90065c0647
Song Liu says: ==================== Calling get_perf_callchain() on perf_events from PEBS entries may cause unwinder errors. To fix this issue, perf subsystem fetches callchain early, and marks perf_events are marked with __PERF_SAMPLE_CALLCHAIN_EARLY. Similar issue exists when BPF program calls get_perf_callchain() via helper functions. For more information about this issue, please refer to discussions in [1]. This set fixes this issue with helper proto bpf_get_stackid_pe and bpf_get_stack_pe. [1] https://lore.kernel.org/lkml/ED7B9430-6489-4260-B3C5-9CFA2E3AA87A@fb.com/ Changes v4 => v5: 1. Return -EPROTO instead of -EINVAL on PERF_EVENT_IOC_SET_BPF errors. (Alexei) 2. Let libbpf print a hint message when PERF_EVENT_IOC_SET_BPF returns -EPROTO. (Alexei) Changes v3 => v4: 1. Fix error check logic in bpf_get_stackid_pe and bpf_get_stack_pe. (Alexei) 2. Do not allow attaching BPF programs with bpf_get_stack|stackid to perf_event with precise_ip > 0, but not proper callchain. (Alexei) 3. Add selftest get_stackid_cannot_attach. Changes v2 => v3: 1. Fix handling of stackmap skip field. (Andrii) 2. Simplify the code in a few places. (Andrii) Changes v1 => v2: 1. Simplify the design and avoid introducing new helper function. (Andrii) ==================== Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.