Allow profiling kprobes/uprobes with --fdtransfer #1300
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fandreuz
reviewed
May 19, 2025
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| #define RESTARTABLE(call) ({ ssize_t ret; while ((ret = call) < 0 && errno == EINTR); ret; }) | ||
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| #define MAX_PROBE_LEN 256 |
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Maybe this could be documented for users?
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This will be superfluous, IMO. I can't imagine a reasonable function name with more than 256 characters. The only thing we must ensure is that async-profiler does not crash due to out-of-bounds access.
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Looks good to me |
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Description
Extend fdtransfer protocol to pass probe name in perf_event requests.
Motivation and context
Async-profiler can profile kprobes and uprobes, e.g.
asprof -e kprobe:fd_install. However, this does not work with--fdtransferoption. The reason is,perf_event_attrstructure contains a pointer to kprobe/uprobe name, but whenperf_event_attris passed to another process (fdtransfer server), this pointer becomes invalid, since the address belongs to a different process.The proposed solution extends
perf_fd_requeststructure with a new field that contains a name of kprobe/uprobe. For events other than kprobe/uprobe, this field contains an empty string. When fdtransfer server receives non-empty probe name, it adjusts pointer inperf_event_attr.How has this been tested?
Added
KernelTests.kprobetest, which failed before the fix, but passes now.By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.