1 /*
2 * Kernel support for the ptrace() and syscall tracing interfaces.
3 *
4 * Copyright (C) 2000 Hewlett-Packard Co, Linuxcare Inc.
5 * Copyright (C) 2000 Matthew Wilcox <matthew@wil.cx>
6 * Copyright (C) 2000 David Huggins-Daines <dhd@debian.org>
7 * Copyright (C) 2008 Helge Deller <deller@gmx.de>
8 */
9
10 #include <linux/kernel.h>
11 #include <linux/sched.h>
12 #include <linux/mm.h>
13 #include <linux/smp.h>
14 #include <linux/errno.h>
15 #include <linux/ptrace.h>
16 #include <linux/tracehook.h>
17 #include <linux/user.h>
18 #include <linux/personality.h>
19 #include <linux/security.h>
20 #include <linux/seccomp.h>
21 #include <linux/compat.h>
22 #include <linux/signal.h>
23 #include <linux/audit.h>
24
25 #include <asm/uaccess.h>
26 #include <asm/pgtable.h>
27 #include <asm/processor.h>
28 #include <asm/asm-offsets.h>
29
30 /* PSW bits we allow the debugger to modify */
31 #define USER_PSW_BITS (PSW_N | PSW_B | PSW_V | PSW_CB)
32
33 /*
34 * Called by kernel/ptrace.c when detaching..
35 *
36 * Make sure single step bits etc are not set.
37 */
ptrace_disable(struct task_struct * task)38 void ptrace_disable(struct task_struct *task)
39 {
40 clear_tsk_thread_flag(task, TIF_SINGLESTEP);
41 clear_tsk_thread_flag(task, TIF_BLOCKSTEP);
42
43 /* make sure the trap bits are not set */
44 pa_psw(task)->r = 0;
45 pa_psw(task)->t = 0;
46 pa_psw(task)->h = 0;
47 pa_psw(task)->l = 0;
48 }
49
50 /*
51 * The following functions are called by ptrace_resume() when
52 * enabling or disabling single/block tracing.
53 */
user_disable_single_step(struct task_struct * task)54 void user_disable_single_step(struct task_struct *task)
55 {
56 ptrace_disable(task);
57 }
58
user_enable_single_step(struct task_struct * task)59 void user_enable_single_step(struct task_struct *task)
60 {
61 clear_tsk_thread_flag(task, TIF_BLOCKSTEP);
62 set_tsk_thread_flag(task, TIF_SINGLESTEP);
63
64 if (pa_psw(task)->n) {
65 struct siginfo si;
66
67 /* Nullified, just crank over the queue. */
68 task_regs(task)->iaoq[0] = task_regs(task)->iaoq[1];
69 task_regs(task)->iasq[0] = task_regs(task)->iasq[1];
70 task_regs(task)->iaoq[1] = task_regs(task)->iaoq[0] + 4;
71 pa_psw(task)->n = 0;
72 pa_psw(task)->x = 0;
73 pa_psw(task)->y = 0;
74 pa_psw(task)->z = 0;
75 pa_psw(task)->b = 0;
76 ptrace_disable(task);
77 /* Don't wake up the task, but let the
78 parent know something happened. */
79 si.si_code = TRAP_TRACE;
80 si.si_addr = (void __user *) (task_regs(task)->iaoq[0] & ~3);
81 si.si_signo = SIGTRAP;
82 si.si_errno = 0;
83 force_sig_info(SIGTRAP, &si, task);
84 /* notify_parent(task, SIGCHLD); */
85 return;
86 }
87
88 /* Enable recovery counter traps. The recovery counter
89 * itself will be set to zero on a task switch. If the
90 * task is suspended on a syscall then the syscall return
91 * path will overwrite the recovery counter with a suitable
92 * value such that it traps once back in user space. We
93 * disable interrupts in the tasks PSW here also, to avoid
94 * interrupts while the recovery counter is decrementing.
95 */
96 pa_psw(task)->r = 1;
97 pa_psw(task)->t = 0;
98 pa_psw(task)->h = 0;
99 pa_psw(task)->l = 0;
100 }
101
user_enable_block_step(struct task_struct * task)102 void user_enable_block_step(struct task_struct *task)
103 {
104 clear_tsk_thread_flag(task, TIF_SINGLESTEP);
105 set_tsk_thread_flag(task, TIF_BLOCKSTEP);
106
107 /* Enable taken branch trap. */
108 pa_psw(task)->r = 0;
109 pa_psw(task)->t = 1;
110 pa_psw(task)->h = 0;
111 pa_psw(task)->l = 0;
112 }
113
arch_ptrace(struct task_struct * child,long request,unsigned long addr,unsigned long data)114 long arch_ptrace(struct task_struct *child, long request,
115 unsigned long addr, unsigned long data)
116 {
117 unsigned long tmp;
118 long ret = -EIO;
119
120 switch (request) {
121
122 /* Read the word at location addr in the USER area. For ptraced
123 processes, the kernel saves all regs on a syscall. */
124 case PTRACE_PEEKUSR:
125 if ((addr & (sizeof(unsigned long)-1)) ||
126 addr >= sizeof(struct pt_regs))
127 break;
128 tmp = *(unsigned long *) ((char *) task_regs(child) + addr);
129 ret = put_user(tmp, (unsigned long __user *) data);
130 break;
131
132 /* Write the word at location addr in the USER area. This will need
133 to change when the kernel no longer saves all regs on a syscall.
134 FIXME. There is a problem at the moment in that r3-r18 are only
135 saved if the process is ptraced on syscall entry, and even then
136 those values are overwritten by actual register values on syscall
137 exit. */
138 case PTRACE_POKEUSR:
139 /* Some register values written here may be ignored in
140 * entry.S:syscall_restore_rfi; e.g. iaoq is written with
141 * r31/r31+4, and not with the values in pt_regs.
142 */
143 if (addr == PT_PSW) {
144 /* Allow writing to Nullify, Divide-step-correction,
145 * and carry/borrow bits.
146 * BEWARE, if you set N, and then single step, it won't
147 * stop on the nullified instruction.
148 */
149 data &= USER_PSW_BITS;
150 task_regs(child)->gr[0] &= ~USER_PSW_BITS;
151 task_regs(child)->gr[0] |= data;
152 ret = 0;
153 break;
154 }
155
156 if ((addr & (sizeof(unsigned long)-1)) ||
157 addr >= sizeof(struct pt_regs))
158 break;
159 if ((addr >= PT_GR1 && addr <= PT_GR31) ||
160 addr == PT_IAOQ0 || addr == PT_IAOQ1 ||
161 (addr >= PT_FR0 && addr <= PT_FR31 + 4) ||
162 addr == PT_SAR) {
163 *(unsigned long *) ((char *) task_regs(child) + addr) = data;
164 ret = 0;
165 }
166 break;
167
168 default:
169 ret = ptrace_request(child, request, addr, data);
170 break;
171 }
172
173 return ret;
174 }
175
176
177 #ifdef CONFIG_COMPAT
178
179 /* This function is needed to translate 32 bit pt_regs offsets in to
180 * 64 bit pt_regs offsets. For example, a 32 bit gdb under a 64 bit kernel
181 * will request offset 12 if it wants gr3, but the lower 32 bits of
182 * the 64 bit kernels view of gr3 will be at offset 28 (3*8 + 4).
183 * This code relies on a 32 bit pt_regs being comprised of 32 bit values
184 * except for the fp registers which (a) are 64 bits, and (b) follow
185 * the gr registers at the start of pt_regs. The 32 bit pt_regs should
186 * be half the size of the 64 bit pt_regs, plus 32*4 to allow for fr[]
187 * being 64 bit in both cases.
188 */
189
translate_usr_offset(compat_ulong_t offset)190 static compat_ulong_t translate_usr_offset(compat_ulong_t offset)
191 {
192 if (offset < 0)
193 return sizeof(struct pt_regs);
194 else if (offset <= 32*4) /* gr[0..31] */
195 return offset * 2 + 4;
196 else if (offset <= 32*4+32*8) /* gr[0..31] + fr[0..31] */
197 return offset + 32*4;
198 else if (offset < sizeof(struct pt_regs)/2 + 32*4)
199 return offset * 2 + 4 - 32*8;
200 else
201 return sizeof(struct pt_regs);
202 }
203
compat_arch_ptrace(struct task_struct * child,compat_long_t request,compat_ulong_t addr,compat_ulong_t data)204 long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
205 compat_ulong_t addr, compat_ulong_t data)
206 {
207 compat_uint_t tmp;
208 long ret = -EIO;
209
210 switch (request) {
211
212 case PTRACE_PEEKUSR:
213 if (addr & (sizeof(compat_uint_t)-1))
214 break;
215 addr = translate_usr_offset(addr);
216 if (addr >= sizeof(struct pt_regs))
217 break;
218
219 tmp = *(compat_uint_t *) ((char *) task_regs(child) + addr);
220 ret = put_user(tmp, (compat_uint_t *) (unsigned long) data);
221 break;
222
223 /* Write the word at location addr in the USER area. This will need
224 to change when the kernel no longer saves all regs on a syscall.
225 FIXME. There is a problem at the moment in that r3-r18 are only
226 saved if the process is ptraced on syscall entry, and even then
227 those values are overwritten by actual register values on syscall
228 exit. */
229 case PTRACE_POKEUSR:
230 /* Some register values written here may be ignored in
231 * entry.S:syscall_restore_rfi; e.g. iaoq is written with
232 * r31/r31+4, and not with the values in pt_regs.
233 */
234 if (addr == PT_PSW) {
235 /* Since PT_PSW==0, it is valid for 32 bit processes
236 * under 64 bit kernels as well.
237 */
238 ret = arch_ptrace(child, request, addr, data);
239 } else {
240 if (addr & (sizeof(compat_uint_t)-1))
241 break;
242 addr = translate_usr_offset(addr);
243 if (addr >= sizeof(struct pt_regs))
244 break;
245 if (addr >= PT_FR0 && addr <= PT_FR31 + 4) {
246 /* Special case, fp regs are 64 bits anyway */
247 *(__u64 *) ((char *) task_regs(child) + addr) = data;
248 ret = 0;
249 }
250 else if ((addr >= PT_GR1+4 && addr <= PT_GR31+4) ||
251 addr == PT_IAOQ0+4 || addr == PT_IAOQ1+4 ||
252 addr == PT_SAR+4) {
253 /* Zero the top 32 bits */
254 *(__u32 *) ((char *) task_regs(child) + addr - 4) = 0;
255 *(__u32 *) ((char *) task_regs(child) + addr) = data;
256 ret = 0;
257 }
258 }
259 break;
260
261 default:
262 ret = compat_ptrace_request(child, request, addr, data);
263 break;
264 }
265
266 return ret;
267 }
268 #endif
269
do_syscall_trace_enter(struct pt_regs * regs)270 long do_syscall_trace_enter(struct pt_regs *regs)
271 {
272 /* Do the secure computing check first. */
273 secure_computing_strict(regs->gr[20]);
274
275 if (test_thread_flag(TIF_SYSCALL_TRACE) &&
276 tracehook_report_syscall_entry(regs)) {
277 /*
278 * Tracing decided this syscall should not happen or the
279 * debugger stored an invalid system call number. Skip
280 * the system call and the system call restart handling.
281 */
282 regs->gr[20] = -1UL;
283 goto out;
284 }
285
286 #ifdef CONFIG_64BIT
287 if (!is_compat_task())
288 audit_syscall_entry(regs->gr[20], regs->gr[26], regs->gr[25],
289 regs->gr[24], regs->gr[23]);
290 else
291 #endif
292 audit_syscall_entry(regs->gr[20] & 0xffffffff,
293 regs->gr[26] & 0xffffffff,
294 regs->gr[25] & 0xffffffff,
295 regs->gr[24] & 0xffffffff,
296 regs->gr[23] & 0xffffffff);
297
298 out:
299 return regs->gr[20];
300 }
301
do_syscall_trace_exit(struct pt_regs * regs)302 void do_syscall_trace_exit(struct pt_regs *regs)
303 {
304 int stepping = test_thread_flag(TIF_SINGLESTEP) ||
305 test_thread_flag(TIF_BLOCKSTEP);
306
307 audit_syscall_exit(regs);
308
309 if (stepping || test_thread_flag(TIF_SYSCALL_TRACE))
310 tracehook_report_syscall_exit(regs, stepping);
311 }
312