Linux-2.6.12-rc2
[linux-2.6.git] / arch / cris / arch-v10 / kernel / ptrace.c
1 /*
2  * Copyright (C) 2000-2003, Axis Communications AB.
3  */
4
5 #include <linux/kernel.h>
6 #include <linux/sched.h>
7 #include <linux/mm.h>
8 #include <linux/smp.h>
9 #include <linux/smp_lock.h>
10 #include <linux/errno.h>
11 #include <linux/ptrace.h>
12 #include <linux/user.h>
13
14 #include <asm/uaccess.h>
15 #include <asm/page.h>
16 #include <asm/pgtable.h>
17 #include <asm/system.h>
18 #include <asm/processor.h>
19
20 /* 
21  * Determines which bits in DCCR the user has access to.
22  * 1 = access, 0 = no access.
23  */
24 #define DCCR_MASK 0x0000001f     /* XNZVC */
25
26 /*
27  * Get contents of register REGNO in task TASK.
28  */
29 inline long get_reg(struct task_struct *task, unsigned int regno)
30 {
31         /* USP is a special case, it's not in the pt_regs struct but
32          * in the tasks thread struct
33          */
34
35         if (regno == PT_USP)
36                 return task->thread.usp;
37         else if (regno < PT_MAX)
38                 return ((unsigned long *)user_regs(task->thread_info))[regno];
39         else
40                 return 0;
41 }
42
43 /*
44  * Write contents of register REGNO in task TASK.
45  */
46 inline int put_reg(struct task_struct *task, unsigned int regno,
47                           unsigned long data)
48 {
49         if (regno == PT_USP)
50                 task->thread.usp = data;
51         else if (regno < PT_MAX)
52                 ((unsigned long *)user_regs(task->thread_info))[regno] = data;
53         else
54                 return -1;
55         return 0;
56 }
57
58 /*
59  * Called by kernel/ptrace.c when detaching.
60  *
61  * Make sure the single step bit is not set.
62  */
63 void 
64 ptrace_disable(struct task_struct *child)
65 {
66        /* Todo - pending singlesteps? */
67 }
68
69 /* 
70  * Note that this implementation of ptrace behaves differently from vanilla
71  * ptrace.  Contrary to what the man page says, in the PTRACE_PEEKTEXT,
72  * PTRACE_PEEKDATA, and PTRACE_PEEKUSER requests the data variable is not
73  * ignored.  Instead, the data variable is expected to point at a location
74  * (in user space) where the result of the ptrace call is written (instead of
75  * being returned).
76  */
77 asmlinkage int 
78 sys_ptrace(long request, long pid, long addr, long data)
79 {
80         struct task_struct *child;
81         int ret;
82         unsigned long __user *datap = (unsigned long __user *)data;
83
84         lock_kernel();
85         ret = -EPERM;
86         
87         if (request == PTRACE_TRACEME) {
88                 if (current->ptrace & PT_PTRACED)
89                         goto out;
90
91                 current->ptrace |= PT_PTRACED;
92                 ret = 0;
93                 goto out;
94         }
95         
96         ret = -ESRCH;
97         read_lock(&tasklist_lock);
98         child = find_task_by_pid(pid);
99         
100         if (child)
101                 get_task_struct(child);
102         
103         read_unlock(&tasklist_lock);
104         
105         if (!child)
106                 goto out;
107         
108         ret = -EPERM;
109         
110         if (pid == 1)           /* Leave the init process alone! */
111                 goto out_tsk;
112         
113         if (request == PTRACE_ATTACH) {
114                 ret = ptrace_attach(child);
115                 goto out_tsk;
116         }
117         
118         ret = ptrace_check_attach(child, request == PTRACE_KILL);
119         if (ret < 0)
120                 goto out_tsk;
121
122         switch (request) {
123                 /* Read word at location address. */ 
124                 case PTRACE_PEEKTEXT:
125                 case PTRACE_PEEKDATA: {
126                         unsigned long tmp;
127                         int copied;
128
129                         copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
130                         ret = -EIO;
131                         
132                         if (copied != sizeof(tmp))
133                                 break;
134                         
135                         ret = put_user(tmp,datap);
136                         break;
137                 }
138
139                 /* Read the word at location address in the USER area. */
140                 case PTRACE_PEEKUSR: {
141                         unsigned long tmp;
142
143                         ret = -EIO;
144                         if ((addr & 3) || addr < 0 || addr > PT_MAX << 2)
145                                 break;
146
147                         tmp = get_reg(child, addr >> 2);
148                         ret = put_user(tmp, datap);
149                         break;
150                 }
151                 
152                 /* Write the word at location address. */
153                 case PTRACE_POKETEXT:
154                 case PTRACE_POKEDATA:
155                         ret = 0;
156                         
157                         if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
158                                 break;
159                         
160                         ret = -EIO;
161                         break;
162  
163                 /* Write the word at location address in the USER area. */
164                 case PTRACE_POKEUSR:
165                         ret = -EIO;
166                         if ((addr & 3) || addr < 0 || addr > PT_MAX << 2)
167                                 break;
168
169                         addr >>= 2;
170
171                         if (addr == PT_DCCR) {
172                                 /* don't allow the tracing process to change stuff like
173                                  * interrupt enable, kernel/user bit, dma enables etc.
174                                  */
175                                 data &= DCCR_MASK;
176                                 data |= get_reg(child, PT_DCCR) & ~DCCR_MASK;
177                         }
178                         if (put_reg(child, addr, data))
179                                 break;
180                         ret = 0;
181                         break;
182
183                 case PTRACE_SYSCALL:
184                 case PTRACE_CONT:
185                         ret = -EIO;
186                         
187                         if ((unsigned long) data > _NSIG)
188                                 break;
189                         
190                         if (request == PTRACE_SYSCALL) {
191                                 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
192                         }
193                         else {
194                                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
195                         }
196                         
197                         child->exit_code = data;
198                         
199                         /* TODO: make sure any pending breakpoint is killed */
200                         wake_up_process(child);
201                         ret = 0;
202                         
203                         break;
204                 
205                 /* Make the child exit by sending it a sigkill. */
206                 case PTRACE_KILL:
207                         ret = 0;
208                         
209                         if (child->state == TASK_ZOMBIE)
210                                 break;
211                         
212                         child->exit_code = SIGKILL;
213                         
214                         /* TODO: make sure any pending breakpoint is killed */
215                         wake_up_process(child);
216                         break;
217
218                 /* Set the trap flag. */
219                 case PTRACE_SINGLESTEP:
220                         ret = -EIO;
221                         
222                         if ((unsigned long) data > _NSIG)
223                                 break;
224                         
225                         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
226
227                         /* TODO: set some clever breakpoint mechanism... */
228
229                         child->exit_code = data;
230                         wake_up_process(child);
231                         ret = 0;
232                         break;
233
234                 case PTRACE_DETACH:
235                         ret = ptrace_detach(child, data);
236                         break;
237
238                 /* Get all GP registers from the child. */
239                 case PTRACE_GETREGS: {
240                         int i;
241                         unsigned long tmp;
242                         
243                         for (i = 0; i <= PT_MAX; i++) {
244                                 tmp = get_reg(child, i);
245                                 
246                                 if (put_user(tmp, datap)) {
247                                         ret = -EFAULT;
248                                         goto out_tsk;
249                                 }
250                                 
251                                 data += sizeof(long);
252                         }
253
254                         ret = 0;
255                         break;
256                 }
257
258                 /* Set all GP registers in the child. */
259                 case PTRACE_SETREGS: {
260                         int i;
261                         unsigned long tmp;
262                         
263                         for (i = 0; i <= PT_MAX; i++) {
264                                 if (get_user(tmp, datap)) {
265                                         ret = -EFAULT;
266                                         goto out_tsk;
267                                 }
268                                 
269                                 if (i == PT_DCCR) {
270                                         tmp &= DCCR_MASK;
271                                         tmp |= get_reg(child, PT_DCCR) & ~DCCR_MASK;
272                                 }
273                                 
274                                 put_reg(child, i, tmp);
275                                 data += sizeof(long);
276                         }
277                         
278                         ret = 0;
279                         break;
280                 }
281
282                 default:
283                         ret = ptrace_request(child, request, addr, data);
284                         break;
285         }
286 out_tsk:
287         put_task_struct(child);
288 out:
289         unlock_kernel();
290         return ret;
291 }
292
293 void do_syscall_trace(void)
294 {
295         if (!test_thread_flag(TIF_SYSCALL_TRACE))
296                 return;
297         
298         if (!(current->ptrace & PT_PTRACED))
299                 return;
300         
301         /* the 0x80 provides a way for the tracing parent to distinguish
302            between a syscall stop and SIGTRAP delivery */
303         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
304                                  ? 0x80 : 0));
305         
306         /*
307          * This isn't the same as continuing with a signal, but it will do for
308          * normal use.
309          */
310         if (current->exit_code) {
311                 send_sig(current->exit_code, current, 1);
312                 current->exit_code = 0;
313         }
314 }