uio: Use switch statements when handling UIO_READ vs UIO_WRITE

This is mostly to reduce the diff with CheriBSD which adds additional
constants to enum uio_rw, but also matches the normal style used for
uio_segflg.

Reviewed by: kib, emaste
Obtained from: CheriBSD
Differential Revision: https://reviews.freebsd.org/D45142

sys: 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

sys: Remove $FreeBSD$: one-line .c pattern

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

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

lindebugfs: Add `debugfs_create_file_size()`

This is the same as `debugfs_create_file()` but takes the initial size
of the file. In FreeBSD, the given size is ignored and
`debugfs_create_file()` is called.

Reviewed by: emaste, manu
Approved by: manu
Differential Revision: https://reviews.freebsd.org/D37914

lindebugfs: Add missing `debugfs_create_u*()` and `debugfs_create_x*()`

The `debugfs_create_x*()` variants are the same as their
`debugfs_create_u*()` equivalent, but they work with lowercase
hexadecimal.

While here, fix a few style(9) issues.

Reviewed by: manu
Approved by: manu
Differential Revision: https://reviews.freebsd.org/D38087

lindebugfs: Add `debugfs_create_atomic_t()`

Reviewed by: jfree
Approved by: jfree
Differential Revision: https://reviews.freebsd.org/D37915

LinuxKPI,lindebugfs: add u8 base type and blob support

Add debugfs_create_u8() based on other already present implementations.
Add a read-only implementation for debugfs_create_blob().

Both are needed for iwlwifi debugfs support.

Sponsored by: The FreeBSD Foundation
MFC after: 3 days
OKed by: jfree (earlier version)
Differential Revision: https://reviews.freebsd.org/D37090

linuxkpi: drm-kmod debugfs support

This diff extends LinuxKPI to support simple attribute files in debugfs.
These simple attributes are an essential component for compiling drm-kmod
with CONFIG_DEBUG_FS enabled.
This will allow for easier graphics driver debugging using
Intel's igt-gpu-tools.

Reviewed by: hselasky
Differential Revision: https://reviews.freebsd.org/D35883
Sponsored by: Google, Inc. (GSoC 2022)

lindebugfs: The Linux file operations use negative return values in the kernel.

Fix sign.

MFC after: 1 week
Sponsored by: NVIDIA Networking

lindebugfs: Zero the linux_file structure before use.

This avoids clients using garbage values on the stack and makes
debugging easier.

MFC after: 1 week
Sponsored by: NVIDIA Networking

lindebugfs: Fix write

For write operation pseudofs creates an sbuf with the data.
Use this data instead of the uio as it's not usable anymore after
uiomove.

Reviewed by: hselasky
MFC after: 1 week
Sponsored by: Beckhoff Automation GmbH & Co. KG
Differential Revision: https://reviews.freebsd.org/D34114

Add emulation support for the Linux kcov(4) ioctl API.

This makes it possible to run an unmodified Linux syzkaller executor
against the Linuxulator, and have it gather code coverage information.

Sponsored by: The FreeBSD Foundation

compat: clean up empty lines in .c and .h files

LinuxKPI: Finalize move of lindebugfs from ports to base.

The source file was moved to base earlier and also improved upon,
but never compiled in. This patch will:
- Make a module in sys/modules
- Make lindebugfs depend on linuxkpi (for seq_file)
- Check if read/write functions are set before calling, DRM drivers
don't always set both of them.

Reviewed by: hps
Approved by: imp (mentor), hps
MFC after: 1 week

import linux debugfs support

Reviewed by: hps@
MFC after: 1 week
Sponsored by: iX Systems
Differential Revision: https://reviews.freebsd.org/D19258