1 /* Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com 2 * 3 * This program is free software; you can redistribute it and/or 4 * modify it under the terms of version 2 of the GNU General Public 5 * License as published by the Free Software Foundation. 6 */ 7 #include "vmlinux.h" 8 #include <linux/version.h> 9 #include <bpf/bpf_helpers.h> 10 #include <bpf/bpf_tracing.h> 11 #include <bpf/bpf_core_read.h> 12 13 struct { 14 __uint(type, BPF_MAP_TYPE_HASH); 15 __type(key, long); 16 __type(value, long); 17 __uint(max_entries, 1024); 18 } my_map SEC(".maps"); 19 20 /* kprobe is NOT a stable ABI. If kernel internals change this bpf+kprobe 21 * example will no longer be meaningful 22 */ 23 SEC("kprobe/kfree_skb_reason") 24 int bpf_prog2(struct pt_regs *ctx) 25 { 26 long loc = 0; 27 long init_val = 1; 28 long *value; 29 30 /* read ip of kfree_skb_reason caller. 31 * non-portable version of __builtin_return_address(0) 32 */ 33 BPF_KPROBE_READ_RET_IP(loc, ctx); 34 35 value = bpf_map_lookup_elem(&my_map, &loc); 36 if (value) 37 *value += 1; 38 else 39 bpf_map_update_elem(&my_map, &loc, &init_val, BPF_ANY); 40 return 0; 41 } 42 43 static unsigned int log2(unsigned int v) 44 { 45 unsigned int r; 46 unsigned int shift; 47 48 r = (v > 0xFFFF) << 4; v >>= r; 49 shift = (v > 0xFF) << 3; v >>= shift; r |= shift; 50 shift = (v > 0xF) << 2; v >>= shift; r |= shift; 51 shift = (v > 0x3) << 1; v >>= shift; r |= shift; 52 r |= (v >> 1); 53 return r; 54 } 55 56 static unsigned int log2l(unsigned long v) 57 { 58 unsigned int hi = v >> 32; 59 if (hi) 60 return log2(hi) + 32; 61 else 62 return log2(v); 63 } 64 65 struct hist_key { 66 char comm[16]; 67 u64 pid_tgid; 68 u64 uid_gid; 69 u64 index; 70 }; 71 72 struct { 73 __uint(type, BPF_MAP_TYPE_PERCPU_HASH); 74 __uint(key_size, sizeof(struct hist_key)); 75 __uint(value_size, sizeof(long)); 76 __uint(max_entries, 1024); 77 } my_hist_map SEC(".maps"); 78 79 SEC("ksyscall/write") 80 int BPF_KSYSCALL(bpf_prog3, unsigned int fd, const char *buf, size_t count) 81 { 82 long init_val = 1; 83 long *value; 84 struct hist_key key; 85 86 key.index = log2l(count); 87 key.pid_tgid = bpf_get_current_pid_tgid(); 88 key.uid_gid = bpf_get_current_uid_gid(); 89 bpf_get_current_comm(&key.comm, sizeof(key.comm)); 90 91 value = bpf_map_lookup_elem(&my_hist_map, &key); 92 if (value) 93 __sync_fetch_and_add(value, 1); 94 else 95 bpf_map_update_elem(&my_hist_map, &key, &init_val, BPF_ANY); 96 return 0; 97 } 98 char _license[] SEC("license") = "GPL"; 99 u32 _version SEC("version") = LINUX_VERSION_CODE; 100