From patchwork Tue Jan 2 06:47:27 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 759468 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6E75D46B1; Tue, 2 Jan 2024 06:50:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Wa8heIs7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2B069C433CA; Tue, 2 Jan 2024 06:50:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1704178215; bh=WRdTVDlAOr21h6vdX62yZArWAQivJDDm8KoIYemBcBM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Wa8heIs7ON/5Pd+LayIk7L8x/7cxUxcXveLC1B8qu+B6gV+fCp+XftN9pgduwtCis XrGYT7dM6EXTN3wmXKn9f6En4hC55OgduPzwRtSs6ERoRmEk94pILk3N+hgS+YHcwB JVjm2DhQo1bGXKWXtvlBDVNSWfrQD+qaYECrewyYJn/iCR9KSNO7VzLwdProKLvXNk ZLwa2+gZV5xYNAO1/5lhoL7KHue9/XEagnlsEyGULxn/3qwbyWEGfKHoaugTKb7uDU K/a1xka9H8bcR/Un/1EUW8wNKLMUZ7IqII8Opid4MZ/rkUcEPoYpK7rwffzlPjHnRI uFO4tKnU1e0Ag== From: Eric Biggers To: linux-crypto@vger.kernel.org, linux-riscv@lists.infradead.org, Jerry Shih Cc: linux-kernel@vger.kernel.org, Ard Biesheuvel , Heiko Stuebner , Phoebe Chen , hongrong.hsu@sifive.com, Paul Walmsley , Palmer Dabbelt , Albert Ou , Andy Chiu , Greentime Hu , Vincent Chen Subject: [RFC PATCH 01/13] riscv: Add support for kernel mode vector Date: Tue, 2 Jan 2024 00:47:27 -0600 Message-ID: <20240102064743.220490-2-ebiggers@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240102064743.220490-1-ebiggers@kernel.org> References: <20240102064743.220490-1-ebiggers@kernel.org> Precedence: bulk X-Mailing-List: linux-crypto@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Greentime Hu Add kernel_vector_begin() and kernel_vector_end() function declarations and corresponding definitions in kernel_mode_vector.c These are needed to wrap uses of vector in kernel mode. Co-developed-by: Vincent Chen Signed-off-by: Vincent Chen Signed-off-by: Greentime Hu Signed-off-by: Andy Chiu Signed-off-by: Eric Biggers --- arch/riscv/include/asm/processor.h | 13 ++- arch/riscv/include/asm/simd.h | 44 ++++++++++ arch/riscv/include/asm/vector.h | 9 ++ arch/riscv/kernel/Makefile | 1 + arch/riscv/kernel/kernel_mode_vector.c | 116 +++++++++++++++++++++++++ arch/riscv/kernel/process.c | 1 + 6 files changed, 183 insertions(+), 1 deletion(-) create mode 100644 arch/riscv/include/asm/simd.h create mode 100644 arch/riscv/kernel/kernel_mode_vector.c diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h index f19f861cda549..28d19aea24b1d 100644 --- a/arch/riscv/include/asm/processor.h +++ b/arch/riscv/include/asm/processor.h @@ -66,29 +66,40 @@ #define TASK_UNMAPPED_BASE PAGE_ALIGN((UL(1) << MMAP_MIN_VA_BITS) / 3) #else #define TASK_UNMAPPED_BASE PAGE_ALIGN(TASK_SIZE / 3) #endif #ifndef __ASSEMBLY__ struct task_struct; struct pt_regs; +/* + * We use a flag to track in-kernel Vector context. Currently the flag has the + * following meaning: + * + * - bit 0: indicates whether the in-kernel Vector context is active. The + * activation of this state disables the preemption. Currently only 0 and 1 + * are valid value for this field. Other values are reserved for future uses. + */ +#define RISCV_KERNEL_MODE_V 0x1 + /* CPU-specific state of a task */ struct thread_struct { /* Callee-saved registers */ unsigned long ra; unsigned long sp; /* Kernel mode stack */ unsigned long s[12]; /* s[0]: frame pointer */ struct __riscv_d_ext_state fstate; unsigned long bad_cause; - unsigned long vstate_ctrl; + u32 riscv_v_flags; + u32 vstate_ctrl; struct __riscv_v_ext_state vstate; unsigned long align_ctl; }; /* Whitelist the fstate from the task_struct for hardened usercopy */ static inline void arch_thread_struct_whitelist(unsigned long *offset, unsigned long *size) { *offset = offsetof(struct thread_struct, fstate); *size = sizeof_field(struct thread_struct, fstate); diff --git a/arch/riscv/include/asm/simd.h b/arch/riscv/include/asm/simd.h new file mode 100644 index 0000000000000..ef8af413a9fc7 --- /dev/null +++ b/arch/riscv/include/asm/simd.h @@ -0,0 +1,44 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2017 Linaro Ltd. + * Copyright (C) 2023 SiFive + */ + +#ifndef __ASM_SIMD_H +#define __ASM_SIMD_H + +#include +#include +#include +#include +#include + +#include + +#ifdef CONFIG_RISCV_ISA_V +/* + * may_use_simd - whether it is allowable at this time to issue vector + * instructions or access the vector register file + * + * Callers must not assume that the result remains true beyond the next + * preempt_enable() or return from softirq context. + */ +static __must_check inline bool may_use_simd(void) +{ + /* + * RISCV_KERNEL_MODE_V is only set while preemption is disabled, + * and is clear whenever preemption is enabled. + */ + return !in_hardirq() && !in_nmi() && !(riscv_v_flags() & RISCV_KERNEL_MODE_V); +} + +#else /* ! CONFIG_RISCV_ISA_V */ + +static __must_check inline bool may_use_simd(void) +{ + return false; +} + +#endif /* ! CONFIG_RISCV_ISA_V */ + +#endif diff --git a/arch/riscv/include/asm/vector.h b/arch/riscv/include/asm/vector.h index 87aaef656257c..71af3404fda14 100644 --- a/arch/riscv/include/asm/vector.h +++ b/arch/riscv/include/asm/vector.h @@ -15,20 +15,29 @@ #include #include #include #include #include #include extern unsigned long riscv_v_vsize; int riscv_v_setup_vsize(void); bool riscv_v_first_use_handler(struct pt_regs *regs); +void kernel_vector_begin(void); +void kernel_vector_end(void); +void get_cpu_vector_context(void); +void put_cpu_vector_context(void); + +static inline u32 riscv_v_flags(void) +{ + return current->thread.riscv_v_flags; +} static __always_inline bool has_vector(void) { return riscv_has_extension_unlikely(RISCV_ISA_EXT_v); } static inline void __riscv_v_vstate_clean(struct pt_regs *regs) { regs->status = (regs->status & ~SR_VS) | SR_VS_CLEAN; } diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index fee22a3d1b534..8c58595696b32 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -56,20 +56,21 @@ obj-y += riscv_ksyms.o obj-y += stacktrace.o obj-y += cacheinfo.o obj-y += patch.o obj-y += probes/ obj-y += tests/ obj-$(CONFIG_MMU) += vdso.o vdso/ obj-$(CONFIG_RISCV_MISALIGNED) += traps_misaligned.o obj-$(CONFIG_FPU) += fpu.o obj-$(CONFIG_RISCV_ISA_V) += vector.o +obj-$(CONFIG_RISCV_ISA_V) += kernel_mode_vector.o obj-$(CONFIG_SMP) += smpboot.o obj-$(CONFIG_SMP) += smp.o obj-$(CONFIG_SMP) += cpu_ops.o obj-$(CONFIG_RISCV_BOOT_SPINWAIT) += cpu_ops_spinwait.o obj-$(CONFIG_MODULES) += module.o obj-$(CONFIG_MODULE_SECTIONS) += module-sections.o obj-$(CONFIG_CPU_PM) += suspend_entry.o suspend.o obj-$(CONFIG_HIBERNATION) += hibernate.o hibernate-asm.o diff --git a/arch/riscv/kernel/kernel_mode_vector.c b/arch/riscv/kernel/kernel_mode_vector.c new file mode 100644 index 0000000000000..114cf4f0a0eb6 --- /dev/null +++ b/arch/riscv/kernel/kernel_mode_vector.c @@ -0,0 +1,116 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2012 ARM Ltd. + * Author: Catalin Marinas + * Copyright (C) 2017 Linaro Ltd. + * Copyright (C) 2021 SiFive + */ +#include +#include +#include +#include +#include + +#include +#include +#include + +static inline void riscv_v_flags_set(u32 flags) +{ + current->thread.riscv_v_flags = flags; +} + +static inline void riscv_v_start(u32 flags) +{ + int orig; + + orig = riscv_v_flags(); + BUG_ON((orig & flags) != 0); + riscv_v_flags_set(orig | flags); +} + +static inline void riscv_v_stop(u32 flags) +{ + int orig; + + orig = riscv_v_flags(); + BUG_ON((orig & flags) == 0); + riscv_v_flags_set(orig & ~flags); +} + +/* + * Claim ownership of the CPU vector context for use by the calling context. + * + * The caller may freely manipulate the vector context metadata until + * put_cpu_vector_context() is called. + */ +void get_cpu_vector_context(void) +{ + preempt_disable(); + + riscv_v_start(RISCV_KERNEL_MODE_V); +} + +/* + * Release the CPU vector context. + * + * Must be called from a context in which get_cpu_vector_context() was + * previously called, with no call to put_cpu_vector_context() in the + * meantime. + */ +void put_cpu_vector_context(void) +{ + riscv_v_stop(RISCV_KERNEL_MODE_V); + + preempt_enable(); +} + +/* + * kernel_vector_begin(): obtain the CPU vector registers for use by the calling + * context + * + * Must not be called unless may_use_simd() returns true. + * Task context in the vector registers is saved back to memory as necessary. + * + * A matching call to kernel_vector_end() must be made before returning from the + * calling context. + * + * The caller may freely use the vector registers until kernel_vector_end() is + * called. + */ +void kernel_vector_begin(void) +{ + if (WARN_ON(!has_vector())) + return; + + BUG_ON(!may_use_simd()); + + get_cpu_vector_context(); + + riscv_v_vstate_save(current, task_pt_regs(current)); + + riscv_v_enable(); +} +EXPORT_SYMBOL_GPL(kernel_vector_begin); + +/* + * kernel_vector_end(): give the CPU vector registers back to the current task + * + * Must be called from a context in which kernel_vector_begin() was previously + * called, with no call to kernel_vector_end() in the meantime. + * + * The caller must not use the vector registers after this function is called, + * unless kernel_vector_begin() is called again in the meantime. + */ +void kernel_vector_end(void) +{ + if (WARN_ON(!has_vector())) + return; + + riscv_v_vstate_restore(current, task_pt_regs(current)); + + riscv_v_disable(); + + put_cpu_vector_context(); +} +EXPORT_SYMBOL_GPL(kernel_vector_end); diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c index 4f21d970a1292..4a1275db11460 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -214,14 +214,15 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) *childregs = *(current_pt_regs()); /* Turn off status.VS */ riscv_v_vstate_off(childregs); if (usp) /* User fork */ childregs->sp = usp; if (clone_flags & CLONE_SETTLS) childregs->tp = tls; childregs->a0 = 0; /* Return value of fork() */ p->thread.s[0] = 0; } + p->thread.riscv_v_flags = 0; p->thread.ra = (unsigned long)ret_from_fork; p->thread.sp = (unsigned long)childregs; /* kernel sp */ return 0; }