arch/alpha/kernel/ptrace.c

   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
  17 #include <asm/uaccess.h>
  18 #include <asm/pgtable.h>
  19 #include <asm/fpu.h>
  20
  21 #include "proto.h"
  22
  23 #define DEBUG   DBG_MEM
  24 #undef DEBUG
  25
  26 #ifdef DEBUG
  27 enum {
  28         DBG_MEM         = (1<<0),
  29         DBG_BPT         = (1<<1),
  30         DBG_MEM_ALL     = (1<<2)
  31 };
  32 #define DBG(fac,args)   {if ((fac) & DEBUG) printk args;}
  33 #else
  34 #define DBG(fac,args)
  35 #endif
  36
  37 #define BREAKINST       0x00000080      /* call_pal bpt */
  38
  39 /*
  40  * does not yet catch signals sent when the child dies.
  41  * in exit.c or in signal.c.
  42  */
  43
  44 /*
  45  * Processes always block with the following stack-layout:
  46  *
  47  *  +================================+ <---- task + 2*PAGE_SIZE
  48  *  | PALcode saved frame (ps, pc,   | ^
  49  *  | gp, a0, a1, a2)                | |
  50  *  +================================+ | struct pt_regs
  51  *  |                                | |
  52  *  | frame generated by SAVE_ALL    | |
  53  *  |                                | v
  54  *  +================================+
  55  *  |                                | ^
  56  *  | frame saved by do_switch_stack | | struct switch_stack
  57  *  |                                | v
  58  *  +================================+
  59  */
  60
  61 /*
  62  * The following table maps a register index into the stack offset at
  63  * which the register is saved.  Register indices are 0-31 for integer
  64  * regs, 32-63 for fp regs, and 64 for the pc.  Notice that sp and
  65  * zero have no stack-slot and need to be treated specially (see
  66  * get_reg/put_reg below).
  67  */
  68 enum {
  69         REG_R0 = 0, REG_F0 = 32, REG_FPCR = 63, REG_PC = 64
  70 };
  71
  72 #define PT_REG(reg) \
  73   (PAGE_SIZE*2 - sizeof(struct pt_regs) + offsetof(struct pt_regs, reg))
  74
  75 #define SW_REG(reg) \
  76  (PAGE_SIZE*2 - sizeof(struct pt_regs) - sizeof(struct switch_stack) \
  77   + offsetof(struct switch_stack, reg))
  78
  79 static int regoff[] = {
  80         PT_REG(    r0), PT_REG(    r1), PT_REG(    r2), PT_REG(   r3),
  81         PT_REG(    r4), PT_REG(    r5), PT_REG(    r6), PT_REG(   r7),
  82         PT_REG(    r8), SW_REG(    r9), SW_REG(   r10), SW_REG(  r11),
  83         SW_REG(   r12), SW_REG(   r13), SW_REG(   r14), SW_REG(  r15),
  84         PT_REG(   r16), PT_REG(   r17), PT_REG(   r18), PT_REG(  r19),
  85         PT_REG(   r20), PT_REG(   r21), PT_REG(   r22), PT_REG(  r23),
  86         PT_REG(   r24), PT_REG(   r25), PT_REG(   r26), PT_REG(  r27),
  87         PT_REG(   r28), PT_REG(    gp),            -1,             -1,
  88         SW_REG(fp[ 0]), SW_REG(fp[ 1]), SW_REG(fp[ 2]), SW_REG(fp[ 3]),
  89         SW_REG(fp[ 4]), SW_REG(fp[ 5]), SW_REG(fp[ 6]), SW_REG(fp[ 7]),
  90         SW_REG(fp[ 8]), SW_REG(fp[ 9]), SW_REG(fp[10]), SW_REG(fp[11]),
  91         SW_REG(fp[12]), SW_REG(fp[13]), SW_REG(fp[14]), SW_REG(fp[15]),
  92         SW_REG(fp[16]), SW_REG(fp[17]), SW_REG(fp[18]), SW_REG(fp[19]),
  93         SW_REG(fp[20]), SW_REG(fp[21]), SW_REG(fp[22]), SW_REG(fp[23]),
  94         SW_REG(fp[24]), SW_REG(fp[25]), SW_REG(fp[26]), SW_REG(fp[27]),
  95         SW_REG(fp[28]), SW_REG(fp[29]), SW_REG(fp[30]), SW_REG(fp[31]),
  96         PT_REG(    pc)
  97 };
  98
  99 static unsigned long zero;
 100
 101 /*
 102  * Get address of register REGNO in task TASK.
 103  */
 104 static unsigned long *
 105 get_reg_addr(struct task_struct * task, unsigned long regno)
 106 {
 107         unsigned long *addr;
 108
 109         if (regno == 30) {
 110                 addr = &task_thread_info(task)->pcb.usp;
 111         } else if (regno == 65) {
 112                 addr = &task_thread_info(task)->pcb.unique;
 113         } else if (regno == 31 || regno > 65) {
 114                 zero = 0;
 115                 addr = &zero;
 116         } else {
 117                 addr = task_stack_page(task) + regoff[regno];
 118         }
 119         return addr;
 120 }
 121
 122 /*
 123  * Get contents of register REGNO in task TASK.
 124  */
 125 static unsigned long
 126 get_reg(struct task_struct * task, unsigned long regno)
 127 {
 128         /* Special hack for fpcr -- combine hardware and software bits.  */
 129         if (regno == 63) {
 130                 unsigned long fpcr = *get_reg_addr(task, regno);
 131                 unsigned long swcr
 132                   = task_thread_info(task)->ieee_state & IEEE_SW_MASK;
 133                 swcr = swcr_update_status(swcr, fpcr);
 134                 return fpcr | swcr;
 135         }
 136         return *get_reg_addr(task, regno);
 137 }
 138
 139 /*
 140  * Write contents of register REGNO in task TASK.
 141  */
 142 static int
 143 put_reg(struct task_struct *task, unsigned long regno, unsigned long data)
 144 {
 145         if (regno == 63) {
 146                 task_thread_info(task)->ieee_state
 147                   = ((task_thread_info(task)->ieee_state & ~IEEE_SW_MASK)
 148                      | (data & IEEE_SW_MASK));
 149                 data = (data & FPCR_DYN_MASK) | ieee_swcr_to_fpcr(data);
 150         }
 151         *get_reg_addr(task, regno) = data;
 152         return 0;
 153 }
 154
 155 static inline int
 156 read_int(struct task_struct *task, unsigned long addr, int * data)
 157 {
 158         int copied = access_process_vm(task, addr, data, sizeof(int), 0);
 159         return (copied == sizeof(int)) ? 0 : -EIO;
 160 }
 161
 162 static inline int
 163 write_int(struct task_struct *task, unsigned long addr, int data)
 164 {
 165         int copied = access_process_vm(task, addr, &data, sizeof(int), 1);
 166         return (copied == sizeof(int)) ? 0 : -EIO;
 167 }
 168
 169 /*
 170  * Set breakpoint.
 171  */
 172 int
 173 ptrace_set_bpt(struct task_struct * child)
 174 {
 175         int displ, i, res, reg_b, nsaved = 0;
 176         unsigned int insn, op_code;
 177         unsigned long pc;
 178
 179         pc  = get_reg(child, REG_PC);
 180         res = read_int(child, pc, (int *) &insn);
 181         if (res < 0)
 182                 return res;
 183
 184         op_code = insn >> 26;
 185         if (op_code >= 0x30) {
 186                 /*
 187                  * It's a branch: instead of trying to figure out
 188                  * whether the branch will be taken or not, we'll put
 189                  * a breakpoint at either location.  This is simpler,
 190                  * more reliable, and probably not a whole lot slower
 191                  * than the alternative approach of emulating the
 192                  * branch (emulation can be tricky for fp branches).
 193                  */
 194                 displ = ((s32)(insn << 11)) >> 9;
 195                 task_thread_info(child)->bpt_addr[nsaved++] = pc + 4;
 196                 if (displ)              /* guard against unoptimized code */
 197                         task_thread_info(child)->bpt_addr[nsaved++]
 198                           = pc + 4 + displ;
 199                 DBG(DBG_BPT, ("execing branch\n"));
 200         } else if (op_code == 0x1a) {
 201                 reg_b = (insn >> 16) & 0x1f;
 202                 task_thread_info(child)->bpt_addr[nsaved++] = get_reg(child, reg_b);
 203                 DBG(DBG_BPT, ("execing jump\n"));
 204         } else {
 205                 task_thread_info(child)->bpt_addr[nsaved++] = pc + 4;
 206                 DBG(DBG_BPT, ("execing normal insn\n"));
 207         }
 208
 209         /* install breakpoints: */
 210         for (i = 0; i < nsaved; ++i) {
 211                 res = read_int(child, task_thread_info(child)->bpt_addr[i],
 212                                (int *) &insn);
 213                 if (res < 0)
 214                         return res;
 215                 task_thread_info(child)->bpt_insn[i] = insn;
 216                 DBG(DBG_BPT, ("    -> next_pc=%lx\n",
 217                               task_thread_info(child)->bpt_addr[i]));
 218                 res = write_int(child, task_thread_info(child)->bpt_addr[i],
 219                                 BREAKINST);
 220                 if (res < 0)
 221                         return res;
 222         }
 223         task_thread_info(child)->bpt_nsaved = nsaved;
 224         return 0;
 225 }
 226
 227 /*
 228  * Ensure no single-step breakpoint is pending.  Returns non-zero
 229  * value if child was being single-stepped.
 230  */
 231 int
 232 ptrace_cancel_bpt(struct task_struct * child)
 233 {
 234         int i, nsaved = task_thread_info(child)->bpt_nsaved;
 235
 236         task_thread_info(child)->bpt_nsaved = 0;
 237
 238         if (nsaved > 2) {
 239                 printk("ptrace_cancel_bpt: bogus nsaved: %d!\n", nsaved);
 240                 nsaved = 2;
 241         }
 242
 243         for (i = 0; i < nsaved; ++i) {
 244                 write_int(child, task_thread_info(child)->bpt_addr[i],
 245                           task_thread_info(child)->bpt_insn[i]);
 246         }
 247         return (nsaved != 0);
 248 }
 249
 250 void user_enable_single_step(struct task_struct *child)
 251 {
 252         /* Mark single stepping.  */
 253         task_thread_info(child)->bpt_nsaved = -1;
 254 }
 255
 256 void user_disable_single_step(struct task_struct *child)
 257 {
 258         ptrace_cancel_bpt(child);
 259 }
 260
 261 /*
 262  * Called by kernel/ptrace.c when detaching..
 263  *
 264  * Make sure the single step bit is not set.
 265  */
 266 void ptrace_disable(struct task_struct *child)
 267 {
 268         user_disable_single_step(child);
 269 }
 270
 271 long arch_ptrace(struct task_struct *child, long request,
 272                  unsigned long addr, unsigned long data)
 273 {
 274         unsigned long tmp;
 275         size_t copied;
 276         long ret;
 277
 278         switch (request) {
 279         /* When I and D space are separate, these will need to be fixed.  */
 280         case PTRACE_PEEKTEXT: /* read word at location addr. */
 281         case PTRACE_PEEKDATA:
 282                 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 283                 ret = -EIO;
 284                 if (copied != sizeof(tmp))
 285                         break;
 286
 287                 force_successful_syscall_return();
 288                 ret = tmp;
 289                 break;
 290
 291         /* Read register number ADDR. */
 292         case PTRACE_PEEKUSR:
 293                 force_successful_syscall_return();
 294                 ret = get_reg(child, addr);
 295                 DBG(DBG_MEM, ("peek $%lu->%#lx\n", addr, ret));
 296                 break;
 297
 298         /* When I and D space are separate, this will have to be fixed.  */
 299         case PTRACE_POKETEXT: /* write the word at location addr. */
 300         case PTRACE_POKEDATA:
 301                 ret = generic_ptrace_pokedata(child, addr, data);
 302                 break;
 303
 304         case PTRACE_POKEUSR: /* write the specified register */
 305                 DBG(DBG_MEM, ("poke $%lu<-%#lx\n", addr, data));
 306                 ret = put_reg(child, addr, data);
 307                 break;
 308         default:
 309                 ret = ptrace_request(child, request, addr, data);
 310                 break;
 311         }
 312         return ret;
 313 }
 314
 315 asmlinkage void
 316 syscall_trace(void)
 317 {
 318         if (!test_thread_flag(TIF_SYSCALL_TRACE))
 319                 return;
 320         if (!(current->ptrace & PT_PTRACED))
 321                 return;
 322         /* The 0x80 provides a way for the tracing parent to distinguish
 323            between a syscall stop and SIGTRAP delivery */
 324         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 325                                  ? 0x80 : 0));
 326
 327         /*
 328          * This isn't the same as continuing with a signal, but it will do
 329          * for normal use.  strace only continues with a signal if the
 330          * stopping signal is not SIGTRAP.  -brl
 331          */
 332         if (current->exit_code) {
 333                 send_sig(current->exit_code, current, 1);
 334                 current->exit_code = 0;
 335         }
 336 }