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[/] [or1k/] [trunk/] [rc203soc/] [sw/] [uClinux/] [arch/] [mips/] [kernel/] [ptrace.c] - Blame information for rev 1765

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Line No. Rev Author Line
1 1624 jcastillo
/* ptrace.c */
2
/* By Ross Biro 1/23/92 */
3
/* edited by Linus Torvalds */
4
 
5
#include <linux/head.h>
6
#include <linux/kernel.h>
7
#include <linux/sched.h>
8
#include <linux/mm.h>
9
#include <linux/errno.h>
10
#include <linux/ptrace.h>
11
#include <linux/user.h>
12
 
13
#include <asm/segment.h>
14
#include <asm/pgtable.h>
15
#include <asm/system.h>
16
 
17
#if 0
18
/*
19
 * does not yet catch signals sent when the child dies.
20
 * in exit.c or in signal.c.
21
 */
22
 
23
/* determines which flags the user has access to. */
24
/* 1 = access 0 = no access */
25
#define FLAG_MASK 0x00044dd5
26
 
27
/* set's the trap flag. */
28
#define TRAP_FLAG 0x100
29
 
30
/*
31
 * this is the number to subtract from the top of the stack. To find
32
 * the local frame.
33
 */
34
#define MAGICNUMBER 68
35
 
36
/* change a pid into a task struct. */
37
static inline struct task_struct * get_task(int pid)
38
{
39
        int i;
40
 
41
        for (i = 1; i < NR_TASKS; i++) {
42
                if (task[i] != NULL && (task[i]->pid == pid))
43
                        return task[i];
44
        }
45
        return NULL;
46
}
47
 
48
/*
49
 * this routine will get a word off of the processes privileged stack.
50
 * the offset is how far from the base addr as stored in the TSS.
51
 * this routine assumes that all the privileged stacks are in our
52
 * data space.
53
 */
54
static inline int get_stack_long(struct task_struct *task, int offset)
55
{
56
        unsigned char *stack;
57
 
58
        stack = (unsigned char *)task->tss.esp0;
59
        stack += offset;
60
        return (*((int *)stack));
61
}
62
 
63
/*
64
 * this routine will put a word on the processes privileged stack.
65
 * the offset is how far from the base addr as stored in the TSS.
66
 * this routine assumes that all the privileged stacks are in our
67
 * data space.
68
 */
69
static inline int put_stack_long(struct task_struct *task, int offset,
70
        unsigned long data)
71
{
72
        unsigned char * stack;
73
 
74
        stack = (unsigned char *) task->tss.esp0;
75
        stack += offset;
76
        *(unsigned long *) stack = data;
77
        return 0;
78
}
79
 
80
/*
81
 * This routine gets a long from any process space by following the page
82
 * tables. NOTE! You should check that the long isn't on a page boundary,
83
 * and that it is in the task area before calling this: this routine does
84
 * no checking.
85
 */
86
static unsigned long get_long(struct vm_area_struct * vma, unsigned long addr)
87
{
88
        pgd_t * pgdir;
89
        pte_t * pgtable;
90
        unsigned long page;
91
 
92
repeat:
93
        pgdir = PAGE_DIR_OFFSET(vma->vm_mm, addr);
94
        if (pgd_none(*pgdir)) {
95
                do_no_page(vma, addr, 0);
96
                goto repeat;
97
        }
98
        if (pgd_bad(*pgdir)) {
99
                printk("ptrace: bad page directory %08lx\n", pgd_val(*pgdir));
100
                pgd_clear(pgdir);
101
                return 0;
102
        }
103
        pgtable = (pte_t *) (PAGE_PTR(addr) + pgd_page(*pgdir));
104
        if (!pte_present(*pgtable)) {
105
                do_no_page(vma, addr, 0);
106
                goto repeat;
107
        }
108
        page = pte_page(*pgtable);
109
/* this is a hack for non-kernel-mapped video buffers and similar */
110
        if (page >= high_memory)
111
                return 0;
112
        page += addr & ~PAGE_MASK;
113
        return *(unsigned long *) page;
114
}
115
 
116
/*
117
 * This routine puts a long into any process space by following the page
118
 * tables. NOTE! You should check that the long isn't on a page boundary,
119
 * and that it is in the task area before calling this: this routine does
120
 * no checking.
121
 *
122
 * Now keeps R/W state of page so that a text page stays readonly
123
 * even if a debugger scribbles breakpoints into it.  -M.U-
124
 */
125
static void put_long(struct vm_area_struct * vma, unsigned long addr,
126
        unsigned long data)
127
{
128
        pgd_t *pgdir;
129
        pte_t *pgtable;
130
        unsigned long page;
131
 
132
repeat:
133
        pgdir = PAGE_DIR_OFFSET(vma->vm_mm, addr);
134
        if (!pgd_present(*pgdir)) {
135
                do_no_page(vma, addr, 1);
136
                goto repeat;
137
        }
138
        if (pgd_bad(*pgdir)) {
139
                printk("ptrace: bad page directory %08lx\n", pgd_val(*pgdir));
140
                pgd_clear(pgdir);
141
                return;
142
        }
143
        pgtable = (pte_t *) (PAGE_PTR(addr) + pgd_page(*pgdir));
144
        if (!pte_present(*pgtable)) {
145
                do_no_page(vma, addr, 1);
146
                goto repeat;
147
        }
148
        page = pte_page(*pgtable);
149
        if (!pte_write(*pgtable)) {
150
                do_wp_page(vma, addr, 1);
151
                goto repeat;
152
        }
153
/* this is a hack for non-kernel-mapped video buffers and similar */
154
        if (page < high_memory)
155
                *(unsigned long *) (page + (addr & ~PAGE_MASK)) = data;
156
/* we're bypassing pagetables, so we have to set the dirty bit ourselves */
157
/* this should also re-instate whatever read-only mode there was before */
158
        set_pte(pgtable, pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
159
        invalidate();
160
}
161
 
162
static struct vm_area_struct * find_extend_vma(struct task_struct * tsk, unsigned long addr)
163
{
164
        struct vm_area_struct * vma;
165
 
166
        addr &= PAGE_MASK;
167
        vma = find_vma(tsk, addr);
168
        if (!vma)
169
                return NULL;
170
        if (vma->vm_start <= addr)
171
                return vma;
172
        if (!(vma->vm_flags & VM_GROWSDOWN))
173
                return NULL;
174
        if (vma->vm_end - addr > tsk->rlim[RLIMIT_STACK].rlim_cur)
175
                return NULL;
176
        vma->vm_offset -= vma->vm_start - addr;
177
        vma->vm_start = addr;
178
        return vma;
179
}
180
 
181
/*
182
 * This routine checks the page boundaries, and that the offset is
183
 * within the task area. It then calls get_long() to read a long.
184
 */
185
static int read_long(struct task_struct * tsk, unsigned long addr,
186
        unsigned long * result)
187
{
188
        struct vm_area_struct * vma = find_extend_vma(tsk, addr);
189
 
190
        if (!vma)
191
                return -EIO;
192
        if ((addr & ~PAGE_MASK) > PAGE_SIZE-sizeof(long)) {
193
                unsigned long low,high;
194
                struct vm_area_struct * vma_high = vma;
195
 
196
                if (addr + sizeof(long) >= vma->vm_end) {
197
                        vma_high = vma->vm_next;
198
                        if (!vma_high || vma_high->vm_start != vma->vm_end)
199
                                return -EIO;
200
                }
201
                low = get_long(vma, addr & ~(sizeof(long)-1));
202
                high = get_long(vma_high, (addr+sizeof(long)) & ~(sizeof(long)-1));
203
                switch (addr & (sizeof(long)-1)) {
204
                        case 1:
205
                                low >>= 8;
206
                                low |= high << 24;
207
                                break;
208
                        case 2:
209
                                low >>= 16;
210
                                low |= high << 16;
211
                                break;
212
                        case 3:
213
                                low >>= 24;
214
                                low |= high << 8;
215
                                break;
216
                }
217
                *result = low;
218
        } else
219
                *result = get_long(vma, addr);
220
        return 0;
221
}
222
 
223
/*
224
 * This routine checks the page boundaries, and that the offset is
225
 * within the task area. It then calls put_long() to write a long.
226
 */
227
static int write_long(struct task_struct * tsk, unsigned long addr,
228
        unsigned long data)
229
{
230
        struct vm_area_struct * vma = find_extend_vma(tsk, addr);
231
 
232
        if (!vma)
233
                return -EIO;
234
        if ((addr & ~PAGE_MASK) > PAGE_SIZE-sizeof(long)) {
235
                unsigned long low,high;
236
                struct vm_area_struct * vma_high = vma;
237
 
238
                if (addr + sizeof(long) >= vma->vm_end) {
239
                        vma_high = vma->vm_next;
240
                        if (!vma_high || vma_high->vm_start != vma->vm_end)
241
                                return -EIO;
242
                }
243
                low = get_long(vma, addr & ~(sizeof(long)-1));
244
                high = get_long(vma_high, (addr+sizeof(long)) & ~(sizeof(long)-1));
245
                switch (addr & (sizeof(long)-1)) {
246
                        case 0: /* shouldn't happen, but safety first */
247
                                low = data;
248
                                break;
249
                        case 1:
250
                                low &= 0x000000ff;
251
                                low |= data << 8;
252
                                high &= ~0xff;
253
                                high |= data >> 24;
254
                                break;
255
                        case 2:
256
                                low &= 0x0000ffff;
257
                                low |= data << 16;
258
                                high &= ~0xffff;
259
                                high |= data >> 16;
260
                                break;
261
                        case 3:
262
                                low &= 0x00ffffff;
263
                                low |= data << 24;
264
                                high &= ~0xffffff;
265
                                high |= data >> 8;
266
                                break;
267
                }
268
                put_long(vma, addr & ~(sizeof(long)-1),low);
269
                put_long(vma_high, (addr+sizeof(long)) & ~(sizeof(long)-1),high);
270
        } else
271
                put_long(vma, addr, data);
272
        return 0;
273
}
274
#endif
275
 
276
asmlinkage int sys_ptrace(long request, long pid, long addr, long data)
277
{
278
#if 1
279
        return -ENOSYS;
280
#else
281
        struct task_struct *child;
282
        struct user * dummy;
283
        int i;
284
 
285
 
286
        dummy = NULL;
287
 
288
        if (request == PTRACE_TRACEME) {
289
                /* are we already being traced? */
290
                if (current->flags & PF_PTRACED)
291
                        return -EPERM;
292
                /* set the ptrace bit in the process flags. */
293
                current->flags |= PF_PTRACED;
294
                return 0;
295
        }
296
        if (pid == 1)           /* you may not mess with init */
297
                return -EPERM;
298
        if (!(child = get_task(pid)))
299
                return -ESRCH;
300
        if (request == PTRACE_ATTACH) {
301
                if (child == current)
302
                        return -EPERM;
303
                if ((!child->dumpable ||
304
                    (current->uid != child->euid) ||
305
                    (current->uid != child->uid) ||
306
                    (current->gid != child->egid) ||
307
                    (current->gid != child->gid)) && !suser())
308
                        return -EPERM;
309
                /* the same process cannot be attached many times */
310
                if (child->flags & PF_PTRACED)
311
                        return -EPERM;
312
                child->flags |= PF_PTRACED;
313
                if (child->p_pptr != current) {
314
                        REMOVE_LINKS(child);
315
                        child->p_pptr = current;
316
                        SET_LINKS(child);
317
                }
318
                send_sig(SIGSTOP, child, 1);
319
                return 0;
320
        }
321
        if (!(child->flags & PF_PTRACED))
322
                return -ESRCH;
323
        if (child->state != TASK_STOPPED) {
324
                if (request != PTRACE_KILL)
325
                        return -ESRCH;
326
        }
327
        if (child->p_pptr != current)
328
                return -ESRCH;
329
 
330
        switch (request) {
331
        /* when I and D space are separate, these will need to be fixed. */
332
                case PTRACE_PEEKTEXT: /* read word at location addr. */
333
                case PTRACE_PEEKDATA: {
334
                        unsigned long tmp;
335
                        int res;
336
 
337
                        res = read_long(child, addr, &tmp);
338
                        if (res < 0)
339
                                return res;
340
                        res = verify_area(VERIFY_WRITE, (void *) data, sizeof(long));
341
                        if (!res)
342
                                put_fs_long(tmp,(unsigned long *) data);
343
                        return res;
344
                }
345
 
346
        /* read the word at location addr in the USER area. */
347
                case PTRACE_PEEKUSR: {
348
                        unsigned long tmp;
349
                        int res;
350
 
351
                        if ((addr & 3) || addr < 0 ||
352
                            addr > sizeof(struct user) - 3)
353
                                return -EIO;
354
 
355
                        res = verify_area(VERIFY_WRITE, (void *) data, sizeof(long));
356
                        if (res)
357
                                return res;
358
                        tmp = 0;  /* Default return condition */
359
                        if(addr < 17*sizeof(long)) {
360
                          addr = addr >> 2; /* temporary hack. */
361
 
362
                          tmp = get_stack_long(child, sizeof(long)*addr - MAGICNUMBER);
363
                          if (addr == DS || addr == ES ||
364
                              addr == FS || addr == GS ||
365
                              addr == CS || addr == SS)
366
                            tmp &= 0xffff;
367
                        };
368
                        if(addr >= (long) &dummy->u_debugreg[0] &&
369
                           addr <= (long) &dummy->u_debugreg[7]){
370
                                addr -= (long) &dummy->u_debugreg[0];
371
                                addr = addr >> 2;
372
                                tmp = child->debugreg[addr];
373
                        };
374
                        put_fs_long(tmp,(unsigned long *) data);
375
                        return 0;
376
                }
377
 
378
      /* when I and D space are separate, this will have to be fixed. */
379
                case PTRACE_POKETEXT: /* write the word at location addr. */
380
                case PTRACE_POKEDATA:
381
                        return write_long(child,addr,data);
382
 
383
                case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
384
                        if ((addr & 3) || addr < 0 ||
385
                            addr > sizeof(struct user) - 3)
386
                                return -EIO;
387
 
388
                        addr = addr >> 2; /* temporary hack. */
389
 
390
                        if (addr == ORIG_EAX)
391
                                return -EIO;
392
                        if (addr == DS || addr == ES ||
393
                            addr == FS || addr == GS ||
394
                            addr == CS || addr == SS) {
395
                                data &= 0xffff;
396
                                if (data && (data & 3) != 3)
397
                                        return -EIO;
398
                        }
399
                        if (addr == EFL) {   /* flags. */
400
                                data &= FLAG_MASK;
401
                                data |= get_stack_long(child, EFL*sizeof(long)-MAGICNUMBER)  & ~FLAG_MASK;
402
                        }
403
                  /* Do not allow the user to set the debug register for kernel
404
                     address space */
405
                  if(addr < 17){
406
                          if (put_stack_long(child, sizeof(long)*addr-MAGICNUMBER, data))
407
                                return -EIO;
408
                        return 0;
409
                        };
410
 
411
                  /* We need to be very careful here.  We implicitly
412
                     want to modify a portion of the task_struct, and we
413
                     have to be selective about what portions we allow someone
414
                     to modify. */
415
 
416
                  addr = addr << 2;  /* Convert back again */
417
                  if(addr >= (long) &dummy->u_debugreg[0] &&
418
                     addr <= (long) &dummy->u_debugreg[7]){
419
 
420
                          if(addr == (long) &dummy->u_debugreg[4]) return -EIO;
421
                          if(addr == (long) &dummy->u_debugreg[5]) return -EIO;
422
                          if(addr < (long) &dummy->u_debugreg[4] &&
423
                             ((unsigned long) data) >= 0xbffffffd) return -EIO;
424
 
425
                          if(addr == (long) &dummy->u_debugreg[7]) {
426
                                  data &= ~DR_CONTROL_RESERVED;
427
                                  for(i=0; i<4; i++)
428
                                          if ((0x5f54 >> ((data >> (16 + 4*i)) & 0xf)) & 1)
429
                                                  return -EIO;
430
                          };
431
 
432
                          addr -= (long) &dummy->u_debugreg;
433
                          addr = addr >> 2;
434
                          child->debugreg[addr] = data;
435
                          return 0;
436
                  };
437
                  return -EIO;
438
 
439
                case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
440
                case PTRACE_CONT: { /* restart after signal. */
441
                        long tmp;
442
 
443
                        if ((unsigned long) data > NSIG)
444
                                return -EIO;
445
                        if (request == PTRACE_SYSCALL)
446
                                child->flags |= PF_TRACESYS;
447
                        else
448
                                child->flags &= ~PF_TRACESYS;
449
                        child->exit_code = data;
450
                        wake_up_process(child);
451
        /* make sure the single step bit is not set. */
452
                        tmp = get_stack_long(child, sizeof(long)*EFL-MAGICNUMBER) & ~TRAP_FLAG;
453
                        put_stack_long(child, sizeof(long)*EFL-MAGICNUMBER,tmp);
454
                        return 0;
455
                }
456
 
457
/*
458
 * make the child exit.  Best I can do is send it a sigkill.
459
 * perhaps it should be put in the status that it wants to
460
 * exit.
461
 */
462
                case PTRACE_KILL: {
463
                        long tmp;
464
 
465
                        if (child->state == TASK_ZOMBIE)        /* already dead */
466
                                return 0;
467
                        wake_up_process(child);
468
                        child->exit_code = SIGKILL;
469
        /* make sure the single step bit is not set. */
470
                        tmp = get_stack_long(child, sizeof(long)*EFL-MAGICNUMBER) & ~TRAP_FLAG;
471
                        put_stack_long(child, sizeof(long)*EFL-MAGICNUMBER,tmp);
472
                        return 0;
473
                }
474
 
475
                case PTRACE_SINGLESTEP: {  /* set the trap flag. */
476
                        long tmp;
477
 
478
                        if ((unsigned long) data > NSIG)
479
                                return -EIO;
480
                        child->flags &= ~PF_TRACESYS;
481
                        tmp = get_stack_long(child, sizeof(long)*EFL-MAGICNUMBER) | TRAP_FLAG;
482
                        put_stack_long(child, sizeof(long)*EFL-MAGICNUMBER,tmp);
483
                        wake_up_process(child);
484
                        child->exit_code = data;
485
        /* give it a chance to run. */
486
                        return 0;
487
                }
488
 
489
                case PTRACE_DETACH: { /* detach a process that was attached. */
490
                        long tmp;
491
 
492
                        if ((unsigned long) data > NSIG)
493
                                return -EIO;
494
                        child->flags &= ~(PF_PTRACED|PF_TRACESYS);
495
                        wake_up_process(child);
496
                        child->exit_code = data;
497
                        REMOVE_LINKS(child);
498
                        child->p_pptr = child->p_opptr;
499
                        SET_LINKS(child);
500
                        /* make sure the single step bit is not set. */
501
                        tmp = get_stack_long(child, sizeof(long)*EFL-MAGICNUMBER) & ~TRAP_FLAG;
502
                        put_stack_long(child, sizeof(long)*EFL-MAGICNUMBER,tmp);
503
                        return 0;
504
                }
505
 
506
                default:
507
                        return -EIO;
508
        }
509
#endif
510
}
511
 
512
asmlinkage void syscall_trace(void)
513
{
514
        if ((current->flags & (PF_PTRACED|PF_TRACESYS))
515
                        != (PF_PTRACED|PF_TRACESYS))
516
                return;
517
        current->exit_code = SIGTRAP;
518
        current->state = TASK_STOPPED;
519
        notify_parent(current);
520
        schedule();
521
        /*
522
         * this isn't the same as continuing with a signal, but it will do
523
         * for normal use.  strace only continues with a signal if the
524
         * stopping signal is not SIGTRAP.  -brl
525
         */
526
        if (current->exit_code)
527
                current->signal |= (1 << (current->exit_code - 1));
528
        current->exit_code = 0;
529
}

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