| 1 | /* |
| 2 | * Copyright (C) 2014 David Goulet <dgoulet@efficios.com> |
| 3 | * |
| 4 | * SPDX-License-Identifier: GPL-2.0-only |
| 5 | * |
| 6 | */ |
| 7 | |
| 8 | #define _LGPL_SOURCE |
| 9 | #include "kernel.hpp" |
| 10 | #include "lttng-sessiond.hpp" |
| 11 | #include "lttng-syscall.hpp" |
| 12 | #include "utils.hpp" |
| 13 | |
| 14 | #include <common/common.hpp> |
| 15 | #include <common/kernel-ctl/kernel-ctl.hpp> |
| 16 | #include <common/urcu.hpp> |
| 17 | |
| 18 | #include <stdbool.h> |
| 19 | |
| 20 | /* Global syscall table. */ |
| 21 | std::vector<struct syscall> syscall_table; |
| 22 | |
| 23 | /* |
| 24 | * Populate the system call table using the kernel tracer. |
| 25 | * |
| 26 | * Return 0 on success and the syscall table is allocated. On error, a negative |
| 27 | * value is returned. |
| 28 | */ |
| 29 | int syscall_init_table(int tracer_fd) |
| 30 | { |
| 31 | int ret, fd, err; |
| 32 | FILE *fp; |
| 33 | /* Syscall data from the kernel. */ |
| 34 | size_t index = 0; |
| 35 | uint32_t bitness; |
| 36 | char name[SYSCALL_NAME_LEN]; |
| 37 | |
| 38 | #if (SYSCALL_NAME_LEN == 255) |
| 39 | #define SYSCALL_NAME_LEN_SCANF_IS_A_BROKEN_API "254" |
| 40 | #endif |
| 41 | |
| 42 | DBG3("Syscall init system call table"); |
| 43 | |
| 44 | fd = kernctl_syscall_list(tracer_fd); |
| 45 | if (fd < 0) { |
| 46 | ret = fd; |
| 47 | PERROR("kernelctl syscall list"); |
| 48 | goto error_ioctl; |
| 49 | } |
| 50 | |
| 51 | fp = fdopen(fd, "r"); |
| 52 | if (!fp) { |
| 53 | ret = -errno; |
| 54 | PERROR("syscall list fdopen"); |
| 55 | goto error_fp; |
| 56 | } |
| 57 | |
| 58 | while (fscanf(fp, |
| 59 | "syscall { index = %zu; \ |
| 60 | name = %" SYSCALL_NAME_LEN_SCANF_IS_A_BROKEN_API "[^;]; \ |
| 61 | bitness = %u; };\n", |
| 62 | &index, |
| 63 | name, |
| 64 | &bitness) == 3) { |
| 65 | try { |
| 66 | syscall_table.emplace_back(index, bitness, name); |
| 67 | } catch (const std::bad_alloc&) { |
| 68 | ERR_FMT("Failed to add syscall to syscall table: table_current_element_count={}, syscall_name=`{}`", |
| 69 | syscall_table.size(), |
| 70 | name); |
| 71 | ret = ENOMEM; |
| 72 | goto error; |
| 73 | } catch (const lttng::invalid_argument_error& ex) { |
| 74 | ERR_FMT("Failed to add syscall to syscall table: table_current_element_count={}, reason=`{}`", |
| 75 | syscall_table.size(), |
| 76 | name, |
| 77 | ex.what()); |
| 78 | ret = EINVAL; |
| 79 | goto error; |
| 80 | } |
| 81 | } |
| 82 | |
| 83 | ret = 0; |
| 84 | |
| 85 | error: |
| 86 | err = fclose(fp); |
| 87 | if (err) { |
| 88 | PERROR("syscall list fclose"); |
| 89 | } |
| 90 | return ret; |
| 91 | |
| 92 | error_fp: |
| 93 | err = close(fd); |
| 94 | if (err) { |
| 95 | PERROR("syscall list close"); |
| 96 | } |
| 97 | |
| 98 | error_ioctl: |
| 99 | return ret; |
| 100 | } |
| 101 | |
| 102 | /* |
| 103 | * Helper function for the list syscalls command that empty the temporary |
| 104 | * syscall hashtable used to track duplicate between 32 and 64 bit arch. |
| 105 | * |
| 106 | * This empty the hash table and destroys it after. After this, the pointer is |
| 107 | * unsuable. RCU read side lock MUST NOT be acquired before calling this. |
| 108 | */ |
| 109 | static void destroy_syscall_ht(struct lttng_ht *ht) |
| 110 | { |
| 111 | DBG3("Destroying syscall hash table."); |
| 112 | |
| 113 | if (!ht) { |
| 114 | return; |
| 115 | } |
| 116 | |
| 117 | for (auto *ksyscall : lttng::urcu::lfht_iteration_adapter<struct syscall, |
| 118 | decltype(syscall::node), |
| 119 | &syscall::node>(*ht->ht)) { |
| 120 | const auto ret = cds_lfht_del(ht->ht, &ksyscall->node.node); |
| 121 | LTTNG_ASSERT(!ret); |
| 122 | delete ksyscall; |
| 123 | } |
| 124 | |
| 125 | lttng_ht_destroy(ht); |
| 126 | } |
| 127 | |
| 128 | /* |
| 129 | * Allocate the given hashtable pointer. |
| 130 | * |
| 131 | * Return 0 on success else a negative LTTNG error value. |
| 132 | */ |
| 133 | static int init_syscall_ht(struct lttng_ht **ht) |
| 134 | { |
| 135 | int ret; |
| 136 | |
| 137 | *ht = lttng_ht_new(0, LTTNG_HT_TYPE_STRING); |
| 138 | if (!*ht) { |
| 139 | ret = -LTTNG_ERR_NOMEM; |
| 140 | } else { |
| 141 | ret = 0; |
| 142 | } |
| 143 | |
| 144 | return ret; |
| 145 | } |
| 146 | |
| 147 | /* |
| 148 | * Lookup a syscall in the given hash table by name. |
| 149 | * |
| 150 | * RCU read lock MUST be acquired by the callers of this function. |
| 151 | * |
| 152 | * Return syscall object if found or else NULL. |
| 153 | */ |
| 154 | static struct syscall *lookup_syscall(struct lttng_ht *ht, const char *name) |
| 155 | { |
| 156 | struct lttng_ht_node_str *node; |
| 157 | struct lttng_ht_iter iter; |
| 158 | struct syscall *ksyscall = nullptr; |
| 159 | |
| 160 | LTTNG_ASSERT(ht); |
| 161 | LTTNG_ASSERT(name); |
| 162 | |
| 163 | lttng_ht_lookup(ht, (void *) name, &iter); |
| 164 | node = lttng_ht_iter_get_node<lttng_ht_node_str>(&iter); |
| 165 | if (node) { |
| 166 | ksyscall = lttng::utils::container_of(node, &syscall::node); |
| 167 | } |
| 168 | |
| 169 | return ksyscall; |
| 170 | } |
| 171 | |
| 172 | /* |
| 173 | * Using the given syscall object in the events array with the bitness of the |
| 174 | * syscall at index in the syscall table. |
| 175 | */ |
| 176 | static void update_event_syscall_bitness(struct lttng_event *events, |
| 177 | unsigned int index, |
| 178 | unsigned int syscall_index) |
| 179 | { |
| 180 | LTTNG_ASSERT(events); |
| 181 | |
| 182 | if (syscall_table[index].bitness == 32) { |
| 183 | events[syscall_index].flags = (lttng_event_flag) (events[syscall_index].flags | |
| 184 | LTTNG_EVENT_FLAG_SYSCALL_32); |
| 185 | } else { |
| 186 | events[syscall_index].flags = (lttng_event_flag) (events[syscall_index].flags | |
| 187 | LTTNG_EVENT_FLAG_SYSCALL_64); |
| 188 | } |
| 189 | } |
| 190 | |
| 191 | /* |
| 192 | * Allocate and initialize syscall object and add it to the given hashtable. |
| 193 | * |
| 194 | * Return 0 on success else -LTTNG_ERR_NOMEM. |
| 195 | */ |
| 196 | static int add_syscall_to_ht(struct lttng_ht *ht, unsigned int index, unsigned int syscall_index) |
| 197 | { |
| 198 | int ret; |
| 199 | struct syscall *ksyscall; |
| 200 | |
| 201 | LTTNG_ASSERT(ht); |
| 202 | |
| 203 | try { |
| 204 | ksyscall = new struct syscall( |
| 205 | syscall_index, syscall_table[index].bitness, syscall_table[index].name); |
| 206 | } catch (const std::bad_alloc& ex) { |
| 207 | ERR_FMT("Failed to allocate syscall entry when adding it to the global syscall hash table: syscall name=`{}`", |
| 208 | syscall_table[index].name); |
| 209 | ret = -LTTNG_ERR_NOMEM; |
| 210 | goto error; |
| 211 | } |
| 212 | |
| 213 | lttng_ht_add_unique_str(ht, &ksyscall->node); |
| 214 | ret = 0; |
| 215 | |
| 216 | error: |
| 217 | return ret; |
| 218 | } |
| 219 | |
| 220 | /* |
| 221 | * List syscalls present in the kernel syscall global array, allocate and |
| 222 | * populate the events structure with them. Skip the empty syscall name. |
| 223 | * |
| 224 | * Return the number of entries in the array else a negative value. |
| 225 | */ |
| 226 | ssize_t syscall_table_list(struct lttng_event **_events) |
| 227 | { |
| 228 | int i, index = 0; |
| 229 | ssize_t ret; |
| 230 | struct lttng_event *events; |
| 231 | /* Hash table used to filter duplicate out. */ |
| 232 | struct lttng_ht *syscalls_ht = nullptr; |
| 233 | |
| 234 | LTTNG_ASSERT(_events); |
| 235 | |
| 236 | DBG("Syscall table listing."); |
| 237 | |
| 238 | /* |
| 239 | * Allocate at least the number of total syscall we have even if some of |
| 240 | * them might not be valid. The count below will make sure to return the |
| 241 | * right size of the events array. |
| 242 | */ |
| 243 | events = calloc<lttng_event>(syscall_table.size()); |
| 244 | if (!events) { |
| 245 | PERROR("syscall table list zmalloc"); |
| 246 | ret = -LTTNG_ERR_NOMEM; |
| 247 | goto error; |
| 248 | } |
| 249 | |
| 250 | ret = init_syscall_ht(&syscalls_ht); |
| 251 | if (ret < 0) { |
| 252 | goto error; |
| 253 | } |
| 254 | |
| 255 | for (i = 0; i < syscall_table.size(); i++) { |
| 256 | /* Skip empty syscalls. */ |
| 257 | if (*syscall_table[i].name == '\0') { |
| 258 | continue; |
| 259 | } |
| 260 | |
| 261 | { |
| 262 | const lttng::urcu::read_lock_guard read_lock; |
| 263 | struct syscall *ksyscall; |
| 264 | |
| 265 | ksyscall = lookup_syscall(syscalls_ht, syscall_table[i].name); |
| 266 | if (ksyscall) { |
| 267 | update_event_syscall_bitness(events, i, ksyscall->index); |
| 268 | continue; |
| 269 | } |
| 270 | } |
| 271 | |
| 272 | ret = add_syscall_to_ht(syscalls_ht, i, index); |
| 273 | if (ret < 0) { |
| 274 | goto error; |
| 275 | } |
| 276 | |
| 277 | /* Copy the event information in the event's array. */ |
| 278 | strncpy(events[index].name, syscall_table[i].name, sizeof(events[index].name)); |
| 279 | update_event_syscall_bitness(events, i, index); |
| 280 | events[index].type = LTTNG_EVENT_SYSCALL; |
| 281 | /* This makes the command line not print the enabled/disabled field. */ |
| 282 | events[index].enabled = -1; |
| 283 | index++; |
| 284 | } |
| 285 | |
| 286 | destroy_syscall_ht(syscalls_ht); |
| 287 | *_events = events; |
| 288 | return index; |
| 289 | |
| 290 | error: |
| 291 | destroy_syscall_ht(syscalls_ht); |
| 292 | free(events); |
| 293 | return ret; |
| 294 | } |