arch/tile: don't allow user code to set the PL via ptrace or signal return
[linux-2.6.git] / arch / tile / kernel / ptrace.c
1 /*
2  * Copyright 2010 Tilera Corporation. All Rights Reserved.
3  *
4  *   This program is free software; you can redistribute it and/or
5  *   modify it under the terms of the GNU General Public License
6  *   as published by the Free Software Foundation, version 2.
7  *
8  *   This program is distributed in the hope that it will be useful, but
9  *   WITHOUT ANY WARRANTY; without even the implied warranty of
10  *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
11  *   NON INFRINGEMENT.  See the GNU General Public License for
12  *   more details.
13  *
14  * Copied from i386: Ross Biro 1/23/92
15  */
16
17 #include <linux/kernel.h>
18 #include <linux/ptrace.h>
19 #include <linux/kprobes.h>
20 #include <linux/compat.h>
21 #include <linux/uaccess.h>
22 #include <asm/traps.h>
23
24 void user_enable_single_step(struct task_struct *child)
25 {
26         set_tsk_thread_flag(child, TIF_SINGLESTEP);
27 }
28
29 void user_disable_single_step(struct task_struct *child)
30 {
31         clear_tsk_thread_flag(child, TIF_SINGLESTEP);
32 }
33
34 /*
35  * Called by kernel/ptrace.c when detaching..
36  */
37 void ptrace_disable(struct task_struct *child)
38 {
39         clear_tsk_thread_flag(child, TIF_SINGLESTEP);
40
41         /*
42          * These two are currently unused, but will be set by arch_ptrace()
43          * and used in the syscall assembly when we do support them.
44          */
45         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
46 }
47
48 long arch_ptrace(struct task_struct *child, long request,
49                  unsigned long addr, unsigned long data)
50 {
51         unsigned long __user *datap = (long __user __force *)data;
52         unsigned long tmp;
53         long ret = -EIO;
54         char *childreg;
55         struct pt_regs copyregs;
56         int ex1_offset;
57
58         switch (request) {
59
60         case PTRACE_PEEKUSR:  /* Read register from pt_regs. */
61                 if (addr >= PTREGS_SIZE)
62                         break;
63                 childreg = (char *)task_pt_regs(child) + addr;
64 #ifdef CONFIG_COMPAT
65                 if (is_compat_task()) {
66                         if (addr & (sizeof(compat_long_t)-1))
67                                 break;
68                         ret = put_user(*(compat_long_t *)childreg,
69                                        (compat_long_t __user *)datap);
70                 } else
71 #endif
72                 {
73                         if (addr & (sizeof(long)-1))
74                                 break;
75                         ret = put_user(*(long *)childreg, datap);
76                 }
77                 break;
78
79         case PTRACE_POKEUSR:  /* Write register in pt_regs. */
80                 if (addr >= PTREGS_SIZE)
81                         break;
82                 childreg = (char *)task_pt_regs(child) + addr;
83
84                 /* Guard against overwrites of the privilege level. */
85                 ex1_offset = PTREGS_OFFSET_EX1;
86 #if defined(CONFIG_COMPAT) && defined(__BIG_ENDIAN)
87                 if (is_compat_task())   /* point at low word */
88                         ex1_offset += sizeof(compat_long_t);
89 #endif
90                 if (addr == ex1_offset)
91                         data = PL_ICS_EX1(USER_PL, EX1_ICS(data));
92
93 #ifdef CONFIG_COMPAT
94                 if (is_compat_task()) {
95                         if (addr & (sizeof(compat_long_t)-1))
96                                 break;
97                         *(compat_long_t *)childreg = data;
98                 } else
99 #endif
100                 {
101                         if (addr & (sizeof(long)-1))
102                                 break;
103                         *(long *)childreg = data;
104                 }
105                 ret = 0;
106                 break;
107
108         case PTRACE_GETREGS:  /* Get all registers from the child. */
109                 if (copy_to_user(datap, task_pt_regs(child),
110                                  sizeof(struct pt_regs)) == 0) {
111                         ret = 0;
112                 }
113                 break;
114
115         case PTRACE_SETREGS:  /* Set all registers in the child. */
116                 if (copy_from_user(&copyregs, datap,
117                                    sizeof(struct pt_regs)) == 0) {
118                         copyregs.ex1 =
119                                 PL_ICS_EX1(USER_PL, EX1_ICS(copyregs.ex1));
120                         *task_pt_regs(child) = copyregs;
121                         ret = 0;
122                 }
123                 break;
124
125         case PTRACE_GETFPREGS:  /* Get the child FPU state. */
126         case PTRACE_SETFPREGS:  /* Set the child FPU state. */
127                 break;
128
129         case PTRACE_SETOPTIONS:
130                 /* Support TILE-specific ptrace options. */
131                 child->ptrace &= ~PT_TRACE_MASK_TILE;
132                 tmp = data & PTRACE_O_MASK_TILE;
133                 data &= ~PTRACE_O_MASK_TILE;
134                 ret = ptrace_request(child, request, addr, data);
135                 if (tmp & PTRACE_O_TRACEMIGRATE)
136                         child->ptrace |= PT_TRACE_MIGRATE;
137                 break;
138
139         default:
140 #ifdef CONFIG_COMPAT
141                 if (task_thread_info(current)->status & TS_COMPAT) {
142                         ret = compat_ptrace_request(child, request,
143                                                     addr, data);
144                         break;
145                 }
146 #endif
147                 ret = ptrace_request(child, request, addr, data);
148                 break;
149         }
150
151         return ret;
152 }
153
154 #ifdef CONFIG_COMPAT
155 /* Not used; we handle compat issues in arch_ptrace() directly. */
156 long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
157                                compat_ulong_t addr, compat_ulong_t data)
158 {
159         BUG();
160 }
161 #endif
162
163 void do_syscall_trace(void)
164 {
165         if (!test_thread_flag(TIF_SYSCALL_TRACE))
166                 return;
167
168         if (!(current->ptrace & PT_PTRACED))
169                 return;
170
171         /*
172          * The 0x80 provides a way for the tracing parent to distinguish
173          * between a syscall stop and SIGTRAP delivery
174          */
175         ptrace_notify(SIGTRAP|((current->ptrace & PT_TRACESYSGOOD) ? 0x80 : 0));
176
177         /*
178          * this isn't the same as continuing with a signal, but it will do
179          * for normal use.  strace only continues with a signal if the
180          * stopping signal is not SIGTRAP.  -brl
181          */
182         if (current->exit_code) {
183                 send_sig(current->exit_code, current, 1);
184                 current->exit_code = 0;
185         }
186 }
187
188 void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs, int error_code)
189 {
190         struct siginfo info;
191
192         memset(&info, 0, sizeof(info));
193         info.si_signo = SIGTRAP;
194         info.si_code  = TRAP_BRKPT;
195         info.si_addr  = (void __user *) regs->pc;
196
197         /* Send us the fakey SIGTRAP */
198         force_sig_info(SIGTRAP, &info, tsk);
199 }
200
201 /* Handle synthetic interrupt delivered only by the simulator. */
202 void __kprobes do_breakpoint(struct pt_regs* regs, int fault_num)
203 {
204         send_sigtrap(current, regs, fault_num);
205 }