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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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Jann HornandAndrew Morton
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>
111 lines
3.2 KiB
C
111 lines
3.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_KCOV_H
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#define _LINUX_KCOV_H
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#include <linux/sched.h>
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#include <uapi/linux/kcov.h>
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struct task_struct;
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#ifdef CONFIG_KCOV
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enum kcov_mode {
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/* Coverage collection is not enabled yet. */
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KCOV_MODE_DISABLED = 0,
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/* KCOV was initialized, but tracing mode hasn't been chosen yet. */
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KCOV_MODE_INIT = 1,
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/*
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* Tracing coverage collection mode.
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* Covered PCs are collected in a per-task buffer.
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*/
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KCOV_MODE_TRACE_PC = 2,
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/* Collecting comparison operands mode. */
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KCOV_MODE_TRACE_CMP = 3,
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};
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#define KCOV_IN_CTXSW (1 << 30)
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void kcov_task_init(struct task_struct *t);
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void kcov_task_exit(struct task_struct *t);
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#define kcov_prepare_switch(t) \
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do { \
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(t)->kcov_mode |= KCOV_IN_CTXSW; \
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} while (0)
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#define kcov_finish_switch(t) \
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do { \
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(t)->kcov_mode &= ~KCOV_IN_CTXSW; \
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} while (0)
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/* See Documentation/dev-tools/kcov.rst for usage details. */
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void kcov_remote_start(u64 handle);
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void kcov_remote_stop(void);
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struct kcov_common_handle_id kcov_common_handle(void);
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static inline void kcov_remote_start_common(struct kcov_common_handle_id id)
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{
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kcov_remote_start(kcov_remote_handle(KCOV_SUBSYSTEM_COMMON, id.val));
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}
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static inline void kcov_remote_start_usb(u64 id)
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{
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kcov_remote_start(kcov_remote_handle(KCOV_SUBSYSTEM_USB, id));
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}
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/*
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* The softirq flavor of kcov_remote_*() functions is introduced as a temporary
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* work around for kcov's lack of nested remote coverage sections support in
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* task context. Adding support for nested sections is tracked in:
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* https://bugzilla.kernel.org/show_bug.cgi?id=210337
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*/
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static inline void kcov_remote_start_usb_softirq(u64 id)
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{
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if (in_serving_softirq() && !in_hardirq())
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kcov_remote_start_usb(id);
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}
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static inline void kcov_remote_stop_softirq(void)
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{
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if (in_serving_softirq() && !in_hardirq())
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kcov_remote_stop();
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}
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#ifdef CONFIG_64BIT
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typedef unsigned long kcov_u64;
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#else
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typedef unsigned long long kcov_u64;
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#endif
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void __sanitizer_cov_trace_pc(void);
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void __sanitizer_cov_trace_cmp1(u8 arg1, u8 arg2);
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void __sanitizer_cov_trace_cmp2(u16 arg1, u16 arg2);
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void __sanitizer_cov_trace_cmp4(u32 arg1, u32 arg2);
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void __sanitizer_cov_trace_cmp8(kcov_u64 arg1, kcov_u64 arg2);
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void __sanitizer_cov_trace_const_cmp1(u8 arg1, u8 arg2);
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void __sanitizer_cov_trace_const_cmp2(u16 arg1, u16 arg2);
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void __sanitizer_cov_trace_const_cmp4(u32 arg1, u32 arg2);
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void __sanitizer_cov_trace_const_cmp8(kcov_u64 arg1, kcov_u64 arg2);
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void __sanitizer_cov_trace_switch(kcov_u64 val, void *cases);
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#else
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static inline void kcov_task_init(struct task_struct *t) {}
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static inline void kcov_task_exit(struct task_struct *t) {}
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static inline void kcov_prepare_switch(struct task_struct *t) {}
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static inline void kcov_finish_switch(struct task_struct *t) {}
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static inline void kcov_remote_start(u64 handle) {}
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static inline void kcov_remote_stop(void) {}
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static inline struct kcov_common_handle_id kcov_common_handle(void)
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{
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return (struct kcov_common_handle_id){};
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}
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static inline void kcov_remote_start_common(struct kcov_common_handle_id id) {}
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static inline void kcov_remote_start_usb(u64 id) {}
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static inline void kcov_remote_start_usb_softirq(u64 id) {}
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static inline void kcov_remote_stop_softirq(void) {}
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#endif /* CONFIG_KCOV */
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#endif /* _LINUX_KCOV_H */
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