From patchwork Mon Nov 13 17:42:33 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 13454257 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 686E7C4167D for ; Mon, 13 Nov 2023 17:44:19 +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:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=pvb8qKOwz4oZGAgqDD+e9PrxbA/d+WhsQN3rAP4y9PY=; b=H5LXJ/PYQFB7GU GA38PyH9j28lSIAawS0QN34Lx6J69V9xFj2/CPfvLCXb7o81pAzdEU013EhlkMm6aXTexSTsi0gGE BpbQuKaw1NSKiE1zuLNw5yNZvo4yWODSl5zkBdP+ll1IvJo1vR86X4U77y1QSRhQOx2wKqdvGmjop PzngHlbRY+/mG4k33hBg0mSiB4SxWb9WI4M5VebOzcFWVLQZs7vvKx8R5dLsAZE3aO9N9kPLVYf7F 3fGy2PGnQcpwhDK9lXyF1Wd9sOcjqlwox0k0iYgJCQCQMKMJ4D/1sJKO3bEKvj1+Ch4U0E9M6JWJH XCOkvTOfny+p4TGIMqiQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1r2ayb-00EQ8M-1o; Mon, 13 Nov 2023 17:43:57 +0000 Received: from sin.source.kernel.org ([2604:1380:40e1:4800::1]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1r2ayQ-00EPyw-1x for linux-arm-kernel@lists.infradead.org; Mon, 13 Nov 2023 17:43:49 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id EF199CE17C5; Mon, 13 Nov 2023 17:43:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 34441C433C7; Mon, 13 Nov 2023 17:43:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1699897424; bh=2/jpT2ThMNpF5uIulka4/RucBPTS/TEVnwOufL80Y8k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZdOCqQwwdfTo6fqv9v+Yq1poDjjMXq0ivHQPPjntOi4C2hUzE76Tyjzi+ytIGD86E 0AZadXivOc7KbvJwuPcEhYWnx5inBOGpvaPwz0n27Zm+jUdU6l7AyrhIbo8GklJl7P FH2hNngO75QJq2tmcBq15x3tmI7XV8/FlCnBNG9WuU19Esrycy/3M0LcHeL2rABh5K b1VBa0aIx+l7k2Uhec5SMjgugWbWH9hTbtwcVTmM3s9LU9QW/52vmbNsw4wPInWNLh c8ZeWKrcbzMHqo2zWebyUyDOJKfCiXwO/1Z8DAwhNHmDM6wscYltBlzG+YdU3U9Zhv gamOP6op30sEQ== Received: from sofa.misterjones.org ([185.219.108.64] helo=valley-girl.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1r2ayL-00CkQ4-Oy; Mon, 13 Nov 2023 17:43:42 +0000 From: Marc Zyngier To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev Cc: Catalin Marinas , Will Deacon , Mark Rutland , James Morse , Suzuki K Poulose , Oliver Upton , Zenghui Yu Subject: [PATCH 01/12] arm64: cpufeatures: Correctly handle signed values Date: Mon, 13 Nov 2023 17:42:33 +0000 Message-Id: <20231113174244.3026520-2-maz@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20231113174244.3026520-1-maz@kernel.org> References: <20231113174244.3026520-1-maz@kernel.org> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, catalin.marinas@arm.com, will@kernel.org, mark.rutland@arm.com, james.morse@arm.com, suzuki.poulose@arm.com, oliver.upton@linux.dev, yuzenghui@huawei.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231113_094346_990011_278711BD X-CRM114-Status: GOOD ( 18.15 ) 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 Although we've had signed values for some features such as PMUv3 and FP, the code that handles the comparaison with some limit has a couple of annoying issues: - the min_field_value is always unsigned, meaning that we cannot easily compare it with a negative value - it is not possible to have a range of values, let alone a range of negative values Fix this by: - adding an upper limit to the comparison, defaulting to all bits being set to the maximum positive value - ensuring that the signess of the min and max values are taken into account A ARM64_CPUID_FIELDS_NEG() macro is provided for signed features, but nothing is using it yet. Signed-off-by: Marc Zyngier --- arch/arm64/include/asm/cpufeature.h | 1 + arch/arm64/kernel/cpufeature.c | 66 +++++++++++++++++++++++++---- 2 files changed, 58 insertions(+), 9 deletions(-) diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index f6d416fe49b0..5f3f62efebd5 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -363,6 +363,7 @@ struct arm64_cpu_capabilities { u8 field_pos; u8 field_width; u8 min_field_value; + u8 max_field_value; u8 hwcap_type; bool sign; unsigned long hwcap; diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 646591c67e7a..e52d2c2b757f 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -140,12 +140,43 @@ void dump_cpu_features(void) pr_emerg("0x%*pb\n", ARM64_NCAPS, &system_cpucaps); } +#define __ARM64_EXPAND_RFV(reg, field, val) reg##_##field##_##val +#define __ARM64_MAX_POSITIVE(reg, field) \ + ((reg##_##field##_SIGNED ? \ + BIT(reg##_##field##_WIDTH - 1) : \ + BIT(reg##_##field##_WIDTH)) - 1) + +#define __ARM64_MIN_NEGATIVE(reg, field) BIT(reg##_##field##_WIDTH - 1) + +#define __ARM64_CPUID_FIELDS(reg, field, min_value, max_value) \ + .sys_reg = SYS_##reg, \ + .field_pos = reg##_##field##_SHIFT, \ + .field_width = reg##_##field##_WIDTH, \ + .sign = reg##_##field##_SIGNED, \ + .min_field_value = min_value, \ + .max_field_value = max_value, + +/* + * ARM64_CPUID_FIELDS() encodes a field with a range from min_value to + * an implicit maximum that depends on the sign-ess of the field. + * + * An unsigned field will be capped at all ones, while a signed field + * will be limited to the positive half only. + */ #define ARM64_CPUID_FIELDS(reg, field, min_value) \ - .sys_reg = SYS_##reg, \ - .field_pos = reg##_##field##_SHIFT, \ - .field_width = reg##_##field##_WIDTH, \ - .sign = reg##_##field##_SIGNED, \ - .min_field_value = reg##_##field##_##min_value, + __ARM64_CPUID_FIELDS(reg, field, \ + __ARM64_EXPAND_RFV(reg, field, min_value), \ + __ARM64_MAX_POSITIVE(reg, field)) + +/* + * ARM64_CPUID_FIELDS_NEG() encodes a field with a range from an + * implicit minimal value to max_value. This should be used when + * matching a non-implemented property. + */ +#define ARM64_CPUID_FIELDS_NEG(reg, field, max_value) \ + __ARM64_CPUID_FIELDS(reg, field, \ + __ARM64_MIN_NEGATIVE(reg, field), \ + __ARM64_EXPAND_RFV(reg, field, max_value)) #define __ARM64_FTR_BITS(SIGNED, VISIBLE, STRICT, TYPE, SHIFT, WIDTH, SAFE_VAL) \ { \ @@ -1470,11 +1501,28 @@ has_always(const struct arm64_cpu_capabilities *entry, int scope) static bool feature_matches(u64 reg, const struct arm64_cpu_capabilities *entry) { - int val = cpuid_feature_extract_field_width(reg, entry->field_pos, - entry->field_width, - entry->sign); + int val, min, max; + u64 tmp; + + val = cpuid_feature_extract_field_width(reg, entry->field_pos, + entry->field_width, + entry->sign); + + tmp = entry->min_field_value; + tmp <<= entry->field_pos; + + min = cpuid_feature_extract_field_width(tmp, entry->field_pos, + entry->field_width, + entry->sign); + + tmp = entry->max_field_value; + tmp <<= entry->field_pos; + + max = cpuid_feature_extract_field_width(tmp, entry->field_pos, + entry->field_width, + entry->sign); - return val >= entry->min_field_value; + return val >= min && val <= max; } static u64