2d92ef7da2
Leon Hwang says: ==================== selftests/bpf: Introduce experimental bpf_in_interrupt() Filtering pid_tgid is meanlingless when the current task is preempted by an interrupt. To address this, introduce 'bpf_in_interrupt()' helper function, which allows BPF programs to determine whether they are executing in interrupt context. 'get_preempt_count()': * On x86, '*(int *) bpf_this_cpu_ptr(&__preempt_count)'. * On arm64, 'bpf_get_current_task_btf()->thread_info.preempt.count'. Then 'bpf_in_interrupt()' will be: * If !PREEMPT_RT, 'get_preempt_count() & (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_MASK)'. * If PREEMPT_RT, '(get_preempt_count() & (NMI_MASK | HARDIRQ_MASK)) | (bpf_get_current_task_btf()->softirq_disable_cnt & SOFTIRQ_MASK)'. 'bpf_in_interrupt()' runs well when PREEMPT_RT is enabled. But it's difficult for me to test it well because I'm not familiar with PREEMPT_RT. Changes: v2 -> v3: * Address comments from Alexei: * Move bpf_in_interrupt() to bpf_experimental.h. * Add support for arm64. v2: https://lore.kernel.org/bpf/20250825131502.54269-1-leon.hwang@linux.dev/ v1 -> v2: * Fix a build error reported by test bot. ==================== Link: https://patch.msgid.link/20250903140438.59517-1-leon.hwang@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
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README
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 reStructuredText 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.