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Linux/arch/parisc/kernel/ptrace.c

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  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  */
 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  */
 54 void user_disable_single_step(struct task_struct *task)
 55 {
 56         ptrace_disable(task);
 57 }
 58 
 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 
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 
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 
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 
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 
270 long do_syscall_trace_enter(struct pt_regs *regs)
271 {
272         long ret = 0;
273 
274         /* Do the secure computing check first. */
275         secure_computing_strict(regs->gr[20]);
276 
277         if (test_thread_flag(TIF_SYSCALL_TRACE) &&
278             tracehook_report_syscall_entry(regs))
279                 ret = -1L;
280 
281 #ifdef CONFIG_64BIT
282         if (!is_compat_task())
283                 audit_syscall_entry(regs->gr[20], regs->gr[26], regs->gr[25],
284                                     regs->gr[24], regs->gr[23]);
285         else
286 #endif
287                 audit_syscall_entry(regs->gr[20] & 0xffffffff,
288                         regs->gr[26] & 0xffffffff,
289                         regs->gr[25] & 0xffffffff,
290                         regs->gr[24] & 0xffffffff,
291                         regs->gr[23] & 0xffffffff);
292 
293         return ret ? : regs->gr[20];
294 }
295 
296 void do_syscall_trace_exit(struct pt_regs *regs)
297 {
298         int stepping = test_thread_flag(TIF_SINGLESTEP) ||
299                 test_thread_flag(TIF_BLOCKSTEP);
300 
301         audit_syscall_exit(regs);
302 
303         if (stepping || test_thread_flag(TIF_SYSCALL_TRACE))
304                 tracehook_report_syscall_exit(regs, stepping);
305 }
306 

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