tests: Automated cleanup of cdefs and other formatting

Apply the following automated changes to try to eliminate
no-longer-needed sys/cdefs.h includes as well as now-empty
blank lines in a row.

Rem

tests: Automated cleanup of cdefs and other formatting

Apply the following automated changes to try to eliminate
no-longer-needed sys/cdefs.h includes as well as now-empty
blank lines in a row.

Remove /^#if.*\n#endif.*\n#include\s+<sys/cdefs.h>.*\n/
Remove /\n+#include\s+<sys/cdefs.h>.*\n+#if.*\n#endif.*\n+/
Remove /\n+#if.*\n#endif.*\n+/
Remove /^#if.*\n#endif.*\n/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/types.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/param.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/capsicum.h>/

Sponsored by: Netflix

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Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

Remove PAGE_SIZE from the kcov tests

To allow for a dynamic page size on arm64 remove the static valud from
the kcov tests

Sponsored by: The FreeBSD Foundation

Enable the kcov tests on supported architectures

i386 and 32-bit powerpc lack support for the needed atomic operations
in userspace.

Sponsored by: The FreeBSD Foundation

MFhead@r344527

Merge ^/head r344178 through r344512.

Allow the kcov buffer to be mmaped multiple times.

After r344391 this restriction is no longer needed.

Sponsored by: DARPA, AFRL

Use KCOV_ENTRY_SIZE for the entry size.

Previously it was sizeof(uint64_t). While this is currently true, it may
not be on all future architectures.

Sponsored by: DARPA, AFRL

Add support for the Clang Coverage Sanitizer in the kernel (KCOV).

When building with KCOV enabled the compiler will insert function calls
to probes allowing us to trace the execution of the kernel

Add support for the Clang Coverage Sanitizer in the kernel (KCOV).

When building with KCOV enabled the compiler will insert function calls
to probes allowing us to trace the execution of the kernel from userspace.
These probes are on function entry (trace-pc) and on comparison operations
(trace-cmp).

Userspace can enable the use of these probes on a single kernel thread with
an ioctl interface. It can allocate space for the probe with KIOSETBUFSIZE,
then mmap the allocated buffer and enable tracing with KIOENABLE, with the
trace mode being passed in as the int argument. When complete KIODISABLE
is used to disable tracing.

The first item in the buffer is the number of trace event that have
happened. Userspace can write 0 to this to reset the tracing, and is
expected to do so on first use.

The format of the buffer depends on the trace mode. When in PC tracing just
the return address of the probe is stored. Under comparison tracing the
comparison type, the two arguments, and the return address are traced. The
former method uses on entry per trace event, while the later uses 4. As
such they are incompatible so only a single mode may be enabled.

KCOV is expected to help fuzzing the kernel, and while in development has
already found a number of issues. It is required for the syzkaller system
call fuzzer [1]. Other kernel fuzzers could also make use of it, either
with the current interface, or by extending it with new modes.

A man page is currently being worked on and is expected to be committed
soon, however having the code in the kernel now is useful for other
developers to use.

[1] https://github.com/google/syzkaller

Submitted by: Mitchell Horne <mhorne063@gmail.com> (Earlier version)
Reviewed by: kib
Testing by: tuexen
Sponsored by: DARPA, AFRL
Sponsored by: The FreeBSD Foundation (Mitchell Horne)
Differential Revision: https://reviews.freebsd.org/D14599

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