From patchwork Tue Jun 7 10:02:10 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: 12871695 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 2EC9ECCA47F for ; Tue, 7 Jun 2022 10:18:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-Id:Date:Subject:Cc :To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=2nfeRuBx3c39ol0MT4SzfXRe8xjKMbxw/7VFRjJL9C0=; b=L0F4Ebg2IULcxF 1rtA6z7Vw/+TclANlQo/ZmTPLUQO+nUo3gaWYoEb6UdvrLlFoosniNSEmDC1K3KNGCp+maOHE7lVz dJTyTTqcB87aTl6AriwV5NxPIefOZ13eLYJ9yD3z7PYkiWmQCWPHtGqXbEZYcqPW/KZYNrBojScjN ViG3Pm/Ou4Wgx5ufkgy3BzUFZ+e47nD8mtM/sme91tGraXl1ixMvQS7LrrJuf9Je8MNdLnwW7Fxvg HcgwiAT4c9fphcfy+tAJzWh5jWRsE57wG9I4FRKGzsZTl2g20cnk7C57dMs5WxV1LocvWZ+nHUbuc Ozi6n43tUFktbdYLJ4xw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nyWGQ-006Zm3-Ny; Tue, 07 Jun 2022 10:16:43 +0000 Received: from ams.source.kernel.org ([145.40.68.75]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nyW4q-006VES-DR for linux-arm-kernel@lists.infradead.org; Tue, 07 Jun 2022 10:04:46 +0000 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 143B5B81E80; Tue, 7 Jun 2022 10:04:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F04A6C385A5; Tue, 7 Jun 2022 10:04:40 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="iR3hBvkj" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1654596278; 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=OKKnwfWRjXfV4VlPDoXITVO4Illa+tP0RaVK4KGOf9w=; b=iR3hBvkj//2qjwgFAMucgvSLO09HGGZF81DprAXWg/f0qOfVkB+myILqE9WNTmIjSJ1ig7 yOX6HiMu6QGihlATGC3H4CIxRwq9GJs1MmbbTJk59KJOokPMD9Yyzej7OpmSrU073aBGZa h42uTYtERhqqUdbx9lhxnd9jSrUQvGo= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 498453e0 (TLSv1.3:AEAD-AES256-GCM-SHA384:256:NO); Tue, 7 Jun 2022 10:04:38 +0000 (UTC) From: "Jason A. Donenfeld" To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: "Jason A. Donenfeld" , Stephen Boyd , Ard Biesheuvel , Catalin Marinas , Russell King , Arnd Bergmann , Phil Elwell Subject: [PATCH] random: do not use jump labels before they are initialized Date: Tue, 7 Jun 2022 12:02:10 +0200 Message-Id: <20220607100210.683136-1-Jason@zx2c4.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220607_030444_785777_599452B6 X-CRM114-Status: GOOD ( 22.24 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org [ I would like to pursue fixing this more directly first before actually merging this, but I thought I'd send this to the list now anyway as a the "backup" plan. If I can't figure out how to make headway on the main plan in the next few days, it'll be easy to just do this. ] Stephen reported that a static key warning splat appears during early boot on systems that credit randomness from device trees that contain an "rng-seed" property, because because setup_machine_fdt() is called before jump_label_init() during setup_arch(): static_key_enable_cpuslocked(): static key '0xffffffe51c6fcfc0' used before call to jump_label_init() WARNING: CPU: 0 PID: 0 at kernel/jump_label.c:166 static_key_enable_cpuslocked+0xb0/0xb8 Modules linked in: CPU: 0 PID: 0 Comm: swapper Not tainted 5.18.0+ #224 44b43e377bfc84bc99bb5ab885ff694984ee09ff pstate: 600001c9 (nZCv dAIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : static_key_enable_cpuslocked+0xb0/0xb8 lr : static_key_enable_cpuslocked+0xb0/0xb8 sp : ffffffe51c393cf0 x29: ffffffe51c393cf0 x28: 000000008185054c x27: 00000000f1042f10 x26: 0000000000000000 x25: 00000000f10302b2 x24: 0000002513200000 x23: 0000002513200000 x22: ffffffe51c1c9000 x21: fffffffdfdc00000 x20: ffffffe51c2f0831 x19: ffffffe51c6fcfc0 x18: 00000000ffff1020 x17: 00000000e1e2ac90 x16: 00000000000000e0 x15: ffffffe51b710708 x14: 0000000000000066 x13: 0000000000000018 x12: 0000000000000000 x11: 0000000000000000 x10: 00000000ffffffff x9 : 0000000000000000 x8 : 0000000000000000 x7 : 61632065726f6665 x6 : 6220646573752027 x5 : ffffffe51c641d25 x4 : ffffffe51c13142c x3 : ffff0a00ffffff05 x2 : 40000000ffffe003 x1 : 00000000000001c0 x0 : 0000000000000065 Call trace: static_key_enable_cpuslocked+0xb0/0xb8 static_key_enable+0x2c/0x40 crng_set_ready+0x24/0x30 execute_in_process_context+0x80/0x90 _credit_init_bits+0x100/0x154 add_bootloader_randomness+0x64/0x78 early_init_dt_scan_chosen+0x140/0x184 early_init_dt_scan_nodes+0x28/0x4c early_init_dt_scan+0x40/0x44 setup_machine_fdt+0x7c/0x120 setup_arch+0x74/0x1d8 start_kernel+0x84/0x44c __primary_switched+0xc0/0xc8 ---[ end trace 0000000000000000 ]--- random: crng init done Machine model: Google Lazor (rev1 - 2) with LTE A trivial fix went in to address this on arm64, 73e2d827a501 ("arm64: Initialize jump labels before setup_machine_fdt()"). But it appears that fixing it on other platforms might not be so trivial. Instead, defer the setting of the static branch until later in the boot process. Fixes: f5bda35fba61 ("random: use static branch for crng_ready()") Reported-by: Stephen Boyd Cc: Ard Biesheuvel Cc: Catalin Marinas Cc: Russell King Cc: Arnd Bergmann Cc: Phil Elwell Signed-off-by: Jason A. Donenfeld Reviewed-by: Ard Biesheuvel --- drivers/char/random.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/char/random.c b/drivers/char/random.c index 4862d4d3ec49..f9a020ec08b9 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -650,7 +650,8 @@ static void __cold _credit_init_bits(size_t bits) if (orig < POOL_READY_BITS && new >= POOL_READY_BITS) { crng_reseed(); /* Sets crng_init to CRNG_READY under base_crng.lock. */ - execute_in_process_context(crng_set_ready, &set_ready); + if (static_key_initialized) + execute_in_process_context(crng_set_ready, &set_ready); wake_up_interruptible(&crng_init_wait); kill_fasync(&fasync, SIGIO, POLL_IN); pr_notice("crng init done\n"); @@ -779,6 +780,14 @@ int __init random_init(const char *command_line) unsigned int i, arch_bytes; unsigned long entropy; + /* + * If we were initialized by the bootloader before jump labels are + * initialized, then we should enable the static branch here, where + * it's guaranteed that jump labels have been initialized. + */ + if (!static_branch_likely(&crng_is_ready) && crng_init >= CRNG_READY) + crng_set_ready(NULL); + #if defined(LATENT_ENTROPY_PLUGIN) static const u8 compiletime_seed[BLAKE2S_BLOCK_SIZE] __initconst __latent_entropy; _mix_pool_bytes(compiletime_seed, sizeof(compiletime_seed));