arch/riscv/kernel/ptrace.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright 2010 Tilera Corporation. All Rights Reserved.
   4  * Copyright 2015 Regents of the University of California
   5  * Copyright 2017 SiFive
   6  *
   7  * Copied from arch/tile/kernel/ptrace.c
   8  */
   9
  10 #include <asm/ptrace.h>
  11 #include <asm/syscall.h>
  12 #include <asm/thread_info.h>
  13 #include <asm/switch_to.h>
  14 #include <linux/audit.h>
  15 #include <linux/compat.h>
  16 #include <linux/ptrace.h>
  17 #include <linux/elf.h>
  18 #include <linux/regset.h>
  19 #include <linux/sched.h>
  20 #include <linux/sched/task_stack.h>
  21
  22 #define CREATE_TRACE_POINTS
  23 #include <trace/events/syscalls.h>
  24
  25 enum riscv_regset {
  26         REGSET_X,
  27 #ifdef CONFIG_FPU
  28         REGSET_F,
  29 #endif
  30 };
  31
  32 static int riscv_gpr_get(struct task_struct *target,
  33                          const struct user_regset *regset,
  34                          struct membuf to)
  35 {
  36         return membuf_write(&to, task_pt_regs(target),
  37                             sizeof(struct user_regs_struct));
  38 }
  39
  40 static int riscv_gpr_set(struct task_struct *target,
  41                          const struct user_regset *regset,
  42                          unsigned int pos, unsigned int count,
  43                          const void *kbuf, const void __user *ubuf)
  44 {
  45         struct pt_regs *regs;
  46
  47         regs = task_pt_regs(target);
  48         return user_regset_copyin(&pos, &count, &kbuf, &ubuf, regs, 0, -1);
  49 }
  50
  51 #ifdef CONFIG_FPU
  52 static int riscv_fpr_get(struct task_struct *target,
  53                          const struct user_regset *regset,
  54                          struct membuf to)
  55 {
  56         struct __riscv_d_ext_state *fstate = &target->thread.fstate;
  57
  58         if (target == current)
  59                 fstate_save(current, task_pt_regs(current));
  60
  61         membuf_write(&to, fstate, offsetof(struct __riscv_d_ext_state, fcsr));
  62         membuf_store(&to, fstate->fcsr);
  63         return membuf_zero(&to, 4);     // explicitly pad
  64 }
  65
  66 static int riscv_fpr_set(struct task_struct *target,
  67                          const struct user_regset *regset,
  68                          unsigned int pos, unsigned int count,
  69                          const void *kbuf, const void __user *ubuf)
  70 {
  71         int ret;
  72         struct __riscv_d_ext_state *fstate = &target->thread.fstate;
  73
  74         ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, fstate, 0,
  75                                  offsetof(struct __riscv_d_ext_state, fcsr));
  76         if (!ret) {
  77                 ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, fstate, 0,
  78                                          offsetof(struct __riscv_d_ext_state, fcsr) +
  79                                          sizeof(fstate->fcsr));
  80         }
  81
  82         return ret;
  83 }
  84 #endif
  85
  86 static const struct user_regset riscv_user_regset[] = {
  87         [REGSET_X] = {
  88                 .core_note_type = NT_PRSTATUS,
  89                 .n = ELF_NGREG,
  90                 .size = sizeof(elf_greg_t),
  91                 .align = sizeof(elf_greg_t),
  92                 .regset_get = riscv_gpr_get,
  93                 .set = riscv_gpr_set,
  94         },
  95 #ifdef CONFIG_FPU
  96         [REGSET_F] = {
  97                 .core_note_type = NT_PRFPREG,
  98                 .n = ELF_NFPREG,
  99                 .size = sizeof(elf_fpreg_t),
 100                 .align = sizeof(elf_fpreg_t),
 101                 .regset_get = riscv_fpr_get,
 102                 .set = riscv_fpr_set,
 103         },
 104 #endif
 105 };
 106
 107 static const struct user_regset_view riscv_user_native_view = {
 108         .name = "riscv",
 109         .e_machine = EM_RISCV,
 110         .regsets = riscv_user_regset,
 111         .n = ARRAY_SIZE(riscv_user_regset),
 112 };
 113
 114 struct pt_regs_offset {
 115         const char *name;
 116         int offset;
 117 };
 118
 119 #define REG_OFFSET_NAME(r) {.name = #r, .offset = offsetof(struct pt_regs, r)}
 120 #define REG_OFFSET_END {.name = NULL, .offset = 0}
 121
 122 static const struct pt_regs_offset regoffset_table[] = {
 123         REG_OFFSET_NAME(epc),
 124         REG_OFFSET_NAME(ra),
 125         REG_OFFSET_NAME(sp),
 126         REG_OFFSET_NAME(gp),
 127         REG_OFFSET_NAME(tp),
 128         REG_OFFSET_NAME(t0),
 129         REG_OFFSET_NAME(t1),
 130         REG_OFFSET_NAME(t2),
 131         REG_OFFSET_NAME(s0),
 132         REG_OFFSET_NAME(s1),
 133         REG_OFFSET_NAME(a0),
 134         REG_OFFSET_NAME(a1),
 135         REG_OFFSET_NAME(a2),
 136         REG_OFFSET_NAME(a3),
 137         REG_OFFSET_NAME(a4),
 138         REG_OFFSET_NAME(a5),
 139         REG_OFFSET_NAME(a6),
 140         REG_OFFSET_NAME(a7),
 141         REG_OFFSET_NAME(s2),
 142         REG_OFFSET_NAME(s3),
 143         REG_OFFSET_NAME(s4),
 144         REG_OFFSET_NAME(s5),
 145         REG_OFFSET_NAME(s6),
 146         REG_OFFSET_NAME(s7),
 147         REG_OFFSET_NAME(s8),
 148         REG_OFFSET_NAME(s9),
 149         REG_OFFSET_NAME(s10),
 150         REG_OFFSET_NAME(s11),
 151         REG_OFFSET_NAME(t3),
 152         REG_OFFSET_NAME(t4),
 153         REG_OFFSET_NAME(t5),
 154         REG_OFFSET_NAME(t6),
 155         REG_OFFSET_NAME(status),
 156         REG_OFFSET_NAME(badaddr),
 157         REG_OFFSET_NAME(cause),
 158         REG_OFFSET_NAME(orig_a0),
 159         REG_OFFSET_END,
 160 };
 161
 162 /**
 163  * regs_query_register_offset() - query register offset from its name
 164  * @name:       the name of a register
 165  *
 166  * regs_query_register_offset() returns the offset of a register in struct
 167  * pt_regs from its name. If the name is invalid, this returns -EINVAL;
 168  */
 169 int regs_query_register_offset(const char *name)
 170 {
 171         const struct pt_regs_offset *roff;
 172
 173         for (roff = regoffset_table; roff->name != NULL; roff++)
 174                 if (!strcmp(roff->name, name))
 175                         return roff->offset;
 176         return -EINVAL;
 177 }
 178
 179 /**
 180  * regs_within_kernel_stack() - check the address in the stack
 181  * @regs:      pt_regs which contains kernel stack pointer.
 182  * @addr:      address which is checked.
 183  *
 184  * regs_within_kernel_stack() checks @addr is within the kernel stack page(s).
 185  * If @addr is within the kernel stack, it returns true. If not, returns false.
 186  */
 187 static bool regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr)
 188 {
 189         return (addr & ~(THREAD_SIZE - 1))  ==
 190                 (kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1));
 191 }
 192
 193 /**
 194  * regs_get_kernel_stack_nth() - get Nth entry of the stack
 195  * @regs:       pt_regs which contains kernel stack pointer.
 196  * @n:          stack entry number.
 197  *
 198  * regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which
 199  * is specified by @regs. If the @n th entry is NOT in the kernel stack,
 200  * this returns 0.
 201  */
 202 unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, unsigned int n)
 203 {
 204         unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs);
 205
 206         addr += n;
 207         if (regs_within_kernel_stack(regs, (unsigned long)addr))
 208                 return *addr;
 209         else
 210                 return 0;
 211 }
 212
 213 void ptrace_disable(struct task_struct *child)
 214 {
 215         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 216 }
 217
 218 long arch_ptrace(struct task_struct *child, long request,
 219                  unsigned long addr, unsigned long data)
 220 {
 221         long ret = -EIO;
 222
 223         switch (request) {
 224         default:
 225                 ret = ptrace_request(child, request, addr, data);
 226                 break;
 227         }
 228
 229         return ret;
 230 }
 231
 232 /*
 233  * Allows PTRACE_SYSCALL to work.  These are called from entry.S in
 234  * {handle,ret_from}_syscall.
 235  */
 236 __visible int do_syscall_trace_enter(struct pt_regs *regs)
 237 {
 238         if (test_thread_flag(TIF_SYSCALL_TRACE))
 239                 if (ptrace_report_syscall_entry(regs))
 240                         return -1;
 241
 242         /*
 243          * Do the secure computing after ptrace; failures should be fast.
 244          * If this fails we might have return value in a0 from seccomp
 245          * (via SECCOMP_RET_ERRNO/TRACE).
 246          */
 247         if (secure_computing() == -1)
 248                 return -1;
 249
 250 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
 251         if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
 252                 trace_sys_enter(regs, syscall_get_nr(current, regs));
 253 #endif
 254
 255         audit_syscall_entry(regs->a7, regs->a0, regs->a1, regs->a2, regs->a3);
 256         return 0;
 257 }
 258
 259 __visible void do_syscall_trace_exit(struct pt_regs *regs)
 260 {
 261         audit_syscall_exit(regs);
 262
 263         if (test_thread_flag(TIF_SYSCALL_TRACE))
 264                 ptrace_report_syscall_exit(regs, 0);
 265
 266 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
 267         if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
 268                 trace_sys_exit(regs, regs_return_value(regs));
 269 #endif
 270 }
 271
 272 #ifdef CONFIG_COMPAT
 273 static int compat_riscv_gpr_get(struct task_struct *target,
 274                                 const struct user_regset *regset,
 275                                 struct membuf to)
 276 {
 277         struct compat_user_regs_struct cregs;
 278
 279         regs_to_cregs(&cregs, task_pt_regs(target));
 280
 281         return membuf_write(&to, &cregs,
 282                             sizeof(struct compat_user_regs_struct));
 283 }
 284
 285 static int compat_riscv_gpr_set(struct task_struct *target,
 286                                 const struct user_regset *regset,
 287                                 unsigned int pos, unsigned int count,
 288                                 const void *kbuf, const void __user *ubuf)
 289 {
 290         int ret;
 291         struct compat_user_regs_struct cregs;
 292
 293         ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &cregs, 0, -1);
 294
 295         cregs_to_regs(&cregs, task_pt_regs(target));
 296
 297         return ret;
 298 }
 299
 300 static const struct user_regset compat_riscv_user_regset[] = {
 301         [REGSET_X] = {
 302                 .core_note_type = NT_PRSTATUS,
 303                 .n = ELF_NGREG,
 304                 .size = sizeof(compat_elf_greg_t),
 305                 .align = sizeof(compat_elf_greg_t),
 306                 .regset_get = compat_riscv_gpr_get,
 307                 .set = compat_riscv_gpr_set,
 308         },
 309 #ifdef CONFIG_FPU
 310         [REGSET_F] = {
 311                 .core_note_type = NT_PRFPREG,
 312                 .n = ELF_NFPREG,
 313                 .size = sizeof(elf_fpreg_t),
 314                 .align = sizeof(elf_fpreg_t),
 315                 .regset_get = riscv_fpr_get,
 316                 .set = riscv_fpr_set,
 317         },
 318 #endif
 319 };
 320
 321 static const struct user_regset_view compat_riscv_user_native_view = {
 322         .name = "riscv",
 323         .e_machine = EM_RISCV,
 324         .regsets = compat_riscv_user_regset,
 325         .n = ARRAY_SIZE(compat_riscv_user_regset),
 326 };
 327
 328 long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
 329                         compat_ulong_t caddr, compat_ulong_t cdata)
 330 {
 331         long ret = -EIO;
 332
 333         switch (request) {
 334         default:
 335                 ret = compat_ptrace_request(child, request, caddr, cdata);
 336                 break;
 337         }
 338
 339         return ret;
 340 }
 341 #endif /* CONFIG_COMPAT */
 342
 343 const struct user_regset_view *task_user_regset_view(struct task_struct *task)
 344 {
 345 #ifdef CONFIG_COMPAT
 346         if (test_tsk_thread_flag(task, TIF_32BIT))
 347                 return &compat_riscv_user_native_view;
 348         else
 349 #endif
 350                 return &riscv_user_native_view;
 351 }