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bcc_proc.c
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bcc_proc.c
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/*
* Copyright (c) 2016 GitHub, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <stdint.h>
#include <ctype.h>
#include <stdio.h>
#include <math.h>
#include "bcc_perf_map.h"
#include "bcc_proc.h"
#include "bcc_elf.h"
static bool is_exe(const char *path) {
struct stat s;
if (access(path, X_OK) < 0)
return false;
if (stat(path, &s) < 0)
return false;
return S_ISREG(s.st_mode);
}
char *bcc_procutils_which(const char *binpath) {
char buffer[4096];
const char *PATH;
if (strchr(binpath, '/'))
return is_exe(binpath) ? strdup(binpath) : 0;
if (!(PATH = getenv("PATH")))
return 0;
while (PATH) {
const char *next = strchr(PATH, ':') ?: strchr(PATH, '\0');
const size_t path_len = next - PATH;
if (path_len) {
memcpy(buffer, PATH, path_len);
buffer[path_len] = '/';
strcpy(buffer + path_len + 1, binpath);
if (is_exe(buffer))
return strdup(buffer);
}
PATH = *next ? (next + 1) : 0;
}
return 0;
}
int bcc_procutils_each_module(int pid, bcc_procutils_modulecb callback,
void *payload) {
char procmap_filename[128];
FILE *procmap;
int ret;
sprintf(procmap_filename, "/proc/%ld/maps", (long)pid);
procmap = fopen(procmap_filename, "r");
if (!procmap)
return -1;
do {
char endline[4096];
char perm[8], dev[8];
long long begin, end, size, inode;
ret = fscanf(procmap, "%llx-%llx %s %llx %s %lld", &begin, &end, perm,
&size, dev, &inode);
if (!fgets(endline, sizeof(endline), procmap))
break;
if (ret == 6) {
char *mapname = endline;
char *newline = strchr(endline, '\n');
if (newline)
newline[0] = '\0';
while (isspace(mapname[0])) mapname++;
if (strchr(perm, 'x') && mapname[0] && mapname[0] != '[') {
if (callback(mapname, (uint64_t)begin, (uint64_t)end, payload) < 0)
break;
}
}
} while (ret && ret != EOF);
fclose(procmap);
// Add a mapping to /tmp/perf-pid.map for the entire address space. This will
// be used if symbols aren't resolved in an earlier mapping.
char map_path[4096];
if (bcc_perf_map_path(map_path, sizeof(map_path), pid))
callback(map_path, 0, -1, payload);
return 0;
}
int bcc_procutils_each_ksym(bcc_procutils_ksymcb callback, void *payload) {
char line[2048];
FILE *kallsyms;
/* root is needed to list ksym addresses */
if (geteuid() != 0)
return -1;
kallsyms = fopen("/proc/kallsyms", "r");
if (!kallsyms)
return -1;
if (!fgets(line, sizeof(line), kallsyms)) {
fclose(kallsyms);
return -1;
}
while (fgets(line, sizeof(line), kallsyms)) {
char *symname, *endsym;
unsigned long long addr;
addr = strtoull(line, &symname, 16);
endsym = symname = symname + 3;
while (*endsym && !isspace(*endsym)) endsym++;
*endsym = '\0';
callback(symname, addr, payload);
}
fclose(kallsyms);
return 0;
}
#define CACHE1_HEADER "ld.so-1.7.0"
#define CACHE1_HEADER_LEN (sizeof(CACHE1_HEADER) - 1)
#define CACHE2_HEADER "glibc-ld.so.cache"
#define CACHE2_HEADER_LEN (sizeof(CACHE2_HEADER) - 1)
#define CACHE2_VERSION "1.1"
struct ld_cache1_entry {
int32_t flags;
uint32_t key;
uint32_t value;
};
struct ld_cache1 {
char header[CACHE1_HEADER_LEN];
uint32_t entry_count;
struct ld_cache1_entry entries[0];
};
struct ld_cache2_entry {
int32_t flags;
uint32_t key;
uint32_t value;
uint32_t pad1_;
uint64_t pad2_;
};
struct ld_cache2 {
char header[CACHE2_HEADER_LEN];
char version[3];
uint32_t entry_count;
uint32_t string_table_len;
uint32_t pad_[5];
struct ld_cache2_entry entries[0];
};
static int lib_cache_count;
static struct ld_lib {
char *libname;
char *path;
int flags;
} * lib_cache;
static int read_cache1(const char *ld_map) {
struct ld_cache1 *ldcache = (struct ld_cache1 *)ld_map;
const char *ldstrings =
(const char *)(ldcache->entries + ldcache->entry_count);
uint32_t i;
lib_cache =
(struct ld_lib *)malloc(ldcache->entry_count * sizeof(struct ld_lib));
lib_cache_count = (int)ldcache->entry_count;
for (i = 0; i < ldcache->entry_count; ++i) {
const char *key = ldstrings + ldcache->entries[i].key;
const char *val = ldstrings + ldcache->entries[i].value;
const int flags = ldcache->entries[i].flags;
lib_cache[i].libname = strdup(key);
lib_cache[i].path = strdup(val);
lib_cache[i].flags = flags;
}
return 0;
}
static int read_cache2(const char *ld_map) {
struct ld_cache2 *ldcache = (struct ld_cache2 *)ld_map;
uint32_t i;
if (memcmp(ld_map, CACHE2_HEADER, CACHE2_HEADER_LEN))
return -1;
lib_cache =
(struct ld_lib *)malloc(ldcache->entry_count * sizeof(struct ld_lib));
lib_cache_count = (int)ldcache->entry_count;
for (i = 0; i < ldcache->entry_count; ++i) {
const char *key = ld_map + ldcache->entries[i].key;
const char *val = ld_map + ldcache->entries[i].value;
const int flags = ldcache->entries[i].flags;
lib_cache[i].libname = strdup(key);
lib_cache[i].path = strdup(val);
lib_cache[i].flags = flags;
}
return 0;
}
static int load_ld_cache(const char *cache_path) {
struct stat st;
size_t ld_size;
const char *ld_map;
int ret, fd = open(cache_path, O_RDONLY);
if (fd < 0)
return -1;
if (fstat(fd, &st) < 0 || st.st_size < sizeof(struct ld_cache1)) {
close(fd);
return -1;
}
ld_size = st.st_size;
ld_map = (const char *)mmap(NULL, ld_size, PROT_READ, MAP_PRIVATE, fd, 0);
if (ld_map == MAP_FAILED) {
close(fd);
return -1;
}
if (memcmp(ld_map, CACHE1_HEADER, CACHE1_HEADER_LEN) == 0) {
const struct ld_cache1 *cache1 = (struct ld_cache1 *)ld_map;
size_t cache1_len = sizeof(struct ld_cache1) +
(cache1->entry_count * sizeof(struct ld_cache1_entry));
cache1_len = (cache1_len + 0x7) & ~0x7ULL;
if (ld_size > (cache1_len + sizeof(struct ld_cache2)))
ret = read_cache2(ld_map + cache1_len);
else
ret = read_cache1(ld_map);
} else {
ret = read_cache2(ld_map);
}
munmap((void *)ld_map, ld_size);
close(fd);
return ret;
}
#define LD_SO_CACHE "/etc/ld.so.cache"
#define FLAG_TYPE_MASK 0x00ff
#define TYPE_ELF_LIBC6 0x0003
#define FLAG_ABI_MASK 0xff00
#define ABI_SPARC_LIB64 0x0100
#define ABI_IA64_LIB64 0x0200
#define ABI_X8664_LIB64 0x0300
#define ABI_S390_LIB64 0x0400
#define ABI_POWERPC_LIB64 0x0500
static bool match_so_flags(int flags) {
if ((flags & FLAG_TYPE_MASK) != TYPE_ELF_LIBC6)
return false;
switch (flags & FLAG_ABI_MASK) {
case ABI_SPARC_LIB64:
case ABI_IA64_LIB64:
case ABI_X8664_LIB64:
case ABI_S390_LIB64:
case ABI_POWERPC_LIB64:
return (sizeof(void *) == 8);
}
return true;
}
static bool which_so_in_process(const char* libname, int pid, char* libpath) {
int ret, found = false;
char endline[4096], *mapname = NULL, *newline;
char mappings_file[128];
const size_t search_len = strlen(libname) + strlen("/lib.");
char search1[search_len + 1];
char search2[search_len + 1];
sprintf(mappings_file, "/proc/%ld/maps", (long)pid);
FILE *fp = fopen(mappings_file, "r");
if (!fp)
return NULL;
snprintf(search1, search_len + 1, "/lib%s.", libname);
snprintf(search2, search_len + 1, "/lib%s-", libname);
do {
ret = fscanf(fp, "%*x-%*x %*s %*x %*s %*d");
if (!fgets(endline, sizeof(endline), fp))
break;
mapname = endline;
newline = strchr(endline, '\n');
if (newline)
newline[0] = '\0';
while (isspace(mapname[0])) mapname++;
if (strstr(mapname, ".so") && (strstr(mapname, search1) ||
strstr(mapname, search2))) {
found = true;
memcpy(libpath, mapname, strlen(mapname) + 1);
break;
}
} while (ret != EOF);
fclose(fp);
return found;
}
char *bcc_procutils_which_so(const char *libname, int pid) {
const size_t soname_len = strlen(libname) + strlen("lib.so");
char soname[soname_len + 1];
char libpath[4096];
int i;
if (strchr(libname, '/'))
return strdup(libname);
if (pid && which_so_in_process(libname, pid, libpath))
return strdup(libpath);
if (lib_cache_count < 0)
return NULL;
if (!lib_cache_count && load_ld_cache(LD_SO_CACHE) < 0) {
lib_cache_count = -1;
return NULL;
}
snprintf(soname, soname_len + 1, "lib%s.so", libname);
for (i = 0; i < lib_cache_count; ++i) {
if (!strncmp(lib_cache[i].libname, soname, soname_len) &&
match_so_flags(lib_cache[i].flags)) {
return strdup(lib_cache[i].path);
}
}
return NULL;
}
void bcc_procutils_free(const char *ptr) {
free((void *)ptr);
}