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
  31 enum {
  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  */
  72 enum {
  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
  83 static 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
 103 static unsigned long zero;
 104
 105 /*
 106  * Get address of register REGNO in task TASK.
 107  */
 108 static unsigned long *
 109 get_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  */
 129 static unsigned long
 130 get_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  */
 146 static int
 147 put_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
 159 static inline int
 160 read_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
 167 static inline int
 168 write_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  */
 178 int
 179 ptrace_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  */
 237 int
 238 ptrace_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
 256 void user_enable_single_step(struct task_struct *child)
 257 {
 258         /* Mark single stepping.  */
 259         task_thread_info(child)->bpt_nsaved = -1;
 260 }
 261
 262 void 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  */
 272 void ptrace_disable(struct task_struct *child)
 273 {
 274         user_disable_single_step(child);
 275 }
 276
 277 long 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
 322 asmlinkage 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
 333 asmlinkage void
 334 syscall_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 }