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 */
38void 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 */
54void user_disable_single_step(struct task_struct *task)
55{
56	ptrace_disable(task);
57}
58
59void 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
102void 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
114long 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
190static 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
204long 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
270long 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
298out:
299	return regs->gr[20];
300}
301
302void 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