318 /* make sure the single step bit is not set. */
319 tmp = get_stack_long(child, EFL_OFFSET);
320 tmp &= ~TRAP_FLAG;
321 put_stack_long(child, EFL_OFFSET,tmp);
322 wake_up_process(child);
323 ret = 0;
324 break;
325 }
326
327 /*
328 * make the child exit. Best I can do is send it a sigkill.
329 * perhaps it should be put in the status that it wants to
330 * exit.
331 */
332 case PTRACE_KILL: {
333 long tmp;
334
335 ret = 0;
336 if (child->state == TASK_ZOMBIE) /* already dead */
337 break;
338 child->exit_code = SIGKILL;
339 /* make sure the single step bit is not set. */
340 tmp = get_stack_long(child, EFL_OFFSET) & ~TRAP_FLAG;
341 put_stack_long(child, EFL_OFFSET, tmp);
342 wake_up_process(child);
343 break;
344 }
345
346 case PTRACE_SINGLESTEP: { /* set the trap flag. */
347 long tmp;
348
349 ret = -EIO;
350 if ((unsigned long) data > _NSIG)
351 break;
352 child->ptrace &= ~PT_TRACESYS;
353 if ((child->ptrace & PT_DTRACE) == 0) {
354 /* Spurious delayed TF traps may occur */
355 child->ptrace |= PT_DTRACE;
356 }
357 tmp = get_stack_long(child, EFL_OFFSET) | TRAP_FLAG;
358 put_stack_long(child, EFL_OFFSET, tmp);
359 child->exit_code = data;
360 /* give it a chance to run. */
361 wake_up_process(child);
362 ret = 0;
363 break;
364 }
365
366 case PTRACE_DETACH:
367 /* detach a process that was attached. */
368 ret = ptrace_detach(child, data);
369 break;
370
371 case PTRACE_GETREGS: { /* Get all gp regs from the child. */
372 if (!access_ok(VERIFY_WRITE, (unsigned *)data, FRAME_SIZE)) {
373 ret = -EIO;
374 break;
375 }
376 for ( i = 0; i < sizeof(struct user_regs_struct); i += sizeof(long) ) {
377 __put_user(getreg(child, i),(unsigned long *) data);
378 data += sizeof(long);
379 }
380 ret = 0;
381 break;
382 }
383
384 case PTRACE_SETREGS: { /* Set all gp regs in the child. */
385 unsigned long tmp;
386 if (!access_ok(VERIFY_READ, (unsigned *)data, FRAME_SIZE)) {
387 ret = -EIO;
388 break;
389 }
390 for ( i = 0; i < sizeof(struct user_regs_struct); i += sizeof(long) ) {
391 __get_user(tmp, (unsigned long *) data);
392 putreg(child, i, tmp);
393 data += sizeof(long);
394 }
395 ret = 0;
396 break;
397 }
398
399 case PTRACE_GETFPREGS: { /* Get the child extended FPU state. */
400 if (!access_ok(VERIFY_WRITE, (unsigned *)data,
401 sizeof(struct user_i387_struct))) {
402 ret = -EIO;
403 break;
404 }
405 ret = get_fpregs((struct user_i387_struct *)data, child);
406 break;
407 }
408
409 case PTRACE_SETFPREGS: { /* Set the child extended FPU state. */
410 if (!access_ok(VERIFY_READ, (unsigned *)data,
411 sizeof(struct user_i387_struct))) {
412 ret = -EIO;
413 break;
414 }
415 unlazy_fpu(child);
416 ret = set_fpregs(child, (struct user_i387_struct *)data);
417 if (!ret)
418 child->used_math = 1;
419 break;
420 }
421
422 case PTRACE_SETOPTIONS: {
423 if (data & PTRACE_O_TRACESYSGOOD)
424 child->ptrace |= PT_TRACESYSGOOD;
425 else
426 child->ptrace &= ~PT_TRACESYSGOOD;
427 ret = 0;
428 break;
429 }
430
431 default:
432 ret = -EIO;
433 break;
434 }
435 out_tsk:
436 free_task_struct(child);
437 out:
438 unlock_kernel();
439 return ret;
440 }
441
syscall_trace(struct pt_regs * regs)442 asmlinkage void syscall_trace(struct pt_regs *regs)
443 {
444 if ((current->ptrace & (PT_PTRACED|PT_TRACESYS)) !=
445 (PT_PTRACED|PT_TRACESYS))
446 return;
447
448 current->exit_code = SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
449 ? 0x80 : 0);
450 current->state = TASK_STOPPED;
451 notify_parent(current, SIGCHLD);
452 schedule();
453 /*
454 * this isn't the same as continuing with a signal, but it will do
455 * for normal use. strace only continues with a signal if the
456 * stopping signal is not SIGTRAP. -brl
457 */
458 if (current->exit_code) {
459 send_sig(current->exit_code, current, 1);
460 current->exit_code = 0;
461 }
462 }
463