test_kprobes: Add recursed kprobe test case

Add a recursed kprobe test case to the KUnit test module for kprobes.
This will probe a function which is called from the pre_handler and
post_handler itself. If the kprobe is correctly implemented, the recursed
kprobe handlers will be skipped and the number of skipped kprobe will
be counted on kprobe::nmissed.

Link: https://lore.kernel.org/all/167414238758.2301956.258548940194352895.stgit@devnote3/

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

treewide: use get_random_u32_{above,below}() instead of manual loop

These cases were done with this Coccinelle:

@@
expression E;
identifier I;
@@
- do {
... when != I
- I = get_random_u32();
... when != I
- } while (I > E);
+ I = get_random_u32_below(E + 1);

@@
expression E;
identifier I;
@@
- do {
... when != I
- I = get_random_u32();
... when != I
- } while (I >= E);
+ I = get_random_u32_below(E);

@@
expression E;
identifier I;
@@
- do {
... when != I
- I = get_random_u32();
... when != I
- } while (I < E);
+ I = get_random_u32_above(E - 1);

@@
expression E;
identifier I;
@@
- do {
... when != I
- I = get_random_u32();
... when != I
- } while (I <= E);
+ I = get_random_u32_above(E);

@@
identifier I;
@@
- do {
... when != I
- I = get_random_u32();
... when != I
- } while (!I);
+ I = get_random_u32_above(0);

@@
identifier I;
@@
- do {
... when != I
- I = get_random_u32();
... when != I
- } while (I == 0);
+ I = get_random_u32_above(0);

@@
expression E;
@@
- E + 1 + get_random_u32_below(U32_MAX - E)
+ get_random_u32_above(E)

Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

treewide: use get_random_u32() when possible

The prandom_u32() function has been a deprecated inline wrapper around
get_random_u32() for several releases now, and compiles down to the
exact same code. Replace the deprecated wrapper with a direct call to
the real function. The same also applies to get_random_int(), which is
just a wrapper around get_random_u32(). This was done as a basic find
and replace.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Yury Norov <yury.norov@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz> # for ext4
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk> # for sch_cake
Acked-by: Chuck Lever <chuck.lever@oracle.com> # for nfsd
Acked-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com> # for thunderbolt
Acked-by: Darrick J. Wong <djwong@kernel.org> # for xfs
Acked-by: Helge Deller <deller@gmx.de> # for parisc
Acked-by: Heiko Carstens <hca@linux.ibm.com> # for s390
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

test_kprobes: Move it from kernel/ to lib/

Since config KPROBES_SANITY_TEST is in lib/Kconfig.debug, it is better to
let test_kprobes.c in lib/, just like other similar tests found in lib/.

Link: https://lkml.kernel.org/r/1635213091-24387-4-git-send-email-yangtiezhu@loongson.cn

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>