From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9BF64FA3744 for ; Fri, 2 Jan 2026 13:12:55 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4djPHz1LQWz2yFw; Sat, 03 Jan 2026 00:12:47 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1767359567; cv=none; b=oSkbH+FgzH42054kpM5LXtbzY9j0WHPYaTnxTtkpGReAvNQLXc4fX6XMDHaZRWVsokRBPuWwbnJRGIJFB5idYpqalJ3IMWyAwdi+8Uv92Zs3eQEMewes5sRAFsLeBmXxQpcdnuG3s4cem4zktISlvKLeFq6SiVozipHSB1OzpmP86MhzDrmKsxbRjwXSNz4VYmoscjYR/ssUb1nItb6ev+ft7KmjgyEEU8Zj/Q+klWjHRaJaSBksnHuqA6szhIh4BbMffI3Q4CgQ88vgohRVAt6/H/X8Jd9lG6PaEUL84Y56FcIrRjwa3vHV64y6k+F6UNhHkzjI1ivbJEWUzAFRcA== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1767359567; c=relaxed/relaxed; bh=MWto1Q0kowHhw4FoeBdAHUQM9hEeAI3jz0BnUWumgVU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Xsez6sZG86nIkBGWblDuM9aEyKwW4dB1eowEE1GxjgydsboGZBn2LwodXPzWggP44M4ifSO2iVgZ9FyQbAfeoqJK5A3xDMyT1o6hzcXe4bgqK9hlawM1G2TNZO9r3txvA+nfhoBV3seZJR+j8NOvZxo5mgH89AYp/pPmD4Z3Bb/w0g9TCGoVp/TOb1p06/mmWHwCHE2yB6tlf4cdVHu5D1X/uEukwY1A5ieOCcA4zpA1IU9pDYUvVkwEa9wG6ubBpdQ0En1gbve/G5jfak7bHpHpCbGKa4B1H+gNtfPGrI5rSzsU1rZLQS09ObwaKdNyzv3Vm8xx45fYFKa8hNcgMw== ARC-Authentication-Results: i=1; lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass (client-ip=217.140.110.172; helo=foss.arm.com; envelope-from=ryan.roberts@arm.com; receiver=lists.ozlabs.org) smtp.mailfrom=arm.com Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=arm.com (client-ip=217.140.110.172; helo=foss.arm.com; envelope-from=ryan.roberts@arm.com; receiver=lists.ozlabs.org) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lists.ozlabs.org (Postfix) with ESMTP id 4djPHy2lhCz2xTh for ; Sat, 03 Jan 2026 00:12:46 +1100 (AEDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 95E961515; Fri, 2 Jan 2026 05:12:08 -0800 (PST) Received: from e125769.cambridge.arm.com (e125769.cambridge.arm.com [10.1.196.27]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0CF7F3F5A1; Fri, 2 Jan 2026 05:12:11 -0800 (PST) From: Ryan Roberts To: Catalin Marinas , Will Deacon , Huacai Chen , Madhavan Srinivasan , Michael Ellerman , Paul Walmsley , Palmer Dabbelt , Albert Ou , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , Kees Cook , "Gustavo A. R. Silva" , Arnd Bergmann , Mark Rutland , "Jason A. Donenfeld" , Ard Biesheuvel , Jeremy Linton Cc: Ryan Roberts , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH v3 2/3] prandom: Convert prandom_u32_state() to __always_inline Date: Fri, 2 Jan 2026 13:11:53 +0000 Message-ID: <20260102131156.3265118-3-ryan.roberts@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260102131156.3265118-1-ryan.roberts@arm.com> References: <20260102131156.3265118-1-ryan.roberts@arm.com> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 --- 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 #include -/** - * 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