[{"id":1780800,"web_url":"http://patchwork.ozlabs.org/comment/1780800/","msgid":"<0136d727-d125-7eed-ca13-02011cbdf921@linaro.org>","list_archive_url":null,"date":"2017-10-05T16:32:27","subject":"Re: [Qemu-devel] [PATCH 08/20] target/arm: Don't warn about\n\texception return with PC low bit set for v8M","submitter":{"id":72104,"url":"http://patchwork.ozlabs.org/api/people/72104/","name":"Richard Henderson","email":"richard.henderson@linaro.org"},"content":"On 09/22/2017 10:59 AM, Peter Maydell wrote:\n> + if ((env->regs[15] & 1) && !arm_feature(env, ARM_FEATURE_V8)) {\n> qemu_log_mask(LOG_GUEST_ERROR,\n> \"M profile return from interrupt with misaligned \"\n> - \"PC is UNPREDICTABLE\\n\");\n> - /* Actual hardware seems to ignore the lsbit, and there are several\n> - * RTOSes out there which incorrectly assume the r15 in the stack\n> - * frame should be a Thumb-style \"lsbit indicates ARM/Thumb\" value.\n> - */\n> - env->regs[15] &= ~1U;\n> + \"PC is UNPREDICTABLE on v7M\\n\");\n> }\n> + env->regs[15] &= ~1U;\n\nIf you're going to always test regs[15] & 1, you might as well use that and\navoid an unlikely(?) writeback.\n\n if (env->regs[15] & 1) {\n if (!arm_feature(env, ARM_FEATURE_V8)) {\n qemu_log_mask(...);\n }\n env->regs[15] &= ~1U;\n }\n\nOtherwise,\nReviewed-by: Richard Henderson \n\n\nr~","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@bilbo.ozlabs.org","Authentication-Results":["ozlabs.org;\n\tspf=pass (mailfrom) smtp.mailfrom=nongnu.org\n\t(client-ip=2001:4830:134:3::11; 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a=rsa-sha256; c=relaxed/relaxed;\n\td=1e100.net; s=20161025;\n\th=x-gm-message-state:subject:to:cc:references:from:message-id:date\n\t:user-agent:mime-version:in-reply-to:content-language\n\t:content-transfer-encoding;\n\tbh=dZtZ+pq1KvrbsVgI/NZKeWWzBySnlwXux5fNRF87+vY=;\n\tb=KfqT3UZTAS6rCZZa3OgiHIZC458HaTbG7tZjvaxEDfoZOuFagG5AWCN7Vdz3aMT6at\n\ty1CnPjFc5DG5VPOS8eMRdI7kxq/UThf1pi+0Ff8Jmr0/+CnzLV7MyBKKHA9GG2DidbwT\n\toyClsLvwvQ3gTM6XCdCqZrHxEi6BAH4R5iXqM5g8iOlgW4vOO+aaM5gJnPlb29LaglI6\n\tZ+xy0DFfvl5SSh1QwCfWZosmd7XZTsAkEqPxoBIM4gJZeYJt4FDF5p+wb/npOTVHVs4W\n\t4VQZM9dL1xvmrRVoDsz3ItFjb6sKJJ0gk4OV62QTw5fjcdEajL3WtUabNa8hqrIdDLdO\n\tPWkw==","X-Gm-Message-State":"AHPjjUg2In5GtM7F2lPC8pY50qGjEKjH5TlG6mP7Iho27yMmvf7OgjNx\n\teNIiAWItBKm7nFF0gVX3pjrUyQ==","X-Google-Smtp-Source":"AOwi7QDXacInP8t7UFRdYvc86GLkm8gJZCtyFH7OL3FLkIc70T7yRQ6zYuW+mnWPW3tMUzQrRmLIsQ==","X-Received":"by 10.129.232.1 with SMTP id a1mr20684301ywm.34.1507221149988;\n\tThu, 05 Oct 2017 09:32:29 -0700 (PDT)","To":"Peter Maydell , qemu-arm@nongnu.org,\n\tqemu-devel@nongnu.org","References":"<1506092407-26985-1-git-send-email-peter.maydell@linaro.org>\n\t<1506092407-26985-9-git-send-email-peter.maydell@linaro.org>","From":"Richard Henderson ","Message-ID":"<0136d727-d125-7eed-ca13-02011cbdf921@linaro.org>","Date":"Thu, 5 Oct 2017 12:32:27 -0400","User-Agent":"Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101\n\tThunderbird/52.3.0","MIME-Version":"1.0","In-Reply-To":"<1506092407-26985-9-git-send-email-peter.maydell@linaro.org>","Content-Type":"text/plain; charset=utf-8","Content-Language":"en-US","Content-Transfer-Encoding":"7bit","X-detected-operating-system":"by eggs.gnu.org: Genre and OS details not\n\trecognized.","X-Received-From":"2607:f8b0:400d:c0d::233","Subject":"Re: [Qemu-devel] [PATCH 08/20] target/arm: Don't warn about\n\texception return with PC low bit set for v8M","X-BeenThere":"qemu-devel@nongnu.org","X-Mailman-Version":"2.1.21","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Cc":"patches@linaro.org","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"\"Qemu-devel\"\n\t"}},{"id":1780817,"web_url":"http://patchwork.ozlabs.org/comment/1780817/","msgid":"<4aa8a101-7de4-43d5-716a-b188a7190277@linaro.org>","list_archive_url":null,"date":"2017-10-05T16:34:53","subject":"Re: [Qemu-devel] [PATCH 08/20] target/arm: Don't warn about\n\texception return with PC low bit set for v8M","submitter":{"id":72104,"url":"http://patchwork.ozlabs.org/api/people/72104/","name":"Richard Henderson","email":"richard.henderson@linaro.org"},"content":"On 10/05/2017 12:32 PM, Richard Henderson wrote:\n> if (env->regs[15] & 1) {\n> if (!arm_feature(env, ARM_FEATURE_V8)) {\n> qemu_log_mask(...);\n> }\n> env->regs[15] &= ~1U;\n> }\n\nBah. Even better to move the bit clear statement before the feature check.\nThe two loads from env->regs[15] will no longer be separated by a function call\nand therefore CSEd by the compiler.\n\n\nr~","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@bilbo.ozlabs.org","Authentication-Results":["ozlabs.org;\n\tspf=pass (mailfrom) smtp.mailfrom=nongnu.org\n\t(client-ip=2001:4830:134:3::11; helo=lists.gnu.org;\n\tenvelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org;\n\treceiver=)","ozlabs.org; dkim=pass (1024-bit key;\n\tunprotected) header.d=linaro.org header.i=@linaro.org\n\theader.b=\"AmIUg2EM\"; dkim-atps=neutral"],"Received":["from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11])\n\t(using TLSv1 with cipher AES256-SHA (256/256 bits))\n\t(No client certificate requested)\n\tby ozlabs.org (Postfix) with ESMTPS id 3y7JkK0jdFz9t3C\n\tfor ;\n\tFri, 6 Oct 2017 03:53:29 +1100 (AEDT)","from localhost ([::1]:40926 helo=lists.gnu.org)\n\tby lists.gnu.org with esmtp (Exim 4.71) (envelope-from\n\t)\n\tid 1e09Op-0001fn-5I\n\tfor incoming@patchwork.ozlabs.org; Thu, 05 Oct 2017 12:53:27 -0400","from eggs.gnu.org ([2001:4830:134:3::10]:49312)\n\tby lists.gnu.org with esmtp (Exim 4.71)\n\t(envelope-from ) id 1e096v-00031s-Tl\n\tfor qemu-devel@nongnu.org; Thu, 05 Oct 2017 12:34:58 -0400","from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)\n\t(envelope-from ) id 1e096u-0004gi-VP\n\tfor qemu-devel@nongnu.org; Thu, 05 Oct 2017 12:34:57 -0400","from mail-qt0-x22a.google.com ([2607:f8b0:400d:c0d::22a]:45907)\n\tby eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16)\n\t(Exim 4.71) (envelope-from )\n\tid 1e096u-0004gJ-S1\n\tfor qemu-devel@nongnu.org; Thu, 05 Oct 2017 12:34:56 -0400","by mail-qt0-x22a.google.com with SMTP id k1so15487516qti.2\n\tfor ; Thu, 05 Oct 2017 09:34:56 -0700 (PDT)","from bigtime.twiddle.net ([2606:a000:7a4a:b100::1b])\n\tby smtp.gmail.com with ESMTPSA id\n\ts127sm6738034ywc.49.2017.10.05.09.34.55\n\t(version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128);\n\tThu, 05 Oct 2017 09:34:55 -0700 (PDT)"],"DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google;\n\th=subject:from:to:cc:references:message-id:date:user-agent\n\t:mime-version:in-reply-to:content-language:content-transfer-encoding; \n\tbh=S4JPJsr/3Y0s2D9U0e1gsZZPNPmdppNkGXs9CmLE6I0=;\n\tb=AmIUg2EM1ZVgr2V3qWgBWhrQT27S1ilIqXfg5UI4DJI7IeARBrZmmeyl3pseKkJfaM\n\tBrA52yWFc/YeS65+Ki/K74BZtEWiyx+2CyITNC/nI/BOiZ88E0MZcRBMCGWxZa1Bquxr\n\ttUIgwfib2ss3EZhWkWK3OSA/yrd3Ys6w/ehcE=","X-Google-DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed;\n\td=1e100.net; s=20161025;\n\th=x-gm-message-state:subject:from:to:cc:references:message-id:date\n\t:user-agent:mime-version:in-reply-to:content-language\n\t:content-transfer-encoding;\n\tbh=S4JPJsr/3Y0s2D9U0e1gsZZPNPmdppNkGXs9CmLE6I0=;\n\tb=jhmYnYV2A3tfxLuU0133MiYnBPVoViQl/1vlNu6bGmD2kStesk5gWd98XfoOZXJK1W\n\tODCybcK1vQNlnpcjkeET2eo8CJixnWQuJMPqiG/xBKYmOxDobIkEuL1NMdKeQ1UIoQ/y\n\t93GMIDcedqbec7gaoUSFINoBdZODGjZMCEg3U4iYywAvLnl4ydZJJ8rwOn3FY67FZ5ut\n\tA3WPBLnoRSXkHZ5hEyuaeIXe9z8CgcXpAl2NLg4ktDqXdb5L00vVTon53bueIq51XuLs\n\t8HmzFizrjKu1uxE6fbnsy7chNolpzoRYugxIkChFDSS7N5ofnbR6uxBJHS8zCT3p4C2Q\n\tnUOg==","X-Gm-Message-State":"AMCzsaXQmWl1s4K8EzwHePCaFzAwBmOmHdLxACasxLPYFupjUIX95Xwb\n\tpCqDqE0U22cuClTC8nXAr3AnFw==","X-Google-Smtp-Source":"AOwi7QD+rjIVwHTsY4PiZpcM4T+64PX6sGq+OiZaP6CM3AklZBVnxIR8fQChJl1fucY9+gDn+9HETw==","X-Received":"by 10.129.60.4 with SMTP id j4mr1184758ywa.353.1507221296314;\n\tThu, 05 Oct 2017 09:34:56 -0700 (PDT)","From":"Richard Henderson ","To":"Peter Maydell , qemu-arm@nongnu.org,\n\tqemu-devel@nongnu.org","References":"<1506092407-26985-1-git-send-email-peter.maydell@linaro.org>\n\t<1506092407-26985-9-git-send-email-peter.maydell@linaro.org>\n\t<0136d727-d125-7eed-ca13-02011cbdf921@linaro.org>","Message-ID":"<4aa8a101-7de4-43d5-716a-b188a7190277@linaro.org>","Date":"Thu, 5 Oct 2017 12:34:53 -0400","User-Agent":"Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101\n\tThunderbird/52.3.0","MIME-Version":"1.0","In-Reply-To":"<0136d727-d125-7eed-ca13-02011cbdf921@linaro.org>","Content-Type":"text/plain; charset=utf-8","Content-Language":"en-US","Content-Transfer-Encoding":"7bit","X-detected-operating-system":"by eggs.gnu.org: Genre and OS details not\n\trecognized.","X-Received-From":"2607:f8b0:400d:c0d::22a","Subject":"Re: [Qemu-devel] [PATCH 08/20] target/arm: Don't warn about\n\texception return with PC low bit set for v8M","X-BeenThere":"qemu-devel@nongnu.org","X-Mailman-Version":"2.1.21","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Cc":"patches@linaro.org","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"\"Qemu-devel\"\n\t"}}]