LXR linux/arch/alpha/kernel/ptrace.c

   1// SPDX-License-Identifier: GPL-2.0
   2/* ptrace.c */
   3/* By Ross Biro 1/23/92 */
   4/* edited by Linus Torvalds */
   5/* mangled further by Bob Manson (manson@santafe.edu) */
   6/* more mutilation by David Mosberger (davidm@azstarnet.com) */
   7
   8#include <linux/kernel.h>
   9#include <linux/sched.h>
  10#include <linux/sched/task_stack.h>
  11#include <linux/mm.h>
  12#include <linux/smp.h>
  13#include <linux/errno.h>
  14#include <linux/ptrace.h>
  15#include <linux/user.h>
  16#include <linux/security.h>
  17#include <linux/signal.h>
  18#include <linux/tracehook.h>
  19#include <linux/audit.h>
  20
  21#include <linux/uaccess.h>
  22#include <asm/pgtable.h>
  23#include <asm/fpu.h>
  24
  25#include "proto.h"
  26
  27#define DEBUG   DBG_MEM
  28#undef DEBUG
  29
  30#ifdef DEBUG
  31enum {
  32        DBG_MEM         = (1<<0),
  33        DBG_BPT         = (1<<1),
  34        DBG_MEM_ALL     = (1<<2)
  35};
  36#define DBG(fac,args)   {if ((fac) & DEBUG) printk args;}
  37#else
  38#define DBG(fac,args)
  39#endif
  40
  41#define BREAKINST       0x00000080      /* call_pal bpt */
  42
  43/*
  44 * does not yet catch signals sent when the child dies.
  45 * in exit.c or in signal.c.
  46 */
  47
  48/*
  49 * Processes always block with the following stack-layout:
  50 *
  51 *  +================================+ <---- task + 2*PAGE_SIZE
  52 *  | PALcode saved frame (ps, pc,   | ^
  53 *  | gp, a0, a1, a2)                | |
  54 *  +================================+ | struct pt_regs
  55 *  |                                | |
  56 *  | frame generated by SAVE_ALL    | |
  57 *  |                                | v
  58 *  +================================+
  59 *  |                                | ^
  60 *  | frame saved by do_switch_stack | | struct switch_stack
  61 *  |                                | v
  62 *  +================================+
  63 */
  64
  65/* 
  66 * The following table maps a register index into the stack offset at
  67 * which the register is saved.  Register indices are 0-31 for integer
  68 * regs, 32-63 for fp regs, and 64 for the pc.  Notice that sp and
  69 * zero have no stack-slot and need to be treated specially (see
  70 * get_reg/put_reg below).
  71 */
  72enum {
  73        REG_R0 = 0, REG_F0 = 32, REG_FPCR = 63, REG_PC = 64
  74};
  75
  76#define PT_REG(reg) \
  77  (PAGE_SIZE*2 - sizeof(struct pt_regs) + offsetof(struct pt_regs, reg))
  78
  79#define SW_REG(reg) \
  80 (PAGE_SIZE*2 - sizeof(struct pt_regs) - sizeof(struct switch_stack) \
  81  + offsetof(struct switch_stack, reg))
  82
  83static int regoff[] = {
  84        PT_REG(    r0), PT_REG(    r1), PT_REG(    r2), PT_REG(   r3),
  85        PT_REG(    r4), PT_REG(    r5), PT_REG(    r6), PT_REG(   r7),
  86        PT_REG(    r8), SW_REG(    r9), SW_REG(   r10), SW_REG(  r11),
  87        SW_REG(   r12), SW_REG(   r13), SW_REG(   r14), SW_REG(  r15),
  88        PT_REG(   r16), PT_REG(   r17), PT_REG(   r18), PT_REG(  r19),
  89        PT_REG(   r20), PT_REG(   r21), PT_REG(   r22), PT_REG(  r23),
  90        PT_REG(   r24), PT_REG(   r25), PT_REG(   r26), PT_REG(  r27),
  91        PT_REG(   r28), PT_REG(    gp),            -1,             -1,
  92        SW_REG(fp[ 0]), SW_REG(fp[ 1]), SW_REG(fp[ 2]), SW_REG(fp[ 3]),
  93        SW_REG(fp[ 4]), SW_REG(fp[ 5]), SW_REG(fp[ 6]), SW_REG(fp[ 7]),
  94        SW_REG(fp[ 8]), SW_REG(fp[ 9]), SW_REG(fp[10]), SW_REG(fp[11]),
  95        SW_REG(fp[12]), SW_REG(fp[13]), SW_REG(fp[14]), SW_REG(fp[15]),
  96        SW_REG(fp[16]), SW_REG(fp[17]), SW_REG(fp[18]), SW_REG(fp[19]),
  97        SW_REG(fp[20]), SW_REG(fp[21]), SW_REG(fp[22]), SW_REG(fp[23]),
  98        SW_REG(fp[24]), SW_REG(fp[25]), SW_REG(fp[26]), SW_REG(fp[27]),
  99        SW_REG(fp[28]), SW_REG(fp[29]), SW_REG(fp[30]), SW_REG(fp[31]),
 100        PT_REG(    pc)
 101};
 102
 103static unsigned long zero;
 104
 105/*
 106 * Get address of register REGNO in task TASK.
 107 */
 108static unsigned long *
 109get_reg_addr(struct task_struct * task, unsigned long regno)
 110{
 111        unsigned long *addr;
 112
 113        if (regno == 30) {
 114                addr = &task_thread_info(task)->pcb.usp;
 115        } else if (regno == 65) {
 116                addr = &task_thread_info(task)->pcb.unique;
 117        } else if (regno == 31 || regno > 65) {
 118                zero = 0;
 119                addr = &zero;
 120        } else {
 121                addr = task_stack_page(task) + regoff[regno];
 122        }
 123        return addr;
 124}
 125
 126/*
 127 * Get contents of register REGNO in task TASK.
 128 */
 129static unsigned long
 130get_reg(struct task_struct * task, unsigned long regno)
 131{
 132        /* Special hack for fpcr -- combine hardware and software bits.  */
 133        if (regno == 63) {
 134                unsigned long fpcr = *get_reg_addr(task, regno);
 135                unsigned long swcr
 136                  = task_thread_info(task)->ieee_state & IEEE_SW_MASK;
 137                swcr = swcr_update_status(swcr, fpcr);
 138                return fpcr | swcr;
 139        }
 140        return *get_reg_addr(task, regno);
 141}
 142
 143/*
 144 * Write contents of register REGNO in task TASK.
 145 */
 146static int
 147put_reg(struct task_struct *task, unsigned long regno, unsigned long data)
 148{
 149        if (regno == 63) {
 150                task_thread_info(task)->ieee_state
 151                  = ((task_thread_info(task)->ieee_state & ~IEEE_SW_MASK)
 152                     | (data & IEEE_SW_MASK));
 153                data = (data & FPCR_DYN_MASK) | ieee_swcr_to_fpcr(data);
 154        }
 155        *get_reg_addr(task, regno) = data;
 156        return 0;
 157}
 158
 159static inline int
 160read_int(struct task_struct *task, unsigned long addr, int * data)
 161{
 162        int copied = access_process_vm(task, addr, data, sizeof(int),
 163                        FOLL_FORCE);
 164        return (copied == sizeof(int)) ? 0 : -EIO;
 165}
 166
 167static inline int
 168write_int(struct task_struct *task, unsigned long addr, int data)
 169{
 170        int copied = access_process_vm(task, addr, &data, sizeof(int),
 171                        FOLL_FORCE | FOLL_WRITE);
 172        return (copied == sizeof(int)) ? 0 : -EIO;
 173}
 174
 175/*
 176 * Set breakpoint.
 177 */
 178int
 179ptrace_set_bpt(struct task_struct * child)
 180{
 181        int displ, i, res, reg_b, nsaved = 0;
 182        unsigned int insn, op_code;
 183        unsigned long pc;
 184
 185        pc  = get_reg(child, REG_PC);
 186        res = read_int(child, pc, (int *) &insn);
 187        if (res < 0)
 188                return res;
 189
 190        op_code = insn >> 26;
 191        if (op_code >= 0x30) {
 192                /*
 193                 * It's a branch: instead of trying to figure out
 194                 * whether the branch will be taken or not, we'll put
 195                 * a breakpoint at either location.  This is simpler,
 196                 * more reliable, and probably not a whole lot slower
 197                 * than the alternative approach of emulating the
 198                 * branch (emulation can be tricky for fp branches).
 199                 */
 200                displ = ((s32)(insn << 11)) >> 9;
 201                task_thread_info(child)->bpt_addr[nsaved++] = pc + 4;
 202                if (displ)              /* guard against unoptimized code */
 203                        task_thread_info(child)->bpt_addr[nsaved++]
 204                          = pc + 4 + displ;
 205                DBG(DBG_BPT, ("execing branch\n"));
 206        } else if (op_code == 0x1a) {
 207                reg_b = (insn >> 16) & 0x1f;
 208                task_thread_info(child)->bpt_addr[nsaved++] = get_reg(child, reg_b);
 209                DBG(DBG_BPT, ("execing jump\n"));
 210        } else {
 211                task_thread_info(child)->bpt_addr[nsaved++] = pc + 4;
 212                DBG(DBG_BPT, ("execing normal insn\n"));
 213        }
 214
 215        /* install breakpoints: */
 216        for (i = 0; i < nsaved; ++i) {
 217                res = read_int(child, task_thread_info(child)->bpt_addr[i],
 218                               (int *) &insn);
 219                if (res < 0)
 220                        return res;
 221                task_thread_info(child)->bpt_insn[i] = insn;
 222                DBG(DBG_BPT, ("    -> next_pc=%lx\n",
 223                              task_thread_info(child)->bpt_addr[i]));
 224                res = write_int(child, task_thread_info(child)->bpt_addr[i],
 225                                BREAKINST);
 226                if (res < 0)
 227                        return res;
 228        }
 229        task_thread_info(child)->bpt_nsaved = nsaved;
 230        return 0;
 231}
 232
 233/*
 234 * Ensure no single-step breakpoint is pending.  Returns non-zero
 235 * value if child was being single-stepped.
 236 */
 237int
 238ptrace_cancel_bpt(struct task_struct * child)
 239{
 240        int i, nsaved = task_thread_info(child)->bpt_nsaved;
 241
 242        task_thread_info(child)->bpt_nsaved = 0;
 243
 244        if (nsaved > 2) {
 245                printk("ptrace_cancel_bpt: bogus nsaved: %d!\n", nsaved);
 246                nsaved = 2;
 247        }
 248
 249        for (i = 0; i < nsaved; ++i) {
 250                write_int(child, task_thread_info(child)->bpt_addr[i],
 251                          task_thread_info(child)->bpt_insn[i]);
 252        }
 253        return (nsaved != 0);
 254}
 255
 256void user_enable_single_step(struct task_struct *child)
 257{
 258        /* Mark single stepping.  */
 259        task_thread_info(child)->bpt_nsaved = -1;
 260}
 261
 262void user_disable_single_step(struct task_struct *child)
 263{
 264        ptrace_cancel_bpt(child);
 265}
 266
 267/*
 268 * Called by kernel/ptrace.c when detaching..
 269 *
 270 * Make sure the single step bit is not set.
 271 */
 272void ptrace_disable(struct task_struct *child)
 273{ 
 274        user_disable_single_step(child);
 275}
 276
 277long arch_ptrace(struct task_struct *child, long request,
 278                 unsigned long addr, unsigned long data)
 279{
 280        unsigned long tmp;
 281        size_t copied;
 282        long ret;
 283
 284        switch (request) {
 285        /* When I and D space are separate, these will need to be fixed.  */
 286        case PTRACE_PEEKTEXT: /* read word at location addr. */
 287        case PTRACE_PEEKDATA:
 288                copied = ptrace_access_vm(child, addr, &tmp, sizeof(tmp),
 289                                FOLL_FORCE);
 290                ret = -EIO;
 291                if (copied != sizeof(tmp))
 292                        break;
 293                
 294                force_successful_syscall_return();
 295                ret = tmp;
 296                break;
 297
 298        /* Read register number ADDR. */
 299        case PTRACE_PEEKUSR:
 300                force_successful_syscall_return();
 301                ret = get_reg(child, addr);
 302                DBG(DBG_MEM, ("peek $%lu->%#lx\n", addr, ret));
 303                break;
 304
 305        /* When I and D space are separate, this will have to be fixed.  */
 306        case PTRACE_POKETEXT: /* write the word at location addr. */
 307        case PTRACE_POKEDATA:
 308                ret = generic_ptrace_pokedata(child, addr, data);
 309                break;
 310
 311        case PTRACE_POKEUSR: /* write the specified register */
 312                DBG(DBG_MEM, ("poke $%lu<-%#lx\n", addr, data));
 313                ret = put_reg(child, addr, data);
 314                break;
 315        default:
 316                ret = ptrace_request(child, request, addr, data);
 317                break;
 318        }
 319        return ret;
 320}
 321
 322asmlinkage unsigned long syscall_trace_enter(void)
 323{
 324        unsigned long ret = 0;
 325        struct pt_regs *regs = current_pt_regs();
 326        if (test_thread_flag(TIF_SYSCALL_TRACE) &&
 327            tracehook_report_syscall_entry(current_pt_regs()))
 328                ret = -1UL;
 329        audit_syscall_entry(regs->r0, regs->r16, regs->r17, regs->r18, regs->r19);
 330        return ret ?: current_pt_regs()->r0;
 331}
 332
 333asmlinkage void
 334syscall_trace_leave(void)
 335{
 336        audit_syscall_exit(current_pt_regs());
 337        if (test_thread_flag(TIF_SYSCALL_TRACE))
 338                tracehook_report_syscall_exit(current_pt_regs(), 0);
 339}
 340