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/ptrace.h>
  16 #include <linux/elf.h>
  17 #include <linux/regset.h>
  18 #include <linux/sched.h>
  19 #include <linux/sched/task_stack.h>
  20 #include <linux/tracehook.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         int ret;
  46         struct pt_regs *regs;
  47
  48         regs = task_pt_regs(target);
  49         ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, regs, 0, -1);
  50         return ret;
  51 }
  52
  53 #ifdef CONFIG_FPU
  54 static int riscv_fpr_get(struct task_struct *target,
  55                          const struct user_regset *regset,
  56                          struct membuf to)
  57 {
  58         struct __riscv_d_ext_state *fstate = &target->thread.fstate;
  59
  60         if (target == current)
  61                 fstate_save(current, task_pt_regs(current));
  62
  63         membuf_write(&to, fstate, offsetof(struct __riscv_d_ext_state, fcsr));
  64         membuf_store(&to, fstate->fcsr);
  65         return membuf_zero(&to, 4);     // explicitly pad
  66 }
  67
  68 static int riscv_fpr_set(struct task_struct *target,
  69                          const struct user_regset *regset,
  70                          unsigned int pos, unsigned int count,
  71                          const void *kbuf, const void __user *ubuf)
  72 {
  73         int ret;
  74         struct __riscv_d_ext_state *fstate = &target->thread.fstate;
  75
  76         ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, fstate, 0,
  77                                  offsetof(struct __riscv_d_ext_state, fcsr));
  78         if (!ret) {
  79                 ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, fstate, 0,
  80                                          offsetof(struct __riscv_d_ext_state, fcsr) +
  81                                          sizeof(fstate->fcsr));
  82         }
  83
  84         return ret;
  85 }
  86 #endif
  87
  88 static const struct user_regset riscv_user_regset[] = {
  89         [REGSET_X] = {
  90                 .core_note_type = NT_PRSTATUS,
  91                 .n = ELF_NGREG,
  92                 .size = sizeof(elf_greg_t),
  93                 .align = sizeof(elf_greg_t),
  94                 .regset_get = riscv_gpr_get,
  95                 .set = riscv_gpr_set,
  96         },
  97 #ifdef CONFIG_FPU
  98         [REGSET_F] = {
  99                 .core_note_type = NT_PRFPREG,
 100                 .n = ELF_NFPREG,
 101                 .size = sizeof(elf_fpreg_t),
 102                 .align = sizeof(elf_fpreg_t),
 103                 .regset_get = riscv_fpr_get,
 104                 .set = riscv_fpr_set,
 105         },
 106 #endif
 107 };
 108
 109 static const struct user_regset_view riscv_user_native_view = {
 110         .name = "riscv",
 111         .e_machine = EM_RISCV,
 112         .regsets = riscv_user_regset,
 113         .n = ARRAY_SIZE(riscv_user_regset),
 114 };
 115
 116 const struct user_regset_view *task_user_regset_view(struct task_struct *task)
 117 {
 118         return &riscv_user_native_view;
 119 }
 120
 121 struct pt_regs_offset {
 122         const char *name;
 123         int offset;
 124 };
 125
 126 #define REG_OFFSET_NAME(r) {.name = #r, .offset = offsetof(struct pt_regs, r)}
 127 #define REG_OFFSET_END {.name = NULL, .offset = 0}
 128
 129 static const struct pt_regs_offset regoffset_table[] = {
 130         REG_OFFSET_NAME(epc),
 131         REG_OFFSET_NAME(ra),
 132         REG_OFFSET_NAME(sp),
 133         REG_OFFSET_NAME(gp),
 134         REG_OFFSET_NAME(tp),
 135         REG_OFFSET_NAME(t0),
 136         REG_OFFSET_NAME(t1),
 137         REG_OFFSET_NAME(t2),
 138         REG_OFFSET_NAME(s0),
 139         REG_OFFSET_NAME(s1),
 140         REG_OFFSET_NAME(a0),
 141         REG_OFFSET_NAME(a1),
 142         REG_OFFSET_NAME(a2),
 143         REG_OFFSET_NAME(a3),
 144         REG_OFFSET_NAME(a4),
 145         REG_OFFSET_NAME(a5),
 146         REG_OFFSET_NAME(a6),
 147         REG_OFFSET_NAME(a7),
 148         REG_OFFSET_NAME(s2),
 149         REG_OFFSET_NAME(s3),
 150         REG_OFFSET_NAME(s4),
 151         REG_OFFSET_NAME(s5),
 152         REG_OFFSET_NAME(s6),
 153         REG_OFFSET_NAME(s7),
 154         REG_OFFSET_NAME(s8),
 155         REG_OFFSET_NAME(s9),
 156         REG_OFFSET_NAME(s10),
 157         REG_OFFSET_NAME(s11),
 158         REG_OFFSET_NAME(t3),
 159         REG_OFFSET_NAME(t4),
 160         REG_OFFSET_NAME(t5),
 161         REG_OFFSET_NAME(t6),
 162         REG_OFFSET_NAME(status),
 163         REG_OFFSET_NAME(badaddr),
 164         REG_OFFSET_NAME(cause),
 165         REG_OFFSET_NAME(orig_a0),
 166         REG_OFFSET_END,
 167 };
 168
 169 /**
 170  * regs_query_register_offset() - query register offset from its name
 171  * @name:       the name of a register
 172  *
 173  * regs_query_register_offset() returns the offset of a register in struct
 174  * pt_regs from its name. If the name is invalid, this returns -EINVAL;
 175  */
 176 int regs_query_register_offset(const char *name)
 177 {
 178         const struct pt_regs_offset *roff;
 179
 180         for (roff = regoffset_table; roff->name != NULL; roff++)
 181                 if (!strcmp(roff->name, name))
 182                         return roff->offset;
 183         return -EINVAL;
 184 }
 185
 186 /**
 187  * regs_within_kernel_stack() - check the address in the stack
 188  * @regs:      pt_regs which contains kernel stack pointer.
 189  * @addr:      address which is checked.
 190  *
 191  * regs_within_kernel_stack() checks @addr is within the kernel stack page(s).
 192  * If @addr is within the kernel stack, it returns true. If not, returns false.
 193  */
 194 static bool regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr)
 195 {
 196         return (addr & ~(THREAD_SIZE - 1))  ==
 197                 (kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1));
 198 }
 199
 200 /**
 201  * regs_get_kernel_stack_nth() - get Nth entry of the stack
 202  * @regs:       pt_regs which contains kernel stack pointer.
 203  * @n:          stack entry number.
 204  *
 205  * regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which
 206  * is specified by @regs. If the @n th entry is NOT in the kernel stack,
 207  * this returns 0.
 208  */
 209 unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, unsigned int n)
 210 {
 211         unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs);
 212
 213         addr += n;
 214         if (regs_within_kernel_stack(regs, (unsigned long)addr))
 215                 return *addr;
 216         else
 217                 return 0;
 218 }
 219
 220 void ptrace_disable(struct task_struct *child)
 221 {
 222         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 223 }
 224
 225 long arch_ptrace(struct task_struct *child, long request,
 226                  unsigned long addr, unsigned long data)
 227 {
 228         long ret = -EIO;
 229
 230         switch (request) {
 231         default:
 232                 ret = ptrace_request(child, request, addr, data);
 233                 break;
 234         }
 235
 236         return ret;
 237 }
 238
 239 /*
 240  * Allows PTRACE_SYSCALL to work.  These are called from entry.S in
 241  * {handle,ret_from}_syscall.
 242  */
 243 __visible int do_syscall_trace_enter(struct pt_regs *regs)
 244 {
 245         if (test_thread_flag(TIF_SYSCALL_TRACE))
 246                 if (tracehook_report_syscall_entry(regs))
 247                         return -1;
 248
 249         /*
 250          * Do the secure computing after ptrace; failures should be fast.
 251          * If this fails we might have return value in a0 from seccomp
 252          * (via SECCOMP_RET_ERRNO/TRACE).
 253          */
 254         if (secure_computing() == -1)
 255                 return -1;
 256
 257 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
 258         if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
 259                 trace_sys_enter(regs, syscall_get_nr(current, regs));
 260 #endif
 261
 262         audit_syscall_entry(regs->a7, regs->a0, regs->a1, regs->a2, regs->a3);
 263         return 0;
 264 }
 265
 266 __visible void do_syscall_trace_exit(struct pt_regs *regs)
 267 {
 268         audit_syscall_exit(regs);
 269
 270         if (test_thread_flag(TIF_SYSCALL_TRACE))
 271                 tracehook_report_syscall_exit(regs, 0);
 272
 273 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
 274         if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
 275                 trace_sys_exit(regs, regs_return_value(regs));
 276 #endif
 277 }