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[2620:137:e000::1:20]) by mx.google.com with ESMTP id y7-20020a056402358700b0046ba0b85e8asi10729809edc.624.2022.12.04.09.59.28; Sun, 04 Dec 2022 09:59:50 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=tQtG9KFp; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230322AbiLDR4w (ORCPT + 99 others); Sun, 4 Dec 2022 12:56:52 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41486 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230289AbiLDR4a (ORCPT ); Sun, 4 Dec 2022 12:56:30 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 94FE4140D0; Sun, 4 Dec 2022 09:56:29 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 2956560EDD; Sun, 4 Dec 2022 17:56:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 449FEC433D7; Sun, 4 Dec 2022 17:56:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1670176588; bh=pXsh8SVW/sBp/P3v6mc5bVyqy/bCl/0yI5e+z8DIwis=; h=From:To:Cc:Subject:Date:From; b=tQtG9KFpqkqGYmeGkTRbDw7dFD2tA0xqcHOa0rvlzLlRNlTklMnnb7Hra23zr673O UCxXyY7ZxAa3ZBtBTYDJeszodPtvzxBSViHCAcKhduKrmfuYT1ucDpKIVxQQLWlZPd /9Fa9kenqy3+BcN/nvOQNhPzOqI6CW+73bWJsAwuB7sTGorl3ggYWGdz+JXhI2Ut44 NUveSgkXxxfHMYikHN1Kj5TUi2lieXGxvSO2FtsArZzbtAzrh056c/CR3gkcp3n0T2 DFgdkDRbbkub+pvLLVU2PtGrbkQl2iXvvfC71aTAThHCKS9kwApzekms9ahM4gjg7T Cf803DYekHhSw== From: Jisheng Zhang To: Palmer Dabbelt , Paul Walmsley , Albert Ou , Anup Patel , Atish Patra , Heiko Stuebner , Andrew Jones Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, kvm-riscv@lists.infradead.org Subject: [PATCH v2 00/13] riscv: improve boot time isa extensions handling Date: Mon, 5 Dec 2022 01:46:19 +0800 Message-Id: <20221204174632.3677-1-jszhang@kernel.org> X-Mailer: git-send-email 2.37.2 MIME-Version: 1.0 X-Spam-Status: No, score=-7.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_HI, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1751307298124479409?= X-GMAIL-MSGID: =?utf-8?q?1751307298124479409?= Generally, riscv ISA extensions are fixed for any specific hardware platform, that's to say, the hart features won't change any more after booting, this chacteristic make it straightforward to use static branch to check one specific ISA extension is supported or not to optimize performance. However, some ISA extensions such as SVPBMT and ZICBOM are handled via. the alternative sequences. Basically, for ease of maintenance, we prefer to use static branches in C code, but recently, Samuel found that the static branch usage in cpu_relax() breaks building with CONFIG_CC_OPTIMIZE_FOR_SIZE[1]. As Samuel pointed out, "Having a static branch in cpu_relax() is problematic because that function is widely inlined, including in some quite complex functions like in the VDSO. A quick measurement shows this static branch is responsible by itself for around 40% of the jump table." Samuel's findings pointed out one of a few downsides of static branches usage in C code to handle ISA extensions detected at boot time: static branch's metadata in the __jump_table section, which is not discarded after ISA extensions are finalized, wastes some space. I want to try to solve the issue for all possible dynamic handling of ISA extensions at boot time. Inspired by Mark[2], this patch introduces riscv_has_extension_*() helpers, which work like static branches but are patched using alternatives, thus the metadata can be freed after patching. Since v1 - rebase on v6.1-rc7 + Heiko's alternative improvements[3] - collect Reviewed-by tag - add one patch to update jal offsets in patched alternatives - add one patch to switch to relative alternative entries - add patches to patch vdso [1]https://lore.kernel.org/linux-riscv/20220922060958.44203-1-samuel@sholland.org/ [2]https://lore.kernel.org/linux-arm-kernel/20220912162210.3626215-8-mark.rutland@arm.com/ [3]https://lore.kernel.org/linux-riscv/20221130225614.1594256-1-heiko@sntech.de/ Andrew Jones (1): riscv: KVM: Switch has_svinval() to riscv_has_extension_unlikely() Jisheng Zhang (12): riscv: fix jal offsets in patched alternatives riscv: move riscv_noncoherent_supported() out of ZICBOM probe riscv: cpufeature: detect RISCV_ALTERNATIVES_EARLY_BOOT earlier riscv: hwcap: make ISA extension ids can be used in asm riscv: cpufeature: extend riscv_cpufeature_patch_func to all ISA extensions riscv: introduce riscv_has_extension_[un]likely() riscv: fpu: switch has_fpu() to riscv_has_extension_likely() riscv: module: move find_section to module.h riscv: switch to relative alternative entries riscv: alternative: patch alternatives in the vDSO riscv: cpu_relax: switch to riscv_has_extension_likely() riscv: remove riscv_isa_ext_keys[] array and related usage arch/riscv/errata/sifive/errata.c | 4 +- arch/riscv/errata/thead/errata.c | 11 ++- arch/riscv/include/asm/alternative-macros.h | 20 ++--- arch/riscv/include/asm/alternative.h | 14 +-- arch/riscv/include/asm/errata_list.h | 9 +- arch/riscv/include/asm/hwcap.h | 96 +++++++++++---------- arch/riscv/include/asm/module.h | 15 ++++ arch/riscv/include/asm/switch_to.h | 3 +- arch/riscv/include/asm/vdso.h | 4 + arch/riscv/include/asm/vdso/processor.h | 2 +- arch/riscv/kernel/alternative.c | 63 ++++++++++++++ arch/riscv/kernel/cpufeature.c | 82 +++--------------- arch/riscv/kernel/module.c | 15 ---- arch/riscv/kernel/setup.c | 2 + arch/riscv/kernel/vdso.c | 5 -- arch/riscv/kernel/vdso/vdso.lds.S | 7 ++ arch/riscv/kvm/tlb.c | 3 +- 17 files changed, 191 insertions(+), 164 deletions(-)