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1da177e4 LT |
1 | /* ptrace.c */ |
2 | /* By Ross Biro 1/23/92 */ | |
3 | /* edited by Linus Torvalds */ | |
4 | /* mangled further by Bob Manson (manson@santafe.edu) */ | |
5 | /* more mutilation by David Mosberger (davidm@azstarnet.com) */ | |
6 | ||
7 | #include <linux/kernel.h> | |
8 | #include <linux/sched.h> | |
9 | #include <linux/mm.h> | |
10 | #include <linux/smp.h> | |
11 | #include <linux/smp_lock.h> | |
12 | #include <linux/errno.h> | |
13 | #include <linux/ptrace.h> | |
14 | #include <linux/user.h> | |
15 | #include <linux/slab.h> | |
16 | #include <linux/security.h> | |
7ed20e1a | 17 | #include <linux/signal.h> |
1da177e4 LT |
18 | |
19 | #include <asm/uaccess.h> | |
20 | #include <asm/pgtable.h> | |
21 | #include <asm/system.h> | |
22 | #include <asm/fpu.h> | |
23 | ||
24 | #include "proto.h" | |
25 | ||
26 | #define DEBUG DBG_MEM | |
27 | #undef DEBUG | |
28 | ||
29 | #ifdef DEBUG | |
30 | enum { | |
31 | DBG_MEM = (1<<0), | |
32 | DBG_BPT = (1<<1), | |
33 | DBG_MEM_ALL = (1<<2) | |
34 | }; | |
35 | #define DBG(fac,args) {if ((fac) & DEBUG) printk args;} | |
36 | #else | |
37 | #define DBG(fac,args) | |
38 | #endif | |
39 | ||
40 | #define BREAKINST 0x00000080 /* call_pal bpt */ | |
41 | ||
42 | /* | |
43 | * does not yet catch signals sent when the child dies. | |
44 | * in exit.c or in signal.c. | |
45 | */ | |
46 | ||
47 | /* | |
48 | * Processes always block with the following stack-layout: | |
49 | * | |
50 | * +================================+ <---- task + 2*PAGE_SIZE | |
51 | * | PALcode saved frame (ps, pc, | ^ | |
52 | * | gp, a0, a1, a2) | | | |
53 | * +================================+ | struct pt_regs | |
54 | * | | | | |
55 | * | frame generated by SAVE_ALL | | | |
56 | * | | v | |
57 | * +================================+ | |
58 | * | | ^ | |
59 | * | frame saved by do_switch_stack | | struct switch_stack | |
60 | * | | v | |
61 | * +================================+ | |
62 | */ | |
63 | ||
64 | /* | |
65 | * The following table maps a register index into the stack offset at | |
66 | * which the register is saved. Register indices are 0-31 for integer | |
67 | * regs, 32-63 for fp regs, and 64 for the pc. Notice that sp and | |
68 | * zero have no stack-slot and need to be treated specially (see | |
69 | * get_reg/put_reg below). | |
70 | */ | |
71 | enum { | |
72 | REG_R0 = 0, REG_F0 = 32, REG_FPCR = 63, REG_PC = 64 | |
73 | }; | |
74 | ||
75 | static int regoff[] = { | |
76 | PT_REG( r0), PT_REG( r1), PT_REG( r2), PT_REG( r3), | |
77 | PT_REG( r4), PT_REG( r5), PT_REG( r6), PT_REG( r7), | |
78 | PT_REG( r8), SW_REG( r9), SW_REG( r10), SW_REG( r11), | |
79 | SW_REG( r12), SW_REG( r13), SW_REG( r14), SW_REG( r15), | |
80 | PT_REG( r16), PT_REG( r17), PT_REG( r18), PT_REG( r19), | |
81 | PT_REG( r20), PT_REG( r21), PT_REG( r22), PT_REG( r23), | |
82 | PT_REG( r24), PT_REG( r25), PT_REG( r26), PT_REG( r27), | |
83 | PT_REG( r28), PT_REG( gp), -1, -1, | |
84 | SW_REG(fp[ 0]), SW_REG(fp[ 1]), SW_REG(fp[ 2]), SW_REG(fp[ 3]), | |
85 | SW_REG(fp[ 4]), SW_REG(fp[ 5]), SW_REG(fp[ 6]), SW_REG(fp[ 7]), | |
86 | SW_REG(fp[ 8]), SW_REG(fp[ 9]), SW_REG(fp[10]), SW_REG(fp[11]), | |
87 | SW_REG(fp[12]), SW_REG(fp[13]), SW_REG(fp[14]), SW_REG(fp[15]), | |
88 | SW_REG(fp[16]), SW_REG(fp[17]), SW_REG(fp[18]), SW_REG(fp[19]), | |
89 | SW_REG(fp[20]), SW_REG(fp[21]), SW_REG(fp[22]), SW_REG(fp[23]), | |
90 | SW_REG(fp[24]), SW_REG(fp[25]), SW_REG(fp[26]), SW_REG(fp[27]), | |
91 | SW_REG(fp[28]), SW_REG(fp[29]), SW_REG(fp[30]), SW_REG(fp[31]), | |
92 | PT_REG( pc) | |
93 | }; | |
94 | ||
95 | static unsigned long zero; | |
96 | ||
97 | /* | |
98 | * Get address of register REGNO in task TASK. | |
99 | */ | |
100 | static unsigned long * | |
101 | get_reg_addr(struct task_struct * task, unsigned long regno) | |
102 | { | |
103 | unsigned long *addr; | |
104 | ||
105 | if (regno == 30) { | |
106 | addr = &task->thread_info->pcb.usp; | |
107 | } else if (regno == 65) { | |
108 | addr = &task->thread_info->pcb.unique; | |
109 | } else if (regno == 31 || regno > 65) { | |
110 | zero = 0; | |
111 | addr = &zero; | |
112 | } else { | |
113 | addr = (void *)task->thread_info + regoff[regno]; | |
114 | } | |
115 | return addr; | |
116 | } | |
117 | ||
118 | /* | |
119 | * Get contents of register REGNO in task TASK. | |
120 | */ | |
121 | static unsigned long | |
122 | get_reg(struct task_struct * task, unsigned long regno) | |
123 | { | |
124 | /* Special hack for fpcr -- combine hardware and software bits. */ | |
125 | if (regno == 63) { | |
126 | unsigned long fpcr = *get_reg_addr(task, regno); | |
127 | unsigned long swcr | |
128 | = task->thread_info->ieee_state & IEEE_SW_MASK; | |
129 | swcr = swcr_update_status(swcr, fpcr); | |
130 | return fpcr | swcr; | |
131 | } | |
132 | return *get_reg_addr(task, regno); | |
133 | } | |
134 | ||
135 | /* | |
136 | * Write contents of register REGNO in task TASK. | |
137 | */ | |
138 | static int | |
139 | put_reg(struct task_struct *task, unsigned long regno, unsigned long data) | |
140 | { | |
141 | if (regno == 63) { | |
142 | task->thread_info->ieee_state | |
143 | = ((task->thread_info->ieee_state & ~IEEE_SW_MASK) | |
144 | | (data & IEEE_SW_MASK)); | |
145 | data = (data & FPCR_DYN_MASK) | ieee_swcr_to_fpcr(data); | |
146 | } | |
147 | *get_reg_addr(task, regno) = data; | |
148 | return 0; | |
149 | } | |
150 | ||
151 | static inline int | |
152 | read_int(struct task_struct *task, unsigned long addr, int * data) | |
153 | { | |
154 | int copied = access_process_vm(task, addr, data, sizeof(int), 0); | |
155 | return (copied == sizeof(int)) ? 0 : -EIO; | |
156 | } | |
157 | ||
158 | static inline int | |
159 | write_int(struct task_struct *task, unsigned long addr, int data) | |
160 | { | |
161 | int copied = access_process_vm(task, addr, &data, sizeof(int), 1); | |
162 | return (copied == sizeof(int)) ? 0 : -EIO; | |
163 | } | |
164 | ||
165 | /* | |
166 | * Set breakpoint. | |
167 | */ | |
168 | int | |
169 | ptrace_set_bpt(struct task_struct * child) | |
170 | { | |
171 | int displ, i, res, reg_b, nsaved = 0; | |
172 | unsigned int insn, op_code; | |
173 | unsigned long pc; | |
174 | ||
175 | pc = get_reg(child, REG_PC); | |
176 | res = read_int(child, pc, (int *) &insn); | |
177 | if (res < 0) | |
178 | return res; | |
179 | ||
180 | op_code = insn >> 26; | |
181 | if (op_code >= 0x30) { | |
182 | /* | |
183 | * It's a branch: instead of trying to figure out | |
184 | * whether the branch will be taken or not, we'll put | |
185 | * a breakpoint at either location. This is simpler, | |
186 | * more reliable, and probably not a whole lot slower | |
187 | * than the alternative approach of emulating the | |
188 | * branch (emulation can be tricky for fp branches). | |
189 | */ | |
190 | displ = ((s32)(insn << 11)) >> 9; | |
191 | child->thread_info->bpt_addr[nsaved++] = pc + 4; | |
192 | if (displ) /* guard against unoptimized code */ | |
193 | child->thread_info->bpt_addr[nsaved++] | |
194 | = pc + 4 + displ; | |
195 | DBG(DBG_BPT, ("execing branch\n")); | |
196 | } else if (op_code == 0x1a) { | |
197 | reg_b = (insn >> 16) & 0x1f; | |
198 | child->thread_info->bpt_addr[nsaved++] = get_reg(child, reg_b); | |
199 | DBG(DBG_BPT, ("execing jump\n")); | |
200 | } else { | |
201 | child->thread_info->bpt_addr[nsaved++] = pc + 4; | |
202 | DBG(DBG_BPT, ("execing normal insn\n")); | |
203 | } | |
204 | ||
205 | /* install breakpoints: */ | |
206 | for (i = 0; i < nsaved; ++i) { | |
207 | res = read_int(child, child->thread_info->bpt_addr[i], | |
208 | (int *) &insn); | |
209 | if (res < 0) | |
210 | return res; | |
211 | child->thread_info->bpt_insn[i] = insn; | |
212 | DBG(DBG_BPT, (" -> next_pc=%lx\n", | |
213 | child->thread_info->bpt_addr[i])); | |
214 | res = write_int(child, child->thread_info->bpt_addr[i], | |
215 | BREAKINST); | |
216 | if (res < 0) | |
217 | return res; | |
218 | } | |
219 | child->thread_info->bpt_nsaved = nsaved; | |
220 | return 0; | |
221 | } | |
222 | ||
223 | /* | |
224 | * Ensure no single-step breakpoint is pending. Returns non-zero | |
225 | * value if child was being single-stepped. | |
226 | */ | |
227 | int | |
228 | ptrace_cancel_bpt(struct task_struct * child) | |
229 | { | |
230 | int i, nsaved = child->thread_info->bpt_nsaved; | |
231 | ||
232 | child->thread_info->bpt_nsaved = 0; | |
233 | ||
234 | if (nsaved > 2) { | |
235 | printk("ptrace_cancel_bpt: bogus nsaved: %d!\n", nsaved); | |
236 | nsaved = 2; | |
237 | } | |
238 | ||
239 | for (i = 0; i < nsaved; ++i) { | |
240 | write_int(child, child->thread_info->bpt_addr[i], | |
241 | child->thread_info->bpt_insn[i]); | |
242 | } | |
243 | return (nsaved != 0); | |
244 | } | |
245 | ||
246 | /* | |
247 | * Called by kernel/ptrace.c when detaching.. | |
248 | * | |
249 | * Make sure the single step bit is not set. | |
250 | */ | |
251 | void ptrace_disable(struct task_struct *child) | |
252 | { | |
253 | ptrace_cancel_bpt(child); | |
254 | } | |
255 | ||
256 | asmlinkage long | |
257 | do_sys_ptrace(long request, long pid, long addr, long data, | |
258 | struct pt_regs *regs) | |
259 | { | |
260 | struct task_struct *child; | |
261 | unsigned long tmp; | |
262 | size_t copied; | |
263 | long ret; | |
264 | ||
265 | lock_kernel(); | |
266 | DBG(DBG_MEM, ("request=%ld pid=%ld addr=0x%lx data=0x%lx\n", | |
267 | request, pid, addr, data)); | |
268 | ret = -EPERM; | |
269 | if (request == PTRACE_TRACEME) { | |
270 | /* are we already being traced? */ | |
271 | if (current->ptrace & PT_PTRACED) | |
272 | goto out_notsk; | |
273 | ret = security_ptrace(current->parent, current); | |
274 | if (ret) | |
275 | goto out_notsk; | |
276 | /* set the ptrace bit in the process ptrace flags. */ | |
277 | current->ptrace |= PT_PTRACED; | |
278 | ret = 0; | |
279 | goto out_notsk; | |
280 | } | |
281 | if (pid == 1) /* you may not mess with init */ | |
282 | goto out_notsk; | |
283 | ||
284 | ret = -ESRCH; | |
285 | read_lock(&tasklist_lock); | |
286 | child = find_task_by_pid(pid); | |
287 | if (child) | |
288 | get_task_struct(child); | |
289 | read_unlock(&tasklist_lock); | |
290 | if (!child) | |
291 | goto out_notsk; | |
292 | ||
293 | if (request == PTRACE_ATTACH) { | |
294 | ret = ptrace_attach(child); | |
295 | goto out; | |
296 | } | |
297 | ||
298 | ret = ptrace_check_attach(child, request == PTRACE_KILL); | |
299 | if (ret < 0) | |
300 | goto out; | |
301 | ||
302 | switch (request) { | |
303 | /* When I and D space are separate, these will need to be fixed. */ | |
304 | case PTRACE_PEEKTEXT: /* read word at location addr. */ | |
305 | case PTRACE_PEEKDATA: | |
306 | copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0); | |
307 | ret = -EIO; | |
308 | if (copied != sizeof(tmp)) | |
309 | break; | |
310 | ||
311 | regs->r0 = 0; /* special return: no errors */ | |
312 | ret = tmp; | |
313 | break; | |
314 | ||
315 | /* Read register number ADDR. */ | |
316 | case PTRACE_PEEKUSR: | |
317 | regs->r0 = 0; /* special return: no errors */ | |
318 | ret = get_reg(child, addr); | |
319 | DBG(DBG_MEM, ("peek $%ld->%#lx\n", addr, ret)); | |
320 | break; | |
321 | ||
322 | /* When I and D space are separate, this will have to be fixed. */ | |
323 | case PTRACE_POKETEXT: /* write the word at location addr. */ | |
324 | case PTRACE_POKEDATA: | |
325 | tmp = data; | |
326 | copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 1); | |
327 | ret = (copied == sizeof(tmp)) ? 0 : -EIO; | |
328 | break; | |
329 | ||
330 | case PTRACE_POKEUSR: /* write the specified register */ | |
331 | DBG(DBG_MEM, ("poke $%ld<-%#lx\n", addr, data)); | |
332 | ret = put_reg(child, addr, data); | |
333 | break; | |
334 | ||
335 | case PTRACE_SYSCALL: | |
336 | /* continue and stop at next (return from) syscall */ | |
337 | case PTRACE_CONT: /* restart after signal. */ | |
338 | ret = -EIO; | |
7ed20e1a | 339 | if (!valid_signal(data)) |
1da177e4 LT |
340 | break; |
341 | if (request == PTRACE_SYSCALL) | |
342 | set_tsk_thread_flag(child, TIF_SYSCALL_TRACE); | |
343 | else | |
344 | clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); | |
345 | child->exit_code = data; | |
346 | /* make sure single-step breakpoint is gone. */ | |
347 | ptrace_cancel_bpt(child); | |
348 | wake_up_process(child); | |
349 | ret = 0; | |
350 | break; | |
351 | ||
352 | /* | |
353 | * Make the child exit. Best I can do is send it a sigkill. | |
354 | * perhaps it should be put in the status that it wants to | |
355 | * exit. | |
356 | */ | |
357 | case PTRACE_KILL: | |
358 | ret = 0; | |
359 | if (child->exit_state == EXIT_ZOMBIE) | |
360 | break; | |
361 | child->exit_code = SIGKILL; | |
362 | /* make sure single-step breakpoint is gone. */ | |
363 | ptrace_cancel_bpt(child); | |
364 | wake_up_process(child); | |
365 | goto out; | |
366 | ||
367 | case PTRACE_SINGLESTEP: /* execute single instruction. */ | |
368 | ret = -EIO; | |
7ed20e1a | 369 | if (!valid_signal(data)) |
1da177e4 LT |
370 | break; |
371 | /* Mark single stepping. */ | |
372 | child->thread_info->bpt_nsaved = -1; | |
373 | clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); | |
374 | child->exit_code = data; | |
375 | wake_up_process(child); | |
376 | /* give it a chance to run. */ | |
377 | ret = 0; | |
378 | goto out; | |
379 | ||
380 | case PTRACE_DETACH: /* detach a process that was attached. */ | |
381 | ret = ptrace_detach(child, data); | |
382 | goto out; | |
383 | ||
384 | default: | |
385 | ret = ptrace_request(child, request, addr, data); | |
386 | goto out; | |
387 | } | |
388 | out: | |
389 | put_task_struct(child); | |
390 | out_notsk: | |
391 | unlock_kernel(); | |
392 | return ret; | |
393 | } | |
394 | ||
395 | asmlinkage void | |
396 | syscall_trace(void) | |
397 | { | |
398 | if (!test_thread_flag(TIF_SYSCALL_TRACE)) | |
399 | return; | |
400 | if (!(current->ptrace & PT_PTRACED)) | |
401 | return; | |
402 | /* The 0x80 provides a way for the tracing parent to distinguish | |
403 | between a syscall stop and SIGTRAP delivery */ | |
404 | ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) | |
405 | ? 0x80 : 0)); | |
406 | ||
407 | /* | |
408 | * This isn't the same as continuing with a signal, but it will do | |
409 | * for normal use. strace only continues with a signal if the | |
410 | * stopping signal is not SIGTRAP. -brl | |
411 | */ | |
412 | if (current->exit_code) { | |
413 | send_sig(current->exit_code, current, 1); | |
414 | current->exit_code = 0; | |
415 | } | |
416 | } |