tools/verification: Use tools/build makefiles on rv

Use tools/build/ makefiles to build rv, inheriting the benefits of
it. For example, having a proper way to handle dependencies.

Link: https://lkml.kernel.org/r/2a38a8f7b8dc65fa790381ec9ab42fb62beb2e25.1710519524.git.bristot@kernel.org

Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: John Kacur <jkacur@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>

tools/rv: Fix Makefile compiler options for clang

The following errors are showing up when compiling rv with clang:

$ make HOSTCC=clang CC=clang LLVM_IAS=1
[...]
clang -O -g -DVERSION=\"6.8.0-rc1\" -flto=auto -ffat-lto-objects
-fexceptions -fstack-protector-strong -fasynchronous-unwind-tables
-fstack-clash-protection -Wall -Werror=format-security
-Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS
-Wno-maybe-uninitialized $(pkg-config --cflags libtracefs)
-I include -c -o src/utils.o src/utils.c
clang: warning: optimization flag '-ffat-lto-objects' is not supported [-Wignored-optimization-argument]
warning: unknown warning option '-Wno-maybe-uninitialized'; did you mean '-Wno-uninitialized'? [-Wunknown-warning-option]
1 warning generated.

clang -o rv -ggdb src/in_kernel.o src/rv.o src/trace.o src/utils.o $(pkg-config --libs libtracefs)
src/in_kernel.o: file not recognized: file format not recognized
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [Makefile:110: rv] Error 1

Solve these issues by:
- removing -ffat-lto-objects and -Wno-maybe-uninitialized if using clang
- informing the linker about -flto=auto

Link: https://lkml.kernel.org/r/ed94a8ddc2ca8c8ef663cfb7ae9dd196c4a66b33.1707217097.git.bristot@kernel.org

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Bill Wendling <morbo@google.com>
Cc: Justin Stitt <justinstitt@google.com>
Fixes: 4bc4b131d44c ("rv: Add rv tool")
Suggested-by: Donald Zickus <dzickus@redhat.com>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>

Documentation/rv: Add verification/rv man pages

Add man pages for the rv command line, using the same scheme we used
in rtla.

Link: https://lkml.kernel.org/r/e841d7cfbdfc3ebdaf7cbd40278571940145d829.1668180100.git.bristot@kernel.org

Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

rv: Add rv tool

This is the (user-space) runtime verification tool, named rv.

This tool aims to be the interface for in-kernel rv monitors, as
well as the home for monitors in user-space (online asynchronous),
and in *eBPF.

The tool receives a command as the first argument, the current
commands are:

list - list all available monitors
mon - run a given monitor

Each monitor is an independent piece of software inside the
tool and can have their own arguments.

There is no monitor implemented in this patch, it only
adds the basic structure of the tool, based on rtla.

# rv --help
rv version 6.1.0-rc4: help

usage: rv command [-h] [command_options]

-h/--help: print this menu

command: run one of the following command:
list: list all available monitors
mon: run a monitor

[command options]: each command has its own set of options
run rv command -h for further information

*dot2bpf is the next patch set, depends on this, doing cleanups.

Link: https://lkml.kernel.org/r/fb51184f3b95aea0d7bfdc33ec09f4153aee84fa.1668180100.git.bristot@kernel.org

Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>