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[59.124.168.89]) by smtp.gmail.com with ESMTPSA id cv1sm1940511pjb.48.2021.11.09.01.48.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 09 Nov 2021 01:48:45 -0800 (PST) From: Greentime Hu To: palmer@dabbelt.com, paul.walmsley@sifive.com, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, aou@eecs.berkeley.edu Subject: [PATCH v9 09/17] riscv: Add task switch support for vector Date: Tue, 9 Nov 2021 17:48:21 +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 This patch adds task switch support for vector. It supports partial lazy save and restore mechanism. It also supports all lengths of vlen. [guoren@linux.alibaba.com: First available porting to support vector context switching] [nick.knight@sifive.com: Rewrite vector.S to support dynamic vlen, xlen and code refine] [vincent.chen@sifive.com: Fix the might_sleep issue in vstate_save, vstate_restore] [andrew@sifive.com: Optimize task switch codes of vector] Suggested-by: Andrew Waterman Co-developed-by: Nick Knight Signed-off-by: Nick Knight Co-developed-by: Guo Ren Signed-off-by: Guo Ren Co-developed-by: Vincent Chen Signed-off-by: Vincent Chen Signed-off-by: Greentime Hu --- arch/riscv/include/asm/switch_to.h | 65 ++++++++++++++++++++++++ arch/riscv/kernel/Makefile | 1 + arch/riscv/kernel/process.c | 49 ++++++++++++++++++ arch/riscv/kernel/vector.S | 81 ++++++++++++++++++++++++++++++ 4 files changed, 196 insertions(+) create mode 100644 arch/riscv/kernel/vector.S diff --git a/arch/riscv/include/asm/switch_to.h b/arch/riscv/include/asm/switch_to.h index ec83770b3d98..576204217e0f 100644 --- a/arch/riscv/include/asm/switch_to.h +++ b/arch/riscv/include/asm/switch_to.h @@ -7,10 +7,12 @@ #define _ASM_RISCV_SWITCH_TO_H #include +#include #include #include #include #include +#include #ifdef CONFIG_FPU extern void __fstate_save(struct task_struct *save_to); @@ -68,6 +70,67 @@ static __always_inline bool has_fpu(void) { return false; } #define __switch_to_fpu(__prev, __next) do { } while (0) #endif +#ifdef CONFIG_VECTOR +extern struct static_key_false cpu_hwcap_vector; +static __always_inline bool has_vector(void) +{ + return static_branch_likely(&cpu_hwcap_vector); +} +extern unsigned long riscv_vsize; +extern void __vstate_save(struct __riscv_v_state *save_to, void *datap); +extern void __vstate_restore(struct __riscv_v_state *restore_from, void *datap); + +static inline void __vstate_clean(struct pt_regs *regs) +{ + regs->status = (regs->status & ~(SR_VS)) | SR_VS_CLEAN; +} + +static inline void vstate_off(struct task_struct *task, + struct pt_regs *regs) +{ + regs->status = (regs->status & ~SR_VS) | SR_VS_OFF; +} + +static inline void vstate_save(struct task_struct *task, + struct pt_regs *regs) +{ + if ((regs->status & SR_VS) == SR_VS_DIRTY) { + struct __riscv_v_state *vstate = &(task->thread.vstate); + + __vstate_save(vstate, vstate->datap); + __vstate_clean(regs); + } +} + +static inline void vstate_restore(struct task_struct *task, + struct pt_regs *regs) +{ + if ((regs->status & SR_VS) != SR_VS_OFF) { + struct __riscv_v_state *vstate = &(task->thread.vstate); + __vstate_restore(vstate, vstate->datap); + __vstate_clean(regs); + } +} + +static inline void __switch_to_vector(struct task_struct *prev, + struct task_struct *next) +{ + struct pt_regs *regs; + + regs = task_pt_regs(prev); + if (unlikely(regs->status & SR_SD)) + vstate_save(prev, regs); + vstate_restore(next, task_pt_regs(next)); +} + +#else +static __always_inline bool has_vector(void) { return false; } +#define riscv_vsize (0) +#define vstate_save(task, regs) do { } while (0) +#define vstate_restore(task, regs) do { } while (0) +#define __switch_to_vector(__prev, __next) do { } while (0) +#endif + extern struct task_struct *__switch_to(struct task_struct *, struct task_struct *); @@ -77,6 +140,8 @@ do { \ struct task_struct *__next = (next); \ if (has_fpu()) \ __switch_to_fpu(__prev, __next); \ + if (has_vector()) \ + __switch_to_vector(__prev, __next); \ ((last) = __switch_to(__prev, __next)); \ } while (0) diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index 3397ddac1a30..344078080839 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -40,6 +40,7 @@ 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-$(CONFIG_SMP) += smpboot.o obj-$(CONFIG_SMP) += smp.o obj-$(CONFIG_SMP) += cpu_ops.o diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c index 03ac3aa611f5..62540815ba1c 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -95,6 +95,25 @@ void start_thread(struct pt_regs *regs, unsigned long pc, */ fstate_restore(current, regs); } + + if (has_vector()) { + struct __riscv_v_state *vstate = &(current->thread.vstate); + + /* Enable vector and allocate memory for vector registers. */ + if (!vstate->datap) { + vstate->datap = kzalloc(riscv_vsize, GFP_KERNEL); + if (WARN_ON(!vstate->datap)) + return; + } + regs->status |= SR_VS_INITIAL; + + /* + * Restore the initial value to the vector register + * before starting the user program. + */ + vstate_restore(current, regs); + } + regs->epc = pc; regs->sp = sp; } @@ -110,15 +129,45 @@ void flush_thread(void) fstate_off(current, task_pt_regs(current)); memset(¤t->thread.fstate, 0, sizeof(current->thread.fstate)); #endif +#ifdef CONFIG_VECTOR + /* Reset vector state and keep datap pointer. */ + vstate_off(current, task_pt_regs(current)); + memset(¤t->thread.vstate, 0, RISCV_V_STATE_DATAP); + if (current->thread.vstate.datap) + memset(current->thread.vstate.datap, 0, riscv_vsize); +#endif } int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) { fstate_save(src, task_pt_regs(src)); + if (has_vector()) + /* To make sure every dirty vector context is saved. */ + vstate_save(src, task_pt_regs(src)); *dst = *src; + if (has_vector()) { + /* Copy vector context to the forked task from parent. */ + if ((task_pt_regs(src)->status & SR_VS) != SR_VS_OFF) { + dst->thread.vstate.datap = kzalloc(riscv_vsize, GFP_KERNEL); + /* Failed to allocate memory. */ + if (!dst->thread.vstate.datap) + return -ENOMEM; + /* Copy the src vector context to dst. */ + memcpy(dst->thread.vstate.datap, + src->thread.vstate.datap, riscv_vsize); + } + } + return 0; } +void arch_release_task_struct(struct task_struct *tsk) +{ + /* Free the vector context of datap. */ + if (has_vector()) + kfree(tsk->thread.vstate.datap); +} + int copy_thread(unsigned long clone_flags, unsigned long usp, unsigned long arg, struct task_struct *p, unsigned long tls) { diff --git a/arch/riscv/kernel/vector.S b/arch/riscv/kernel/vector.S new file mode 100644 index 000000000000..7f3e3a838424 --- /dev/null +++ b/arch/riscv/kernel/vector.S @@ -0,0 +1,81 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2012 Regents of the University of California + * Copyright (C) 2017 SiFive + * Copyright (C) 2019 Alibaba Group Holding Limited + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation, version 2. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include + +#include +#include +#include + +#define vstatep a0 +#define datap a1 +#define x_vstart t0 +#define x_vtype t1 +#define x_vl t2 +#define x_vcsr t3 +#define incr t4 +#define status t5 + +ENTRY(__vstate_save) + li status, SR_VS + csrs sstatus, status + + csrr x_vstart, CSR_VSTART + csrr x_vtype, CSR_VTYPE + csrr x_vl, CSR_VL + csrr x_vcsr, CSR_VCSR + vsetvli incr, x0, e8, m8 + vse8.v v0, (datap) + add datap, datap, incr + vse8.v v8, (datap) + add datap, datap, incr + vse8.v v16, (datap) + add datap, datap, incr + vse8.v v24, (datap) + + REG_S x_vstart, RISCV_V_STATE_VSTART(vstatep) + REG_S x_vtype, RISCV_V_STATE_VTYPE(vstatep) + REG_S x_vl, RISCV_V_STATE_VL(vstatep) + REG_S x_vcsr, RISCV_V_STATE_VCSR(vstatep) + + csrc sstatus, status + ret +ENDPROC(__vstate_save) + +ENTRY(__vstate_restore) + li status, SR_VS + csrs sstatus, status + + vsetvli incr, x0, e8, m8 + vle8.v v0, (datap) + add datap, datap, incr + vle8.v v8, (datap) + add datap, datap, incr + vle8.v v16, (datap) + add datap, datap, incr + vle8.v v24, (datap) + + REG_L x_vstart, RISCV_V_STATE_VSTART(vstatep) + REG_L x_vtype, RISCV_V_STATE_VTYPE(vstatep) + REG_L x_vl, RISCV_V_STATE_VL(vstatep) + REG_L x_vcsr, RISCV_V_STATE_VCSR(vstatep) + vsetvl x0, x_vl, x_vtype + csrw CSR_VSTART, x_vstart + csrw CSR_VCSR, x_vcsr + + csrc sstatus, status + ret +ENDPROC(__vstate_restore) -- 2.31.1