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#include <linux/tracehook.h>
  17#include <linux/audit.h>
  18
  19#include <asm/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
  29enum {
  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 */
  70enum {
  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
  81static 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
 101static unsigned long zero;
 102
 103/*
 104 * Get address of register REGNO in task TASK.
 105 */
 106static unsigned long *
 107get_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 */
 127static unsigned long
 128get_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 */
 144static int
 145put_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
 157static inline int
 158read_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
 165static inline int
 166write_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 */
 176int
 177ptrace_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 */
 235int
 236ptrace_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
 254void user_enable_single_step(struct task_struct *child)
 255{
 256        /* Mark single stepping.  */
 257        task_thread_info(child)->bpt_nsaved = -1;
 258}
 259
 260void 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 */
 270void ptrace_disable(struct task_struct *child)
 271{ 
 272        user_disable_single_step(child);
 273}
 274
 275long 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 = access_process_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
 320asmlinkage 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
 331asmlinkage void
 332syscall_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