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[59.124.168.89]) by smtp.gmail.com with ESMTPSA id b5sm3108466pfr.26.2021.09.08.10.45.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Sep 2021 10:45:55 -0700 (PDT) From: Greentime Hu To: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, aou@eecs.berkeley.edu, palmer@dabbelt.com, paul.walmsley@sifive.com, vincent.chen@sifive.com Subject: [RFC PATCH v8 13/21] riscv: Add support for kernel mode vector Date: Thu, 9 Sep 2021 01:45:25 +0800 Message-Id: X-Mailer: git-send-email 2.31.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add containing kernel_rvv_begin()/kernel_rvv_end() function declarations and corresponding definitions in kernel_mode_vector.c These are needed to wrap uses of vector in kernel mode. Signed-off-by: Greentime Hu Co-developed-by: Vincent Chen Signed-off-by: Vincent Chen --- arch/riscv/include/asm/vector.h | 14 ++ arch/riscv/kernel/Makefile | 6 + arch/riscv/kernel/kernel_mode_vector.c | 184 +++++++++++++++++++++++++ 3 files changed, 204 insertions(+) create mode 100644 arch/riscv/include/asm/vector.h create mode 100644 arch/riscv/kernel/kernel_mode_vector.c diff --git a/arch/riscv/include/asm/vector.h b/arch/riscv/include/asm/vector.h new file mode 100644 index 000000000000..5d7f14453f68 --- /dev/null +++ b/arch/riscv/include/asm/vector.h @@ -0,0 +1,14 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Copyright (C) 2020 SiFive + */ + +#ifndef __ASM_RISCV_VECTOR_H +#define __ASM_RISCV_VECTOR_H + +#include + +void kernel_rvv_begin(void); +void kernel_rvv_end(void); + +#endif /* ! __ASM_RISCV_VECTOR_H */ diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index 344078080839..a2efd3646cd8 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -41,6 +41,12 @@ obj-$(CONFIG_MMU) += vdso.o vdso/ obj-$(CONFIG_RISCV_M_MODE) += traps_misaligned.o obj-$(CONFIG_FPU) += fpu.o obj-$(CONFIG_VECTOR) += vector.o +obj-$(CONFIG_VECTOR) += kernel_mode_vector.o +riscv-march-cflags-$(CONFIG_ARCH_RV32I) := rv32ima +riscv-march-cflags-$(CONFIG_ARCH_RV64I) := rv64ima +riscv-march-cflags-$(CONFIG_RISCV_ISA_C) := $(riscv-march-cflags-y)c +riscv-march-cflags-$(CONFIG_VECTOR) := $(riscv-march-cflags-y)v +CFLAGS_kernel_mode_vector.o += -march=$(riscv-march-cflags-y) obj-$(CONFIG_SMP) += smpboot.o obj-$(CONFIG_SMP) += smp.o obj-$(CONFIG_SMP) += cpu_ops.o diff --git a/arch/riscv/kernel/kernel_mode_vector.c b/arch/riscv/kernel/kernel_mode_vector.c new file mode 100644 index 000000000000..108cfafe7496 --- /dev/null +++ b/arch/riscv/kernel/kernel_mode_vector.c @@ -0,0 +1,184 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2012 ARM Ltd. + * Author: Catalin Marinas + * Copyright (C) 2017 Linaro Ltd. + * Copyright (C) 2020 SiFive + */ +#include +#include +#include +#include +#include + +#include +#include + +DECLARE_PER_CPU(bool, vector_context_busy); +DEFINE_PER_CPU(bool, vector_context_busy); + +/* + * may_use_vector - 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_vector(void) +{ + /* + * vector_context_busy is only set while preemption is disabled, + * and is clear whenever preemption is enabled. Since + * this_cpu_read() is atomic w.r.t. preemption, vector_context_busy + * cannot change under our feet -- if it's set we cannot be + * migrated, and if it's clear we cannot be migrated to a CPU + * where it is set. + */ + return !in_irq() && !irqs_disabled() && !in_nmi() && + !this_cpu_read(vector_context_busy); +} + + + +/* + * 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. + */ +static void get_cpu_vector_context(void) +{ + bool busy; + + preempt_disable(); + busy = __this_cpu_xchg(vector_context_busy, true); + + WARN_ON(busy); +} + +/* + * 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. + */ +static void put_cpu_vector_context(void) +{ + bool busy = __this_cpu_xchg(vector_context_busy, false); + + WARN_ON(!busy); + preempt_enable(); +} + +static void rvv_enable(void) +{ + csr_set(CSR_STATUS, SR_VS); +} + +static void rvv_disable(void) +{ + csr_clear(CSR_STATUS, SR_VS); +} + +static void vector_flush_cpu_state(void) +{ + long tmp; + + __asm__ __volatile__ ( + "vsetvli %0, x0, e8, m1\n" + "vmv.v.i v0, 0\n" + "vmv.v.i v1, 0\n" + "vmv.v.i v2, 0\n" + "vmv.v.i v3, 0\n" + "vmv.v.i v4, 0\n" + "vmv.v.i v5, 0\n" + "vmv.v.i v6, 0\n" + "vmv.v.i v7, 0\n" + "vmv.v.i v8, 0\n" + "vmv.v.i v9, 0\n" + "vmv.v.i v10, 0\n" + "vmv.v.i v11, 0\n" + "vmv.v.i v12, 0\n" + "vmv.v.i v13, 0\n" + "vmv.v.i v14, 0\n" + "vmv.v.i v15, 0\n" + "vmv.v.i v16, 0\n" + "vmv.v.i v17, 0\n" + "vmv.v.i v18, 0\n" + "vmv.v.i v19, 0\n" + "vmv.v.i v20, 0\n" + "vmv.v.i v21, 0\n" + "vmv.v.i v22, 0\n" + "vmv.v.i v23, 0\n" + "vmv.v.i v24, 0\n" + "vmv.v.i v25, 0\n" + "vmv.v.i v26, 0\n" + "vmv.v.i v27, 0\n" + "vmv.v.i v28, 0\n" + "vmv.v.i v29, 0\n" + "vmv.v.i v30, 0\n" + "vmv.v.i v31, 0\n":"=r"(tmp)::); +} + +/* + * kernel_rvv_begin(): obtain the CPU vector registers for use by the calling + * context + * + * Must not be called unless may_use_vector() returns true. + * Task context in the vector registers is saved back to memory as necessary. + * + * A matching call to kernel_rvv_end() must be made before returning from the + * calling context. + * + * The caller may freely use the vector registers until kernel_rvv_end() is + * called. + */ +void kernel_rvv_begin(void) +{ + if (WARN_ON(!has_vector)) + return; + + WARN_ON(!may_use_vector()); + + /* Acquire kernel mode vector */ + get_cpu_vector_context(); + + /* Save vector state, if any */ + vstate_save(current, task_pt_regs(current)); + + /* Enable vector */ + rvv_enable(); + + /* Invalidate vector regs */ + vector_flush_cpu_state(); +} +EXPORT_SYMBOL(kernel_rvv_begin); + +/* + * kernel_rvv_end(): give the CPU vector registers back to the current task + * + * Must be called from a context in which kernel_rvv_begin() was previously + * called, with no call to kernel_rvv_end() in the meantime. + * + * The caller must not use the vector registers after this function is called, + * unless kernel_rvv_begin() is called again in the meantime. + */ +void kernel_rvv_end(void) +{ + if (WARN_ON(!has_vector)) + return; + + /* Invalidate vector regs */ + vector_flush_cpu_state(); + + /* Restore vector state, if any */ + vstate_restore(current, task_pt_regs(current)); + + /* disable vector */ + rvv_disable(); + + /* release kernel mode vector */ + put_cpu_vector_context(); +} +EXPORT_SYMBOL(kernel_rvv_end); -- 2.31.1