From patchwork Fri Apr 8 17:53:17 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Jason A. Donenfeld" X-Patchwork-Id: 558932 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AD6BCC433EF for ; Fri, 8 Apr 2022 17:53:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234926AbiDHRzk (ORCPT ); Fri, 8 Apr 2022 13:55:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45662 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229556AbiDHRzj (ORCPT ); Fri, 8 Apr 2022 13:55:39 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 475C0E6F; Fri, 8 Apr 2022 10:53:35 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id EE254B82C8F; Fri, 8 Apr 2022 17:53:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BB564C385A3; Fri, 8 Apr 2022 17:53:31 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="Wm8m1w8Z" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1649440409; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=5zTBxxqGHBh1YMYwKpsz6sj1OtWasH7QBHDbsBR2tQI=; b=Wm8m1w8ZuQw2ZAuuVODA7It85g7bEKhVeUcxEeFGPXglBrYWyog48wvnUojKl7o24N9Xfg dHn8gOp2kqJrIGxpqB0HzRTc9Av+P8lswqWsL8EESNEk14upHnQ8RCYkrXOVdq3wIO4TGG 9A0dBymn7bOtUV89ep8riIP5a4Omq1s= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 7dd1ebb5 (TLSv1.3:AEAD-AES256-GCM-SHA384:256:NO); Fri, 8 Apr 2022 17:53:29 +0000 (UTC) From: "Jason A. Donenfeld" To: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org Cc: "Jason A. Donenfeld" , Dominik Brodowski , Thomas Gleixner , Theodore Ts'o Subject: [PATCH] random: make random_get_entropy() return an unsigned long Date: Fri, 8 Apr 2022 19:53:17 +0200 Message-Id: <20220408175317.140778-1-Jason@zx2c4.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org Some implementations were returning type `unsigned long`, while others that fell back to get_cycles() were implicitly returning a `cycles_t` or an untyped constant int literal. That makes for weird and confusing code, and basically all code in the kernel already handled it like it was an `unsigned long`. I recently tried to handle it as the largest type it could be, a `cycles_t`, but doing so doesn't really help with much. Instead let's just make random_get_entropy() return an unsigned long all the time. This also matches the commonly used `arch_get_random_long()` function, so now RDRAND and RDTSC return the same sized integer, which means one can fallback to the other more gracefully. Cc: Dominik Brodowski Cc: Thomas Gleixner Cc: Theodore Ts'o Signed-off-by: Jason A. Donenfeld Acked-by: Thomas Gleixner --- drivers/char/random.c | 20 +++++++------------- include/linux/timex.h | 2 +- 2 files changed, 8 insertions(+), 14 deletions(-) diff --git a/drivers/char/random.c b/drivers/char/random.c index df43c5060f00..6b01b2be9dd4 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1018,7 +1018,7 @@ int __init rand_initialize(void) */ void add_device_randomness(const void *buf, size_t size) { - cycles_t cycles = random_get_entropy(); + unsigned long cycles = random_get_entropy(); unsigned long flags, now = jiffies; if (crng_init == 0 && size) @@ -1049,8 +1049,7 @@ struct timer_rand_state { */ static void add_timer_randomness(struct timer_rand_state *state, unsigned int num) { - cycles_t cycles = random_get_entropy(); - unsigned long flags, now = jiffies; + unsigned long cycles = random_get_entropy(), now = jiffies, flags; long delta, delta2, delta3; spin_lock_irqsave(&input_pool.lock, flags); @@ -1339,8 +1338,7 @@ static void mix_interrupt_randomness(struct work_struct *work) void add_interrupt_randomness(int irq) { enum { MIX_INFLIGHT = 1U << 31 }; - cycles_t cycles = random_get_entropy(); - unsigned long now = jiffies; + unsigned long cycles = random_get_entropy(), now = jiffies; struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness); struct pt_regs *regs = get_irq_regs(); unsigned int new_count; @@ -1353,16 +1351,12 @@ void add_interrupt_randomness(int irq) if (cycles == 0) cycles = get_reg(fast_pool, regs); - if (sizeof(cycles) == 8) + if (sizeof(unsigned long) == 8) { irq_data.u64[0] = cycles ^ rol64(now, 32) ^ irq; - else { + irq_data.u64[1] = regs ? instruction_pointer(regs) : _RET_IP_; + } else { irq_data.u32[0] = cycles ^ irq; irq_data.u32[1] = now; - } - - if (sizeof(unsigned long) == 8) - irq_data.u64[1] = regs ? instruction_pointer(regs) : _RET_IP_; - else { irq_data.u32[2] = regs ? instruction_pointer(regs) : _RET_IP_; irq_data.u32[3] = get_reg(fast_pool, regs); } @@ -1409,7 +1403,7 @@ static void entropy_timer(struct timer_list *t) static void try_to_generate_entropy(void) { struct { - cycles_t cycles; + unsigned long cycles; struct timer_list timer; } stack; diff --git a/include/linux/timex.h b/include/linux/timex.h index 059b18eb1f1f..5745c90c8800 100644 --- a/include/linux/timex.h +++ b/include/linux/timex.h @@ -75,7 +75,7 @@ * By default we use get_cycles() for this purpose, but individual * architectures may override this in their asm/timex.h header file. */ -#define random_get_entropy() get_cycles() +#define random_get_entropy() ((unsigned long)get_cycles()) #endif /*