From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Wed, 01 Jun 2022 12:14:08 +0200 Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by lore.white.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1nwLMe-00H3LX-Cp for lore@lore.pengutronix.de; Wed, 01 Jun 2022 12:14:08 +0200 Received: from bombadil.infradead.org ([2607:7c80:54:3::133]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1nwLMc-0000gp-Nl for lore@pengutronix.de; Wed, 01 Jun 2022 12:14:07 +0200 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:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=ACymDZ/Pg6+s1BP8JdGvT5xaHAWBPMKL8psBY86dWDA=; b=cbJtjjiFrRAoWF Li6NhEVxdl6QgUxYZ1t/ITT0aFGs2FBqlo+FOAk3i33Asot34bRawRbshVaH85AmsPeeBlm125ulP Cmpw+g8YS2Fgg4Q9w43IBiHCV0npo8fPD9K/M0VUUCICSRNC5wNT8pDW07z9PAYJh9gK4sdmKqT7F aznI2258iYdh6xM4JpTb2u+cIN1Z/lD3VEMcCS5He+owgjY/4jNuy+1gzZEgmN7NwVNyAvesPP2kI BMT5f3fSqPRfG8I0il3bR6SQtevxf8oM1xUqrbPpV91+G5dj8+mbw3HusHvVGxmn3D79G/5X25JSS ev8cMOTh0rBL5jt5nMSA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nwLKb-00FBOL-OB; Wed, 01 Jun 2022 10:12:01 +0000 Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nwL12-00F3Ce-2A for barebox@lists.infradead.org; Wed, 01 Jun 2022 09:51:50 +0000 Received: from ptx.hi.pengutronix.de ([2001:67c:670:100:1d::c0]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1nwL0w-000422-1m; Wed, 01 Jun 2022 11:51:42 +0200 Received: from sha by ptx.hi.pengutronix.de with local (Exim 4.92) (envelope-from ) id 1nwL0v-0006QE-PP; Wed, 01 Jun 2022 11:51:41 +0200 Date: Wed, 1 Jun 2022 11:51:41 +0200 From: Sascha Hauer To: Ahmad Fatoum Cc: barebox@lists.infradead.org, lst@pengutronix.de Message-ID: <20220601095141.GZ1615@pengutronix.de> References: <20220531082914.1654316-1-a.fatoum@pengutronix.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220531082914.1654316-1-a.fatoum@pengutronix.de> X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-Accept-Language: de,en X-Accept-Content-Type: text/plain User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220601_025148_157253_41F78A72 X-CRM114-Status: GOOD ( 30.24 ) X-BeenThere: barebox@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" X-SA-Exim-Connect-IP: 2607:7c80:54:3::133 X-SA-Exim-Mail-From: barebox-bounces+lore=pengutronix.de@lists.infradead.org X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on metis.ext.pengutronix.de X-Spam-Level: X-Spam-Status: No, score=-3.8 required=4.0 tests=AWL,BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_NONE,T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.2 Subject: Re: [PATCH master v2] ARM: cpu: don't clobber sp when booted in HYP mode X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on metis.ext.pengutronix.de) On Tue, May 31, 2022 at 10:29:14AM +0200, Ahmad Fatoum wrote: > arm_cpu_lowlevel_init() is usually called first thing and will ensure > barebox runs in SVC mode. If barebox is started in HYP mode instead, > like is the case on Raspberry Pi 2-3, it will do an exception return > into SVC mode, which will bank the previously used SP_Hyp and > restore SP_Svc that may not have been properly initialized by barebox. > > This wasn't too bad so far, because arm_setup_stack was usually called > after arm_cpu_lowlevel_init, but with ENTRY_FUNCTION_WITHSTACK, SP is > initialized early on in the naked entry point with > arm_cpu_lowlevel_init() being called after that. > > This can lead to spurious boot hangs in the Raspberry Pi 2 and 3 entry > points. Fix this by always saving sp to r3 and restoring it, like we do > with lr. This is safe to do, because r3 isn't clobbered by any > instruction in arm_cpu_lowlevel_init() and because it's an argument > register, callers have to expect it being overwritten by the callee. > > Fixes: b267578d0567 ("ARM: rpi: use ENTRY_FUNCTION_WITHSTACK to prepare for ARM64 support") > Fixes: 41292192c01b ("ARM: safely switch from HYP to SVC mode if required") > Signed-off-by: Ahmad Fatoum > --- > v1 -> v2: > - add source code comment on why sp is saved (Sascha) > --- > arch/arm/cpu/lowlevel.S | 3 +++ > 1 file changed, 3 insertions(+) Applied, thanks Sascha > > diff --git a/arch/arm/cpu/lowlevel.S b/arch/arm/cpu/lowlevel.S > index 5a7dd3c2093f..960a92b78c0a 100644 > --- a/arch/arm/cpu/lowlevel.S > +++ b/arch/arm/cpu/lowlevel.S > @@ -9,6 +9,8 @@ > ENTRY(arm_cpu_lowlevel_init) > /* save lr, since it may be banked away with a processor mode change */ > mov r2, lr > + /* save sp, because possible HYP -> SVC transition below clobbers it */ > + mov r3, sp > > #ifdef CONFIG_CPU_32v7 > /* careful: the hyp install corrupts r0 and r1 */ > @@ -77,6 +79,7 @@ THUMB( orr r12, r12, #PSR_T_BIT ) > > mcr p15, 0, r12, c1, c0, 0 /* SCTLR */ > > + mov sp, r3 > mov pc, r2 > ENDPROC(arm_cpu_lowlevel_init) > > -- > 2.30.2 > > > _______________________________________________ > barebox mailing list > barebox@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/barebox > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox