trace_probe_tmpl.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Traceprobe fetch helper inlines
   4  */
   5
   6 static nokprobe_inline void
   7 fetch_store_raw(unsigned long val, struct fetch_insn *code, void *buf)
   8 {
   9         switch (code->size) {
  10         case 1:
  11                 *(u8 *)buf = (u8)val;
  12                 break;
  13         case 2:
  14                 *(u16 *)buf = (u16)val;
  15                 break;
  16         case 4:
  17                 *(u32 *)buf = (u32)val;
  18                 break;
  19         case 8:
  20                 //TBD: 32bit signed
  21                 *(u64 *)buf = (u64)val;
  22                 break;
  23         default:
  24                 *(unsigned long *)buf = val;
  25         }
  26 }
  27
  28 static nokprobe_inline void
  29 fetch_apply_bitfield(struct fetch_insn *code, void *buf)
  30 {
  31         switch (code->basesize) {
  32         case 1:
  33                 *(u8 *)buf <<= code->lshift;
  34                 *(u8 *)buf >>= code->rshift;
  35                 break;
  36         case 2:
  37                 *(u16 *)buf <<= code->lshift;
  38                 *(u16 *)buf >>= code->rshift;
  39                 break;
  40         case 4:
  41                 *(u32 *)buf <<= code->lshift;
  42                 *(u32 *)buf >>= code->rshift;
  43                 break;
  44         case 8:
  45                 *(u64 *)buf <<= code->lshift;
  46                 *(u64 *)buf >>= code->rshift;
  47                 break;
  48         }
  49 }
  50
  51 /*
  52  * These functions must be defined for each callsite.
  53  * Return consumed dynamic data size (>= 0), or error (< 0).
  54  * If dest is NULL, don't store result and return required dynamic data size.
  55  */
  56 static int
  57 process_fetch_insn(struct fetch_insn *code, void *rec,
  58                    void *dest, void *base);
  59 static nokprobe_inline int fetch_store_strlen(unsigned long addr);
  60 static nokprobe_inline int
  61 fetch_store_string(unsigned long addr, void *dest, void *base);
  62 static nokprobe_inline int fetch_store_strlen_user(unsigned long addr);
  63 static nokprobe_inline int
  64 fetch_store_string_user(unsigned long addr, void *dest, void *base);
  65 static nokprobe_inline int
  66 probe_mem_read(void *dest, void *src, size_t size);
  67 static nokprobe_inline int
  68 probe_mem_read_user(void *dest, void *src, size_t size);
  69
  70 static nokprobe_inline int
  71 fetch_store_symstrlen(unsigned long addr)
  72 {
  73         char namebuf[KSYM_SYMBOL_LEN];
  74         int ret;
  75
  76         ret = sprint_symbol(namebuf, addr);
  77         if (ret < 0)
  78                 return 0;
  79
  80         return ret + 1;
  81 }
  82
  83 /*
  84  * Fetch a null-terminated symbol string + offset. Caller MUST set *(u32 *)buf
  85  * with max length and relative data location.
  86  */
  87 static nokprobe_inline int
  88 fetch_store_symstring(unsigned long addr, void *dest, void *base)
  89 {
  90         int maxlen = get_loc_len(*(u32 *)dest);
  91         void *__dest;
  92
  93         if (unlikely(!maxlen))
  94                 return -ENOMEM;
  95
  96         __dest = get_loc_data(dest, base);
  97
  98         return sprint_symbol(__dest, addr);
  99 }
 100
 101 /* From the 2nd stage, routine is same */
 102 static nokprobe_inline int
 103 process_fetch_insn_bottom(struct fetch_insn *code, unsigned long val,
 104                            void *dest, void *base)
 105 {
 106         struct fetch_insn *s3 = NULL;
 107         int total = 0, ret = 0, i = 0;
 108         u32 loc = 0;
 109         unsigned long lval = val;
 110
 111 stage2:
 112         /* 2nd stage: dereference memory if needed */
 113         do {
 114                 if (code->op == FETCH_OP_DEREF) {
 115                         lval = val;
 116                         ret = probe_mem_read(&val, (void *)val + code->offset,
 117                                              sizeof(val));
 118                 } else if (code->op == FETCH_OP_UDEREF) {
 119                         lval = val;
 120                         ret = probe_mem_read_user(&val,
 121                                  (void *)val + code->offset, sizeof(val));
 122                 } else
 123                         break;
 124                 if (ret)
 125                         return ret;
 126                 code++;
 127         } while (1);
 128
 129         s3 = code;
 130 stage3:
 131         /* 3rd stage: store value to buffer */
 132         if (unlikely(!dest)) {
 133                 switch (code->op) {
 134                 case FETCH_OP_ST_STRING:
 135                         ret = fetch_store_strlen(val + code->offset);
 136                         code++;
 137                         goto array;
 138                 case FETCH_OP_ST_USTRING:
 139                         ret = fetch_store_strlen_user(val + code->offset);
 140                         code++;
 141                         goto array;
 142                 case FETCH_OP_ST_SYMSTR:
 143                         ret = fetch_store_symstrlen(val + code->offset);
 144                         code++;
 145                         goto array;
 146                 default:
 147                         return -EILSEQ;
 148                 }
 149         }
 150
 151         switch (code->op) {
 152         case FETCH_OP_ST_RAW:
 153                 fetch_store_raw(val, code, dest);
 154                 break;
 155         case FETCH_OP_ST_MEM:
 156                 probe_mem_read(dest, (void *)val + code->offset, code->size);
 157                 break;
 158         case FETCH_OP_ST_UMEM:
 159                 probe_mem_read_user(dest, (void *)val + code->offset, code->size);
 160                 break;
 161         case FETCH_OP_ST_STRING:
 162                 loc = *(u32 *)dest;
 163                 ret = fetch_store_string(val + code->offset, dest, base);
 164                 break;
 165         case FETCH_OP_ST_USTRING:
 166                 loc = *(u32 *)dest;
 167                 ret = fetch_store_string_user(val + code->offset, dest, base);
 168                 break;
 169         case FETCH_OP_ST_SYMSTR:
 170                 loc = *(u32 *)dest;
 171                 ret = fetch_store_symstring(val + code->offset, dest, base);
 172                 break;
 173         default:
 174                 return -EILSEQ;
 175         }
 176         code++;
 177
 178         /* 4th stage: modify stored value if needed */
 179         if (code->op == FETCH_OP_MOD_BF) {
 180                 fetch_apply_bitfield(code, dest);
 181                 code++;
 182         }
 183
 184 array:
 185         /* the last stage: Loop on array */
 186         if (code->op == FETCH_OP_LP_ARRAY) {
 187                 if (ret < 0)
 188                         ret = 0;
 189                 total += ret;
 190                 if (++i < code->param) {
 191                         code = s3;
 192                         if (s3->op != FETCH_OP_ST_STRING &&
 193                             s3->op != FETCH_OP_ST_USTRING) {
 194                                 dest += s3->size;
 195                                 val += s3->size;
 196                                 goto stage3;
 197                         }
 198                         code--;
 199                         val = lval + sizeof(char *);
 200                         if (dest) {
 201                                 dest += sizeof(u32);
 202                                 *(u32 *)dest = update_data_loc(loc, ret);
 203                         }
 204                         goto stage2;
 205                 }
 206                 code++;
 207                 ret = total;
 208         }
 209
 210         return code->op == FETCH_OP_END ? ret : -EILSEQ;
 211 }
 212
 213 /* Sum up total data length for dynamic arrays (strings) */
 214 static nokprobe_inline int
 215 __get_data_size(struct trace_probe *tp, struct pt_regs *regs)
 216 {
 217         struct probe_arg *arg;
 218         int i, len, ret = 0;
 219
 220         for (i = 0; i < tp->nr_args; i++) {
 221                 arg = tp->args + i;
 222                 if (unlikely(arg->dynamic)) {
 223                         len = process_fetch_insn(arg->code, regs, NULL, NULL);
 224                         if (len > 0)
 225                                 ret += len;
 226                 }
 227         }
 228
 229         return ret;
 230 }
 231
 232 /* Store the value of each argument */
 233 static nokprobe_inline void
 234 store_trace_args(void *data, struct trace_probe *tp, void *rec,
 235                  int header_size, int maxlen)
 236 {
 237         struct probe_arg *arg;
 238         void *base = data - header_size;
 239         void *dyndata = data + tp->size;
 240         u32 *dl;        /* Data location */
 241         int ret, i;
 242
 243         for (i = 0; i < tp->nr_args; i++) {
 244                 arg = tp->args + i;
 245                 dl = data + arg->offset;
 246                 /* Point the dynamic data area if needed */
 247                 if (unlikely(arg->dynamic))
 248                         *dl = make_data_loc(maxlen, dyndata - base);
 249                 ret = process_fetch_insn(arg->code, rec, dl, base);
 250                 if (arg->dynamic && likely(ret > 0)) {
 251                         dyndata += ret;
 252                         maxlen -= ret;
 253                 }
 254         }
 255 }
 256
 257 static inline int
 258 print_probe_args(struct trace_seq *s, struct probe_arg *args, int nr_args,
 259                  u8 *data, void *field)
 260 {
 261         void *p;
 262         int i, j;
 263
 264         for (i = 0; i < nr_args; i++) {
 265                 struct probe_arg *a = args + i;
 266
 267                 trace_seq_printf(s, " %s=", a->name);
 268                 if (likely(!a->count)) {
 269                         if (!a->type->print(s, data + a->offset, field))
 270                                 return -ENOMEM;
 271                         continue;
 272                 }
 273                 trace_seq_putc(s, '{');
 274                 p = data + a->offset;
 275                 for (j = 0; j < a->count; j++) {
 276                         if (!a->type->print(s, p, field))
 277                                 return -ENOMEM;
 278                         trace_seq_putc(s, j == a->count - 1 ? '}' : ',');
 279                         p += a->type->size;
 280                 }
 281         }
 282         return 0;
 283 }