On Fri, Jan 02, 2026 at 01:11:53PM +0000, Ryan Roberts wrote: > We will shortly use prandom_u32_state() to implement kstack offset > randomization and some arches need to call it from non-instrumentable > context. Given the function is just a handful of operations and doesn't > call out to any other functions, let's take the easy path and make it > __always_inline. > > Signed-off-by: Ryan Roberts <[email protected]>
I see there were some comments about keeping an out-of-line wrapper. With or without that, this looks good to me, and either way: Acked-by: Mark Rutland <[email protected]> Mark. > --- > include/linux/prandom.h | 19 ++++++++++++++++++- > lib/random32.c | 19 ------------------- > 2 files changed, 18 insertions(+), 20 deletions(-) > > diff --git a/include/linux/prandom.h b/include/linux/prandom.h > index ff7dcc3fa105..e797b3709f5c 100644 > --- a/include/linux/prandom.h > +++ b/include/linux/prandom.h > @@ -17,7 +17,24 @@ struct rnd_state { > __u32 s1, s2, s3, s4; > }; > > -u32 prandom_u32_state(struct rnd_state *state); > +/** > + * prandom_u32_state - seeded pseudo-random number generator. > + * @state: pointer to state structure holding seeded state. > + * > + * This is used for pseudo-randomness with no outside seeding. > + * For more random results, use get_random_u32(). > + */ > +static __always_inline u32 prandom_u32_state(struct rnd_state *state) > +{ > +#define TAUSWORTHE(s, a, b, c, d) ((s & c) << d) ^ (((s << a) ^ s) >> b) > + state->s1 = TAUSWORTHE(state->s1, 6U, 13U, 4294967294U, 18U); > + state->s2 = TAUSWORTHE(state->s2, 2U, 27U, 4294967288U, 2U); > + state->s3 = TAUSWORTHE(state->s3, 13U, 21U, 4294967280U, 7U); > + state->s4 = TAUSWORTHE(state->s4, 3U, 12U, 4294967168U, 13U); > + > + return (state->s1 ^ state->s2 ^ state->s3 ^ state->s4); > +} > + > void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes); > void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state); > > diff --git a/lib/random32.c b/lib/random32.c > index 24e7acd9343f..d57baf489d4a 100644 > --- a/lib/random32.c > +++ b/lib/random32.c > @@ -42,25 +42,6 @@ > #include <linux/slab.h> > #include <linux/unaligned.h> > > -/** > - * prandom_u32_state - seeded pseudo-random number generator. > - * @state: pointer to state structure holding seeded state. > - * > - * This is used for pseudo-randomness with no outside seeding. > - * For more random results, use get_random_u32(). > - */ > -u32 prandom_u32_state(struct rnd_state *state) > -{ > -#define TAUSWORTHE(s, a, b, c, d) ((s & c) << d) ^ (((s << a) ^ s) >> b) > - state->s1 = TAUSWORTHE(state->s1, 6U, 13U, 4294967294U, 18U); > - state->s2 = TAUSWORTHE(state->s2, 2U, 27U, 4294967288U, 2U); > - state->s3 = TAUSWORTHE(state->s3, 13U, 21U, 4294967280U, 7U); > - state->s4 = TAUSWORTHE(state->s4, 3U, 12U, 4294967168U, 13U); > - > - return (state->s1 ^ state->s2 ^ state->s3 ^ state->s4); > -} > -EXPORT_SYMBOL(prandom_u32_state); > - > /** > * prandom_bytes_state - get the requested number of pseudo-random bytes > * > -- > 2.43.0 >
