From patchwork Tue Sep 19 09:28:27 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 13391032 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 B5A10CD54AB for ; Tue, 19 Sep 2023 09:30:29 +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=iufHQ2tjAE1JN4nmcTqKwzCmrqslpVfmk0od4HKYaNE=; b=3kGCldMK+y8Hhe I7ERecayA1sk8v8D3Q74Hk6NJvqX9CPKdr4xPozeu/wbw93xAMIMfI8emfzvnkmDvc5dXxQNTVnny VHI9ysQkLg+kwPeiwDFBydoGLpvhFUc5moSr7lC6Kg40ytTHaWji6cAX1mtZEwCsi4z1pcPEKT/T9 WhygbwuzflxpGKaNUhbgA20NWJO9OYPKyt0Ipi0yPIgZNDVT6QEFu/6VY5D5jaDM/M7ppXhJU+UR4 yu7Ou9+b7zHhvh8YUyDd68hUmtRqStfHAjBspVkceiTuR9fwW4mtGCtBGzI51M9o1S5ocWc3yCBC9 zjiAU1IzIVPz1hC7ugFw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qiX3V-00HT6o-0A; Tue, 19 Sep 2023 09:30:05 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qiX3F-00HSuc-21 for linux-arm-kernel@lists.infradead.org; Tue, 19 Sep 2023 09:29:51 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6CAB81FB; Tue, 19 Sep 2023 02:30:26 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id EB6CD3F59C; Tue, 19 Sep 2023 02:29:46 -0700 (PDT) From: Mark Rutland To: linux-arm-kernel@lists.infradead.org Cc: ardb@kernel.org, bertrand.marquis@arm.com, boris.ostrovsky@oracle.com, broonie@kernel.org, catalin.marinas@arm.com, daniel.lezcano@linaro.org, james.morse@arm.com, jgross@suse.com, mark.rutland@arm.com, maz@kernel.org, oliver.upton@linux.dev, pcc@google.com, sstabellini@kernel.org, suzuki.poulose@arm.com, tglx@linutronix.de, vladimir.murzin@arm.com, will@kernel.org Subject: [PATCH 14/37] arm64: Avoid cpus_have_const_cap() for ARM64_HAS_ARMv8_4_TTL Date: Tue, 19 Sep 2023 10:28:27 +0100 Message-Id: <20230919092850.1940729-15-mark.rutland@arm.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20230919092850.1940729-1-mark.rutland@arm.com> References: <20230919092850.1940729-1-mark.rutland@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230919_022949_709280_FB53DA24 X-CRM114-Status: GOOD ( 17.95 ) 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 In __tlbi_level() we use cpus_have_const_cap() to check for ARM64_HAS_ARMv8_4_TTL, but this is not necessary and alternative_has_cap_*() would be preferable. For historical reasons, cpus_have_const_cap() is more complicated than it needs to be. Before cpucaps are finalized, it will perform a bitmap test of the system_cpucaps bitmap, and once cpucaps are finalized it will use an alternative branch. This used to be necessary to handle some race conditions in the window between cpucap detection and the subsequent patching of alternatives and static branches, where different branches could be out-of-sync with one another (or w.r.t. alternative sequences). Now that we use alternative branches instead of static branches, these are all patched atomically w.r.t. one another, and there are only a handful of cases that need special care in the window between cpucap detection and alternative patching. Due to the above, it would be nice to remove cpus_have_const_cap(), and migrate callers over to alternative_has_cap_*(), cpus_have_final_cap(), or cpus_have_cap() depending on when their requirements. This will remove redundant instructions and improve code generation, and will make it easier to determine how each callsite will behave before, during, and after alternative patching. In the window between detecting the ARM64_HAS_ARMv8_4_TTL cpucap and patching alternative branches, we do not perform any TLB invalidation, and even if we were to perform TLB invalidation here it would not be functionally necessary to optimize this by using the TTL hint. Hence there's no need to use cpus_have_const_cap(), and alternative_has_cap_unlikely() is sufficient. This patch replaces the use of cpus_have_const_cap() with alternative_has_cap_unlikely(), which will avoid generating code to test the system_cpucaps bitmap and should be better for all subsequent calls at runtime. Signed-off-by: Mark Rutland Cc: Catalin Marinas Cc: Suzuki K Poulose Cc: Will Deacon --- arch/arm64/include/asm/tlbflush.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h index b149cf9f91bc9..53ed194626e1a 100644 --- a/arch/arm64/include/asm/tlbflush.h +++ b/arch/arm64/include/asm/tlbflush.h @@ -105,7 +105,7 @@ static inline unsigned long get_trans_granule(void) #define __tlbi_level(op, addr, level) do { \ u64 arg = addr; \ \ - if (cpus_have_const_cap(ARM64_HAS_ARMv8_4_TTL) && \ + if (alternative_has_cap_unlikely(ARM64_HAS_ARMv8_4_TTL) && \ level) { \ u64 ttl = level & 3; \ ttl |= get_trans_granule() << 2; \