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/system.h>
19 #include <asm/processor.h>
20
21 /*
22 * Determines which bits in DCCR the user has access to.
23 * 1 = access, 0 = no access.
24 */
25 #define DCCR_MASK 0x0000001f /* XNZVC */
26
27 /*
28 * Get contents of register REGNO in task TASK.
29 */
get_reg(struct task_struct * task,unsigned int regno)30 inline long get_reg(struct task_struct *task, unsigned int regno)
31 {
32 /* USP is a special case, it's not in the pt_regs struct but
33 * in the tasks thread struct
34 */
35
36 if (regno == PT_USP)
37 return task->thread.usp;
38 else if (regno < PT_MAX)
39 return ((unsigned long *)task_pt_regs(task))[regno];
40 else
41 return 0;
42 }
43
44 /*
45 * Write contents of register REGNO in task TASK.
46 */
put_reg(struct task_struct * task,unsigned int regno,unsigned long data)47 inline int put_reg(struct task_struct *task, unsigned int regno,
48 unsigned long data)
49 {
50 if (regno == PT_USP)
51 task->thread.usp = data;
52 else if (regno < PT_MAX)
53 ((unsigned long *)task_pt_regs(task))[regno] = data;
54 else
55 return -1;
56 return 0;
57 }
58
59 /*
60 * Called by kernel/ptrace.c when detaching.
61 *
62 * Make sure the single step bit is not set.
63 */
64 void
ptrace_disable(struct task_struct * child)65 ptrace_disable(struct task_struct *child)
66 {
67 /* Todo - pending singlesteps? */
68 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
69 }
70
71 /*
72 * Note that this implementation of ptrace behaves differently from vanilla
73 * ptrace. Contrary to what the man page says, in the PTRACE_PEEKTEXT,
74 * PTRACE_PEEKDATA, and PTRACE_PEEKUSER requests the data variable is not
75 * ignored. Instead, the data variable is expected to point at a location
76 * (in user space) where the result of the ptrace call is written (instead of
77 * being returned).
78 */
arch_ptrace(struct task_struct * child,long request,unsigned long addr,unsigned long data)79 long arch_ptrace(struct task_struct *child, long request,
80 unsigned long addr, unsigned long data)
81 {
82 int ret;
83 unsigned int regno = addr >> 2;
84 unsigned long __user *datap = (unsigned long __user *)data;
85
86 switch (request) {
87 /* Read word at location address. */
88 case PTRACE_PEEKTEXT:
89 case PTRACE_PEEKDATA:
90 ret = generic_ptrace_peekdata(child, addr, data);
91 break;
92
93 /* Read the word at location address in the USER area. */
94 case PTRACE_PEEKUSR: {
95 unsigned long tmp;
96
97 ret = -EIO;
98 if ((addr & 3) || regno > PT_MAX)
99 break;
100
101 tmp = get_reg(child, regno);
102 ret = put_user(tmp, datap);
103 break;
104 }
105
106 /* Write the word at location address. */
107 case PTRACE_POKETEXT:
108 case PTRACE_POKEDATA:
109 ret = generic_ptrace_pokedata(child, addr, data);
110 break;
111
112 /* Write the word at location address in the USER area. */
113 case PTRACE_POKEUSR:
114 ret = -EIO;
115 if ((addr & 3) || regno > PT_MAX)
116 break;
117
118 if (regno == PT_DCCR) {
119 /* don't allow the tracing process to change stuff like
120 * interrupt enable, kernel/user bit, dma enables etc.
121 */
122 data &= DCCR_MASK;
123 data |= get_reg(child, PT_DCCR) & ~DCCR_MASK;
124 }
125 if (put_reg(child, regno, data))
126 break;
127 ret = 0;
128 break;
129
130 /* Get all GP registers from the child. */
131 case PTRACE_GETREGS: {
132 int i;
133 unsigned long tmp;
134
135 ret = 0;
136 for (i = 0; i <= PT_MAX; i++) {
137 tmp = get_reg(child, i);
138
139 if (put_user(tmp, datap)) {
140 ret = -EFAULT;
141 break;
142 }
143
144 datap++;
145 }
146
147 break;
148 }
149
150 /* Set all GP registers in the child. */
151 case PTRACE_SETREGS: {
152 int i;
153 unsigned long tmp;
154
155 ret = 0;
156 for (i = 0; i <= PT_MAX; i++) {
157 if (get_user(tmp, datap)) {
158 ret = -EFAULT;
159 break;
160 }
161
162 if (i == PT_DCCR) {
163 tmp &= DCCR_MASK;
164 tmp |= get_reg(child, PT_DCCR) & ~DCCR_MASK;
165 }
166
167 put_reg(child, i, tmp);
168 datap++;
169 }
170
171 break;
172 }
173
174 default:
175 ret = ptrace_request(child, request, addr, data);
176 break;
177 }
178
179 return ret;
180 }
181
do_syscall_trace(void)182 void do_syscall_trace(void)
183 {
184 if (!test_thread_flag(TIF_SYSCALL_TRACE))
185 return;
186
187 if (!(current->ptrace & PT_PTRACED))
188 return;
189
190 /* the 0x80 provides a way for the tracing parent to distinguish
191 between a syscall stop and SIGTRAP delivery */
192 ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
193 ? 0x80 : 0));
194
195 /*
196 * This isn't the same as continuing with a signal, but it will do for
197 * normal use.
198 */
199 if (current->exit_code) {
200 send_sig(current->exit_code, current, 1);
201 current->exit_code = 0;
202 }
203 }
204