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1d9c949369
Allow the same userspace thread to simultaneously collect normal coverage in syscall context (KCOV_ENABLE) and remote coverage of asynchronous work created by the thread (KCOV_REMOTE_ENABLE). With this, remote KCOV coverage becomes useful for generic fuzzing and not just fuzzing of specific data injection interfaces. This requires that the task_struct::kcov_* fields are separated into ones that are used by the task that generates coverage, and ones that are used by the task that requested remote coverage. To split this up: - Split task_struct::kcov into kcov and kcov_remote. kcov_task_exit() now has to clean up both separately. - Only use task_struct::kcov_mode on the task that generates coverage. - Only reset task_struct::kcov_handle on the task that requested remote coverage. After this change, fields used by the task that generates coverage are: - kcov_mode - kcov_size - kcov_area - kcov - kcov_sequence - kcov_softirq Fields used by the task that requested remote coverage are: - kcov_remote - kcov_handle [jannh@google.com: remove unused constant KCOV_MODE_REMOTE, per Dmitry] Link: https://lore.kernel.org/20260515-kcov-simultaneous-remote-v2-1-56fde1cfa509@google.com [jannh@google.com: update documentation on remote coverage collection] Link: https://lore.kernel.org/20260519-kcov-docs-v1-1-5bb22f4cb20c@google.com [jannh@google.com: move and reword sentence on simultaneous normal/remote collection Link: https://lore.kernel.org/20260520-kcov-docs-v2-1-819f78778763@google.com Link: https://lore.kernel.org/20260505-kcov-simultaneous-remote-v1-1-a670ba7cefd2@google.com Signed-off-by: Jann Horn <jannh@google.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Marco Elver <elver@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>