mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-20 17:41:09 +00:00
d822a19268
this example has two probes in one C file that attach to different kprove events and use two different maps. 1st probe is x64 specific equivalent of dropmon. It attaches to kfree_skb, retrevies 'ip' address of kfree_skb() caller and counts number of packet drops at that 'ip' address. User space prints 'location - count' map every second. 2nd probe attaches to kprobe:sys_write and computes a histogram of different write sizes Usage: $ sudo tracex2 location 0xffffffff81695995 count 1 location 0xffffffff816d0da9 count 2 location 0xffffffff81695995 count 2 location 0xffffffff816d0da9 count 2 location 0xffffffff81695995 count 3 location 0xffffffff816d0da9 count 2 557145+0 records in 557145+0 records out 285258240 bytes (285 MB) copied, 1.02379 s, 279 MB/s syscall write() stats byte_size : count distribution 1 -> 1 : 3 | | 2 -> 3 : 0 | | 4 -> 7 : 0 | | 8 -> 15 : 0 | | 16 -> 31 : 2 | | 32 -> 63 : 3 | | 64 -> 127 : 1 | | 128 -> 255 : 1 | | 256 -> 511 : 0 | | 512 -> 1023 : 1118968 |************************************* | Ctrl-C at any time. Kernel will auto cleanup maps and programs $ addr2line -ape ./bld_x64/vmlinux 0xffffffff81695995 0xffffffff816d0da9 0xffffffff81695995: ./bld_x64/../net/ipv4/icmp.c:1038 0xffffffff816d0da9: ./bld_x64/../net/unix/af_unix.c:1231 Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/1427312966-8434-8-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
86 lines
2 KiB
C
86 lines
2 KiB
C
/* Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of version 2 of the GNU General Public
|
|
* License as published by the Free Software Foundation.
|
|
*/
|
|
#include <linux/skbuff.h>
|
|
#include <linux/netdevice.h>
|
|
#include <linux/version.h>
|
|
#include <uapi/linux/bpf.h>
|
|
#include "bpf_helpers.h"
|
|
|
|
struct bpf_map_def SEC("maps") my_map = {
|
|
.type = BPF_MAP_TYPE_HASH,
|
|
.key_size = sizeof(long),
|
|
.value_size = sizeof(long),
|
|
.max_entries = 1024,
|
|
};
|
|
|
|
/* kprobe is NOT a stable ABI. If kernel internals change this bpf+kprobe
|
|
* example will no longer be meaningful
|
|
*/
|
|
SEC("kprobe/kfree_skb")
|
|
int bpf_prog2(struct pt_regs *ctx)
|
|
{
|
|
long loc = 0;
|
|
long init_val = 1;
|
|
long *value;
|
|
|
|
/* x64 specific: read ip of kfree_skb caller.
|
|
* non-portable version of __builtin_return_address(0)
|
|
*/
|
|
bpf_probe_read(&loc, sizeof(loc), (void *)ctx->sp);
|
|
|
|
value = bpf_map_lookup_elem(&my_map, &loc);
|
|
if (value)
|
|
*value += 1;
|
|
else
|
|
bpf_map_update_elem(&my_map, &loc, &init_val, BPF_ANY);
|
|
return 0;
|
|
}
|
|
|
|
static unsigned int log2(unsigned int v)
|
|
{
|
|
unsigned int r;
|
|
unsigned int shift;
|
|
|
|
r = (v > 0xFFFF) << 4; v >>= r;
|
|
shift = (v > 0xFF) << 3; v >>= shift; r |= shift;
|
|
shift = (v > 0xF) << 2; v >>= shift; r |= shift;
|
|
shift = (v > 0x3) << 1; v >>= shift; r |= shift;
|
|
r |= (v >> 1);
|
|
return r;
|
|
}
|
|
|
|
static unsigned int log2l(unsigned long v)
|
|
{
|
|
unsigned int hi = v >> 32;
|
|
if (hi)
|
|
return log2(hi) + 32;
|
|
else
|
|
return log2(v);
|
|
}
|
|
|
|
struct bpf_map_def SEC("maps") my_hist_map = {
|
|
.type = BPF_MAP_TYPE_ARRAY,
|
|
.key_size = sizeof(u32),
|
|
.value_size = sizeof(long),
|
|
.max_entries = 64,
|
|
};
|
|
|
|
SEC("kprobe/sys_write")
|
|
int bpf_prog3(struct pt_regs *ctx)
|
|
{
|
|
long write_size = ctx->dx; /* arg3 */
|
|
long init_val = 1;
|
|
long *value;
|
|
u32 index = log2l(write_size);
|
|
|
|
value = bpf_map_lookup_elem(&my_hist_map, &index);
|
|
if (value)
|
|
__sync_fetch_and_add(value, 1);
|
|
return 0;
|
|
}
|
|
char _license[] SEC("license") = "GPL";
|
|
u32 _version SEC("version") = LINUX_VERSION_CODE;
|