tools/perf/util/bpf-utils.c

   1 // SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
   2
   3 #ifndef _GNU_SOURCE
   4 #define _GNU_SOURCE
   5 #endif
   6
   7 #include <errno.h>
   8 #include <stdlib.h>
   9 #include <linux/err.h>
  10 #include <linux/kernel.h>
  11 #include <bpf/bpf.h>
  12 #include "bpf-utils.h"
  13 #include "debug.h"
  14
  15 struct bpil_array_desc {
  16         int     array_offset;   /* e.g. offset of jited_prog_insns */
  17         int     count_offset;   /* e.g. offset of jited_prog_len */
  18         int     size_offset;    /* > 0: offset of rec size,
  19                                  * < 0: fix size of -size_offset
  20                                  */
  21 };
  22
  23 static struct bpil_array_desc bpil_array_desc[] = {
  24         [PERF_BPIL_JITED_INSNS] = {
  25                 offsetof(struct bpf_prog_info, jited_prog_insns),
  26                 offsetof(struct bpf_prog_info, jited_prog_len),
  27                 -1,
  28         },
  29         [PERF_BPIL_XLATED_INSNS] = {
  30                 offsetof(struct bpf_prog_info, xlated_prog_insns),
  31                 offsetof(struct bpf_prog_info, xlated_prog_len),
  32                 -1,
  33         },
  34         [PERF_BPIL_MAP_IDS] = {
  35                 offsetof(struct bpf_prog_info, map_ids),
  36                 offsetof(struct bpf_prog_info, nr_map_ids),
  37                 -(int)sizeof(__u32),
  38         },
  39         [PERF_BPIL_JITED_KSYMS] = {
  40                 offsetof(struct bpf_prog_info, jited_ksyms),
  41                 offsetof(struct bpf_prog_info, nr_jited_ksyms),
  42                 -(int)sizeof(__u64),
  43         },
  44         [PERF_BPIL_JITED_FUNC_LENS] = {
  45                 offsetof(struct bpf_prog_info, jited_func_lens),
  46                 offsetof(struct bpf_prog_info, nr_jited_func_lens),
  47                 -(int)sizeof(__u32),
  48         },
  49         [PERF_BPIL_FUNC_INFO] = {
  50                 offsetof(struct bpf_prog_info, func_info),
  51                 offsetof(struct bpf_prog_info, nr_func_info),
  52                 offsetof(struct bpf_prog_info, func_info_rec_size),
  53         },
  54         [PERF_BPIL_LINE_INFO] = {
  55                 offsetof(struct bpf_prog_info, line_info),
  56                 offsetof(struct bpf_prog_info, nr_line_info),
  57                 offsetof(struct bpf_prog_info, line_info_rec_size),
  58         },
  59         [PERF_BPIL_JITED_LINE_INFO] = {
  60                 offsetof(struct bpf_prog_info, jited_line_info),
  61                 offsetof(struct bpf_prog_info, nr_jited_line_info),
  62                 offsetof(struct bpf_prog_info, jited_line_info_rec_size),
  63         },
  64         [PERF_BPIL_PROG_TAGS] = {
  65                 offsetof(struct bpf_prog_info, prog_tags),
  66                 offsetof(struct bpf_prog_info, nr_prog_tags),
  67                 -(int)sizeof(__u8) * BPF_TAG_SIZE,
  68         },
  69
  70 };
  71
  72 static __u32 bpf_prog_info_read_offset_u32(struct bpf_prog_info *info,
  73                                            int offset)
  74 {
  75         __u32 *array = (__u32 *)info;
  76
  77         if (offset >= 0)
  78                 return array[offset / sizeof(__u32)];
  79         return -(int)offset;
  80 }
  81
  82 static __u64 bpf_prog_info_read_offset_u64(struct bpf_prog_info *info,
  83                                            int offset)
  84 {
  85         __u64 *array = (__u64 *)info;
  86
  87         if (offset >= 0)
  88                 return array[offset / sizeof(__u64)];
  89         return -(int)offset;
  90 }
  91
  92 static void bpf_prog_info_set_offset_u32(struct bpf_prog_info *info, int offset,
  93                                          __u32 val)
  94 {
  95         __u32 *array = (__u32 *)info;
  96
  97         if (offset >= 0)
  98                 array[offset / sizeof(__u32)] = val;
  99 }
 100
 101 static void bpf_prog_info_set_offset_u64(struct bpf_prog_info *info, int offset,
 102                                          __u64 val)
 103 {
 104         __u64 *array = (__u64 *)info;
 105
 106         if (offset >= 0)
 107                 array[offset / sizeof(__u64)] = val;
 108 }
 109
 110 struct perf_bpil *
 111 get_bpf_prog_info_linear(int fd, __u64 arrays)
 112 {
 113         struct bpf_prog_info info = {};
 114         struct perf_bpil *info_linear;
 115         __u32 info_len = sizeof(info);
 116         __u32 data_len = 0;
 117         int i, err;
 118         void *ptr;
 119
 120         if (arrays >> PERF_BPIL_LAST_ARRAY)
 121                 return ERR_PTR(-EINVAL);
 122
 123         /* step 1: get array dimensions */
 124         err = bpf_obj_get_info_by_fd(fd, &info, &info_len);
 125         if (err) {
 126                 pr_debug("can't get prog info: %s", strerror(errno));
 127                 return ERR_PTR(-EFAULT);
 128         }
 129
 130         /* step 2: calculate total size of all arrays */
 131         for (i = PERF_BPIL_FIRST_ARRAY; i < PERF_BPIL_LAST_ARRAY; ++i) {
 132                 bool include_array = (arrays & (1UL << i)) > 0;
 133                 struct bpil_array_desc *desc;
 134                 __u32 count, size;
 135
 136                 desc = bpil_array_desc + i;
 137
 138                 /* kernel is too old to support this field */
 139                 if (info_len < desc->array_offset + sizeof(__u32) ||
 140                     info_len < desc->count_offset + sizeof(__u32) ||
 141                     (desc->size_offset > 0 && info_len < (__u32)desc->size_offset))
 142                         include_array = false;
 143
 144                 if (!include_array) {
 145                         arrays &= ~(1UL << i);  /* clear the bit */
 146                         continue;
 147                 }
 148
 149                 count = bpf_prog_info_read_offset_u32(&info, desc->count_offset);
 150                 size  = bpf_prog_info_read_offset_u32(&info, desc->size_offset);
 151
 152                 data_len += roundup(count * size, sizeof(__u64));
 153         }
 154
 155         /* step 3: allocate continuous memory */
 156         info_linear = malloc(sizeof(struct perf_bpil) + data_len);
 157         if (!info_linear)
 158                 return ERR_PTR(-ENOMEM);
 159
 160         /* step 4: fill data to info_linear->info */
 161         info_linear->arrays = arrays;
 162         memset(&info_linear->info, 0, sizeof(info));
 163         ptr = info_linear->data;
 164
 165         for (i = PERF_BPIL_FIRST_ARRAY; i < PERF_BPIL_LAST_ARRAY; ++i) {
 166                 struct bpil_array_desc *desc;
 167                 __u32 count, size;
 168
 169                 if ((arrays & (1UL << i)) == 0)
 170                         continue;
 171
 172                 desc  = bpil_array_desc + i;
 173                 count = bpf_prog_info_read_offset_u32(&info, desc->count_offset);
 174                 size  = bpf_prog_info_read_offset_u32(&info, desc->size_offset);
 175                 bpf_prog_info_set_offset_u32(&info_linear->info,
 176                                              desc->count_offset, count);
 177                 bpf_prog_info_set_offset_u32(&info_linear->info,
 178                                              desc->size_offset, size);
 179                 bpf_prog_info_set_offset_u64(&info_linear->info,
 180                                              desc->array_offset,
 181                                              ptr_to_u64(ptr));
 182                 ptr += roundup(count * size, sizeof(__u64));
 183         }
 184
 185         /* step 5: call syscall again to get required arrays */
 186         err = bpf_obj_get_info_by_fd(fd, &info_linear->info, &info_len);
 187         if (err) {
 188                 pr_debug("can't get prog info: %s", strerror(errno));
 189                 free(info_linear);
 190                 return ERR_PTR(-EFAULT);
 191         }
 192
 193         /* step 6: verify the data */
 194         for (i = PERF_BPIL_FIRST_ARRAY; i < PERF_BPIL_LAST_ARRAY; ++i) {
 195                 struct bpil_array_desc *desc;
 196                 __u32 v1, v2;
 197
 198                 if ((arrays & (1UL << i)) == 0)
 199                         continue;
 200
 201                 desc = bpil_array_desc + i;
 202                 v1 = bpf_prog_info_read_offset_u32(&info, desc->count_offset);
 203                 v2 = bpf_prog_info_read_offset_u32(&info_linear->info,
 204                                                    desc->count_offset);
 205                 if (v1 != v2)
 206                         pr_warning("%s: mismatch in element count\n", __func__);
 207
 208                 v1 = bpf_prog_info_read_offset_u32(&info, desc->size_offset);
 209                 v2 = bpf_prog_info_read_offset_u32(&info_linear->info,
 210                                                    desc->size_offset);
 211                 if (v1 != v2)
 212                         pr_warning("%s: mismatch in rec size\n", __func__);
 213         }
 214
 215         /* step 7: update info_len and data_len */
 216         info_linear->info_len = sizeof(struct bpf_prog_info);
 217         info_linear->data_len = data_len;
 218
 219         return info_linear;
 220 }
 221
 222 void bpil_addr_to_offs(struct perf_bpil *info_linear)
 223 {
 224         int i;
 225
 226         for (i = PERF_BPIL_FIRST_ARRAY; i < PERF_BPIL_LAST_ARRAY; ++i) {
 227                 struct bpil_array_desc *desc;
 228                 __u64 addr, offs;
 229
 230                 if ((info_linear->arrays & (1UL << i)) == 0)
 231                         continue;
 232
 233                 desc = bpil_array_desc + i;
 234                 addr = bpf_prog_info_read_offset_u64(&info_linear->info,
 235                                                      desc->array_offset);
 236                 offs = addr - ptr_to_u64(info_linear->data);
 237                 bpf_prog_info_set_offset_u64(&info_linear->info,
 238                                              desc->array_offset, offs);
 239         }
 240 }
 241
 242 void bpil_offs_to_addr(struct perf_bpil *info_linear)
 243 {
 244         int i;
 245
 246         for (i = PERF_BPIL_FIRST_ARRAY; i < PERF_BPIL_LAST_ARRAY; ++i) {
 247                 struct bpil_array_desc *desc;
 248                 __u64 addr, offs;
 249
 250                 if ((info_linear->arrays & (1UL << i)) == 0)
 251                         continue;
 252
 253                 desc = bpil_array_desc + i;
 254                 offs = bpf_prog_info_read_offset_u64(&info_linear->info,
 255                                                      desc->array_offset);
 256                 addr = offs + ptr_to_u64(info_linear->data);
 257                 bpf_prog_info_set_offset_u64(&info_linear->info,
 258                                              desc->array_offset, addr);
 259         }
 260 }