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| author | Yonghong Song <yhs@fb.com> | 2017-08-04 16:00:09 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-08-07 14:09:48 -0700 |
| commit | cf5f5cea270655dd49370760576c64b228583b79 (patch) | |
| tree | 5758e9d56b94542d082d40ed66f8d8effa6287f9 /kernel/events | |
| parent | d226a2b84d0528da7e35e7e19e052293889cdd21 (diff) | |
| download | linux-cf5f5cea270655dd49370760576c64b228583b79.tar.bz2 | |
bpf: add support for sys_enter_* and sys_exit_* tracepoints
Currently, bpf programs cannot be attached to sys_enter_* and sys_exit_*
style tracepoints. The iovisor/bcc issue #748
(https://github.com/iovisor/bcc/issues/748) documents this issue.
For example, if you try to attach a bpf program to tracepoints
syscalls/sys_enter_newfstat, you will get the following error:
# ./tools/trace.py t:syscalls:sys_enter_newfstat
Ioctl(PERF_EVENT_IOC_SET_BPF): Invalid argument
Failed to attach BPF to tracepoint
The main reason is that syscalls/sys_enter_* and syscalls/sys_exit_*
tracepoints are treated differently from other tracepoints and there
is no bpf hook to it.
This patch adds bpf support for these syscalls tracepoints by
. permitting bpf attachment in ioctl PERF_EVENT_IOC_SET_BPF
. calling bpf programs in perf_syscall_enter and perf_syscall_exit
The legality of bpf program ctx access is also checked.
Function trace_event_get_offsets returns correct max offset for each
specific syscall tracepoint, which is compared against the maximum offset
access in bpf program.
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/events')
| -rw-r--r-- | kernel/events/core.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index 426c2ffba16d..a7a6c1d19a49 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -8050,7 +8050,7 @@ static void perf_event_free_bpf_handler(struct perf_event *event) static int perf_event_set_bpf_prog(struct perf_event *event, u32 prog_fd) { - bool is_kprobe, is_tracepoint; + bool is_kprobe, is_tracepoint, is_syscall_tp; struct bpf_prog *prog; if (event->attr.type != PERF_TYPE_TRACEPOINT) @@ -8061,7 +8061,8 @@ static int perf_event_set_bpf_prog(struct perf_event *event, u32 prog_fd) is_kprobe = event->tp_event->flags & TRACE_EVENT_FL_UKPROBE; is_tracepoint = event->tp_event->flags & TRACE_EVENT_FL_TRACEPOINT; - if (!is_kprobe && !is_tracepoint) + is_syscall_tp = is_syscall_trace_event(event->tp_event); + if (!is_kprobe && !is_tracepoint && !is_syscall_tp) /* bpf programs can only be attached to u/kprobe or tracepoint */ return -EINVAL; @@ -8070,13 +8071,14 @@ static int perf_event_set_bpf_prog(struct perf_event *event, u32 prog_fd) return PTR_ERR(prog); if ((is_kprobe && prog->type != BPF_PROG_TYPE_KPROBE) || - (is_tracepoint && prog->type != BPF_PROG_TYPE_TRACEPOINT)) { + (is_tracepoint && prog->type != BPF_PROG_TYPE_TRACEPOINT) || + (is_syscall_tp && prog->type != BPF_PROG_TYPE_TRACEPOINT)) { /* valid fd, but invalid bpf program type */ bpf_prog_put(prog); return -EINVAL; } - if (is_tracepoint) { + if (is_tracepoint || is_syscall_tp) { int off = trace_event_get_offsets(event->tp_event); if (prog->aux->max_ctx_offset > off) { |