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https://github.com/SerenityOS/serenity
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106d4636a4
This reverts commit 9dbec601b0.
For KCOV to be performant (or at least not even slower) we need to
mmap the PC buffer from both user and kernel space at the same time.
You can't mmap a character device, so this change didn't make sense.
Plus even if we did invent a new method to exfiltrate the coverage
information out of the kernel, it would be incompatible with existing
kernel fuzzers. That would be kind of annoying. 🙃
42 lines
1.2 KiB
C++
42 lines
1.2 KiB
C++
/*
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* Copyright (c) 2021, Patrick Meyer <git@the-space.agency>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <Kernel/API/kcov.h>
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#include <LibCore/System.h>
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#include <LibMain/Main.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <sys/ioctl.h>
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#include <sys/mman.h>
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#include <unistd.h>
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// Note: This program requires serenity to be built with the CMake build option
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// ENABLE_KERNEL_COVERAGE_COLLECTION
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ErrorOr<int> serenity_main(Main::Arguments)
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{
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constexpr size_t num_entries = 1024 * 100;
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int fd = TRY(Core::System::open("/dev/kcov"sv, O_RDWR));
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TRY(Core::System::ioctl(fd, KCOV_SETBUFSIZE, num_entries));
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kcov_pc_t* cover = (kcov_pc_t*)TRY(Core::System::mmap(NULL, num_entries * KCOV_ENTRY_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0));
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TRY(Core::System::ioctl(fd, KCOV_ENABLE));
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cover[0] = 0;
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// Example syscall so we actually cover some kernel code.
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getppid();
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TRY(Core::System::ioctl(fd, KCOV_DISABLE));
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u64 cov_idx = cover[0];
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for (size_t idx = 1; idx <= cov_idx; idx++)
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printf("%p\n", (void*)cover[idx]);
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TRY(Core::System::munmap(const_cast<u64*>(cover), num_entries * KCOV_ENTRY_SIZE));
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TRY(Core::System::close(fd));
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return 0;
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}
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