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Linux/arch/alpha/kernel/ptrace.c

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  1 /* ptrace.c */
  2 /* By Ross Biro 1/23/92 */
  3 /* edited by Linus Torvalds */
  4 /* mangled further by Bob Manson (manson@santafe.edu) */
  5 /* more mutilation by David Mosberger (davidm@azstarnet.com) */
  6 
  7 #include <linux/kernel.h>
  8 #include <linux/sched.h>
  9 #include <linux/mm.h>
 10 #include <linux/smp.h>
 11 #include <linux/errno.h>
 12 #include <linux/ptrace.h>
 13 #include <linux/user.h>
 14 #include <linux/security.h>
 15 #include <linux/signal.h>
 16 #include <linux/tracehook.h>
 17 #include <linux/audit.h>
 18 
 19 #include <linux/uaccess.h>
 20 #include <asm/pgtable.h>
 21 #include <asm/fpu.h>
 22 
 23 #include "proto.h"
 24 
 25 #define DEBUG   DBG_MEM
 26 #undef DEBUG
 27 
 28 #ifdef DEBUG
 29 enum {
 30         DBG_MEM         = (1<<0),
 31         DBG_BPT         = (1<<1),
 32         DBG_MEM_ALL     = (1<<2)
 33 };
 34 #define DBG(fac,args)   {if ((fac) & DEBUG) printk args;}
 35 #else
 36 #define DBG(fac,args)
 37 #endif
 38 
 39 #define BREAKINST       0x00000080      /* call_pal bpt */
 40 
 41 /*
 42  * does not yet catch signals sent when the child dies.
 43  * in exit.c or in signal.c.
 44  */
 45 
 46 /*
 47  * Processes always block with the following stack-layout:
 48  *
 49  *  +================================+ <---- task + 2*PAGE_SIZE
 50  *  | PALcode saved frame (ps, pc,   | ^
 51  *  | gp, a0, a1, a2)                | |
 52  *  +================================+ | struct pt_regs
 53  *  |                                | |
 54  *  | frame generated by SAVE_ALL    | |
 55  *  |                                | v
 56  *  +================================+
 57  *  |                                | ^
 58  *  | frame saved by do_switch_stack | | struct switch_stack
 59  *  |                                | v
 60  *  +================================+
 61  */
 62 
 63 /* 
 64  * The following table maps a register index into the stack offset at
 65  * which the register is saved.  Register indices are 0-31 for integer
 66  * regs, 32-63 for fp regs, and 64 for the pc.  Notice that sp and
 67  * zero have no stack-slot and need to be treated specially (see
 68  * get_reg/put_reg below).
 69  */
 70 enum {
 71         REG_R0 = 0, REG_F0 = 32, REG_FPCR = 63, REG_PC = 64
 72 };
 73 
 74 #define PT_REG(reg) \
 75   (PAGE_SIZE*2 - sizeof(struct pt_regs) + offsetof(struct pt_regs, reg))
 76 
 77 #define SW_REG(reg) \
 78  (PAGE_SIZE*2 - sizeof(struct pt_regs) - sizeof(struct switch_stack) \
 79   + offsetof(struct switch_stack, reg))
 80 
 81 static int regoff[] = {
 82         PT_REG(    r0), PT_REG(    r1), PT_REG(    r2), PT_REG(   r3),
 83         PT_REG(    r4), PT_REG(    r5), PT_REG(    r6), PT_REG(   r7),
 84         PT_REG(    r8), SW_REG(    r9), SW_REG(   r10), SW_REG(  r11),
 85         SW_REG(   r12), SW_REG(   r13), SW_REG(   r14), SW_REG(  r15),
 86         PT_REG(   r16), PT_REG(   r17), PT_REG(   r18), PT_REG(  r19),
 87         PT_REG(   r20), PT_REG(   r21), PT_REG(   r22), PT_REG(  r23),
 88         PT_REG(   r24), PT_REG(   r25), PT_REG(   r26), PT_REG(  r27),
 89         PT_REG(   r28), PT_REG(    gp),            -1,             -1,
 90         SW_REG(fp[ 0]), SW_REG(fp[ 1]), SW_REG(fp[ 2]), SW_REG(fp[ 3]),
 91         SW_REG(fp[ 4]), SW_REG(fp[ 5]), SW_REG(fp[ 6]), SW_REG(fp[ 7]),
 92         SW_REG(fp[ 8]), SW_REG(fp[ 9]), SW_REG(fp[10]), SW_REG(fp[11]),
 93         SW_REG(fp[12]), SW_REG(fp[13]), SW_REG(fp[14]), SW_REG(fp[15]),
 94         SW_REG(fp[16]), SW_REG(fp[17]), SW_REG(fp[18]), SW_REG(fp[19]),
 95         SW_REG(fp[20]), SW_REG(fp[21]), SW_REG(fp[22]), SW_REG(fp[23]),
 96         SW_REG(fp[24]), SW_REG(fp[25]), SW_REG(fp[26]), SW_REG(fp[27]),
 97         SW_REG(fp[28]), SW_REG(fp[29]), SW_REG(fp[30]), SW_REG(fp[31]),
 98         PT_REG(    pc)
 99 };
100 
101 static unsigned long zero;
102 
103 /*
104  * Get address of register REGNO in task TASK.
105  */
106 static unsigned long *
107 get_reg_addr(struct task_struct * task, unsigned long regno)
108 {
109         unsigned long *addr;
110 
111         if (regno == 30) {
112                 addr = &task_thread_info(task)->pcb.usp;
113         } else if (regno == 65) {
114                 addr = &task_thread_info(task)->pcb.unique;
115         } else if (regno == 31 || regno > 65) {
116                 zero = 0;
117                 addr = &zero;
118         } else {
119                 addr = task_stack_page(task) + regoff[regno];
120         }
121         return addr;
122 }
123 
124 /*
125  * Get contents of register REGNO in task TASK.
126  */
127 static unsigned long
128 get_reg(struct task_struct * task, unsigned long regno)
129 {
130         /* Special hack for fpcr -- combine hardware and software bits.  */
131         if (regno == 63) {
132                 unsigned long fpcr = *get_reg_addr(task, regno);
133                 unsigned long swcr
134                   = task_thread_info(task)->ieee_state & IEEE_SW_MASK;
135                 swcr = swcr_update_status(swcr, fpcr);
136                 return fpcr | swcr;
137         }
138         return *get_reg_addr(task, regno);
139 }
140 
141 /*
142  * Write contents of register REGNO in task TASK.
143  */
144 static int
145 put_reg(struct task_struct *task, unsigned long regno, unsigned long data)
146 {
147         if (regno == 63) {
148                 task_thread_info(task)->ieee_state
149                   = ((task_thread_info(task)->ieee_state & ~IEEE_SW_MASK)
150                      | (data & IEEE_SW_MASK));
151                 data = (data & FPCR_DYN_MASK) | ieee_swcr_to_fpcr(data);
152         }
153         *get_reg_addr(task, regno) = data;
154         return 0;
155 }
156 
157 static inline int
158 read_int(struct task_struct *task, unsigned long addr, int * data)
159 {
160         int copied = access_process_vm(task, addr, data, sizeof(int),
161                         FOLL_FORCE);
162         return (copied == sizeof(int)) ? 0 : -EIO;
163 }
164 
165 static inline int
166 write_int(struct task_struct *task, unsigned long addr, int data)
167 {
168         int copied = access_process_vm(task, addr, &data, sizeof(int),
169                         FOLL_FORCE | FOLL_WRITE);
170         return (copied == sizeof(int)) ? 0 : -EIO;
171 }
172 
173 /*
174  * Set breakpoint.
175  */
176 int
177 ptrace_set_bpt(struct task_struct * child)
178 {
179         int displ, i, res, reg_b, nsaved = 0;
180         unsigned int insn, op_code;
181         unsigned long pc;
182 
183         pc  = get_reg(child, REG_PC);
184         res = read_int(child, pc, (int *) &insn);
185         if (res < 0)
186                 return res;
187 
188         op_code = insn >> 26;
189         if (op_code >= 0x30) {
190                 /*
191                  * It's a branch: instead of trying to figure out
192                  * whether the branch will be taken or not, we'll put
193                  * a breakpoint at either location.  This is simpler,
194                  * more reliable, and probably not a whole lot slower
195                  * than the alternative approach of emulating the
196                  * branch (emulation can be tricky for fp branches).
197                  */
198                 displ = ((s32)(insn << 11)) >> 9;
199                 task_thread_info(child)->bpt_addr[nsaved++] = pc + 4;
200                 if (displ)              /* guard against unoptimized code */
201                         task_thread_info(child)->bpt_addr[nsaved++]
202                           = pc + 4 + displ;
203                 DBG(DBG_BPT, ("execing branch\n"));
204         } else if (op_code == 0x1a) {
205                 reg_b = (insn >> 16) & 0x1f;
206                 task_thread_info(child)->bpt_addr[nsaved++] = get_reg(child, reg_b);
207                 DBG(DBG_BPT, ("execing jump\n"));
208         } else {
209                 task_thread_info(child)->bpt_addr[nsaved++] = pc + 4;
210                 DBG(DBG_BPT, ("execing normal insn\n"));
211         }
212 
213         /* install breakpoints: */
214         for (i = 0; i < nsaved; ++i) {
215                 res = read_int(child, task_thread_info(child)->bpt_addr[i],
216                                (int *) &insn);
217                 if (res < 0)
218                         return res;
219                 task_thread_info(child)->bpt_insn[i] = insn;
220                 DBG(DBG_BPT, ("    -> next_pc=%lx\n",
221                               task_thread_info(child)->bpt_addr[i]));
222                 res = write_int(child, task_thread_info(child)->bpt_addr[i],
223                                 BREAKINST);
224                 if (res < 0)
225                         return res;
226         }
227         task_thread_info(child)->bpt_nsaved = nsaved;
228         return 0;
229 }
230 
231 /*
232  * Ensure no single-step breakpoint is pending.  Returns non-zero
233  * value if child was being single-stepped.
234  */
235 int
236 ptrace_cancel_bpt(struct task_struct * child)
237 {
238         int i, nsaved = task_thread_info(child)->bpt_nsaved;
239 
240         task_thread_info(child)->bpt_nsaved = 0;
241 
242         if (nsaved > 2) {
243                 printk("ptrace_cancel_bpt: bogus nsaved: %d!\n", nsaved);
244                 nsaved = 2;
245         }
246 
247         for (i = 0; i < nsaved; ++i) {
248                 write_int(child, task_thread_info(child)->bpt_addr[i],
249                           task_thread_info(child)->bpt_insn[i]);
250         }
251         return (nsaved != 0);
252 }
253 
254 void user_enable_single_step(struct task_struct *child)
255 {
256         /* Mark single stepping.  */
257         task_thread_info(child)->bpt_nsaved = -1;
258 }
259 
260 void user_disable_single_step(struct task_struct *child)
261 {
262         ptrace_cancel_bpt(child);
263 }
264 
265 /*
266  * Called by kernel/ptrace.c when detaching..
267  *
268  * Make sure the single step bit is not set.
269  */
270 void ptrace_disable(struct task_struct *child)
271 { 
272         user_disable_single_step(child);
273 }
274 
275 long arch_ptrace(struct task_struct *child, long request,
276                  unsigned long addr, unsigned long data)
277 {
278         unsigned long tmp;
279         size_t copied;
280         long ret;
281 
282         switch (request) {
283         /* When I and D space are separate, these will need to be fixed.  */
284         case PTRACE_PEEKTEXT: /* read word at location addr. */
285         case PTRACE_PEEKDATA:
286                 copied = ptrace_access_vm(child, addr, &tmp, sizeof(tmp),
287                                 FOLL_FORCE);
288                 ret = -EIO;
289                 if (copied != sizeof(tmp))
290                         break;
291                 
292                 force_successful_syscall_return();
293                 ret = tmp;
294                 break;
295 
296         /* Read register number ADDR. */
297         case PTRACE_PEEKUSR:
298                 force_successful_syscall_return();
299                 ret = get_reg(child, addr);
300                 DBG(DBG_MEM, ("peek $%lu->%#lx\n", addr, ret));
301                 break;
302 
303         /* When I and D space are separate, this will have to be fixed.  */
304         case PTRACE_POKETEXT: /* write the word at location addr. */
305         case PTRACE_POKEDATA:
306                 ret = generic_ptrace_pokedata(child, addr, data);
307                 break;
308 
309         case PTRACE_POKEUSR: /* write the specified register */
310                 DBG(DBG_MEM, ("poke $%lu<-%#lx\n", addr, data));
311                 ret = put_reg(child, addr, data);
312                 break;
313         default:
314                 ret = ptrace_request(child, request, addr, data);
315                 break;
316         }
317         return ret;
318 }
319 
320 asmlinkage unsigned long syscall_trace_enter(void)
321 {
322         unsigned long ret = 0;
323         struct pt_regs *regs = current_pt_regs();
324         if (test_thread_flag(TIF_SYSCALL_TRACE) &&
325             tracehook_report_syscall_entry(current_pt_regs()))
326                 ret = -1UL;
327         audit_syscall_entry(regs->r0, regs->r16, regs->r17, regs->r18, regs->r19);
328         return ret ?: current_pt_regs()->r0;
329 }
330 
331 asmlinkage void
332 syscall_trace_leave(void)
333 {
334         audit_syscall_exit(current_pt_regs());
335         if (test_thread_flag(TIF_SYSCALL_TRACE))
336                 tracehook_report_syscall_exit(current_pt_regs(), 0);
337 }
338 

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