From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f47.google.com (mail-wm1-f47.google.com [209.85.128.47]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F1BBB3BB670 for ; Wed, 9 Sep 2026 19:24:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.47 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788981853; cv=none; b=NrNa/KWMorW9uyPCf6cdb536UicrU1XWPG34dOkpoFagxlH0kZlzHXLb+M7ZFPeX1B7xOh1pQQE43tfTlqaP6TVn56g6222hEH8mfKrNym3h6e49FniFgZKOK6fy/16hu9UgPdjpz4VTl8i8/pgFg0lRyBsqCbqKftVuTGG1jHo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788981853; c=relaxed/simple; bh=PDEEd+kGUpRFDlfoMHUOW7eU3z/kpzEs0Dmls+E8O2E=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=PNFgN6P2+j8DvxVQ7L1eEos7IwydZU7Z5LaUua9UmdxFGDwMntkgHKlBakKbRV6cW3Yfau3lFhDVjugrcEnnvXSrTBubkJuketYRDLvCRoT6rpKtrOyJAaqAX7l9MGriaOJjALronetkALzVLw/Svl2kF6e4fK1bgB7IT+72axs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=g7df07NM; arc=none smtp.client-ip=209.85.128.47 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="g7df07NM" Received: by mail-wm1-f47.google.com with SMTP id 5b1f17b1804b1-498028b3d5eso59534665e9.1 for ; Wed, 09 Sep 2026 12:24:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1788981850; x=1789586650; darn=lists.linux.dev; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=ZYBzWSPZN1Lxcn6Xbnnk/C2mw1GBteCvVQmx0ay5t+A=; b=g7df07NMg+YBruKXOnRf3n61adLOqPSLlxHRpgKMgROlfwM6Z9V1m5G0iXGKeJgT75 g/QcRJDDOeW6UUmkSP3beLhNBsevrmNtHU8l6v9M7KtC1aVoeX0RFh+Evnjj38b0eELj bNNvrwJMer3XKb2yKvl9AUf/6w0uy0VKVJEXill/uhkiEDmypp6IqCBMQJAI9a5RwzxV NZHi01tB0yTQ9p2mhn326lTM6OdvMyJmjAJwcTSslFhnQWN2XZxW7K0Pjc57O9KEX0mw uFP1vm5spOSfvhzUUNKeWHCjGttmjBHEYj2YPcEozvKHhv1qaMZqS6Zm6g2rXS4t3oDU kT2g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1788981850; x=1789586650; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=ZYBzWSPZN1Lxcn6Xbnnk/C2mw1GBteCvVQmx0ay5t+A=; b=sr6fITKTGhr7BFsdO9Wn8zXhwbbjwR+0Tb0bMMvwhHwCljbop6NVZACCgkc/zW4WXM KzcQjryLu5sQgmPu9Hlw0fgL5vJcdyazWaXC84e4Q2sRZUBeTp+tEIgMjq2tMvn40DDg 1CC2GdbnU24loDguvcPUSHGpeLIWUqfbzjIEXvLBZ2Zy381kzt/o4k8nLAVUP+/NKLqM utRia8OfMQouj5vR5YJlZUtQ3sQbvhFTL+oC15DrV5YvYV8BxfqVcE/4ZGmLAjIdAPKL mAbST2q5PLKDtp3o+/pOprXvBPdlq5BgL3MhOmq5GJGhEqDoZlCWvIQgQ40Y3ETss+uC oBCg== X-Forwarded-Encrypted: i=1; AKwUvBzDpe8UFE7KI4lo0pI3WyrNJlZtv5MmVRjLy+x4gZbfHbGvSpSzUaHR+tg/RQ12/gyyRtxbtfAma6221A==@lists.linux.dev X-Gm-Message-State: AFuF++mB8Tr8HYspCsEQf3gORSL8wOaSA2kzePpeWxnlzEJVyEVOnKTB rje/sr6kHlxe6CXyqSD71vh9a1Quy7hCgD5y32cTrIalRAbxzTyJbnzf X-Gm-Gg: AYBFou257NgXOLSbevUpmgmDGxbDuVC1EravaKt1DYhLLTWkoWziBmKm5t9/hFF/Gv6 oSXA74JD3rZ9IbbVLmwUyZ0u9t7cZSVdhXq7l8nZjbR9PbBrr5e/zDGFknKkfI7Qb+02+8jd4et t7Zovzr7VflSF2sH9uKWoIvEFgdhOyr4iCxE2kicW3XymbQEM6Lr2K+ny2EJDG5/LJfLqW3WKxW fTvng0BTNBVihVNzPOBiFIDrPSUctdKgiL7LQhh3pwvt/Dng71cdLmS3ypgviWHFd4aScAZnAik B/iMVKYFdu5JKKFrLsp7UmJaG7j+2cpGfhJrhDPZB6ivVNdUIxhNbOkds9HjaxV2uiNfX3ZEF7m 339y1xLwU5qt60cgpzUyB2bXT3rw9CmAhhcegw/nXvE94N5eVE02DV2SA7Weh47CAImRiJo/MSt a4JiUtJbOerm8wlBnZQUdLyff4S+bu9oXJ2841NW1kvE32m4VD+sKA407kaVQytJG623CV/5tND rdNahxQU8i6bdbQLhFlhDAjb+oivo72XlF1As3FTT0= X-Received: by 2002:a05:600c:4e8f:b0:49d:4ef:bf70 with SMTP id 5b1f17b1804b1-49d04efc043mr282755995e9.10.1788981849957; Wed, 09 Sep 2026 12:24:09 -0700 (PDT) Received: from localhost.localdomain (mob-31-26-103-238.net.vodafone.it. [31.26.103.238]) by smtp.googlemail.com with ESMTPSA id 5b1f17b1804b1-49d26bf9490sm10925625e9.9.2026.09.09.12.24.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 09 Sep 2026 12:24:07 -0700 (PDT) From: Oleg Keri To: Catalin Marinas , Will Deacon , Mark Rutland , Sumit Gupta , Beata Michalska , 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 Cc: 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, Jonathan Cameron Subject: [PATCH v2 1/2] arm64: topology: fix arch_freq_get_on_cpu() overflow above 4.19 GHz Date: Wed, 9 Sep 2026 21:23:50 +0200 Message-ID: <20260909192351.33910-2-okerixx@gmail.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260909192351.33910-1-okerixx@gmail.com> References: <20260909192351.33910-1-okerixx@gmail.com> Precedence: bulk X-Mailing-List: driver-core@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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") Suggested-by: Jonathan Cameron Signed-off-by: Oleg Keri --- arch/arm64/kernel/topology.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c index d28438f8b83f..0eca321ff113 100644 --- a/arch/arm64/kernel/topology.c +++ b/arch/arm64/kernel/topology.c @@ -245,8 +245,7 @@ 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; + freq = (scale * arch_scale_freq_ref(cpu)) >> SCHED_CAPACITY_SHIFT; return freq; } -- 2.55.0