tools/lib/bpf/bpf.c

   1 /*
   2  * common eBPF ELF operations.
   3  *
   4  * Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>
   5  * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
   6  * Copyright (C) 2015 Huawei Inc.
   7  */
   8
   9 #include <stdlib.h>
  10 #include <memory.h>
  11 #include <unistd.h>
  12 #include <asm/unistd.h>
  13 #include <linux/bpf.h>
  14 #include "bpf.h"
  15
  16 /*
  17  * When building perf, unistd.h is overrided. __NR_bpf is
  18  * required to be defined explicitly.
  19  */
  20 #ifndef __NR_bpf
  21 # if defined(__i386__)
  22 #  define __NR_bpf 357
  23 # elif defined(__x86_64__)
  24 #  define __NR_bpf 321
  25 # elif defined(__aarch64__)
  26 #  define __NR_bpf 280
  27 # else
  28 #  error __NR_bpf not defined. libbpf does not support your arch.
  29 # endif
  30 #endif
  31
  32 static __u64 ptr_to_u64(void *ptr)
  33 {
  34         return (__u64) (unsigned long) ptr;
  35 }
  36
  37 static int sys_bpf(enum bpf_cmd cmd, union bpf_attr *attr,
  38                    unsigned int size)
  39 {
  40         return syscall(__NR_bpf, cmd, attr, size);
  41 }
  42
  43 int bpf_create_map(enum bpf_map_type map_type, int key_size,
  44                    int value_size, int max_entries)
  45 {
  46         union bpf_attr attr;
  47
  48         memset(&attr, '\0', sizeof(attr));
  49
  50         attr.map_type = map_type;
  51         attr.key_size = key_size;
  52         attr.value_size = value_size;
  53         attr.max_entries = max_entries;
  54
  55         return sys_bpf(BPF_MAP_CREATE, &attr, sizeof(attr));
  56 }
  57
  58 int bpf_load_program(enum bpf_prog_type type, struct bpf_insn *insns,
  59                      size_t insns_cnt, char *license,
  60                      u32 kern_version, char *log_buf, size_t log_buf_sz)
  61 {
  62         int fd;
  63         union bpf_attr attr;
  64
  65         bzero(&attr, sizeof(attr));
  66         attr.prog_type = type;
  67         attr.insn_cnt = (__u32)insns_cnt;
  68         attr.insns = ptr_to_u64(insns);
  69         attr.license = ptr_to_u64(license);
  70         attr.log_buf = ptr_to_u64(NULL);
  71         attr.log_size = 0;
  72         attr.log_level = 0;
  73         attr.kern_version = kern_version;
  74
  75         fd = sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
  76         if (fd >= 0 || !log_buf || !log_buf_sz)
  77                 return fd;
  78
  79         /* Try again with log */
  80         attr.log_buf = ptr_to_u64(log_buf);
  81         attr.log_size = log_buf_sz;
  82         attr.log_level = 1;
  83         log_buf[0] = 0;
  84         return sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
  85 }
  86
  87 int bpf_map_update_elem(int fd, void *key, void *value,
  88                         u64 flags)
  89 {
  90         union bpf_attr attr;
  91
  92         bzero(&attr, sizeof(attr));
  93         attr.map_fd = fd;
  94         attr.key = ptr_to_u64(key);
  95         attr.value = ptr_to_u64(value);
  96         attr.flags = flags;
  97
  98         return sys_bpf(BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr));
  99 }