From nobody Sun Feb 8 23:58:44 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F27EEEB64DC for ; Sat, 22 Jul 2023 07:22:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230128AbjGVHWQ (ORCPT ); Sat, 22 Jul 2023 03:22:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53058 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229684AbjGVHWO (ORCPT ); Sat, 22 Jul 2023 03:22:14 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A3C509B for ; Sat, 22 Jul 2023 00:22:13 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 374C460BA9 for ; Sat, 22 Jul 2023 07:22:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 61F2AC433C7; Sat, 22 Jul 2023 07:22:10 +0000 (UTC) From: Huacai Chen To: Huacai Chen Cc: loongarch@lists.linux.dev, Xuefeng Li , Guo Ren , Xuerui Wang , Jiaxun Yang , linux-kernel@vger.kernel.org, loongson-kernel@lists.loongnix.cn, Huacai Chen Subject: [PATCH] LoongArch: Allow usage of LSX/LASX in the kernel Date: Sat, 22 Jul 2023 15:22:01 +0800 Message-Id: <20230722072201.2677516-1-chenhuacai@loongson.cn> X-Mailer: git-send-email 2.39.3 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Allow usage of LSX/LASX in the kernel by extending kernel_fpu_begin() and kernel_fpu_end(). Signed-off-by: Huacai Chen Reviewed-by: WANG Xuerui --- arch/loongarch/kernel/kfpu.c | 55 +++++++++++++++++++++++++++++++++--- 1 file changed, 51 insertions(+), 4 deletions(-) diff --git a/arch/loongarch/kernel/kfpu.c b/arch/loongarch/kernel/kfpu.c index 5c46ae8c6cac..ec5b28e570c9 100644 --- a/arch/loongarch/kernel/kfpu.c +++ b/arch/loongarch/kernel/kfpu.c @@ -8,19 +8,40 @@ #include #include =20 +static unsigned int euen_mask =3D CSR_EUEN_FPEN; + +/* + * The critical section between kernel_fpu_begin() and kernel_fpu_end() + * is non-reentrant. It is the caller's responsibility to avoid reentrance. + * See drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c as an example. + */ static DEFINE_PER_CPU(bool, in_kernel_fpu); +static DEFINE_PER_CPU(unsigned int, euen_current); =20 void kernel_fpu_begin(void) { + unsigned int *euen_curr; + preempt_disable(); =20 WARN_ON(this_cpu_read(in_kernel_fpu)); =20 this_cpu_write(in_kernel_fpu, true); + euen_curr =3D this_cpu_ptr(&euen_current); =20 - if (!is_fpu_owner()) - enable_fpu(); + *euen_curr =3D csr_xchg32(euen_mask, euen_mask, LOONGARCH_CSR_EUEN); + +#ifdef CONFIG_CPU_HAS_LASX + if (*euen_curr & CSR_EUEN_LASXEN) + _save_lasx(¤t->thread.fpu); + else +#endif +#ifdef CONFIG_CPU_HAS_LSX + if (*euen_curr & CSR_EUEN_LSXEN) + _save_lsx(¤t->thread.fpu); else +#endif + if (*euen_curr & CSR_EUEN_FPEN) _save_fp(¤t->thread.fpu); =20 write_fcsr(LOONGARCH_FCSR0, 0); @@ -29,15 +50,41 @@ EXPORT_SYMBOL_GPL(kernel_fpu_begin); =20 void kernel_fpu_end(void) { + unsigned int *euen_curr; + WARN_ON(!this_cpu_read(in_kernel_fpu)); =20 - if (!is_fpu_owner()) - disable_fpu(); + euen_curr =3D this_cpu_ptr(&euen_current); + +#ifdef CONFIG_CPU_HAS_LASX + if (*euen_curr & CSR_EUEN_LASXEN) + _restore_lasx(¤t->thread.fpu); else +#endif +#ifdef CONFIG_CPU_HAS_LSX + if (*euen_curr & CSR_EUEN_LSXEN) + _restore_lsx(¤t->thread.fpu); + else +#endif + if (*euen_curr & CSR_EUEN_FPEN) _restore_fp(¤t->thread.fpu); =20 + *euen_curr =3D csr_xchg32(*euen_curr, euen_mask, LOONGARCH_CSR_EUEN); + this_cpu_write(in_kernel_fpu, false); =20 preempt_enable(); } EXPORT_SYMBOL_GPL(kernel_fpu_end); + +static int __init init_euen_mask(void) +{ + if (cpu_has_lsx) + euen_mask |=3D CSR_EUEN_LSXEN; + + if (cpu_has_lasx) + euen_mask |=3D CSR_EUEN_LASXEN; + + return 0; +} +arch_initcall(init_euen_mask); --=20 2.39.3