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authorYonghong Song <yhs@fb.com>2017-08-04 16:00:09 -0700
committerDavid S. Miller <davem@davemloft.net>2017-08-07 14:09:48 -0700
commitcf5f5cea270655dd49370760576c64b228583b79 (patch)
tree5758e9d56b94542d082d40ed66f8d8effa6287f9 /kernel/events
parentd226a2b84d0528da7e35e7e19e052293889cdd21 (diff)
downloadlinux-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.c10
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) {