src/libnetdata/ebpf/ebpf.c
// SPDX-License-Identifier: GPL-3.0-or-later
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <dlfcn.h>
#include <sys/utsname.h>
#include "ebpf.h"
#include "../libnetdata.h"
char *ebpf_user_config_dir = CONFIG_DIR;
char *ebpf_stock_config_dir = LIBCONFIG_DIR;
/*
static int clean_kprobe_event(FILE *out, char *filename, char *father_pid, netdata_ebpf_events_t *ptr)
{
int fd = open(filename, O_WRONLY | O_APPEND, 0);
if (fd < 0) {
if (out) {
fprintf(out, "Cannot open %s : %s\n", filename, strerror(errno));
}
return 1;
}
char cmd[1024];
int length = snprintf(cmd, 1023, "-:kprobes/%c_netdata_%s_%s", ptr->type, ptr->name, father_pid);
int ret = 0;
if (length > 0) {
ssize_t written = write(fd, cmd, strlen(cmd));
if (written < 0) {
if (out) {
fprintf(
out, "Cannot remove the event (%d, %d) '%s' from %s : %s\n", getppid(), getpid(), cmd, filename,
strerror((int)errno));
}
ret = 1;
}
}
close(fd);
return ret;
}
int clean_kprobe_events(FILE *out, int pid, netdata_ebpf_events_t *ptr)
{
char filename[FILENAME_MAX + 1];
snprintf(filename, FILENAME_MAX, "%s%s", NETDATA_DEBUGFS, "kprobe_events");
char removeme[16];
snprintf(removeme, 15, "%d", pid);
int i;
for (i = 0; ptr[i].name; i++) {
if (clean_kprobe_event(out, filename, removeme, &ptr[i])) {
break;
}
}
return 0;
}
*/
//----------------------------------------------------------------------------------------------------------------------
/**
* Get Kernel version
*
* Get the current kernel from /proc and returns an integer value representing it
*
* @return it returns a value representing the kernel version.
*/
int ebpf_get_kernel_version()
{
char major[16], minor[16], patch[16];
char ver[VERSION_STRING_LEN];
char *version = ver;
int fd = open("/proc/sys/kernel/osrelease", O_RDONLY | O_CLOEXEC);
if (fd < 0)
return -1;
ssize_t len = read(fd, ver, sizeof(ver));
if (len < 0) {
close(fd);
return -1;
}
close(fd);
char *move = major;
while (*version && *version != '.')
*move++ = *version++;
*move = '\0';
version++;
move = minor;
while (*version && *version != '.')
*move++ = *version++;
*move = '\0';
if (*version)
version++;
else
return -1;
move = patch;
while (*version && *version != '\n' && *version != '-')
*move++ = *version++;
*move = '\0';
// This new rule is fixing kernel version according the formula:
// KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + ((c) > 255 ? 255 : (c)))
// that was extracted from /usr/include/linux/version.h
int ipatch = (int)str2l(patch);
if (ipatch > 255)
ipatch = 255;
return ((int)(str2l(major) * 65536) + (int)(str2l(minor) * 256) + ipatch);
}
/**
* Get RH release
*
* Read Red Hat release from /etc/redhat-release
*
* @return It returns RH release on success and -1 otherwise
*/
int get_redhat_release()
{
char buffer[VERSION_STRING_LEN + 1];
int major, minor;
FILE *fp = fopen("/etc/redhat-release", "r");
if (fp) {
major = 0;
minor = -1;
size_t length = fread(buffer, sizeof(char), VERSION_STRING_LEN, fp);
if (length > 4) {
buffer[length] = '\0';
char *end = strchr(buffer, '.');
char *start;
if (end) {
*end = 0x0;
if (end > buffer) {
start = end - 1;
major = strtol(start, NULL, 10);
start = ++end;
end++;
if (end) {
end = 0x00;
minor = strtol(start, NULL, 10);
} else {
minor = -1;
}
}
}
}
fclose(fp);
return ((major * 256) + minor);
} else {
return -1;
}
}
/**
* Check if the kernel is in a list of rejected ones
*
* @return Returns 1 if the kernel is rejected, 0 otherwise.
*/
static int kernel_is_rejected()
{
// Get kernel version from system
char version_string[VERSION_STRING_LEN + 1];
int version_string_len = 0;
if (read_txt_file("/proc/version_signature", version_string, sizeof(version_string))) {
if (read_txt_file("/proc/version", version_string, sizeof(version_string))) {
struct utsname uname_buf;
if (!uname(&uname_buf)) {
netdata_log_info("Cannot check kernel version");
return 0;
}
version_string_len =
snprintfz(version_string, VERSION_STRING_LEN, "%s %s", uname_buf.release, uname_buf.version);
}
}
if (!version_string_len)
version_string_len = strlen(version_string);
// Open a file with a list of rejected kernels
char *config_dir = getenv("NETDATA_USER_CONFIG_DIR");
if (config_dir == NULL) {
config_dir = CONFIG_DIR;
}
char filename[FILENAME_MAX + 1];
snprintfz(filename, FILENAME_MAX, "%s/ebpf.d/%s", config_dir, EBPF_KERNEL_REJECT_LIST_FILE);
FILE *kernel_reject_list = fopen(filename, "r");
if (!kernel_reject_list) {
// Keep this to have compatibility with old versions
snprintfz(filename, FILENAME_MAX, "%s/%s", config_dir, EBPF_KERNEL_REJECT_LIST_FILE);
kernel_reject_list = fopen(filename, "r");
if (!kernel_reject_list) {
config_dir = getenv("NETDATA_STOCK_CONFIG_DIR");
if (config_dir == NULL) {
config_dir = LIBCONFIG_DIR;
}
snprintfz(filename, FILENAME_MAX, "%s/ebpf.d/%s", config_dir, EBPF_KERNEL_REJECT_LIST_FILE);
kernel_reject_list = fopen(filename, "r");
if (!kernel_reject_list)
return 0;
}
}
// Find if the kernel is in the reject list
char *reject_string = NULL;
size_t buf_len = 0;
ssize_t reject_string_len;
while ((reject_string_len = getline(&reject_string, &buf_len, kernel_reject_list) - 1) > 0) {
if (version_string_len >= reject_string_len) {
if (!strncmp(version_string, reject_string, reject_string_len)) {
netdata_log_info("A buggy kernel is detected");
fclose(kernel_reject_list);
freez(reject_string);
return 1;
}
}
}
fclose(kernel_reject_list);
free(reject_string);
return 0;
}
/**
* Check Kernel Version
*
* Test kernel version
*
* @param version current kernel version
*
* @return It returns 1 when kernel is supported and 0 otherwise
*/
int ebpf_check_kernel_version(int version)
{
if (kernel_is_rejected())
return 0;
// Kernel 4.11.0 or RH > 7.5
return (version >= NETDATA_MINIMUM_EBPF_KERNEL || get_redhat_release() >= NETDATA_MINIMUM_RH_VERSION);
}
/**
* Am I running as Root
*
* Verify the user that is running the collector.
*
* @return It returns 1 for root and 0 otherwise.
*/
int is_ebpf_plugin_running_as_root()
{
uid_t uid = getuid(), euid = geteuid();
if (uid == 0 || euid == 0) {
return 1;
}
return 0;
}
/**
* Can the plugin run eBPF code
*
* This function checks kernel version and permissions.
*
* @param kver the kernel version
* @param name the plugin name.
*
* @return It returns 0 on success and -1 otherwise
*/
int ebpf_can_plugin_load_code(int kver, char *plugin_name)
{
if (!ebpf_check_kernel_version(kver)) {
netdata_log_error("The current collector cannot run on this kernel.");
return -1;
}
if (!is_ebpf_plugin_running_as_root()) {
netdata_log_error(
"%s should either run as root (now running with uid %u, euid %u) or have special capabilities.",
plugin_name, (unsigned int)getuid(), (unsigned int)geteuid());
return -1;
}
return 0;
}
/**
* Adjust memory
*
* Adjust memory values to load eBPF programs.
*
* @return It returns 0 on success and -1 otherwise
*/
int ebpf_adjust_memory_limit()
{
struct rlimit r = { RLIM_INFINITY, RLIM_INFINITY };
if (setrlimit(RLIMIT_MEMLOCK, &r)) {
netdata_log_error("Setrlimit(RLIMIT_MEMLOCK)");
return -1;
}
return 0;
}
//----------------------------------------------------------------------------------------------------------------------
/**
* Kernel Name
*
* Select kernel name used by eBPF programs
*
* Netdata delivers for users eBPF programs with specific suffixes that represent the kernels they were
* compiled, when we load the eBPF program, the suffix must be the nereast possible of the kernel running.
*
* @param selector select the kernel version.
*
* @return It returns the string to load kernel.
*/
static char *ebpf_select_kernel_name(uint32_t selector)
{
static char *kernel_names[] = { NETDATA_IDX_STR_V3_10, NETDATA_IDX_STR_V4_14, NETDATA_IDX_STR_V4_16,
NETDATA_IDX_STR_V4_18, NETDATA_IDX_STR_V5_4, NETDATA_IDX_STR_V5_10,
NETDATA_IDX_STR_V5_11, NETDATA_IDX_STR_V5_14, NETDATA_IDX_STR_V5_15,
NETDATA_IDX_STR_V5_16, NETDATA_IDX_STR_V6_8
};
return kernel_names[selector];
}
/**
* Select Max Index
*
* Select last index that will be tested on host.
*
* @param is_rhf is Red Hat fammily?
* @param kver the kernel version
*
* @return it returns the index to access kernel string.
*/
static int ebpf_select_max_index(int is_rhf, uint32_t kver)
{
if (is_rhf > 0) { // Is Red Hat family
if (kver >= NETDATA_EBPF_KERNEL_5_14)
return NETDATA_IDX_V5_14;
else if (kver >= NETDATA_EBPF_KERNEL_5_4 && kver < NETDATA_EBPF_KERNEL_5_5) // For Oracle Linux
return NETDATA_IDX_V5_4;
else if (kver >= NETDATA_EBPF_KERNEL_4_11)
return NETDATA_IDX_V4_18;
} else { // Kernels from kernel.org
if (kver >= NETDATA_EBPF_KERNEL_6_8)
return NETDATA_IDX_V6_8;
else if (kver >= NETDATA_EBPF_KERNEL_5_16)
return NETDATA_IDX_V5_16;
else if (kver >= NETDATA_EBPF_KERNEL_5_15)
return NETDATA_IDX_V5_15;
else if (kver >= NETDATA_EBPF_KERNEL_5_11)
return NETDATA_IDX_V5_11;
else if (kver >= NETDATA_EBPF_KERNEL_5_10)
return NETDATA_IDX_V5_10;
else if (kver >= NETDATA_EBPF_KERNEL_4_17)
return NETDATA_IDX_V5_4;
else if (kver >= NETDATA_EBPF_KERNEL_4_15)
return NETDATA_IDX_V4_16;
else if (kver >= NETDATA_EBPF_KERNEL_4_11)
return NETDATA_IDX_V4_14;
}
return NETDATA_IDX_V3_10;
}
/**
* Select Index
*
* Select index to load data.
*
* @param kernels is the variable with kernel versions.
* @param is_rhf is Red Hat fammily?
* param kver the kernel version
*/
static uint32_t ebpf_select_index(uint32_t kernels, int is_rhf, uint32_t kver)
{
uint32_t start = ebpf_select_max_index(is_rhf, kver);
uint32_t idx;
if (is_rhf == -1)
kernels &= ~NETDATA_V5_14;
for (idx = start; idx; idx--) {
if (kernels & 1 << idx)
break;
}
return idx;
}
/**
* Mount Name
*
* Mount name of eBPF program to be loaded.
*
* Netdata eBPF programs has the following format:
*
* Tnetdata_ebpf_N.V.o
*
* where:
* T - Is the eBPF type. When starts with 'p', this means we are only adding probes,
* and when they start with 'r' we are using retprobes.
* N - The eBPF program name.
* V - The kernel version in string format.
*
* @param out the vector where the name will be stored
* @param len the size of the out vector.
* @param path where the binaries are stored
* @param kver the kernel version
* @param name the eBPF program name.
* @param is_return is return or entry ?
*/
static void ebpf_mount_name(char *out, size_t len, char *path, uint32_t kver, const char *name,
int is_return, int is_rhf)
{
char *version = ebpf_select_kernel_name(kver);
snprintfz(out, len, "%s/ebpf.d/%cnetdata_ebpf_%s.%s%s.o",
path,
(is_return) ? 'r' : 'p',
name,
version,
(is_rhf != -1) ? ".rhf" : "");
}
//----------------------------------------------------------------------------------------------------------------------
/**
* Statistics from targets
*
* Count the information from targets.
*
* @param report the output structure
* @param targets vector with information about the eBPF plugin.
* @param value factor used to update calculation
*/
static void ebpf_stats_targets(ebpf_plugin_stats_t *report, netdata_ebpf_targets_t *targets, int value)
{
if (!targets) {
report->probes = report->tracepoints = report->trampolines = 0;
return;
}
int i = 0;
while (targets[i].name) {
switch (targets[i].mode) {
case EBPF_LOAD_PROBE: {
report->probes += value;
break;
}
case EBPF_LOAD_RETPROBE: {
report->retprobes += value;
break;
}
case EBPF_LOAD_TRACEPOINT: {
report->tracepoints += value;
break;
}
case EBPF_LOAD_TRAMPOLINE: {
report->trampolines += value;
break;
}
}
i++;
}
}
/**
* Update General stats
*
* Update eBPF plugin statistics that has relationship with the thread.
*
* This function must be called with mutex associated to charts is locked.
*
* @param report the output structure
* @param em the structure with information about how the module/thread is working.
*/
void ebpf_update_stats(ebpf_plugin_stats_t *report, ebpf_module_t *em)
{
int value;
// It is not necessary to report more information.
if (em->enabled > NETDATA_THREAD_EBPF_FUNCTION_RUNNING)
value = -1;
else
value = 1;
report->threads += value;
report->running += value;
// In theory the `else if` is useless, because when this function is called, the module should not stay in
// EBPF_LOAD_PLAY_DICE. We have this additional condition to detect errors from developers.
if (em->load & EBPF_LOAD_LEGACY)
report->legacy += value;
else if (em->load & EBPF_LOAD_CORE)
report->core += value;
if (em->maps_per_core)
report->hash_percpu += value;
else
report->hash_unique += value;
ebpf_stats_targets(report, em->targets, value);
}
/**
* Update Kernel memory with memory
*
* This algorithm is an adaptation of https://elixir.bootlin.com/linux/v6.1.14/source/tools/bpf/bpftool/common.c#L402
* to get 'memlock' data and update report.
*
* @param report the output structure
* @param map pointer to a map.
* @param action What action will be done with this map.
*/
void ebpf_update_kernel_memory(ebpf_plugin_stats_t *report, ebpf_local_maps_t *map, ebpf_stats_action_t action)
{
char filename[FILENAME_MAX+1];
snprintfz(filename, FILENAME_MAX, "/proc/self/fdinfo/%d", map->map_fd);
procfile *ff = procfile_open(filename, " \t", PROCFILE_FLAG_DEFAULT);
if(unlikely(!ff)) {
netdata_log_error("Cannot open %s", filename);
return;
}
ff = procfile_readall(ff);
if(unlikely(!ff))
return;
unsigned long j, lines = procfile_lines(ff);
char *memlock = { "memlock" };
for (j = 0; j < lines ; j++) {
char *cmp = procfile_lineword(ff, j,0);
if (!strncmp(memlock, cmp, 7)) {
uint64_t memsize = (uint64_t) str2l(procfile_lineword(ff, j,1));
switch (action) {
case EBPF_ACTION_STAT_ADD: {
report->memlock_kern += memsize;
report->hash_tables += 1;
#ifdef NETDATA_DEV_MODE
netdata_log_info("Hash table %u: %s (FD = %d) is consuming %lu bytes totalizing %lu bytes",
report->hash_tables, map->name, map->map_fd, memsize, report->memlock_kern);
#endif
break;
}
case EBPF_ACTION_STAT_REMOVE: {
report->memlock_kern -= memsize;
report->hash_tables -= 1;
#ifdef NETDATA_DEV_MODE
netdata_log_info("Hash table %s (FD = %d) was removed releasing %lu bytes, now we have %u tables loaded totalizing %lu bytes.",
map->name, map->map_fd, memsize, report->hash_tables, report->memlock_kern);
#endif
break;
}
default: {
break;
}
}
break;
}
}
procfile_close(ff);
}
/**
* Update Kernel memory with memory
*
* This algorithm is an adaptation of https://elixir.bootlin.com/linux/v6.1.14/source/tools/bpf/bpftool/common.c#L402
* to get 'memlock' data and update report.
*
* @param report the output structure
* @param map pointer to a map. Last map must fish with name = NULL
* @param action should plugin add or remove values from amount.
*/
void ebpf_update_kernel_memory_with_vector(ebpf_plugin_stats_t *report,
ebpf_local_maps_t *maps,
ebpf_stats_action_t action)
{
if (!maps)
return;
ebpf_local_maps_t *map;
int i = 0;
for (map = &maps[i]; maps[i].name; i++, map = &maps[i]) {
int fd = map->map_fd;
if (fd == ND_EBPF_MAP_FD_NOT_INITIALIZED)
continue;
ebpf_update_kernel_memory(report, map, action);
}
}
//----------------------------------------------------------------------------------------------------------------------
void ebpf_update_pid_table(ebpf_local_maps_t *pid, ebpf_module_t *em)
{
pid->user_input = em->pid_map_size;
}
/**
* Update map size
*
* Update map size with information read from configuration files.
*
* @param map the structure with file descriptor to update.
* @param lmap the structure with information from configuration files.
* @param em the structure with information about how the module/thread is working.
* @param map_name the name of the file used to log.
*/
void ebpf_update_map_size(struct bpf_map *map, ebpf_local_maps_t *lmap, ebpf_module_t *em, const char *map_name __maybe_unused)
{
uint32_t define_size = 0;
uint32_t apps_type = NETDATA_EBPF_MAP_PID | NETDATA_EBPF_MAP_RESIZABLE;
if (lmap->user_input && lmap->user_input != lmap->internal_input) {
define_size = lmap->internal_input;
#ifdef NETDATA_INTERNAL_CHECKS
netdata_log_info("Changing map %s from size %u to %u ", map_name, lmap->internal_input, lmap->user_input);
#endif
} else if (((lmap->type & apps_type) == apps_type) && (!em->apps_charts) && (!em->cgroup_charts)) {
lmap->user_input = ND_EBPF_DEFAULT_MIN_PID;
} else if (((em->apps_charts) || (em->cgroup_charts)) && (em->apps_level != NETDATA_APPS_NOT_SET)) {
switch (em->apps_level) {
case NETDATA_APPS_LEVEL_ALL: {
define_size = lmap->user_input;
break;
}
case NETDATA_APPS_LEVEL_PARENT: {
define_size = ND_EBPF_DEFAULT_PID_SIZE / 2;
break;
}
case NETDATA_APPS_LEVEL_REAL_PARENT:
default: {
define_size = ND_EBPF_DEFAULT_PID_SIZE / 3;
}
}
}
if (!define_size)
return;
#ifdef LIBBPF_MAJOR_VERSION
bpf_map__set_max_entries(map, define_size);
#else
bpf_map__resize(map, define_size);
#endif
}
#ifdef LIBBPF_MAJOR_VERSION
/**
* Update map type
*
* Update map type with information given.
*
* @param map the map we want to modify
* @param w a structure with user input
*/
void ebpf_update_map_type(struct bpf_map *map, ebpf_local_maps_t *w)
{
if (bpf_map__set_type(map, w->map_type)) {
netdata_log_error("Cannot modify map type for %s", w->name);
}
}
/**
* Define map type
*
* This PR defines the type used by hash tables according user input.
*
* @param maps the list of maps used with a hash table.
* @param maps_per_core define if map type according user specification.
* @param kver kernel version host is running.
*/
void ebpf_define_map_type(ebpf_local_maps_t *maps, int maps_per_core, int kver)
{
if (!maps)
return;
// Before kernel 4.06 there was not percpu hash tables
if (kver < NETDATA_EBPF_KERNEL_4_06)
maps_per_core = CONFIG_BOOLEAN_NO;
int i = 0;
while (maps[i].name) {
ebpf_local_maps_t *map = &maps[i];
// maps_per_core is a boolean value in configuration files.
if (maps_per_core) {
if (map->map_type == BPF_MAP_TYPE_HASH)
map->map_type = BPF_MAP_TYPE_PERCPU_HASH;
else if (map->map_type == BPF_MAP_TYPE_ARRAY)
map->map_type = BPF_MAP_TYPE_PERCPU_ARRAY;
} else {
if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH)
map->map_type = BPF_MAP_TYPE_HASH;
else if (map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
map->map_type = BPF_MAP_TYPE_ARRAY;
}
i++;
}
}
#endif
/**
* Update Legacy map
*
* Update map for eBPF legacy code.
*
* @param program the structure with values read from binary.
* @param em the structure with information about how the module/thread is working.
*/
static void ebpf_update_legacy_map(struct bpf_object *program, ebpf_module_t *em)
{
struct bpf_map *map;
ebpf_local_maps_t *maps = em->maps;
if (!maps)
return;
bpf_map__for_each(map, program)
{
const char *map_name = bpf_map__name(map);
int i = 0;
while (maps[i].name) {
ebpf_local_maps_t *w = &maps[i];
if (!strcmp(w->name, map_name)) {
// Modify size
if (w->type & NETDATA_EBPF_MAP_RESIZABLE) {
ebpf_update_map_size(map, w, em, map_name);
}
#ifdef LIBBPF_MAJOR_VERSION
ebpf_update_map_type(map, w);
#endif
}
i++;
}
}
}
size_t ebpf_count_programs(struct bpf_object *obj)
{
size_t tot = 0;
struct bpf_program *prog;
bpf_object__for_each_program(prog, obj)
{
tot++;
}
return tot;
}
static ebpf_specify_name_t *ebpf_find_names(ebpf_specify_name_t *names, const char *prog_name)
{
size_t i = 0;
while (names[i].program_name) {
if (!strcmp(prog_name, names[i].program_name))
return &names[i];
i++;
}
return NULL;
}
static struct bpf_link **ebpf_attach_programs(struct bpf_object *obj, size_t length, ebpf_specify_name_t *names)
{
struct bpf_link **links = callocz(length , sizeof(struct bpf_link *));
size_t i = 0;
struct bpf_program *prog;
ebpf_specify_name_t *w;
bpf_object__for_each_program(prog, obj)
{
if (names) {
const char *name = bpf_program__name(prog);
w = ebpf_find_names(names, name);
} else
w = NULL;
if (w) {
enum bpf_prog_type type = bpf_program__get_type(prog);
if (type == BPF_PROG_TYPE_KPROBE)
links[i] = bpf_program__attach_kprobe(prog, w->retprobe, w->optional);
} else
links[i] = bpf_program__attach(prog);
if (libbpf_get_error(links[i])) {
links[i] = NULL;
}
i++;
}
return links;
}
static void ebpf_update_maps(ebpf_module_t *em, struct bpf_object *obj)
{
if (!em->maps)
return;
ebpf_local_maps_t *maps = em->maps;
struct bpf_map *map;
bpf_map__for_each(map, obj)
{
int fd = bpf_map__fd(map);
if (maps) {
const char *map_name = bpf_map__name(map);
int j = 0;
while (maps[j].name) {
ebpf_local_maps_t *w = &maps[j];
if (w->map_fd == ND_EBPF_MAP_FD_NOT_INITIALIZED && !strcmp(map_name, w->name))
w->map_fd = fd;
j++;
}
}
}
}
/**
* Update Controller
*
* Update controller value with user input.
*
* @param fd the table file descriptor
* @param em structure with information about eBPF program we will load.
*/
void ebpf_update_controller(int fd, ebpf_module_t *em)
{
uint32_t values[NETDATA_CONTROLLER_END] = {
(em->apps_charts & NETDATA_EBPF_APPS_FLAG_YES) | em->cgroup_charts,
em->apps_level, 0, 0, 0, 0
};
uint32_t key;
uint32_t end = NETDATA_CONTROLLER_PID_TABLE_ADD;
for (key = NETDATA_CONTROLLER_APPS_ENABLED; key < end; key++) {
int ret = bpf_map_update_elem(fd, &key, &values[key], BPF_ANY);
if (ret)
netdata_log_error("Add key(%u) for controller table failed.", key);
}
}
/**
* Update Legacy controller
*
* Update legacy controller table when eBPF program has it.
*
* @param em structure with information about eBPF program we will load.
* @param obj bpf object with tables.
*/
static void ebpf_update_legacy_controller(ebpf_module_t *em, struct bpf_object *obj)
{
ebpf_local_maps_t *maps = em->maps;
if (!maps)
return;
struct bpf_map *map;
bpf_map__for_each(map, obj)
{
size_t i = 0;
while (maps[i].name) {
ebpf_local_maps_t *w = &maps[i];
if (w->map_fd != ND_EBPF_MAP_FD_NOT_INITIALIZED && (w->type & NETDATA_EBPF_MAP_CONTROLLER)) {
w->type &= ~NETDATA_EBPF_MAP_CONTROLLER;
w->type |= NETDATA_EBPF_MAP_CONTROLLER_UPDATED;
ebpf_update_controller(w->map_fd, em);
}
i++;
}
}
}
/**
* Load Program
*
* Load eBPF program into kernel
*
* @param plugins_dir directory where binary are stored
* @param em structure with information about eBPF program we will load.
* @param kver the kernel version according /usr/include/linux/version.h
* @param is_rhf is a kernel from Red Hat Family?
* @param obj structure where we will store object loaded.
*
* @return it returns a link for each target we associated an eBPF program.
*/
struct bpf_link **ebpf_load_program(char *plugins_dir, ebpf_module_t *em, int kver, int is_rhf,
struct bpf_object **obj)
{
char lpath[4096];
uint32_t idx = ebpf_select_index(em->kernels, is_rhf, kver);
ebpf_mount_name(lpath, 4095, plugins_dir, idx, em->info.thread_name, em->mode, is_rhf);
// When this function is called ebpf.plugin is using legacy code, so we should reset the variable
em->load &= ~ NETDATA_EBPF_LOAD_METHODS;
em->load |= EBPF_LOAD_LEGACY;
*obj = bpf_object__open_file(lpath, NULL);
if (!*obj)
return NULL;
if (libbpf_get_error(obj)) {
bpf_object__close(*obj);
return NULL;
}
ebpf_update_legacy_map(*obj, em);
if (bpf_object__load(*obj)) {
netdata_log_error("ERROR: loading BPF object file failed %s\n", lpath);
bpf_object__close(*obj);
return NULL;
}
ebpf_update_maps(em, *obj);
ebpf_update_legacy_controller(em, *obj);
size_t count_programs = ebpf_count_programs(*obj);
#ifdef NETDATA_INTERNAL_CHECKS
netdata_log_info("eBPF program %s loaded with success!", lpath);
#endif
return ebpf_attach_programs(*obj, count_programs, em->names);
}
char *ebpf_find_symbol(char *search)
{
char filename[FILENAME_MAX + 1];
char *ret = NULL;
snprintfz(filename, FILENAME_MAX, "%s%s", netdata_configured_host_prefix, NETDATA_KALLSYMS);
procfile *ff = procfile_open(filename, " \t", PROCFILE_FLAG_DEFAULT);
if(unlikely(!ff)) {
netdata_log_error("Cannot open %s%s", netdata_configured_host_prefix, NETDATA_KALLSYMS);
return ret;
}
ff = procfile_readall(ff);
if(unlikely(!ff))
return ret;
unsigned long i, lines = procfile_lines(ff);
size_t length = strlen(search);
for(i = 0; i < lines ; i++) {
char *cmp = procfile_lineword(ff, i,2);
if (!strncmp(search, cmp, length)) {
ret = strdupz(cmp);
break;
}
}
procfile_close(ff);
return ret;
}
void ebpf_update_names(ebpf_specify_name_t *opt, ebpf_module_t *em)
{
int mode = em->mode;
em->names = opt;
size_t i = 0;
while (opt[i].program_name) {
opt[i].retprobe = (mode == MODE_RETURN);
opt[i].optional = ebpf_find_symbol(opt[i].function_to_attach);
i++;
}
}
//----------------------------------------------------------------------------------------------------------------------
void ebpf_mount_config_name(char *filename, size_t length, char *path, const char *config)
{
snprintf(filename, length, "%s/ebpf.d/%s", path, config);
}
int ebpf_load_config(struct config *config, char *filename)
{
return appconfig_load(config, filename, 0, NULL);
}
static netdata_run_mode_t ebpf_select_mode(const char *mode)
{
if (!strcasecmp(mode,EBPF_CFG_LOAD_MODE_RETURN ))
return MODE_RETURN;
else if (!strcasecmp(mode, "dev"))
return MODE_DEVMODE;
return MODE_ENTRY;
}
static void ebpf_select_mode_string(char *output, size_t len, netdata_run_mode_t sel)
{
if (sel == MODE_RETURN)
strncpyz(output, EBPF_CFG_LOAD_MODE_RETURN, len);
else
strncpyz(output, EBPF_CFG_LOAD_MODE_DEFAULT, len);
}
/**
* Convert string to load mode
*
* Convert the string given as argument to value present in enum.
*
* @param str value read from configuration file.
*
* @return It returns the value to be used.
*/
netdata_ebpf_load_mode_t epbf_convert_string_to_load_mode(const char *str)
{
if (!strcasecmp(str, EBPF_CFG_CORE_PROGRAM))
return EBPF_LOAD_CORE;
else if (!strcasecmp(str, EBPF_CFG_LEGACY_PROGRAM))
return EBPF_LOAD_LEGACY;
return EBPF_LOAD_PLAY_DICE;
}
/**
* Convert load mode to string
*
* @param mode value that will select the string
*
* @return It returns the string associated to mode.
*/
static char *ebpf_convert_load_mode_to_string(netdata_ebpf_load_mode_t mode)
{
if (mode & EBPF_LOAD_CORE)
return EBPF_CFG_CORE_PROGRAM;
else if (mode & EBPF_LOAD_LEGACY)
return EBPF_CFG_LEGACY_PROGRAM;
return EBPF_CFG_DEFAULT_PROGRAM;
}
/**
* Convert collect pid to string
*
* @param level value that will select the string
*
* @return It returns the string associated to level.
*/
static char *ebpf_convert_collect_pid_to_string(netdata_apps_level_t level)
{
if (level == NETDATA_APPS_LEVEL_REAL_PARENT)
return EBPF_CFG_PID_REAL_PARENT;
else if (level == NETDATA_APPS_LEVEL_PARENT)
return EBPF_CFG_PID_PARENT;
else if (level == NETDATA_APPS_LEVEL_ALL)
return EBPF_CFG_PID_ALL;
return EBPF_CFG_PID_INTERNAL_USAGE;
}
/**
* Convert string to apps level
*
* @param str the argument read from config files
*
* @return it returns the level associated to the string or default when it is a wrong value
*/
netdata_apps_level_t ebpf_convert_string_to_apps_level(const char *str)
{
if (!strcasecmp(str, EBPF_CFG_PID_REAL_PARENT))
return NETDATA_APPS_LEVEL_REAL_PARENT;
else if (!strcasecmp(str, EBPF_CFG_PID_PARENT))
return NETDATA_APPS_LEVEL_PARENT;
else if (!strcasecmp(str, EBPF_CFG_PID_ALL))
return NETDATA_APPS_LEVEL_ALL;
return NETDATA_APPS_NOT_SET;
}
/**
* CO-RE type
*
* Select the preferential type of CO-RE
*
* @param str value read from configuration file.
* @param lmode load mode used by collector.
*/
netdata_ebpf_program_loaded_t ebpf_convert_core_type(const char *str, netdata_run_mode_t lmode)
{
if (!strcasecmp(str, EBPF_CFG_ATTACH_TRACEPOINT))
return EBPF_LOAD_TRACEPOINT;
else if (!strcasecmp(str, EBPF_CFG_ATTACH_PROBE)) {
return (lmode == MODE_ENTRY) ? EBPF_LOAD_PROBE : EBPF_LOAD_RETPROBE;
}
return EBPF_LOAD_TRAMPOLINE;
}
#ifdef LIBBPF_MAJOR_VERSION
/**
* Adjust Thread Load
*
* Adjust thread configuration according specified load.
*
* @param mod the main structure that will be adjusted.
* @param file the btf file used with thread.
*/
void ebpf_adjust_thread_load(ebpf_module_t *mod, struct btf *file)
{
if (!file) {
mod->load &= ~EBPF_LOAD_CORE;
mod->load |= EBPF_LOAD_LEGACY;
} else if (mod->load == EBPF_LOAD_PLAY_DICE && file) {
mod->load &= ~EBPF_LOAD_LEGACY;
mod->load |= EBPF_LOAD_CORE;
}
}
/**
* Parse BTF file
*
* Parse a specific BTF file present on filesystem
*
* @param filename the file that will be parsed.
*
* @return It returns a pointer for the file on success and NULL otherwise.
*/
struct btf *ebpf_parse_btf_file(const char *filename)
{
struct btf *bf = btf__parse(filename, NULL);
if (libbpf_get_error(bf)) {
fprintf(stderr, "Cannot parse btf file");
btf__free(bf);
return NULL;
}
return bf;
}
/**
* Load default btf file
*
* Load the default BTF file on environment.
*
* @param path is the fullpath
* @param filename is the file inside BTF path.
*/
struct btf *ebpf_load_btf_file(const char *path, const char *filename)
{
char fullpath[PATH_MAX + 1];
snprintfz(fullpath, PATH_MAX, "%s/%s", path, filename);
struct btf *ret = ebpf_parse_btf_file(fullpath);
if (!ret)
netdata_log_info("Your environment does not have BTF file %s/%s. The plugin will work with 'legacy' code.",
path, filename);
return ret;
}
/**
* Find BTF attach type
*
* Search type fr current btf file.
*
* @param file is the structure for the btf file already parsed.
*/
static inline const struct btf_type *ebpf_find_btf_attach_type(struct btf *file)
{
int id = btf__find_by_name_kind(file, "bpf_attach_type", BTF_KIND_ENUM);
if (id < 0) {
fprintf(stderr, "Cannot find 'bpf_attach_type'");
return NULL;
}
return btf__type_by_id(file, id);
}
/**
* Is function inside BTF
*
* Look for a specific function inside the given BTF file.
*
* @param file is the structure for the btf file already parsed.
* @param function is the function that we want to find.
*/
int ebpf_is_function_inside_btf(struct btf *file, char *function)
{
const struct btf_type *type = ebpf_find_btf_attach_type(file);
if (!type)
return -1;
const struct btf_enum *e = btf_enum(type);
int i, id;
for (id = -1, i = 0; i < btf_vlen(type); i++, e++) {
if (!strcmp(btf__name_by_offset(file, e->name_off), "BPF_TRACE_FENTRY")) {
id = btf__find_by_name_kind(file, function, BTF_KIND_FUNC);
break;
}
}
return (id > 0) ? 1 : 0;
}
#endif
/**
* Update target with configuration
*
* Update target load mode with value.
*
* @param em the module structure
* @param value value used to update.
*/
static void ebpf_update_target_with_conf(ebpf_module_t *em, netdata_ebpf_program_loaded_t value)
{
netdata_ebpf_targets_t *targets = em->targets;
if (!targets) {
return;
}
int i = 0;
while (targets[i].name) {
targets[i].mode = value;
i++;
}
}
/**
* Select Load Mode
*
* Select the load mode according the given inputs.
*
* @param btf_file a pointer to the loaded btf file.
* @parma load current value.
* @param btf_file a pointer to the loaded btf file.
* @param is_rhf is Red Hat family?
*
* @return it returns the new load mode.
*/
static netdata_ebpf_load_mode_t ebpf_select_load_mode(struct btf *btf_file __maybe_unused,
netdata_ebpf_load_mode_t load,
int kver __maybe_unused,
int is_rh __maybe_unused)
{
#ifdef LIBBPF_MAJOR_VERSION
if ((load & EBPF_LOAD_CORE) || (load & EBPF_LOAD_PLAY_DICE)) {
// Quick fix for Oracle linux 8.x
load = (!btf_file || (is_rh && (kver >= NETDATA_EBPF_KERNEL_5_4 && kver < NETDATA_EBPF_KERNEL_5_5))) ?
EBPF_LOAD_LEGACY : EBPF_LOAD_CORE;
}
#else
load = EBPF_LOAD_LEGACY;
#endif
return load;
}
/**
* Update Module using config
*
* Update configuration for a specific thread.
*
* @param modules structure that will be updated
* @param origin specify the configuration file loaded
* @param btf_file a pointer to the loaded btf file.
* @param is_rhf is Red Hat family?
*/
void ebpf_update_module_using_config(ebpf_module_t *modules, netdata_ebpf_load_mode_t origin, struct btf *btf_file,
int kver, int is_rh)
{
char default_value[EBPF_MAX_MODE_LENGTH + 1];
ebpf_select_mode_string(default_value, EBPF_MAX_MODE_LENGTH, modules->mode);
const char *load_mode = appconfig_get(modules->cfg, EBPF_GLOBAL_SECTION, EBPF_CFG_LOAD_MODE, default_value);
modules->mode = ebpf_select_mode(load_mode);
modules->update_every = (int)appconfig_get_number(modules->cfg, EBPF_GLOBAL_SECTION,
EBPF_CFG_UPDATE_EVERY, modules->update_every);
modules->apps_charts = appconfig_get_boolean(modules->cfg, EBPF_GLOBAL_SECTION, EBPF_CFG_APPLICATION,
(int) (modules->apps_charts & NETDATA_EBPF_APPS_FLAG_YES));
modules->cgroup_charts = appconfig_get_boolean(modules->cfg, EBPF_GLOBAL_SECTION, EBPF_CFG_CGROUP,
modules->cgroup_charts);
modules->pid_map_size = (uint32_t)appconfig_get_number(modules->cfg, EBPF_GLOBAL_SECTION, EBPF_CFG_PID_SIZE,
modules->pid_map_size);
modules->lifetime = (uint32_t) appconfig_get_number(modules->cfg, EBPF_GLOBAL_SECTION,
EBPF_CFG_LIFETIME, EBPF_DEFAULT_LIFETIME);
char *value = ebpf_convert_load_mode_to_string(modules->load & NETDATA_EBPF_LOAD_METHODS);
const char *type_format = appconfig_get(modules->cfg, EBPF_GLOBAL_SECTION, EBPF_CFG_TYPE_FORMAT, value);
netdata_ebpf_load_mode_t load = epbf_convert_string_to_load_mode(type_format);
load = ebpf_select_load_mode(btf_file, load, kver, is_rh);
modules->load = origin | load;
const char *core_attach = appconfig_get(modules->cfg, EBPF_GLOBAL_SECTION, EBPF_CFG_CORE_ATTACH, EBPF_CFG_ATTACH_TRAMPOLINE);
netdata_ebpf_program_loaded_t fill_lm = ebpf_convert_core_type(core_attach, modules->mode);
ebpf_update_target_with_conf(modules, fill_lm);
value = ebpf_convert_collect_pid_to_string(modules->apps_level);
const char *collect_pid = appconfig_get(modules->cfg, EBPF_GLOBAL_SECTION, EBPF_CFG_COLLECT_PID, value);
modules->apps_level = ebpf_convert_string_to_apps_level(collect_pid);
modules->maps_per_core = appconfig_get_boolean(modules->cfg, EBPF_GLOBAL_SECTION, EBPF_CFG_MAPS_PER_CORE,
modules->maps_per_core);
if (kver < NETDATA_EBPF_KERNEL_4_06)
modules->maps_per_core = CONFIG_BOOLEAN_NO;
#ifdef NETDATA_DEV_MODE
netdata_log_info("The thread %s was configured with: mode = %s; update every = %d; apps = %s; cgroup = %s; ebpf type format = %s; ebpf co-re tracing = %s; collect pid = %s; maps per core = %s, lifetime=%u",
modules->info.thread_name,
load_mode,
modules->update_every,
(modules->apps_charts)?"enabled":"disabled",
(modules->cgroup_charts)?"enabled":"disabled",
type_format,
core_attach,
collect_pid,
(modules->maps_per_core)?"enabled":"disabled",
modules->lifetime
);
#endif
}
/**
* Update module
*
* When this function is called, it will load the configuration file and after this
* it updates the global information of ebpf_module.
* If the module has specific configuration, this function will load it, but it will not
* update the variables.
*
* @param em the module structure
* @param btf_file a pointer to the loaded btf file.
* @param is_rhf is Red Hat family?
* @param kver the kernel version
*/
void ebpf_update_module(ebpf_module_t *em, struct btf *btf_file, int kver, int is_rh)
{
char filename[FILENAME_MAX+1];
netdata_ebpf_load_mode_t origin;
ebpf_mount_config_name(filename, FILENAME_MAX, ebpf_user_config_dir, em->config_file);
if (!ebpf_load_config(em->cfg, filename)) {
ebpf_mount_config_name(filename, FILENAME_MAX, ebpf_stock_config_dir, em->config_file);
if (!ebpf_load_config(em->cfg, filename)) {
netdata_log_error("Cannot load the ebpf configuration file %s", em->config_file);
return;
}
// If user defined data globally, we will have here EBPF_LOADED_FROM_USER, we need to consider this, to avoid
// forcing users to configure thread by thread.
origin = (!(em->load & NETDATA_EBPF_LOAD_SOURCE)) ? EBPF_LOADED_FROM_STOCK : em->load & NETDATA_EBPF_LOAD_SOURCE;
} else
origin = EBPF_LOADED_FROM_USER;
ebpf_update_module_using_config(em, origin, btf_file, kver, is_rh);
}
/**
* Adjust Apps Cgroup
*
* Apps and cgroup has internal cleanup that needs attaching tracers to release_task, to avoid overload the function
* we will enable this integration by default, if and only if, we are running with trampolines.
*
* @param em a pointer to the main thread structure.
* @param mode is the mode used with different
*/
void ebpf_adjust_apps_cgroup(ebpf_module_t *em, netdata_ebpf_program_loaded_t mode)
{
if ((em->load & EBPF_LOADED_FROM_STOCK) &&
(em->apps_charts || em->cgroup_charts) &&
mode != EBPF_LOAD_TRAMPOLINE) {
em->apps_charts = NETDATA_EBPF_APPS_FLAG_NO;
em->cgroup_charts = 0;
}
}
//----------------------------------------------------------------------------------------------------------------------
/**
* Load Address
*
* Helper used to get address from /proc/kallsym
*
* @param fa address structure
* @param fd file descriptor loaded inside kernel. If a negative value is given
* the function will load address and it won't update hash table.
*/
void ebpf_load_addresses(ebpf_addresses_t *fa, int fd)
{
if (fa->addr)
return ;
procfile *ff = procfile_open("/proc/kallsyms", " \t:", PROCFILE_FLAG_DEFAULT);
if (!ff)
return;
ff = procfile_readall(ff);
if (!ff)
return;
fa->hash = simple_hash(fa->function);
size_t lines = procfile_lines(ff), l;
for(l = 0; l < lines ;l++) {
char *fcnt = procfile_lineword(ff, l, 2);
uint32_t hash = simple_hash(fcnt);
if (fa->hash == hash && !strcmp(fcnt, fa->function)) {
char *type = procfile_lineword(ff, l, 2);
fa->type = type[0];
if (fd > 0) {
char addr[128];
snprintf(addr, 127, "0x%s", procfile_lineword(ff, l, 0));
fa->addr = (unsigned long) strtoul(addr, NULL, 16);
uint32_t key = 0;
bpf_map_update_elem(fd, &key, &fa->addr, BPF_ANY);
} else
fa->addr = 1;
break;
}
}
procfile_close(ff);
}
//----------------------------------------------------------------------------------------------------------------------
/**
* Fill Algorithms
*
* Set one unique dimension for all vector position.
*
* @param algorithms the output vector
* @param length number of elements of algorithms vector
* @param algorithm algorithm used on charts.
*/
void ebpf_fill_algorithms(int *algorithms, size_t length, int algorithm)
{
size_t i;
for (i = 0; i < length; i++) {
algorithms[i] = algorithm;
}
}
/**
* Fill Histogram dimension
*
* Fill the histogram dimension with the specified ranges
*/
char **ebpf_fill_histogram_dimension(size_t maximum)
{
char *dimensions[] = { "us", "ms", "s"};
int previous_dim = 0, current_dim = 0;
uint32_t previous_level = 1000, current_level = 1000;
uint32_t previous_divisor = 1, current_divisor = 1;
uint32_t current = 1, previous = 0;
uint32_t selector;
char **out = callocz(maximum, sizeof(char *));
char range[128];
size_t end = maximum - 1;
for (selector = 0; selector < end; selector++) {
snprintf(range, 127, "%u%s->%u%s", previous/previous_divisor, dimensions[previous_dim],
current/current_divisor, dimensions[current_dim]);
out[selector] = strdupz(range);
previous = current;
current <<= 1;
if (previous_dim != 2 && previous > previous_level) {
previous_dim++;
previous_divisor *= 1000;
previous_level *= 1000;
}
if (current_dim != 2 && current > current_level) {
current_dim++;
current_divisor *= 1000;
current_level *= 1000;
}
}
snprintf(range, 127, "%u%s->+Inf", previous/previous_divisor, dimensions[previous_dim]);
out[selector] = strdupz(range);
return out;
}
/**
* Histogram dimension cleanup
*
* Cleanup dimensions allocated with function ebpf_fill_histogram_dimension
*
* @param ptr
* @param length
*/
void ebpf_histogram_dimension_cleanup(char **ptr, size_t length)
{
size_t i;
for (i = 0; i < length; i++) {
freez(ptr[i]);
}
freez(ptr);
}
//----------------------------------------------------------------------------------------------------------------------
/**
* Open tracepoint path
*
* @param filename pointer to store the path
* @param length file length
* @param subsys is the name of your subsystem.
* @param eventname is the name of the event to trace.
* @param flags flags used with syscall open
*
* @return it returns a positive value on success and a negative otherwise.
*/
static inline int ebpf_open_tracepoint_path(char *filename, size_t length, char *subsys, char *eventname, int flags)
{
snprintfz(filename, length, "%s/events/%s/%s/enable", NETDATA_DEBUGFS, subsys, eventname);
return open(filename, flags | O_CLOEXEC, 0);
}
/**
* Is tracepoint enabled
*
* Check whether the tracepoint is enabled.
*
* @param subsys is the name of your subsystem.
* @param eventname is the name of the event to trace.
*
* @return it returns 1 when it is enabled, 0 when it is disabled and -1 on error.
*/
int ebpf_is_tracepoint_enabled(char *subsys, char *eventname)
{
char text[FILENAME_MAX + 1];
int fd = ebpf_open_tracepoint_path(text, FILENAME_MAX, subsys, eventname, O_RDONLY);
if (fd < 0) {
return -1;
}
ssize_t length = read(fd, text, 1);
if (length != 1) {
close(fd);
return -1;
}
close(fd);
return (text[0] == '1') ? CONFIG_BOOLEAN_YES : CONFIG_BOOLEAN_NO;
}
/**
* Change Tracing values
*
* Change value for specific tracepoint enabling or disabling it according value given.
*
* @param subsys is the name of your subsystem.
* @param eventname is the name of the event to trace.
* @param value a value to enable (1) or disable (0) a tracepoint.
*
* @return It returns 0 on success and -1 otherwise
*/
static int ebpf_change_tracing_values(char *subsys, char *eventname, char *value)
{
if (strcmp("0", value) && strcmp("1", value)) {
netdata_log_error("Invalid value given to either enable or disable a tracepoint.");
return -1;
}
char filename[1024];
int fd = ebpf_open_tracepoint_path(filename, 1023, subsys, eventname, O_WRONLY);
if (fd < 0) {
return -1;
}
ssize_t written = write(fd, value, strlen(value));
if (written < 0) {
close(fd);
return -1;
}
close(fd);
return 0;
}
/**
* Enable tracing values
*
* Enable a tracepoint on a system
*
* @param subsys is the name of your subsystem.
* @param eventname is the name of the event to trace.
*
* @return It returns 0 on success and -1 otherwise
*/
int ebpf_enable_tracing_values(char *subsys, char *eventname)
{
return ebpf_change_tracing_values(subsys, eventname, "1");
}
/**
* Disable tracing values
*
* Disable tracing points enabled by collector
*
* @param subsys is the name of your subsystem.
* @param eventname is the name of the event to trace.
*
* @return It returns 0 on success and -1 otherwise
*/
int ebpf_disable_tracing_values(char *subsys, char *eventname)
{
return ebpf_change_tracing_values(subsys, eventname, "0");
}
/**
* Select PC prefix
*
* Identify the prefix to run on PC architecture.
*
* @return It returns 32 or 64 according to host arch.
*/
static uint32_t ebpf_select_pc_prefix()
{
long counter = 1;
uint32_t i;
for (i = 0; i < 128; i++) {
counter <<= 1;
if (counter < 0)
break;
}
return counter;
}
/**
* Select Host Prefix
*
* Select prefix to syscall when host is running a kernel newer than 4.17.0
*
* @param output the vector to store data.
* @param length length of output vector.
* @param syscall the syscall that prefix will be attached;
* @param kver the current kernel version in format MAJOR*65536 + MINOR*256 + PATCH
*/
void ebpf_select_host_prefix(char *output, size_t length, char *syscall, int kver)
{
if (kver < NETDATA_EBPF_KERNEL_4_17)
snprintfz(output, length, "sys_%s", syscall);
else {
uint32_t arch = ebpf_select_pc_prefix();
// Prefix selected according https://www.kernel.org/doc/html/latest/process/adding-syscalls.html
char *prefix = (arch == 32) ? "__ia32" : "__x64";
snprintfz(output, length, "%s_sys_%s", prefix, syscall);
}
}