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/errno.h>
10 #include <linux/ptrace.h>
11 #include <linux/user.h>
12 #include <linux/signal.h>
13 #include <linux/security.h>
14
15 #include <asm/uaccess.h>
16 #include <asm/page.h>
17 #include <asm/pgtable.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 */
get_reg(struct task_struct * task,unsigned int regno)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 *)task_pt_regs(task))[regno];
39 else
40 return 0;
41 }
42
43 /*
44 * Write contents of register REGNO in task TASK.
45 */
put_reg(struct task_struct * task,unsigned int regno,unsigned long data)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 *)task_pt_regs(task))[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
ptrace_disable(struct task_struct * child)64 ptrace_disable(struct task_struct *child)
65 {
66 /* Todo - pending singlesteps? */
67 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
68 }
69
70 /*
71 * Note that this implementation of ptrace behaves differently from vanilla
72 * ptrace. Contrary to what the man page says, in the PTRACE_PEEKTEXT,
73 * PTRACE_PEEKDATA, and PTRACE_PEEKUSER requests the data variable is not
74 * ignored. Instead, the data variable is expected to point at a location
75 * (in user space) where the result of the ptrace call is written (instead of
76 * being returned).
77 */
arch_ptrace(struct task_struct * child,long request,unsigned long addr,unsigned long data)78 long arch_ptrace(struct task_struct *child, long request,
79 unsigned long addr, unsigned long data)
80 {
81 int ret;
82 unsigned int regno = addr >> 2;
83 unsigned long __user *datap = (unsigned long __user *)data;
84
85 switch (request) {
86 /* Read word at location address. */
87 case PTRACE_PEEKTEXT:
88 case PTRACE_PEEKDATA:
89 ret = generic_ptrace_peekdata(child, addr, data);
90 break;
91
92 /* Read the word at location address in the USER area. */
93 case PTRACE_PEEKUSR: {
94 unsigned long tmp;
95
96 ret = -EIO;
97 if ((addr & 3) || regno > PT_MAX)
98 break;
99
100 tmp = get_reg(child, regno);
101 ret = put_user(tmp, datap);
102 break;
103 }
104
105 /* Write the word at location address. */
106 case PTRACE_POKETEXT:
107 case PTRACE_POKEDATA:
108 ret = generic_ptrace_pokedata(child, addr, data);
109 break;
110
111 /* Write the word at location address in the USER area. */
112 case PTRACE_POKEUSR:
113 ret = -EIO;
114 if ((addr & 3) || regno > PT_MAX)
115 break;
116
117 if (regno == PT_DCCR) {
118 /* don't allow the tracing process to change stuff like
119 * interrupt enable, kernel/user bit, dma enables etc.
120 */
121 data &= DCCR_MASK;
122 data |= get_reg(child, PT_DCCR) & ~DCCR_MASK;
123 }
124 if (put_reg(child, regno, data))
125 break;
126 ret = 0;
127 break;
128
129 /* Get all GP registers from the child. */
130 case PTRACE_GETREGS: {
131 int i;
132 unsigned long tmp;
133
134 ret = 0;
135 for (i = 0; i <= PT_MAX; i++) {
136 tmp = get_reg(child, i);
137
138 if (put_user(tmp, datap)) {
139 ret = -EFAULT;
140 break;
141 }
142
143 datap++;
144 }
145
146 break;
147 }
148
149 /* Set all GP registers in the child. */
150 case PTRACE_SETREGS: {
151 int i;
152 unsigned long tmp;
153
154 ret = 0;
155 for (i = 0; i <= PT_MAX; i++) {
156 if (get_user(tmp, datap)) {
157 ret = -EFAULT;
158 break;
159 }
160
161 if (i == PT_DCCR) {
162 tmp &= DCCR_MASK;
163 tmp |= get_reg(child, PT_DCCR) & ~DCCR_MASK;
164 }
165
166 put_reg(child, i, tmp);
167 datap++;
168 }
169
170 break;
171 }
172
173 default:
174 ret = ptrace_request(child, request, addr, data);
175 break;
176 }
177
178 return ret;
179 }
180
do_syscall_trace(void)181 void do_syscall_trace(void)
182 {
183 if (!test_thread_flag(TIF_SYSCALL_TRACE))
184 return;
185
186 if (!(current->ptrace & PT_PTRACED))
187 return;
188
189 /* the 0x80 provides a way for the tracing parent to distinguish
190 between a syscall stop and SIGTRAP delivery */
191 ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
192 ? 0x80 : 0));
193
194 /*
195 * This isn't the same as continuing with a signal, but it will do for
196 * normal use.
197 */
198 if (current->exit_code) {
199 send_sig(current->exit_code, current, 1);
200 current->exit_code = 0;
201 }
202 }
203