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