From mboxrd@z Thu Jan 1 00:00:00 1970 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 CEAEFE7D0D5 for ; Fri, 22 Sep 2023 06:52:25 +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: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=tm711zWBxeaoK8iByZzDWas23O2zix4bYISrUQGOm8k=; b=cGsf2x/1OBqf1K xvYbRIYnzuJsYjpyDugLv2+0VtT2Z3QeIlYHaKKnVM6r1730mt/Gd8Qp0tD+0OVm6GUiVOe/nVn9+ 5L7nHg3ma+Ea/rXvSBUEzpeYpQtIpLy2NO4/jBBUwWsA3eXC0lehzB8gAxOi9H5ByvLMt70EsuXTa AGDruR4mJnv0HPoJ7IEXzMVN0zKYaiy5IoPpxzn72R1abaF9B2hYfK1pmLUwuJEa2xO06ulwDQ9e4 241UYqXMK8oUvPKH7kSF1C74VNjkwIfCqoB6o4+NkyNjJoBjyG5oPyPhSJZXlll2dJlOnXAizo2ni Dr4lKub1PHaWy1QAviVQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qja1Y-0085yJ-10; Fri, 22 Sep 2023 06:52:24 +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 1qja1U-0085wv-2r for linux-um@lists.infradead.org; Fri, 22 Sep 2023 06:52:22 +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 1qja1S-002awa-Oe; Fri, 22 Sep 2023 06:52:19 +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 1qja1O-00223P-Es; Fri, 22 Sep 2023 07:52:16 +0100 From: anton.ivanov@cambridgegreys.com To: linux-um@lists.infradead.org Cc: johannes@sipsolutions.net, richard@nod.at, Anton Ivanov Subject: [PATCH v5] um: Enable preemption in UML Date: Fri, 22 Sep 2023 07:52:12 +0100 Message-Id: <20230922065212.484385-1-anton.ivanov@cambridgegreys.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 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_235220_947548_5660D8FB X-CRM114-Status: GOOD ( 20.80 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-um" Errors-To: linux-um-bounces+linux-um=archiver.kernel.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 --- 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 + arch/um/kernel/tlb.c | 9 +++ 7 files changed, 101 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) diff --git a/arch/um/kernel/tlb.c b/arch/um/kernel/tlb.c index 7d050ab0f78a..34ec8e677fb9 100644 --- a/arch/um/kernel/tlb.c +++ b/arch/um/kernel/tlb.c @@ -362,6 +362,9 @@ static int flush_tlb_kernel_range_common(unsigned long start, unsigned long end) mm = &init_mm; hvc = INIT_HVC(mm, force, userspace); + + preempt_disable(); + for (addr = start; addr < end;) { pgd = pgd_offset(mm, addr); if (!pgd_present(*pgd)) { @@ -449,6 +452,9 @@ static int flush_tlb_kernel_range_common(unsigned long start, unsigned long end) if (err < 0) panic("flush_tlb_kernel failed, errno = %d\n", err); + + preempt_enable(); + return updated; } @@ -466,6 +472,8 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned long address) address &= PAGE_MASK; + preempt_disable(); + pgd = pgd_offset(mm, address); if (!pgd_present(*pgd)) goto kill; @@ -520,6 +528,7 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned long address) *pte = pte_mkuptodate(*pte); + preempt_enable(); return; kill: -- 2.30.2 _______________________________________________ linux-um mailing list linux-um@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-um