xref: /linux/arch/mips/kernel/ptrace.c (revision 858259cf7d1c443c836a2022b78cb281f0a9b95e) 
1 /*
2  * This file is subject to the terms and conditions of the GNU General Public
3  * License.  See the file "COPYING" in the main directory of this archive
4  * for more details.
5  *
6  * Copyright (C) 1992 Ross Biro
7  * Copyright (C) Linus Torvalds
8  * Copyright (C) 1994, 95, 96, 97, 98, 2000 Ralf Baechle
9  * Copyright (C) 1996 David S. Miller
10  * Kevin D. Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
11  * Copyright (C) 1999 MIPS Technologies, Inc.
12  * Copyright (C) 2000 Ulf Carlsson
13  *
14  * At this time Linux/MIPS64 only supports syscall tracing, even for 32-bit
15  * binaries.
16  */
17 #include <linux/config.h>
18 #include <linux/compiler.h>
19 #include <linux/kernel.h>
20 #include <linux/sched.h>
21 #include <linux/mm.h>
22 #include <linux/errno.h>
23 #include <linux/ptrace.h>
24 #include <linux/audit.h>
25 #include <linux/smp.h>
26 #include <linux/smp_lock.h>
27 #include <linux/user.h>
28 #include <linux/security.h>
29 #include <linux/signal.h>
30 
31 #include <asm/byteorder.h>
32 #include <asm/cpu.h>
33 #include <asm/dsp.h>
34 #include <asm/fpu.h>
35 #include <asm/mipsregs.h>
36 #include <asm/mipsmtregs.h>
37 #include <asm/pgtable.h>
38 #include <asm/page.h>
39 #include <asm/system.h>
40 #include <asm/uaccess.h>
41 #include <asm/bootinfo.h>
42 #include <asm/reg.h>
43 
44 /*
45  * Called by kernel/ptrace.c when detaching..
46  *
47  * Make sure single step bits etc are not set.
48  */
49 void ptrace_disable(struct task_struct *child)
50 {
51 	/* Nothing to do.. */
52 }
53 
54 /*
55  * Read a general register set.  We always use the 64-bit format, even
56  * for 32-bit kernels and for 32-bit processes on a 64-bit kernel.
57  * Registers are sign extended to fill the available space.
58  */
59 int ptrace_getregs (struct task_struct *child, __s64 __user *data)
60 {
61 	struct pt_regs *regs;
62 	int i;
63 
64 	if (!access_ok(VERIFY_WRITE, data, 38 * 8))
65 		return -EIO;
66 
67 	regs = (struct pt_regs *) ((unsigned long) child->thread_info +
68 	       THREAD_SIZE - 32 - sizeof(struct pt_regs));
69 
70 	for (i = 0; i < 32; i++)
71 		__put_user (regs->regs[i], data + i);
72 	__put_user (regs->lo, data + EF_LO - EF_R0);
73 	__put_user (regs->hi, data + EF_HI - EF_R0);
74 	__put_user (regs->cp0_epc, data + EF_CP0_EPC - EF_R0);
75 	__put_user (regs->cp0_badvaddr, data + EF_CP0_BADVADDR - EF_R0);
76 	__put_user (regs->cp0_status, data + EF_CP0_STATUS - EF_R0);
77 	__put_user (regs->cp0_cause, data + EF_CP0_CAUSE - EF_R0);
78 
79 	return 0;
80 }
81 
82 /*
83  * Write a general register set.  As for PTRACE_GETREGS, we always use
84  * the 64-bit format.  On a 32-bit kernel only the lower order half
85  * (according to endianness) will be used.
86  */
87 int ptrace_setregs (struct task_struct *child, __s64 __user *data)
88 {
89 	struct pt_regs *regs;
90 	int i;
91 
92 	if (!access_ok(VERIFY_READ, data, 38 * 8))
93 		return -EIO;
94 
95 	regs = (struct pt_regs *) ((unsigned long) child->thread_info +
96 	       THREAD_SIZE - 32 - sizeof(struct pt_regs));
97 
98 	for (i = 0; i < 32; i++)
99 		__get_user (regs->regs[i], data + i);
100 	__get_user (regs->lo, data + EF_LO - EF_R0);
101 	__get_user (regs->hi, data + EF_HI - EF_R0);
102 	__get_user (regs->cp0_epc, data + EF_CP0_EPC - EF_R0);
103 
104 	/* badvaddr, status, and cause may not be written.  */
105 
106 	return 0;
107 }
108 
109 int ptrace_getfpregs (struct task_struct *child, __u32 __user *data)
110 {
111 	int i;
112 
113 	if (!access_ok(VERIFY_WRITE, data, 33 * 8))
114 		return -EIO;
115 
116 	if (tsk_used_math(child)) {
117 		fpureg_t *fregs = get_fpu_regs(child);
118 		for (i = 0; i < 32; i++)
119 			__put_user (fregs[i], i + (__u64 __user *) data);
120 	} else {
121 		for (i = 0; i < 32; i++)
122 			__put_user ((__u64) -1, i + (__u64 __user *) data);
123 	}
124 
125 	if (cpu_has_fpu) {
126 		unsigned int flags, tmp;
127 
128 		__put_user (child->thread.fpu.hard.fcr31, data + 64);
129 
130 		preempt_disable();
131 		if (cpu_has_mipsmt) {
132 			unsigned int vpflags = dvpe();
133 			flags = read_c0_status();
134 			__enable_fpu();
135 			__asm__ __volatile__("cfc1\t%0,$0" : "=r" (tmp));
136 			write_c0_status(flags);
137 			evpe(vpflags);
138 		} else {
139 			flags = read_c0_status();
140 			__enable_fpu();
141 			__asm__ __volatile__("cfc1\t%0,$0" : "=r" (tmp));
142 			write_c0_status(flags);
143 		}
144 		preempt_enable();
145 		__put_user (tmp, data + 65);
146 	} else {
147 		__put_user (child->thread.fpu.soft.fcr31, data + 64);
148 		__put_user ((__u32) 0, data + 65);
149 	}
150 
151 	return 0;
152 }
153 
154 int ptrace_setfpregs (struct task_struct *child, __u32 __user *data)
155 {
156 	fpureg_t *fregs;
157 	int i;
158 
159 	if (!access_ok(VERIFY_READ, data, 33 * 8))
160 		return -EIO;
161 
162 	fregs = get_fpu_regs(child);
163 
164 	for (i = 0; i < 32; i++)
165 		__get_user (fregs[i], i + (__u64 __user *) data);
166 
167 	if (cpu_has_fpu)
168 		__get_user (child->thread.fpu.hard.fcr31, data + 64);
169 	else
170 		__get_user (child->thread.fpu.soft.fcr31, data + 64);
171 
172 	/* FIR may not be written.  */
173 
174 	return 0;
175 }
176 
177 asmlinkage long sys_ptrace(long request, long pid, long addr, long data)
178 {
179 	struct task_struct *child;
180 	int ret;
181 
182 #if 0
183 	printk("ptrace(r=%d,pid=%d,addr=%08lx,data=%08lx)\n",
184 	       (int) request, (int) pid, (unsigned long) addr,
185 	       (unsigned long) data);
186 #endif
187 	lock_kernel();
188 	ret = -EPERM;
189 	if (request == PTRACE_TRACEME) {
190 		/* are we already being traced? */
191 		if (current->ptrace & PT_PTRACED)
192 			goto out;
193 		if ((ret = security_ptrace(current->parent, current)))
194 			goto out;
195 		/* set the ptrace bit in the process flags. */
196 		current->ptrace |= PT_PTRACED;
197 		ret = 0;
198 		goto out;
199 	}
200 	ret = -ESRCH;
201 	read_lock(&tasklist_lock);
202 	child = find_task_by_pid(pid);
203 	if (child)
204 		get_task_struct(child);
205 	read_unlock(&tasklist_lock);
206 	if (!child)
207 		goto out;
208 
209 	ret = -EPERM;
210 	if (pid == 1)		/* you may not mess with init */
211 		goto out_tsk;
212 
213 	if (request == PTRACE_ATTACH) {
214 		ret = ptrace_attach(child);
215 		goto out_tsk;
216 	}
217 
218 	ret = ptrace_check_attach(child, request == PTRACE_KILL);
219 	if (ret < 0)
220 		goto out_tsk;
221 
222 	switch (request) {
223 	/* when I and D space are separate, these will need to be fixed. */
224 	case PTRACE_PEEKTEXT: /* read word at location addr. */
225 	case PTRACE_PEEKDATA: {
226 		unsigned long tmp;
227 		int copied;
228 
229 		copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
230 		ret = -EIO;
231 		if (copied != sizeof(tmp))
232 			break;
233 		ret = put_user(tmp,(unsigned long __user *) data);
234 		break;
235 	}
236 
237 	/* Read the word at location addr in the USER area. */
238 	case PTRACE_PEEKUSR: {
239 		struct pt_regs *regs;
240 		unsigned long tmp = 0;
241 
242 		regs = (struct pt_regs *) ((unsigned long) child->thread_info +
243 		       THREAD_SIZE - 32 - sizeof(struct pt_regs));
244 		ret = 0;  /* Default return value. */
245 
246 		switch (addr) {
247 		case 0 ... 31:
248 			tmp = regs->regs[addr];
249 			break;
250 		case FPR_BASE ... FPR_BASE + 31:
251 			if (tsk_used_math(child)) {
252 				fpureg_t *fregs = get_fpu_regs(child);
253 
254 #ifdef CONFIG_32BIT
255 				/*
256 				 * The odd registers are actually the high
257 				 * order bits of the values stored in the even
258 				 * registers - unless we're using r2k_switch.S.
259 				 */
260 				if (addr & 1)
261 					tmp = (unsigned long) (fregs[((addr & ~1) - 32)] >> 32);
262 				else
263 					tmp = (unsigned long) (fregs[(addr - 32)] & 0xffffffff);
264 #endif
265 #ifdef CONFIG_64BIT
266 				tmp = fregs[addr - FPR_BASE];
267 #endif
268 			} else {
269 				tmp = -1;	/* FP not yet used  */
270 			}
271 			break;
272 		case PC:
273 			tmp = regs->cp0_epc;
274 			break;
275 		case CAUSE:
276 			tmp = regs->cp0_cause;
277 			break;
278 		case BADVADDR:
279 			tmp = regs->cp0_badvaddr;
280 			break;
281 		case MMHI:
282 			tmp = regs->hi;
283 			break;
284 		case MMLO:
285 			tmp = regs->lo;
286 			break;
287 		case FPC_CSR:
288 			if (cpu_has_fpu)
289 				tmp = child->thread.fpu.hard.fcr31;
290 			else
291 				tmp = child->thread.fpu.soft.fcr31;
292 			break;
293 		case FPC_EIR: {	/* implementation / version register */
294 			unsigned int flags;
295 
296 			if (!cpu_has_fpu)
297 				break;
298 
299 			preempt_disable();
300 			if (cpu_has_mipsmt) {
301 				unsigned int vpflags = dvpe();
302 				flags = read_c0_status();
303 				__enable_fpu();
304 				__asm__ __volatile__("cfc1\t%0,$0": "=r" (tmp));
305 				write_c0_status(flags);
306 				evpe(vpflags);
307 			} else {
308 				flags = read_c0_status();
309 				__enable_fpu();
310 				__asm__ __volatile__("cfc1\t%0,$0": "=r" (tmp));
311 				write_c0_status(flags);
312 			}
313 			preempt_enable();
314 			break;
315 		}
316 		case DSP_BASE ... DSP_BASE + 5: {
317 			dspreg_t *dregs;
318 
319 			if (!cpu_has_dsp) {
320 				tmp = 0;
321 				ret = -EIO;
322 				goto out_tsk;
323 			}
324 			if (child->thread.dsp.used_dsp) {
325 				dregs = __get_dsp_regs(child);
326 				tmp = (unsigned long) (dregs[addr - DSP_BASE]);
327 			} else {
328 				tmp = -1;	/* DSP registers yet used  */
329 			}
330 			break;
331 		}
332 		case DSP_CONTROL:
333 			if (!cpu_has_dsp) {
334 				tmp = 0;
335 				ret = -EIO;
336 				goto out_tsk;
337 			}
338 			tmp = child->thread.dsp.dspcontrol;
339 			break;
340 		default:
341 			tmp = 0;
342 			ret = -EIO;
343 			goto out_tsk;
344 		}
345 		ret = put_user(tmp, (unsigned long __user *) data);
346 		break;
347 	}
348 
349 	/* when I and D space are separate, this will have to be fixed. */
350 	case PTRACE_POKETEXT: /* write the word at location addr. */
351 	case PTRACE_POKEDATA:
352 		ret = 0;
353 		if (access_process_vm(child, addr, &data, sizeof(data), 1)
354 		    == sizeof(data))
355 			break;
356 		ret = -EIO;
357 		break;
358 
359 	case PTRACE_POKEUSR: {
360 		struct pt_regs *regs;
361 		ret = 0;
362 		regs = (struct pt_regs *) ((unsigned long) child->thread_info +
363 		       THREAD_SIZE - 32 - sizeof(struct pt_regs));
364 
365 		switch (addr) {
366 		case 0 ... 31:
367 			regs->regs[addr] = data;
368 			break;
369 		case FPR_BASE ... FPR_BASE + 31: {
370 			fpureg_t *fregs = get_fpu_regs(child);
371 
372 			if (!tsk_used_math(child)) {
373 				/* FP not yet used  */
374 				memset(&child->thread.fpu.hard, ~0,
375 				       sizeof(child->thread.fpu.hard));
376 				child->thread.fpu.hard.fcr31 = 0;
377 			}
378 #ifdef CONFIG_32BIT
379 			/*
380 			 * The odd registers are actually the high order bits
381 			 * of the values stored in the even registers - unless
382 			 * we're using r2k_switch.S.
383 			 */
384 			if (addr & 1) {
385 				fregs[(addr & ~1) - FPR_BASE] &= 0xffffffff;
386 				fregs[(addr & ~1) - FPR_BASE] |= ((unsigned long long) data) << 32;
387 			} else {
388 				fregs[addr - FPR_BASE] &= ~0xffffffffLL;
389 				fregs[addr - FPR_BASE] |= data;
390 			}
391 #endif
392 #ifdef CONFIG_64BIT
393 			fregs[addr - FPR_BASE] = data;
394 #endif
395 			break;
396 		}
397 		case PC:
398 			regs->cp0_epc = data;
399 			break;
400 		case MMHI:
401 			regs->hi = data;
402 			break;
403 		case MMLO:
404 			regs->lo = data;
405 			break;
406 		case FPC_CSR:
407 			if (cpu_has_fpu)
408 				child->thread.fpu.hard.fcr31 = data;
409 			else
410 				child->thread.fpu.soft.fcr31 = data;
411 			break;
412 		case DSP_BASE ... DSP_BASE + 5: {
413 			dspreg_t *dregs;
414 
415 			if (!cpu_has_dsp) {
416 				ret = -EIO;
417 				break;
418 			}
419 
420 			dregs = __get_dsp_regs(child);
421 			dregs[addr - DSP_BASE] = data;
422 			break;
423 		}
424 		case DSP_CONTROL:
425 			if (!cpu_has_dsp) {
426 				ret = -EIO;
427 				break;
428 			}
429 			child->thread.dsp.dspcontrol = data;
430 			break;
431 		default:
432 			/* The rest are not allowed. */
433 			ret = -EIO;
434 			break;
435 		}
436 		break;
437 		}
438 
439 	case PTRACE_GETREGS:
440 		ret = ptrace_getregs (child, (__u64 __user *) data);
441 		break;
442 
443 	case PTRACE_SETREGS:
444 		ret = ptrace_setregs (child, (__u64 __user *) data);
445 		break;
446 
447 	case PTRACE_GETFPREGS:
448 		ret = ptrace_getfpregs (child, (__u32 __user *) data);
449 		break;
450 
451 	case PTRACE_SETFPREGS:
452 		ret = ptrace_setfpregs (child, (__u32 __user *) data);
453 		break;
454 
455 	case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
456 	case PTRACE_CONT: { /* restart after signal. */
457 		ret = -EIO;
458 		if (!valid_signal(data))
459 			break;
460 		if (request == PTRACE_SYSCALL) {
461 			set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
462 		}
463 		else {
464 			clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
465 		}
466 		child->exit_code = data;
467 		wake_up_process(child);
468 		ret = 0;
469 		break;
470 	}
471 
472 	/*
473 	 * make the child exit.  Best I can do is send it a sigkill.
474 	 * perhaps it should be put in the status that it wants to
475 	 * exit.
476 	 */
477 	case PTRACE_KILL:
478 		ret = 0;
479 		if (child->exit_state == EXIT_ZOMBIE)	/* already dead */
480 			break;
481 		child->exit_code = SIGKILL;
482 		wake_up_process(child);
483 		break;
484 
485 	case PTRACE_DETACH: /* detach a process that was attached. */
486 		ret = ptrace_detach(child, data);
487 		break;
488 
489 	case PTRACE_GET_THREAD_AREA:
490 		ret = put_user(child->thread_info->tp_value,
491 				(unsigned long __user *) data);
492 		break;
493 
494 	default:
495 		ret = ptrace_request(child, request, addr, data);
496 		break;
497 	}
498 
499 out_tsk:
500 	put_task_struct(child);
501 out:
502 	unlock_kernel();
503 	return ret;
504 }
505 
506 static inline int audit_arch(void)
507 {
508 	int arch = EM_MIPS;
509 #ifdef CONFIG_64BIT
510 	arch |=  __AUDIT_ARCH_64BIT;
511 #endif
512 #if defined(__LITTLE_ENDIAN)
513 	arch |=  __AUDIT_ARCH_LE;
514 #endif
515 	return arch;
516 }
517 
518 /*
519  * Notification of system call entry/exit
520  * - triggered by current->work.syscall_trace
521  */
522 asmlinkage void do_syscall_trace(struct pt_regs *regs, int entryexit)
523 {
524 	if (unlikely(current->audit_context) && entryexit)
525 		audit_syscall_exit(current, AUDITSC_RESULT(regs->regs[2]),
526 		                   regs->regs[2]);
527 
528 	if (!(current->ptrace & PT_PTRACED))
529 		goto out;
530 	if (!test_thread_flag(TIF_SYSCALL_TRACE))
531 		goto out;
532 
533 	/* The 0x80 provides a way for the tracing parent to distinguish
534 	   between a syscall stop and SIGTRAP delivery */
535 	ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) ?
536 	                         0x80 : 0));
537 
538 	/*
539 	 * this isn't the same as continuing with a signal, but it will do
540 	 * for normal use.  strace only continues with a signal if the
541 	 * stopping signal is not SIGTRAP.  -brl
542 	 */
543 	if (current->exit_code) {
544 		send_sig(current->exit_code, current, 1);
545 		current->exit_code = 0;
546 	}
547  out:
548 	if (unlikely(current->audit_context) && !entryexit)
549 		audit_syscall_entry(current, audit_arch(), regs->regs[2],
550 				    regs->regs[4], regs->regs[5],
551 				    regs->regs[6], regs->regs[7]);
552 }
553