bpf: tracing session supporting #6172
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The tracing session is something that similar to kprobe session. It allow to attach a single BPF program to both the entry and the exit of the target functions. While a non-zero value is returned by the fentry, the fexit will be skipped, which is similar to kprobe session. Signed-off-by: Menglong Dong <[email protected]> Co-developed-by: Leon Hwang <[email protected]> Signed-off-by: Leon Hwang <[email protected]>
If TRACE_SESSION exists, we will use extra 8-bytes in the stack of the trampoline to store the flags that we needed, and the 8-bytes lie before the function argument count, which means ctx[-2]. And we will store the flag "is_exit" to the first bit of it. Introduce the kfunc bpf_tracing_is_exit(), which is used to tell if it is fexit currently. Signed-off-by: Menglong Dong <[email protected]> Co-developed-by: Leon Hwang <[email protected]> Signed-off-by: Leon Hwang <[email protected]>
Add BPF_TRACE_SESSION supporting to x86_64. invoke_bpf_session_entry and invoke_bpf_session_exit is introduced for this purpose. In invoke_bpf_session_entry(), we will check if the return value of the fentry is 0, and clear the corresponding flag if not. And in invoke_bpf_session_exit(), we will check if the corresponding flag is set. If not set, the fexit will be skipped. Signed-off-by: Menglong Dong <[email protected]> Co-developed-by: Leon Hwang <[email protected]> Signed-off-by: Leon Hwang <[email protected]>
Add BPF_TRACE_SESSION to libbpf and bpftool. Signed-off-by: Menglong Dong <[email protected]>
Add testcases for BPF_TRACE_SESSION. Signed-off-by: Menglong Dong <[email protected]>
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Upstream branch: 48a97ff |
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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=1013178 expired. Closing PR. |
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Pull request for series with
subject: bpf: tracing session supporting
version: 1
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=1013178