2 * Kernel support for the ptrace() and syscall tracing interfaces.
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>
10 #include <linux/kernel.h>
11 #include <linux/sched.h>
13 #include <linux/smp.h>
14 #include <linux/errno.h>
15 #include <linux/ptrace.h>
16 #include <linux/user.h>
17 #include <linux/personality.h>
18 #include <linux/security.h>
19 #include <linux/compat.h>
20 #include <linux/signal.h>
22 #include <asm/uaccess.h>
23 #include <asm/pgtable.h>
24 #include <asm/system.h>
25 #include <asm/processor.h>
26 #include <asm/asm-offsets.h>
28 /* PSW bits we allow the debugger to modify */
29 #define USER_PSW_BITS (PSW_N | PSW_V | PSW_CB)
32 * Called by kernel/ptrace.c when detaching..
34 * Make sure single step bits etc are not set.
36 void ptrace_disable(struct task_struct
*task
)
38 task
->ptrace
&= ~(PT_SINGLESTEP
|PT_BLOCKSTEP
);
40 /* make sure the trap bits are not set */
48 * The following functions are called by ptrace_resume() when
49 * enabling or disabling single/block tracing.
51 void user_disable_single_step(struct task_struct
*task
)
56 void user_enable_single_step(struct task_struct
*task
)
58 task
->ptrace
&= ~PT_BLOCKSTEP
;
59 task
->ptrace
|= PT_SINGLESTEP
;
61 if (pa_psw(task
)->n
) {
64 /* Nullified, just crank over the queue. */
65 task_regs(task
)->iaoq
[0] = task_regs(task
)->iaoq
[1];
66 task_regs(task
)->iasq
[0] = task_regs(task
)->iasq
[1];
67 task_regs(task
)->iaoq
[1] = task_regs(task
)->iaoq
[0] + 4;
74 /* Don't wake up the task, but let the
75 parent know something happened. */
76 si
.si_code
= TRAP_TRACE
;
77 si
.si_addr
= (void __user
*) (task_regs(task
)->iaoq
[0] & ~3);
78 si
.si_signo
= SIGTRAP
;
80 force_sig_info(SIGTRAP
, &si
, task
);
81 /* notify_parent(task, SIGCHLD); */
85 /* Enable recovery counter traps. The recovery counter
86 * itself will be set to zero on a task switch. If the
87 * task is suspended on a syscall then the syscall return
88 * path will overwrite the recovery counter with a suitable
89 * value such that it traps once back in user space. We
90 * disable interrupts in the tasks PSW here also, to avoid
91 * interrupts while the recovery counter is decrementing.
99 void user_enable_block_step(struct task_struct
*task
)
101 task
->ptrace
&= ~PT_SINGLESTEP
;
102 task
->ptrace
|= PT_BLOCKSTEP
;
104 /* Enable taken branch trap. */
111 long arch_ptrace(struct task_struct
*child
, long request
, long addr
, long data
)
118 /* Read the word at location addr in the USER area. For ptraced
119 processes, the kernel saves all regs on a syscall. */
121 if ((addr
& (sizeof(long)-1)) ||
122 (unsigned long) addr
>= sizeof(struct pt_regs
))
124 tmp
= *(unsigned long *) ((char *) task_regs(child
) + addr
);
125 ret
= put_user(tmp
, (unsigned long *) data
);
128 /* Write the word at location addr in the USER area. This will need
129 to change when the kernel no longer saves all regs on a syscall.
130 FIXME. There is a problem at the moment in that r3-r18 are only
131 saved if the process is ptraced on syscall entry, and even then
132 those values are overwritten by actual register values on syscall
135 /* Some register values written here may be ignored in
136 * entry.S:syscall_restore_rfi; e.g. iaoq is written with
137 * r31/r31+4, and not with the values in pt_regs.
139 if (addr
== PT_PSW
) {
140 /* Allow writing to Nullify, Divide-step-correction,
141 * and carry/borrow bits.
142 * BEWARE, if you set N, and then single step, it won't
143 * stop on the nullified instruction.
145 data
&= USER_PSW_BITS
;
146 task_regs(child
)->gr
[0] &= ~USER_PSW_BITS
;
147 task_regs(child
)->gr
[0] |= data
;
152 if ((addr
& (sizeof(long)-1)) ||
153 (unsigned long) addr
>= sizeof(struct pt_regs
))
155 if ((addr
>= PT_GR1
&& addr
<= PT_GR31
) ||
156 addr
== PT_IAOQ0
|| addr
== PT_IAOQ1
||
157 (addr
>= PT_FR0
&& addr
<= PT_FR31
+ 4) ||
159 *(unsigned long *) ((char *) task_regs(child
) + addr
) = data
;
165 ret
= ptrace_request(child
, request
, addr
, data
);
175 /* This function is needed to translate 32 bit pt_regs offsets in to
176 * 64 bit pt_regs offsets. For example, a 32 bit gdb under a 64 bit kernel
177 * will request offset 12 if it wants gr3, but the lower 32 bits of
178 * the 64 bit kernels view of gr3 will be at offset 28 (3*8 + 4).
179 * This code relies on a 32 bit pt_regs being comprised of 32 bit values
180 * except for the fp registers which (a) are 64 bits, and (b) follow
181 * the gr registers at the start of pt_regs. The 32 bit pt_regs should
182 * be half the size of the 64 bit pt_regs, plus 32*4 to allow for fr[]
183 * being 64 bit in both cases.
186 static long translate_usr_offset(long offset
)
190 else if (offset
<= 32*4) /* gr[0..31] */
191 return offset
* 2 + 4;
192 else if (offset
<= 32*4+32*8) /* gr[0..31] + fr[0..31] */
193 return offset
+ 32*4;
194 else if (offset
< sizeof(struct pt_regs
)/2 + 32*4)
195 return offset
* 2 + 4 - 32*8;
200 long compat_arch_ptrace(struct task_struct
*child
, compat_long_t request
,
201 compat_ulong_t addr
, compat_ulong_t data
)
209 if (addr
& (sizeof(compat_uint_t
)-1))
211 addr
= translate_usr_offset(addr
);
215 tmp
= *(compat_uint_t
*) ((char *) task_regs(child
) + addr
);
216 ret
= put_user(tmp
, (compat_uint_t
*) (unsigned long) data
);
219 /* Write the word at location addr in the USER area. This will need
220 to change when the kernel no longer saves all regs on a syscall.
221 FIXME. There is a problem at the moment in that r3-r18 are only
222 saved if the process is ptraced on syscall entry, and even then
223 those values are overwritten by actual register values on syscall
226 /* Some register values written here may be ignored in
227 * entry.S:syscall_restore_rfi; e.g. iaoq is written with
228 * r31/r31+4, and not with the values in pt_regs.
230 if (addr
== PT_PSW
) {
231 /* Since PT_PSW==0, it is valid for 32 bit processes
232 * under 64 bit kernels as well.
234 ret
= arch_ptrace(child
, request
, addr
, data
);
236 if (addr
& (sizeof(compat_uint_t
)-1))
238 addr
= translate_usr_offset(addr
);
241 if (addr
>= PT_FR0
&& addr
<= PT_FR31
+ 4) {
242 /* Special case, fp regs are 64 bits anyway */
243 *(__u64
*) ((char *) task_regs(child
) + addr
) = data
;
246 else if ((addr
>= PT_GR1
+4 && addr
<= PT_GR31
+4) ||
247 addr
== PT_IAOQ0
+4 || addr
== PT_IAOQ1
+4 ||
249 /* Zero the top 32 bits */
250 *(__u32
*) ((char *) task_regs(child
) + addr
- 4) = 0;
251 *(__u32
*) ((char *) task_regs(child
) + addr
) = data
;
258 ret
= compat_ptrace_request(child
, request
, addr
, data
);
267 void syscall_trace(void)
269 if (!test_thread_flag(TIF_SYSCALL_TRACE
))
271 if (!(current
->ptrace
& PT_PTRACED
))
273 ptrace_notify(SIGTRAP
| ((current
->ptrace
& PT_TRACESYSGOOD
)
276 * this isn't the same as continuing with a signal, but it will do
277 * for normal use. strace only continues with a signal if the
278 * stopping signal is not SIGTRAP. -brl
280 if (current
->exit_code
) {
281 send_sig(current
->exit_code
, current
, 1);
282 current
->exit_code
= 0;