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 #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 }