Searched hist:"6939 f4ef16d48f2093f337162cfc041d0e30ed25" (Results 1 – 2 of 2) sorted by relevance
| /openbmc/linux/include/trace/ |
| H A D | bpf_probe.h | diff 6939f4ef16d48f2093f337162cfc041d0e30ed25 Tue Jan 19 06:22:36 CST 2021 Qais Yousef <qais.yousef@arm.com> trace: bpf: Allow bpf to attach to bare tracepoints
Some subsystems only have bare tracepoints (a tracepoint with no
associated trace event) to avoid the problem of trace events being an
ABI that can't be changed.
>From bpf presepective, bare tracepoints are what it calls
RAW_TRACEPOINT().
Since bpf assumed there's 1:1 mapping, it relied on hooking to
DEFINE_EVENT() macro to create bpf mapping of the tracepoints. Since
bare tracepoints use DECLARE_TRACE() to create the tracepoint, bpf had
no knowledge about their existence.
By teaching bpf_probe.h to parse DECLARE_TRACE() in a similar fashion to
DEFINE_EVENT(), bpf can find and attach to the new raw tracepoints.
Enabling that comes with the contract that changes to raw tracepoints
don't constitute a regression if they break existing bpf programs.
We need the ability to continue to morph and modify these raw
tracepoints without worrying about any ABI.
Update Documentation/bpf/bpf_design_QA.rst to document this contract.
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210119122237.2426878-2-qais.yousef@arm.com
|
| /openbmc/linux/Documentation/bpf/ |
| H A D | bpf_design_QA.rst | diff 6939f4ef16d48f2093f337162cfc041d0e30ed25 Tue Jan 19 06:22:36 CST 2021 Qais Yousef <qais.yousef@arm.com> trace: bpf: Allow bpf to attach to bare tracepoints
Some subsystems only have bare tracepoints (a tracepoint with no
associated trace event) to avoid the problem of trace events being an
ABI that can't be changed.
>From bpf presepective, bare tracepoints are what it calls
RAW_TRACEPOINT().
Since bpf assumed there's 1:1 mapping, it relied on hooking to
DEFINE_EVENT() macro to create bpf mapping of the tracepoints. Since
bare tracepoints use DECLARE_TRACE() to create the tracepoint, bpf had
no knowledge about their existence.
By teaching bpf_probe.h to parse DECLARE_TRACE() in a similar fashion to
DEFINE_EVENT(), bpf can find and attach to the new raw tracepoints.
Enabling that comes with the contract that changes to raw tracepoints
don't constitute a regression if they break existing bpf programs.
We need the ability to continue to morph and modify these raw
tracepoints without worrying about any ABI.
Update Documentation/bpf/bpf_design_QA.rst to document this contract.
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210119122237.2426878-2-qais.yousef@arm.com
|