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 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 6FD49C79FB7 for ; Wed, 9 Sep 2026 18:36:54 +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:References:In-Reply-To: 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=9KlLYx45q9tnM5bI/B+8+XYM58Fhf36COCL6TmYxM1Q=; b=ZC1sgyBF8eGQMZ xoDCvmqmtNxzoS/15guygIn6w9p9icPydOQnoOXUgCYjRV4YUvma8eGcMY/B0qvvGNU5Eo9kSmcso R/LKpB4jQnWNsElNwfMJ/vEfGmtDNsS32tU9gQpOCEXzJDusgPX/5V7sQFOJ6TfpnI3AjOzN6sG5J +9W4gD8X1maPNN1FPaXobnURN7Ufb7dX5YBlU6E0w3cqhpc1X++eRD0r6h96Dtq8iqNgHcSCVzSjl MZELUqho7xmShwC3StnoXcmrzm0G4eWhCuNLriTbfbVjeH0qGObahcOyCMKBodpFt/QDmuHEmDBeV SyzEeKc0Tf/Ty4I5MCTw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x4N9x-0000000Cchr-0nsD; Wed, 09 Sep 2026 18:36:37 +0000 Received: from mx0a-0031df01.pphosted.com ([205.220.168.131]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x4N9u-0000000Cch0-0NkD for linux-riscv@lists.infradead.org; Wed, 09 Sep 2026 18:36:35 +0000 Received: from pps.filterd (m0279867.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 689H7T6S3716347 for ; Wed, 9 Sep 2026 18:36:33 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=qualcomm.com; h= cc:content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=qcppdkim1; bh= mIQgohTE2rOvQzNapNCth9eVCnLrSjsevoHbhxyKhm8=; b=f9fHyVhIBtdv6EUr DlNghKVHtEJRyrLKeXFDlVLXSO1UAA+Yn7hGbI1f0UYI1DNCkSV2lKeExYYLGD6g CSPcVJVcKhiTXh+Xxk/ETQTYTWiD579T5wEStNDRoul/rvzTnmVWP+boZ79lxeYB FXY6hC14K1DEc4aUkeAYYXllFrx0NuolQS0A1f6pVA4SDRMZaY7G+8AWxlJU+/m5 q6QTEC2o3J+6eOxTUhYEmqbFUC7PKOZIsJUYrpGkhwey7ynH8YGPR2uJl30S6bXj 1vlfmR5qjsJ07tSDg2GrWJP2dkDKKKIPmCtHs7DDLTuwk43KCYv1lOSTaNjljB4R hLNSRA== Received: from mail-pj1-f71.google.com (mail-pj1-f71.google.com [209.85.216.71]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 4gk7921wrb-1 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NOT) for ; Wed, 09 Sep 2026 18:36:33 +0000 (GMT) Received: by mail-pj1-f71.google.com with SMTP id 98e67ed59e1d1-39512608fb1so12946654a91.1 for ; Wed, 09 Sep 2026 11:36:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oss.qualcomm.com; s=google; t=1788978993; x=1789583793; darn=lists.infradead.org; h=content-transfer-encoding:content-type:mime-version:organization :references:in-reply-to:message-id:subject:cc:to:from:date:from:to :cc:subject:date:message-id:reply-to:content-type; bh=mIQgohTE2rOvQzNapNCth9eVCnLrSjsevoHbhxyKhm8=; b=RT64gjgs8fGKdbNLywcGPXNjleYktlN9/4agdOcUjCZ4zUlVZDPkGLYmpANnKui7Y0 DX8FHf+G0TpRYLmC2tYNjbQaS6iKHGpvR4n33gKBnQ7vRE8KKIOzr+huvuZ1eOX2Rjhv B6doh3PIRLv1F7l46C4bCmK04274XW6SDNkpQDXgg+IpRNxIsIzfkS4/kZ58nNON0NVK 5xsKajZOloIeNwu3/FCQIGCJnX1Ike6ze5+tq3FJCv4HMBUqI4HpTAGOIiw5SKyXUJuR z/UlAuSo3ZtuYIfMIU9EJvXXiWk208U+gXiVIsajnJPGJ4oNFxnyxIRJ9uelEKfHROQx lc4Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1788978993; x=1789583793; h=content-transfer-encoding:content-type:mime-version:organization :references:in-reply-to:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=mIQgohTE2rOvQzNapNCth9eVCnLrSjsevoHbhxyKhm8=; b=hYIGuOijufL3AmpaEzRit9Fmj0xmeVlZIbcxZT7OmwyS8tjJKomHnwnXZLJvV+PU+P F43LKX6UuMG+/UlhqHCB88dlIGsplWw39hKD4M3sAdDg1YMYqwAnu+qWEIILsJy1jwAn sdPQqBt+lARGcJUI0o4qhUHlaphJMlh8PezK7AL4YYspABfNYATjSMCoGI/nIBE7v3Sm hoF8gNcb5oAhv1No6ku7ks045+9lpA1fcGpEOuDMYw1HS9xZ50WWt1zSNswPx/3xuwuD gv1v+QkLfmGEgKEdGf7wf7oVg2to7TNvfgrkUIJxTGrj2wwZ7Mpq2kh1OEPptOw9QT59 ammA== X-Forwarded-Encrypted: i=1; AKwUvBwNGPd1btMXk/eNAmy2nnnTWVyeXpMdSHy2TolUzCOb4VGM7xEJzAfxEOy+rtnfDEBV28I3zd8q10lmGA==@lists.infradead.org X-Gm-Message-State: AFuF++lhODT81ibyf9EnK2I4wGx73neJPkHaLFneox1clryQ7xgT6VW3 VHiqI8baDdq8FEXr4Md1XZp9ViDl73ljrplJw+PMUNBsoZqEj3Sxkc3Xlli8vdfUH+q+k/OYn+u 0tZV/yXWvDVRAHTSxw61gYVNvnr1qazErPLIG4ufVVTFWSGFYZwwbTbEnGjFl+DBEwegkrXk= X-Gm-Gg: AYBFou0MIy2hN34S/wk3j6lgkIah8Igvo5RMtmGhYX5YBMfQ/I7cSbpl8KeX0gtxg1h g1oKQRlGs0zwVyl5hH+LR+pLI9o6PBVheKZOuxqwCM+04gHstrYdLEHL1/Unjv/8rJZyXP2JBVC 0XHjCw0HpnJ/+5vPZDSQae+STWu52Dz9rAGaEmm6eFdOBq8nb4qWxjP9UVijerCnAypngeAy5PT WyjWr+1I6/00OBr4bqixvBIvugp2MJ9UBIZ32mdTgNUTaDNXyIgfQXoi8Bmuz9uXHT5FLmHZ89W zBM4FTfQD/rfR7M/CbiWo4+dMuhOM16aurJSOmweMWxNzuM5C39jP/IzUS/kFVpYqiQnVMqxxKT 8aMIIeLyVDVo44ppQbuFaTPOl/6M= X-Received: by 2002:a17:90b:1d4f:b0:398:9be5:b417 with SMTP id 98e67ed59e1d1-39b26221eb1mr53821143a91.18.1788978992923; Wed, 09 Sep 2026 11:36:32 -0700 (PDT) X-Received: by 2002:a17:90b:1d4f:b0:398:9be5:b417 with SMTP id 98e67ed59e1d1-39b26221eb1mr53821108a91.18.1788978992503; Wed, 09 Sep 2026 11:36:32 -0700 (PDT) Received: from localhost ([50.35.44.179]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-1433171a97esm50371041c88.12.2026.09.09.11.36.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 09 Sep 2026 11:36:31 -0700 (PDT) Date: Wed, 9 Sep 2026 11:36:25 -0700 From: Jonathan Cameron To: Oleg Keri Cc: Catalin Marinas , Will Deacon , Mark Rutland , Beata Michalska , Sumit Gupta , Prasanna Kumar T S M , Russell King , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Sudeep Holla , Greg Kroah-Hartman , "Rafael J. Wysocki" , Danilo Krummrich , Viresh Kumar , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, driver-core@lists.linux.dev, linux-pm@vger.kernel.org Subject: Re: [PATCH v1 1/2] arm64: topology: fix arch_freq_get_on_cpu() overflow above 4.19 GHz Message-ID: <20260909113625.000063be@oss.qualcomm.com> In-Reply-To: <08ee55292c1cedf26067d1a2b02fa5657d9650e8.1788712186.git.okerixx@gmail.com> References: <08ee55292c1cedf26067d1a2b02fa5657d9650e8.1788712186.git.okerixx@gmail.com> Organization: Qualcomm X-Mailer: Claws Mail 4.4.0 (GTK 3.24.51; x86_64-w64-mingw32) MIME-Version: 1.0 X-Authority-Analysis: v=2.4 cv=bd1bluPB c=1 sm=1 tr=0 ts=6aa1a731 cx=c_pps a=UNFcQwm+pnOIJct1K4W+Mw==:117 a=aNnz9XPx1a4JIXSYt2cE/A==:17 a=kj9zAlcOel0A:10 a=VdqzKS8jKosA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=eoimf2acIAo5FJnRuUoq:22 a=pGLkceISAAAA:8 a=vZYCpiARan6kKAuTxo4A:9 a=CjuIK1q_8ugA:10 a=uKXjsCUrEbL0IQVhDsJ9:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTA5MDIwOCBTYWx0ZWRfXyMgWHcCoaJmR SrBvcobWTYRdbWSvHKVpC6mHg3FpHcl7XedOq5EUbzH5h4+BOtgBR1gdDGhd7qqkZPGkKppWmQ9 aZgcYuKSO09lb9kq39m4arFpXaZEp5d0G8tXrWrEcJ05yHmUVdgcS74VOfTu2ihorf2DFvJ5z15 xMpO1BhH+wmRD3jKxnTxNEIuWYt54NYHabcSdV6hqkO0/oVIktHLDgYwHxkISVSJviEsMm9tjZ5 V7ovOW3sRKuVU4z5HNFK+xXT3yybBv8w5Kdptbi18qT5YqWyMaB7EIVBEUUilZZnBvYsmvp0aVm wo+/S2S2h0ZfyTYnrnRBj37DYfU6jWwPZ1ACNnTkurdYS8GS0pWOMirLxM8TxpJ7803T0fbJP/M 0H+brbvdWv2lsDumyDzj0ooycCna2Ds3D+yOW29J0AdK+lGqdsLe4VRg676VHYB7QdfJlJMBqFC wrvyB41i3Z5n344sffA== X-Proofpoint-ORIG-GUID: MH8kBZFCg0FwNjCReyPuJs9omq42Skcm X-Proofpoint-Spam-Info: AW1haW4tMjYwOTA5MDIwOCBTYWx0ZWRfXxDnCdwAu1T+w 3tBLOPMEHRuae/fBOJ2yfhTlS49U09XS3f56TojWpbVvUnG4/mEjMfe/r+e4iL1JvyFXuOuhU2X mB+17zN/FY+AbBhC/BrEuDohdFmNsBk= X-Proofpoint-GUID: MH8kBZFCg0FwNjCReyPuJs9omq42Skcm X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-08_03,2026-09-09_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 clxscore=1011 spamscore=0 lowpriorityscore=0 suspectscore=0 bulkscore=0 impostorscore=0 phishscore=0 priorityscore=1501 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2609090208 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260909_113634_147990_08F0FE7C X-CRM114-Status: GOOD ( 24.04 ) X-BeenThere: linux-riscv@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: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Sun, 6 Sep 2026 18:37:14 +0200 Oleg Keri wrote: > arch_freq_get_on_cpu() computes the product of the frequency scale and > the reference frequency as a u64, but assigns it to an unsigned int > before shifting it back down: > > freq = scale * arch_scale_freq_ref(cpu); > freq >>= SCHED_CAPACITY_SHIFT; > > The product is truncated to 32 bits before the shift, so the result > wraps once arch_scale_freq_ref() exceeds 2^32 / SCHED_CAPACITY_SCALE, > i.e. 4194304 kHz. > > On a Snapdragon X2 Elite (Glymur) laptop, whose boost OPP is 4723200 > kHz, cpuinfo_avg_freq reports 524283 kHz instead of ~4723200 kHz while > the CPU demonstrably runs at the boost frequency: a fixed workload > completes in 1.72 s at the 4723200 kHz OPP versus 2.01 s at 4032000 > kHz, matching the 1.171 frequency ratio. > > Keep the arithmetic in 64 bits until after the shift. > > Fixes: 16d1e27475f6 ("arm64: Provide an AMU-based version of arch_freq_get_on_cpu") > Signed-off-by: Oleg Keri > --- > arch/arm64/kernel/topology.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c > index d28438f8b83f..804758eeb63a 100644 > --- a/arch/arm64/kernel/topology.c > +++ b/arch/arm64/kernel/topology.c > @@ -245,8 +245,9 @@ int arch_freq_get_on_cpu(int cpu) > * (see amu_scale_freq_tick for details) > */ > scale = arch_scale_freq_capacity(cpu); > - freq = scale * arch_scale_freq_ref(cpu); > - freq >>= SCHED_CAPACITY_SHIFT; > + scale *= arch_scale_freq_ref(cpu); > + scale >>= SCHED_CAPACITY_SHIFT; Maybe just do it all one line? freq = (scale * arch_scale_freq_ref(cpu)) >> SCHED_CAPACITY_SHIFT; I was going to suggest that you roll in the arch_scale_freq_capacity() as well but then we'd need a cast to ensure maths was done in 64 bits and that was uglier. I think this should end up the same as what you have. Thanks, Jonathan > + freq = scale; > return freq; > } > _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv