From patchwork Thu Sep 21 15:55:22 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anton Ivanov X-Patchwork-Id: 1837653 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; dkim=pass (2048-bit key; secure) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=avVksFeq; dkim-atps=neutral Authentication-Results: legolas.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=lists.infradead.org (client-ip=2607:7c80:54:3::133; helo=bombadil.infradead.org; envelope-from=linux-um-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org; receiver=patchwork.ozlabs.org) Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:3::133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (secp384r1) server-digest SHA384) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4Rs0Ny4ZSRz1yhR for ; Fri, 22 Sep 2023 01:55:46 +1000 (AEST) 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: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:In-Reply-To:References: List-Owner; bh=vj27u+VTf/pav5tZdQ2K1bGdZnjugtKGJr2GCyavqo4=; b=avVksFeqyQ0673 3GxRjXnxvuu87J/JHQ/bos5HQ8KZv0YWbOFOUa3COJvan0AGs1w8mmIgIdSlTlGx7x1D1WMlPEK86 dQ+7Hk2Zisn3dJ5El4vJs+PTVWLRIl2j2wU8ahyBRXIWEOyaRrY5Dw3Ee0WFQxdPjHWoSSmvCRV1w T/WMRv4p+9e6FQyWaIKTt8WC3WzI/3qyb+QPO/HjpoMwAfcRweDd57qVhZVNPI2pbZk6OmnkXKXxm AeRzuTcDrX6EVq8kqNjdUjS6whO1i4DNJy05MXVERapP+FLc7xa17g6Z/na69dZRyFLMxZZJrjvM0 00RrmaYWKmiRyMXEQn9g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qjM1h-006SK5-0e; Thu, 21 Sep 2023 15:55:37 +0000 Received: from ns1.kot-begemot.co.uk ([217.160.28.25] helo=www.kot-begemot.co.uk) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qjM1e-006SJN-1k for linux-um@lists.infradead.org; Thu, 21 Sep 2023 15:55:36 +0000 Received: from [192.168.17.6] (helo=jain.kot-begemot.co.uk) by www.kot-begemot.co.uk with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1qjM1Z-002ZCR-8P; Thu, 21 Sep 2023 15:55:29 +0000 Received: from jain.kot-begemot.co.uk ([192.168.3.3]) by jain.kot-begemot.co.uk with esmtp (Exim 4.94.2) (envelope-from ) id 1qjM1V-001C2j-9G; Thu, 21 Sep 2023 16:55:27 +0100 From: anton.ivanov@cambridgegreys.com To: linux-um@lists.infradead.org Cc: johannes@sipsolutions.net, richard@nod.at, Anton Ivanov Subject: [PATCH v4] um: Enable preemption in UML Date: Thu, 21 Sep 2023 16:55:22 +0100 Message-Id: <20230921155522.283582-1-anton.ivanov@cambridgegreys.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 X-Spam-Score: -1.0 X-Spam-Score: -1.0 X-Clacks-Overhead: GNU Terry Pratchett X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230921_085534_604473_72FEEE78 X-CRM114-Status: GOOD ( 18.64 ) X-Spam-Score: 0.0 (/) X-Spam-Report: Spam detection software, running on the system "bombadil.infradead.org", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: From: Anton Ivanov Preemption requires saving/restoring FPU state. This patch adds support for it using GCC intrinsics. Signed-off-by: Anton Ivanov --- arch/um/Kconfig | 1 - arch/um/include/asm/fpu/api.h | 9 ++- arch/um/include/asm/processor-generic.h | 3 + arch/um/kernel/Makefile | 4 [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record X-BeenThere: linux-um@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-um" Errors-To: linux-um-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org From: Anton Ivanov Preemption requires saving/restoring FPU state. This patch adds support for it using GCC intrinsics. Signed-off-by: Anton Ivanov Reviewed-by: Peter Lafreniere --- arch/um/Kconfig | 1 - arch/um/include/asm/fpu/api.h | 9 ++- arch/um/include/asm/processor-generic.h | 3 + arch/um/kernel/Makefile | 4 ++ arch/um/kernel/fpu.c | 77 +++++++++++++++++++++++++ arch/um/kernel/irq.c | 2 + 6 files changed, 92 insertions(+), 4 deletions(-) create mode 100644 arch/um/kernel/fpu.c diff --git a/arch/um/Kconfig b/arch/um/Kconfig index b5e179360534..603f5fd82293 100644 --- a/arch/um/Kconfig +++ b/arch/um/Kconfig @@ -11,7 +11,6 @@ config UML select ARCH_HAS_KCOV select ARCH_HAS_STRNCPY_FROM_USER select ARCH_HAS_STRNLEN_USER - select ARCH_NO_PREEMPT select HAVE_ARCH_AUDITSYSCALL select HAVE_ARCH_KASAN if X86_64 select HAVE_ARCH_KASAN_VMALLOC if HAVE_ARCH_KASAN diff --git a/arch/um/include/asm/fpu/api.h b/arch/um/include/asm/fpu/api.h index 71bfd9ef3938..9e7680bf48f0 100644 --- a/arch/um/include/asm/fpu/api.h +++ b/arch/um/include/asm/fpu/api.h @@ -4,12 +4,15 @@ /* Copyright (c) 2020 Cambridge Greys Ltd * Copyright (c) 2020 Red Hat Inc. - * A set of "dummy" defines to allow the direct inclusion - * of x86 optimized copy, xor, etc routines into the - * UML code tree. */ + */ +#if defined(CONFIG_PREEMPT) || defined(CONFIG_PREEMPT_VOLUNTARY) +extern void kernel_fpu_begin(void); +extern void kernel_fpu_end(void); +#else #define kernel_fpu_begin() (void)0 #define kernel_fpu_end() (void)0 +#endif static inline bool irq_fpu_usable(void) { diff --git a/arch/um/include/asm/processor-generic.h b/arch/um/include/asm/processor-generic.h index 7414154b8e9a..c08e8c5b0249 100644 --- a/arch/um/include/asm/processor-generic.h +++ b/arch/um/include/asm/processor-generic.h @@ -44,6 +44,9 @@ struct thread_struct { } cb; } u; } request; +#if defined(CONFIG_PREEMPT) || defined(CONFIG_PREEMPT_VOLUNTARY) + u8 fpu[2048] __aligned(64); /* Intel docs require xsave/xrestore area to be aligned to 64 bytes */ +#endif }; #define INIT_THREAD \ diff --git a/arch/um/kernel/Makefile b/arch/um/kernel/Makefile index 811188be954c..c616e884a488 100644 --- a/arch/um/kernel/Makefile +++ b/arch/um/kernel/Makefile @@ -26,9 +26,13 @@ obj-$(CONFIG_OF) += dtb.o obj-$(CONFIG_EARLY_PRINTK) += early_printk.o obj-$(CONFIG_STACKTRACE) += stacktrace.o obj-$(CONFIG_GENERIC_PCI_IOMAP) += ioport.o +obj-$(CONFIG_PREEMPT) += fpu.o +obj-$(CONFIG_PREEMPT_VOLUNTARY) += fpu.o USER_OBJS := config.o +CFLAGS_fpu.o += -mxsave -mxsaveopt + include $(srctree)/arch/um/scripts/Makefile.rules targets := config.c config.tmp capflags.c diff --git a/arch/um/kernel/fpu.c b/arch/um/kernel/fpu.c new file mode 100644 index 000000000000..346c07236185 --- /dev/null +++ b/arch/um/kernel/fpu.c @@ -0,0 +1,77 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2023 Cambridge Greys Ltd + * Copyright (C) 2023 Red Hat Inc + */ + +#include +#include +#include +#include + +/* + * The critical section between kernel_fpu_begin() and kernel_fpu_end() + * is non-reentrant. It is the caller's responsibility to avoid reentrance. + */ + +static DEFINE_PER_CPU(bool, in_kernel_fpu); + +/* UML and driver code it pulls out of the x86 tree knows about 387 features + * up to and including AVX512. TILE, etc are not yet supported. + */ + +#define KNOWN_387_FEATURES 0xFF + + +void kernel_fpu_begin(void) +{ + preempt_disable(); + + WARN_ON(this_cpu_read(in_kernel_fpu)); + + this_cpu_write(in_kernel_fpu, true); + +#ifdef CONFIG_64BIT + if (likely(cpu_has(&boot_cpu_data, X86_FEATURE_XSAVEOPT))) + __builtin_ia32_xsaveopt64(¤t->thread.fpu, KNOWN_387_FEATURES); + else { + if (likely(cpu_has(&boot_cpu_data, X86_FEATURE_XSAVE))) + __builtin_ia32_xsave64(¤t->thread.fpu, KNOWN_387_FEATURES); + else + __builtin_ia32_fxsave64(¤t->thread.fpu); + } +#else + if (likely(cpu_has(&boot_cpu_data, X86_FEATURE_XSAVEOPT))) + __builtin_ia32_xsaveopt(¤t->thread.fpu, KNOWN_387_FEATURES); + else { + if (likely(cpu_has(&boot_cpu_data, X86_FEATURE_XSAVE))) + __builtin_ia32_xsave(¤t->thread.fpu, KNOWN_387_FEATURES); + else + __builtin_ia32_fxsave(¤t->thread.fpu); + } +#endif +} + +EXPORT_SYMBOL_GPL(kernel_fpu_begin); + +void kernel_fpu_end(void) +{ + WARN_ON(!this_cpu_read(in_kernel_fpu)); + +#ifdef CONFIG_64BIT + if (likely(cpu_has(&boot_cpu_data, X86_FEATURE_XSAVE))) + __builtin_ia32_xrstor64(¤t->thread.fpu, KNOWN_387_FEATURES); + else + __builtin_ia32_fxrstor64(¤t->thread.fpu); +#else + if (likely(cpu_has(&boot_cpu_data, X86_FEATURE_XSAVE))) + __builtin_ia32_xrstor(¤t->thread.fpu, KNOWN_387_FEATURES); + else + __builtin_ia32_fxrstor(¤t->thread.fpu); +#endif + this_cpu_write(in_kernel_fpu, false); + + preempt_enable(); +} +EXPORT_SYMBOL_GPL(kernel_fpu_end); + diff --git a/arch/um/kernel/irq.c b/arch/um/kernel/irq.c index 635d44606bfe..c02525da45df 100644 --- a/arch/um/kernel/irq.c +++ b/arch/um/kernel/irq.c @@ -195,7 +195,9 @@ static void _sigio_handler(struct uml_pt_regs *regs, void sigio_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs) { + preempt_disable(); _sigio_handler(regs, irqs_suspended); + preempt_enable(); } static struct irq_entry *get_irq_entry_by_fd(int fd)