From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
To: Shuah Khan <shuah@kernel.org>, Kees Cook <keescook@chromium.org>
Cc: Petr Mladek <pmladek@suse.com>, Willy Tarreau <w@1wt.eu>,
linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org,
Arpitha Raghunandan <98.arpi@gmail.com>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Brendan Higgins <brendanhiggins@google.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>
Subject: [PATCH 1/4] prandom.h: add *_state variant of prandom_u32_max
Date: Sun, 25 Oct 2020 22:48:39 +0100 [thread overview]
Message-ID: <20201025214842.5924-2-linux@rasmusvillemoes.dk> (raw)
In-Reply-To: <20201025214842.5924-1-linux@rasmusvillemoes.dk>
It is useful for test modules that make use of random numbers to allow
the exact same series of test cases to be repeated (e.g., after fixing
a bug in the code being tested). For that, the test module needs to
obtain its random numbers from a private state that can be seeded by a
known seed, e.g. given as a module parameter (and using a random seed
when that parameter is not given).
There's a few test modules I'm going to modify to follow that
scheme. As preparation, add a _state variant of the existing
prandom_u32_max(), and for convenience, also add a variant that
produces a value in a given range.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
include/linux/prandom.h | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/include/linux/prandom.h b/include/linux/prandom.h
index aa16e6468f91e79e1f31..58ffcd56c705be34fb98 100644
--- a/include/linux/prandom.h
+++ b/include/linux/prandom.h
@@ -46,6 +46,35 @@ static inline u32 prandom_u32_max(u32 ep_ro)
return (u32)(((u64) prandom_u32() * ep_ro) >> 32);
}
+/**
+ * prandom_u32_max_state - get pseudo-random number in internal [0, hi)
+ *
+ * Like prandom_u32_max, but use the given state structure.
+ * @state: pointer to state structure
+ * @hi: (exclusive) upper bound
+ *
+ * Exception: If @hi == 0, this returns 0.
+ */
+static inline u32 prandom_u32_max_state(struct rnd_state *state, u32 hi)
+{
+ return ((u64)prandom_u32_state(state) * hi) >> 32;
+}
+
+/**
+ * prandom_u32_range_state - get pseudo-random number in internal [lo, hi)
+ *
+ * @state: pointer to state structure
+ * @lo: (inclusive) lower bound
+ * @hi: (exclusive) upper bound
+ *
+ * Exception: If @lo == @hi, this returns @lo. Results are unspecified
+ * for @lo > @hi.
+ */
+static inline u32 prandom_u32_range_state(struct rnd_state *state, u32 lo, u32 hi)
+{
+ return lo + prandom_u32_max_state(state, hi - lo);
+}
+
/*
* Handle minimum values for seeds
*/
--
2.23.0
next prev parent reply other threads:[~2020-10-25 21:49 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-25 21:48 [PATCH 0/4] deterministic random testing Rasmus Villemoes
2020-10-25 21:48 ` Rasmus Villemoes [this message]
2020-10-30 16:00 ` [PATCH 1/4] prandom.h: add *_state variant of prandom_u32_max Petr Mladek
2020-10-25 21:48 ` [PATCH 2/4] kselftest_module.h: unconditionally expand the KSTM_MODULE_GLOBALS() macro Rasmus Villemoes
2020-10-30 16:02 ` Petr Mladek
2020-10-25 21:48 ` [PATCH 3/4] kselftest_module.h: add struct rnd_state and seed parameter Rasmus Villemoes
2020-10-30 16:23 ` Petr Mladek
2020-10-25 21:48 ` [PATCH 4/4] lib/test_printf.c: use deterministic sequence of random numbers Rasmus Villemoes
2020-10-30 16:26 ` Petr Mladek
[not found] ` <20201026105927.GC4077@smile.fi.intel.com>
2020-10-30 12:58 ` [PATCH 0/4] deterministic random testing Rasmus Villemoes
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