On 2015/11/16 20:10, Wang Nan wrote:
This patch allows creating only one BPF program for different
'probe_trace_event'(tev) generated by one 'perf_probe_event'(pev), if
their prologues are identical.
This is done by comparing argument list of different tev, and maps type
of prologue and tev using a mapping array. This patch utilizes qsort to
sort tevs. After sorting, tevs with identical argument list will be
grouped together.
Test result:
Sample BPF program:
SEC("inlines=no\n"
"func=SyS_dup? oldfd")
int func(void *ctx)
{
return 1;
}
It would probe at SyS_dup2 and SyS_dup3, extracts oldfd as its argument.
Following cmdline shows BPF program loaded into kernel by perf:
# ./perf record -e ./test_bpf_arg.c sleep 4 & sleep 1 && ls /proc/$!/fd/ -l
| grep bpf-prog
Before this patch:
# ./perf record -e ./test_bpf_arg.c sleep 4 & sleep 1 && ls /proc/$!/fd/ -l
| grep bpf-prog
[1] 24858
lrwx------ 1 root root 64 Nov 14 04:09 3 -> anon_inode:bpf-prog
lrwx------ 1 root root 64 Nov 14 04:09 4 -> anon_inode:bpf-prog
...
After this patch:
# ./perf record -e ./test_bpf_arg.c sleep 4 & sleep 1 && ls /proc/$!/fd/ -l
| grep bpf-prog
[1] 25699
lrwx------ 1 root root 64 Nov 14 04:10 3 -> anon_inode:bpf-prog
...
Signed-off-by: Wang Nan <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Zefan Li <[email protected]>
Cc: [email protected]
---
[SNIP]
@@ -462,7 +570,19 @@ static int hook_load_preprocessor(struct bpf_program *prog)
return -ENOMEM;
}
- err = bpf_program__set_prep(prog, pev->ntevs,
+ priv->type_mapping = malloc(sizeof(int) * pev->ntevs);
+ if (!priv->type_mapping) {
+ pr_debug("No enough memory: alloc type_mapping failed\n");
+ return -ENOMEM;
+ }
+ memset(priv->type_mapping, 0xff,
+ sizeof(int) * pev->ntevs);
+
We can change 0xff to -1 like previous patches. Will do it by resending.
Thank you.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
