On Mon, Sep 9, 2024 at 12:46 AM Jiri Olsa <[email protected]> wrote: > > Adding support to attach bpf program for entry and return probe > of the same function. This is common use case which at the moment > requires to create two uprobe multi links. > > Adding new BPF_TRACE_UPROBE_SESSION attach type that instructs > kernel to attach single link program to both entry and exit probe. > > It's possible to control execution of the bpf program on return > probe simply by returning zero or non zero from the entry bpf > program execution to execute or not the bpf program on return > probe respectively. >
pedantic nit: bpf -> BPF > Signed-off-by: Jiri Olsa <[email protected]> > --- > include/uapi/linux/bpf.h | 1 + > kernel/bpf/syscall.c | 9 +++++++-- > kernel/trace/bpf_trace.c | 32 ++++++++++++++++++++++++-------- > tools/include/uapi/linux/bpf.h | 1 + > tools/lib/bpf/libbpf.c | 1 + > 5 files changed, 34 insertions(+), 10 deletions(-) > LGTM Acked-by: Andrii Nakryiko <[email protected]> [...] > @@ -3336,9 +3347,13 @@ uprobe_multi_link_handler(struct uprobe_consumer *con, > struct pt_regs *regs, > __u64 *data) > { > struct bpf_uprobe *uprobe; > + int ret; > > uprobe = container_of(con, struct bpf_uprobe, consumer); > - return uprobe_prog_run(uprobe, instruction_pointer(regs), regs); > + ret = uprobe_prog_run(uprobe, instruction_pointer(regs), regs); > + if (uprobe->consumer.session) > + return ret ? UPROBE_HANDLER_IGNORE : 0; Should we restrict the return range to [0, 1] for UPROBE_SESSION programs on the verifier side (given it's a new program type and we can do that)? > + return ret; > } > [...]
