LXR linux/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
  27enum {
  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 */
  68enum {
  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
  79static 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
  99static unsigned long zero;
 100
 101/*
 102 * Get address of register REGNO in task TASK.
 103 */
 104static unsigned long *
 105get_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 */
 125static unsigned long
 126get_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 */
 142static int
 143put_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
 155static inline int
 156read_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
 162static inline int
 163write_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 */
 172int
 173ptrace_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 */
 231int
 232ptrace_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
 250void user_enable_single_step(struct task_struct *child)
 251{
 252        /* Mark single stepping.  */
 253        task_thread_info(child)->bpt_nsaved = -1;
 254}
 255
 256void 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 */
 266void ptrace_disable(struct task_struct *child)
 267{ 
 268        user_disable_single_step(child);
 269}
 270
 271long 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
 315asmlinkage void
 316syscall_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}
 337