From ecd2ada8a5e0b464dab54f71d4ba7bbf5708711f Mon Sep 17 00:00:00 2001 From: Greentime Hu Date: Mon, 15 Jan 2024 05:59:20 +0000 Subject: [PATCH 01/10] riscv: Add support for kernel mode vector MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Eric Biggers Tested-by: Björn Töpel Tested-by: Lad Prabhakar Link: https://lore.kernel.org/r/20240115055929.4736-2-andy.chiu@sifive.com Signed-off-by: Palmer Dabbelt --- arch/riscv/include/asm/processor.h | 12 ++- 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, 182 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 f19f861cda54..4809f20a2053 100644 --- a/arch/riscv/include/asm/processor.h +++ b/arch/riscv/include/asm/processor.h @@ -73,6 +73,15 @@ 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. + */ +#define RISCV_KERNEL_MODE_V 0x1 + /* CPU-specific state of a task */ struct thread_struct { /* Callee-saved registers */ @@ -81,7 +90,8 @@ struct thread_struct { 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; }; diff --git a/arch/riscv/include/asm/simd.h b/arch/riscv/include/asm/simd.h new file mode 100644 index 000000000000..ef8af413a9fc --- /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 87aaef656257..71af3404fda1 100644 --- a/arch/riscv/include/asm/vector.h +++ b/arch/riscv/include/asm/vector.h @@ -22,6 +22,15 @@ 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) { diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index fee22a3d1b53..8c58595696b3 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -63,6 +63,7 @@ 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 diff --git a/arch/riscv/kernel/kernel_mode_vector.c b/arch/riscv/kernel/kernel_mode_vector.c new file mode 100644 index 000000000000..114cf4f0a0eb --- /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 4f21d970a129..4a1275db1146 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -221,6 +221,7 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) 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; From 956895b9d8f74df015636288a81872c07c4fded3 Mon Sep 17 00:00:00 2001 From: Andy Chiu Date: Mon, 15 Jan 2024 05:59:21 +0000 Subject: [PATCH 02/10] riscv: vector: make Vector always available for softirq context MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The goal of this patch is to provide full support of Vector in kernel softirq context. So that some of the crypto alogrithms won't need scalar fallbacks. By disabling bottom halves in active kernel-mode Vector, softirq will not be able to nest on top of any kernel-mode Vector. So, softirq context is able to use Vector whenever it runs. After this patch, Vector context cannot start with irqs disabled. Otherwise local_bh_enable() may run in a wrong context. Disabling bh is not enough for RT-kernel to prevent preeemption. So we must disable preemption, which also implies disabling bh on RT. Related-to: commit 696207d4258b ("arm64/sve: Make kernel FPU protection RT friendly") Related-to: commit 66c3ec5a7120 ("arm64: neon: Forbid when irqs are disabled") Signed-off-by: Andy Chiu Reviewed-by: Eric Biggers Tested-by: Björn Töpel Tested-by: Lad Prabhakar Link: https://lore.kernel.org/r/20240115055929.4736-3-andy.chiu@sifive.com Signed-off-by: Palmer Dabbelt --- arch/riscv/include/asm/processor.h | 3 ++- arch/riscv/include/asm/simd.h | 6 +++++- arch/riscv/kernel/kernel_mode_vector.c | 14 ++++++++++++-- 3 files changed, 19 insertions(+), 4 deletions(-) diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h index 4809f20a2053..55ace554f202 100644 --- a/arch/riscv/include/asm/processor.h +++ b/arch/riscv/include/asm/processor.h @@ -78,7 +78,8 @@ struct pt_regs; * following meaning: * * - bit 0: indicates whether the in-kernel Vector context is active. The - * activation of this state disables the preemption. + * activation of this state disables the preemption. On a non-RT kernel, it + * also disable bh. */ #define RISCV_KERNEL_MODE_V 0x1 diff --git a/arch/riscv/include/asm/simd.h b/arch/riscv/include/asm/simd.h index ef8af413a9fc..4d699e16c9a9 100644 --- a/arch/riscv/include/asm/simd.h +++ b/arch/riscv/include/asm/simd.h @@ -28,8 +28,12 @@ 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. + * + * Kernel-mode Vector temporarily disables bh. So we must not return + * true on irq_disabled(). Otherwise we would fail the lockdep check + * calling local_bh_enable() */ - return !in_hardirq() && !in_nmi() && !(riscv_v_flags() & RISCV_KERNEL_MODE_V); + return !in_hardirq() && !in_nmi() && !irqs_disabled() && !(riscv_v_flags() & RISCV_KERNEL_MODE_V); } #else /* ! CONFIG_RISCV_ISA_V */ diff --git a/arch/riscv/kernel/kernel_mode_vector.c b/arch/riscv/kernel/kernel_mode_vector.c index 114cf4f0a0eb..2fc145edae3d 100644 --- a/arch/riscv/kernel/kernel_mode_vector.c +++ b/arch/riscv/kernel/kernel_mode_vector.c @@ -46,7 +46,14 @@ static inline void riscv_v_stop(u32 flags) */ void get_cpu_vector_context(void) { - preempt_disable(); + /* + * disable softirqs so it is impossible for softirqs to nest + * get_cpu_vector_context() when kernel is actively using Vector. + */ + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + local_bh_disable(); + else + preempt_disable(); riscv_v_start(RISCV_KERNEL_MODE_V); } @@ -62,7 +69,10 @@ void put_cpu_vector_context(void) { riscv_v_stop(RISCV_KERNEL_MODE_V); - preempt_enable(); + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + local_bh_enable(); + else + preempt_enable(); } /* From c5674d00cacdb1c47c72e19a552fbae401bc3532 Mon Sep 17 00:00:00 2001 From: Greentime Hu Date: Mon, 15 Jan 2024 05:59:22 +0000 Subject: [PATCH 03/10] riscv: Add vector extension XOR implementation MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This patch adds support for vector optimized XOR and it is tested in qemu. Co-developed-by: Han-Kuan Chen Signed-off-by: Han-Kuan Chen Signed-off-by: Greentime Hu Signed-off-by: Andy Chiu Tested-by: Björn Töpel Tested-by: Lad Prabhakar Link: https://lore.kernel.org/r/20240115055929.4736-4-andy.chiu@sifive.com Signed-off-by: Palmer Dabbelt --- arch/riscv/include/asm/asm-prototypes.h | 18 ++++++ arch/riscv/include/asm/xor.h | 68 +++++++++++++++++++++ arch/riscv/lib/Makefile | 1 + arch/riscv/lib/xor.S | 81 +++++++++++++++++++++++++ 4 files changed, 168 insertions(+) create mode 100644 arch/riscv/include/asm/xor.h create mode 100644 arch/riscv/lib/xor.S diff --git a/arch/riscv/include/asm/asm-prototypes.h b/arch/riscv/include/asm/asm-prototypes.h index 36b955c762ba..6db1a9bbff4c 100644 --- a/arch/riscv/include/asm/asm-prototypes.h +++ b/arch/riscv/include/asm/asm-prototypes.h @@ -9,6 +9,24 @@ long long __lshrti3(long long a, int b); long long __ashrti3(long long a, int b); long long __ashlti3(long long a, int b); +#ifdef CONFIG_RISCV_ISA_V + +void xor_regs_2_(unsigned long bytes, unsigned long *__restrict p1, + const unsigned long *__restrict p2); +void xor_regs_3_(unsigned long bytes, unsigned long *__restrict p1, + const unsigned long *__restrict p2, + const unsigned long *__restrict p3); +void xor_regs_4_(unsigned long bytes, unsigned long *__restrict p1, + const unsigned long *__restrict p2, + const unsigned long *__restrict p3, + const unsigned long *__restrict p4); +void xor_regs_5_(unsigned long bytes, unsigned long *__restrict p1, + const unsigned long *__restrict p2, + const unsigned long *__restrict p3, + const unsigned long *__restrict p4, + const unsigned long *__restrict p5); + +#endif /* CONFIG_RISCV_ISA_V */ #define DECLARE_DO_ERROR_INFO(name) asmlinkage void name(struct pt_regs *regs) diff --git a/arch/riscv/include/asm/xor.h b/arch/riscv/include/asm/xor.h new file mode 100644 index 000000000000..96011861e46b --- /dev/null +++ b/arch/riscv/include/asm/xor.h @@ -0,0 +1,68 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Copyright (C) 2021 SiFive + */ + +#include +#include +#ifdef CONFIG_RISCV_ISA_V +#include +#include +#include + +static void xor_vector_2(unsigned long bytes, unsigned long *__restrict p1, + const unsigned long *__restrict p2) +{ + kernel_vector_begin(); + xor_regs_2_(bytes, p1, p2); + kernel_vector_end(); +} + +static void xor_vector_3(unsigned long bytes, unsigned long *__restrict p1, + const unsigned long *__restrict p2, + const unsigned long *__restrict p3) +{ + kernel_vector_begin(); + xor_regs_3_(bytes, p1, p2, p3); + kernel_vector_end(); +} + +static void xor_vector_4(unsigned long bytes, unsigned long *__restrict p1, + const unsigned long *__restrict p2, + const unsigned long *__restrict p3, + const unsigned long *__restrict p4) +{ + kernel_vector_begin(); + xor_regs_4_(bytes, p1, p2, p3, p4); + kernel_vector_end(); +} + +static void xor_vector_5(unsigned long bytes, unsigned long *__restrict p1, + const unsigned long *__restrict p2, + const unsigned long *__restrict p3, + const unsigned long *__restrict p4, + const unsigned long *__restrict p5) +{ + kernel_vector_begin(); + xor_regs_5_(bytes, p1, p2, p3, p4, p5); + kernel_vector_end(); +} + +static struct xor_block_template xor_block_rvv = { + .name = "rvv", + .do_2 = xor_vector_2, + .do_3 = xor_vector_3, + .do_4 = xor_vector_4, + .do_5 = xor_vector_5 +}; + +#undef XOR_TRY_TEMPLATES +#define XOR_TRY_TEMPLATES \ + do { \ + xor_speed(&xor_block_8regs); \ + xor_speed(&xor_block_32regs); \ + if (has_vector()) { \ + xor_speed(&xor_block_rvv);\ + } \ + } while (0) +#endif diff --git a/arch/riscv/lib/Makefile b/arch/riscv/lib/Makefile index 26cb2502ecf8..494f9cd1a00c 100644 --- a/arch/riscv/lib/Makefile +++ b/arch/riscv/lib/Makefile @@ -11,3 +11,4 @@ lib-$(CONFIG_64BIT) += tishift.o lib-$(CONFIG_RISCV_ISA_ZICBOZ) += clear_page.o obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o +lib-$(CONFIG_RISCV_ISA_V) += xor.o diff --git a/arch/riscv/lib/xor.S b/arch/riscv/lib/xor.S new file mode 100644 index 000000000000..b28f2430e52f --- /dev/null +++ b/arch/riscv/lib/xor.S @@ -0,0 +1,81 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Copyright (C) 2021 SiFive + */ +#include +#include +#include + +SYM_FUNC_START(xor_regs_2_) + vsetvli a3, a0, e8, m8, ta, ma + vle8.v v0, (a1) + vle8.v v8, (a2) + sub a0, a0, a3 + vxor.vv v16, v0, v8 + add a2, a2, a3 + vse8.v v16, (a1) + add a1, a1, a3 + bnez a0, xor_regs_2_ + ret +SYM_FUNC_END(xor_regs_2_) +EXPORT_SYMBOL(xor_regs_2_) + +SYM_FUNC_START(xor_regs_3_) + vsetvli a4, a0, e8, m8, ta, ma + vle8.v v0, (a1) + vle8.v v8, (a2) + sub a0, a0, a4 + vxor.vv v0, v0, v8 + vle8.v v16, (a3) + add a2, a2, a4 + vxor.vv v16, v0, v16 + add a3, a3, a4 + vse8.v v16, (a1) + add a1, a1, a4 + bnez a0, xor_regs_3_ + ret +SYM_FUNC_END(xor_regs_3_) +EXPORT_SYMBOL(xor_regs_3_) + +SYM_FUNC_START(xor_regs_4_) + vsetvli a5, a0, e8, m8, ta, ma + vle8.v v0, (a1) + vle8.v v8, (a2) + sub a0, a0, a5 + vxor.vv v0, v0, v8 + vle8.v v16, (a3) + add a2, a2, a5 + vxor.vv v0, v0, v16 + vle8.v v24, (a4) + add a3, a3, a5 + vxor.vv v16, v0, v24 + add a4, a4, a5 + vse8.v v16, (a1) + add a1, a1, a5 + bnez a0, xor_regs_4_ + ret +SYM_FUNC_END(xor_regs_4_) +EXPORT_SYMBOL(xor_regs_4_) + +SYM_FUNC_START(xor_regs_5_) + vsetvli a6, a0, e8, m8, ta, ma + vle8.v v0, (a1) + vle8.v v8, (a2) + sub a0, a0, a6 + vxor.vv v0, v0, v8 + vle8.v v16, (a3) + add a2, a2, a6 + vxor.vv v0, v0, v16 + vle8.v v24, (a4) + add a3, a3, a6 + vxor.vv v0, v0, v24 + vle8.v v8, (a5) + add a4, a4, a6 + vxor.vv v16, v0, v8 + add a5, a5, a6 + vse8.v v16, (a1) + add a1, a1, a6 + bnez a0, xor_regs_5_ + ret +SYM_FUNC_END(xor_regs_5_) +EXPORT_SYMBOL(xor_regs_5_) From 7df56cbc27e4239807b5d8860f79a7350d63a741 Mon Sep 17 00:00:00 2001 From: Andy Chiu Date: Mon, 15 Jan 2024 05:59:23 +0000 Subject: [PATCH 04/10] riscv: sched: defer restoring Vector context for user MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit User will use its Vector registers only after the kernel really returns to the userspace. So we can delay restoring Vector registers as long as we are still running in kernel mode. So, add a thread flag to indicates the need of restoring Vector and do the restore at the last arch-specific exit-to-user hook. This save the context restoring cost when we switch over multiple processes that run V in kernel mode. For example, if the kernel performs a context swicth from A->B->C, and returns to C's userspace, then there is no need to restore B's V-register. Besides, this also prevents us from repeatedly restoring V context when executing kernel-mode Vector multiple times. The cost of this is that we must disable preemption and mark vector as busy during vstate_{save,restore}. Because then the V context will not get restored back immediately when a trap-causing context switch happens in the middle of vstate_{save,restore}. Signed-off-by: Andy Chiu Acked-by: Conor Dooley Tested-by: Björn Töpel Tested-by: Lad Prabhakar Link: https://lore.kernel.org/r/20240115055929.4736-5-andy.chiu@sifive.com Signed-off-by: Palmer Dabbelt --- arch/riscv/include/asm/entry-common.h | 17 +++++++++++++++++ arch/riscv/include/asm/thread_info.h | 2 ++ arch/riscv/include/asm/vector.h | 11 ++++++++++- arch/riscv/kernel/kernel_mode_vector.c | 2 +- arch/riscv/kernel/process.c | 2 ++ arch/riscv/kernel/ptrace.c | 5 ++++- arch/riscv/kernel/signal.c | 5 ++++- arch/riscv/kernel/vector.c | 2 +- 8 files changed, 41 insertions(+), 5 deletions(-) diff --git a/arch/riscv/include/asm/entry-common.h b/arch/riscv/include/asm/entry-common.h index 7ab5e34318c8..19023c430a9b 100644 --- a/arch/riscv/include/asm/entry-common.h +++ b/arch/riscv/include/asm/entry-common.h @@ -4,6 +4,23 @@ #define _ASM_RISCV_ENTRY_COMMON_H #include +#include +#include + +static inline void arch_exit_to_user_mode_prepare(struct pt_regs *regs, + unsigned long ti_work) +{ + if (ti_work & _TIF_RISCV_V_DEFER_RESTORE) { + clear_thread_flag(TIF_RISCV_V_DEFER_RESTORE); + /* + * We are already called with irq disabled, so go without + * keeping track of riscv_v_flags. + */ + riscv_v_vstate_restore(current, regs); + } +} + +#define arch_exit_to_user_mode_prepare arch_exit_to_user_mode_prepare void handle_page_fault(struct pt_regs *regs); void handle_break(struct pt_regs *regs); diff --git a/arch/riscv/include/asm/thread_info.h b/arch/riscv/include/asm/thread_info.h index 574779900bfb..1047a97ddbc8 100644 --- a/arch/riscv/include/asm/thread_info.h +++ b/arch/riscv/include/asm/thread_info.h @@ -103,12 +103,14 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src); #define TIF_NOTIFY_SIGNAL 9 /* signal notifications exist */ #define TIF_UPROBE 10 /* uprobe breakpoint or singlestep */ #define TIF_32BIT 11 /* compat-mode 32bit process */ +#define TIF_RISCV_V_DEFER_RESTORE 12 /* restore Vector before returing to user */ #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) #define _TIF_NOTIFY_SIGNAL (1 << TIF_NOTIFY_SIGNAL) #define _TIF_UPROBE (1 << TIF_UPROBE) +#define _TIF_RISCV_V_DEFER_RESTORE (1 << TIF_RISCV_V_DEFER_RESTORE) #define _TIF_WORK_MASK \ (_TIF_NOTIFY_RESUME | _TIF_SIGPENDING | _TIF_NEED_RESCHED | \ diff --git a/arch/riscv/include/asm/vector.h b/arch/riscv/include/asm/vector.h index 71af3404fda1..961c4e3d1b62 100644 --- a/arch/riscv/include/asm/vector.h +++ b/arch/riscv/include/asm/vector.h @@ -193,6 +193,15 @@ static inline void riscv_v_vstate_restore(struct task_struct *task, } } +static inline void riscv_v_vstate_set_restore(struct task_struct *task, + struct pt_regs *regs) +{ + if ((regs->status & SR_VS) != SR_VS_OFF) { + set_tsk_thread_flag(task, TIF_RISCV_V_DEFER_RESTORE); + riscv_v_vstate_on(regs); + } +} + static inline void __switch_to_vector(struct task_struct *prev, struct task_struct *next) { @@ -200,7 +209,7 @@ static inline void __switch_to_vector(struct task_struct *prev, regs = task_pt_regs(prev); riscv_v_vstate_save(prev, regs); - riscv_v_vstate_restore(next, task_pt_regs(next)); + riscv_v_vstate_set_restore(next, task_pt_regs(next)); } void riscv_v_vstate_ctrl_init(struct task_struct *tsk); diff --git a/arch/riscv/kernel/kernel_mode_vector.c b/arch/riscv/kernel/kernel_mode_vector.c index 2fc145edae3d..8422c881f452 100644 --- a/arch/riscv/kernel/kernel_mode_vector.c +++ b/arch/riscv/kernel/kernel_mode_vector.c @@ -117,7 +117,7 @@ void kernel_vector_end(void) if (WARN_ON(!has_vector())) return; - riscv_v_vstate_restore(current, task_pt_regs(current)); + riscv_v_vstate_set_restore(current, task_pt_regs(current)); riscv_v_disable(); diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c index 4a1275db1146..36993f408de4 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -171,6 +171,7 @@ void flush_thread(void) riscv_v_vstate_off(task_pt_regs(current)); kfree(current->thread.vstate.datap); memset(¤t->thread.vstate, 0, sizeof(struct __riscv_v_ext_state)); + clear_tsk_thread_flag(current, TIF_RISCV_V_DEFER_RESTORE); #endif } @@ -187,6 +188,7 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) *dst = *src; /* clear entire V context, including datap for a new task */ memset(&dst->thread.vstate, 0, sizeof(struct __riscv_v_ext_state)); + clear_tsk_thread_flag(dst, TIF_RISCV_V_DEFER_RESTORE); return 0; } diff --git a/arch/riscv/kernel/ptrace.c b/arch/riscv/kernel/ptrace.c index 2afe460de16a..7b93bcbdf9fa 100644 --- a/arch/riscv/kernel/ptrace.c +++ b/arch/riscv/kernel/ptrace.c @@ -99,8 +99,11 @@ static int riscv_vr_get(struct task_struct *target, * Ensure the vector registers have been saved to the memory before * copying them to membuf. */ - if (target == current) + if (target == current) { + get_cpu_vector_context(); riscv_v_vstate_save(current, task_pt_regs(current)); + put_cpu_vector_context(); + } ptrace_vstate.vstart = vstate->vstart; ptrace_vstate.vl = vstate->vl; diff --git a/arch/riscv/kernel/signal.c b/arch/riscv/kernel/signal.c index 88b6220b2608..aca4a12c8416 100644 --- a/arch/riscv/kernel/signal.c +++ b/arch/riscv/kernel/signal.c @@ -86,7 +86,10 @@ static long save_v_state(struct pt_regs *regs, void __user **sc_vec) /* datap is designed to be 16 byte aligned for better performance */ WARN_ON(unlikely(!IS_ALIGNED((unsigned long)datap, 16))); + get_cpu_vector_context(); riscv_v_vstate_save(current, regs); + put_cpu_vector_context(); + /* Copy everything of vstate but datap. */ err = __copy_to_user(&state->v_state, ¤t->thread.vstate, offsetof(struct __riscv_v_ext_state, datap)); @@ -134,7 +137,7 @@ static long __restore_v_state(struct pt_regs *regs, void __user *sc_vec) if (unlikely(err)) return err; - riscv_v_vstate_restore(current, regs); + riscv_v_vstate_set_restore(current, regs); return err; } diff --git a/arch/riscv/kernel/vector.c b/arch/riscv/kernel/vector.c index 578b6292487e..66e8c6ab09d2 100644 --- a/arch/riscv/kernel/vector.c +++ b/arch/riscv/kernel/vector.c @@ -167,7 +167,7 @@ bool riscv_v_first_use_handler(struct pt_regs *regs) return true; } riscv_v_vstate_on(regs); - riscv_v_vstate_restore(current, regs); + riscv_v_vstate_set_restore(current, regs); return true; } From c2a658d419246108c9bf065ec347355de5ba8a05 Mon Sep 17 00:00:00 2001 From: Andy Chiu Date: Mon, 15 Jan 2024 05:59:24 +0000 Subject: [PATCH 05/10] riscv: lib: vectorize copy_to_user/copy_from_user MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This patch utilizes Vector to perform copy_to_user/copy_from_user. If Vector is available and the size of copy is large enough for Vector to perform better than scalar, then direct the kernel to do Vector copies for userspace. Though the best programming practice for users is to reduce the copy, this provides a faster variant when copies are inevitable. The optimal size for using Vector, copy_to_user_thres, is only a heuristic for now. We can add DT parsing if people feel the need of customizing it. The exception fixup code of the __asm_vector_usercopy must fallback to the scalar one because accessing user pages might fault, and must be sleepable. Current kernel-mode Vector does not allow tasks to be preemptible, so we must disactivate Vector and perform a scalar fallback in such case. The original implementation of Vector operations comes from https://github.com/sifive/sifive-libc, which we agree to contribute to Linux kernel. Co-developed-by: Jerry Shih Signed-off-by: Jerry Shih Co-developed-by: Nick Knight Signed-off-by: Nick Knight Suggested-by: Guo Ren Signed-off-by: Andy Chiu Tested-by: Björn Töpel Tested-by: Lad Prabhakar Link: https://lore.kernel.org/r/20240115055929.4736-6-andy.chiu@sifive.com Signed-off-by: Palmer Dabbelt --- arch/riscv/Kconfig | 8 ++++ arch/riscv/include/asm/asm-prototypes.h | 4 ++ arch/riscv/lib/Makefile | 6 ++- arch/riscv/lib/riscv_v_helpers.c | 45 +++++++++++++++++++++ arch/riscv/lib/uaccess.S | 10 +++++ arch/riscv/lib/uaccess_vector.S | 53 +++++++++++++++++++++++++ 6 files changed, 125 insertions(+), 1 deletion(-) create mode 100644 arch/riscv/lib/riscv_v_helpers.c create mode 100644 arch/riscv/lib/uaccess_vector.S diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 95a2a06acc6a..3c5ba05e8a2d 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -525,6 +525,14 @@ config RISCV_ISA_V_DEFAULT_ENABLE If you don't know what to do here, say Y. +config RISCV_ISA_V_UCOPY_THRESHOLD + int "Threshold size for vectorized user copies" + depends on RISCV_ISA_V + default 768 + help + Prefer using vectorized copy_to_user()/copy_from_user() when the + workload size exceeds this value. + config TOOLCHAIN_HAS_ZBB bool default y diff --git a/arch/riscv/include/asm/asm-prototypes.h b/arch/riscv/include/asm/asm-prototypes.h index 6db1a9bbff4c..be438932f321 100644 --- a/arch/riscv/include/asm/asm-prototypes.h +++ b/arch/riscv/include/asm/asm-prototypes.h @@ -11,6 +11,10 @@ long long __ashlti3(long long a, int b); #ifdef CONFIG_RISCV_ISA_V +#ifdef CONFIG_MMU +asmlinkage int enter_vector_usercopy(void *dst, void *src, size_t n); +#endif /* CONFIG_MMU */ + void xor_regs_2_(unsigned long bytes, unsigned long *__restrict p1, const unsigned long *__restrict p2); void xor_regs_3_(unsigned long bytes, unsigned long *__restrict p1, diff --git a/arch/riscv/lib/Makefile b/arch/riscv/lib/Makefile index 494f9cd1a00c..c8a6787d5827 100644 --- a/arch/riscv/lib/Makefile +++ b/arch/riscv/lib/Makefile @@ -6,9 +6,13 @@ lib-y += memmove.o lib-y += strcmp.o lib-y += strlen.o lib-y += strncmp.o -lib-$(CONFIG_MMU) += uaccess.o +ifeq ($(CONFIG_MMU), y) +lib-y += uaccess.o +lib-$(CONFIG_RISCV_ISA_V) += uaccess_vector.o +endif lib-$(CONFIG_64BIT) += tishift.o lib-$(CONFIG_RISCV_ISA_ZICBOZ) += clear_page.o obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o lib-$(CONFIG_RISCV_ISA_V) += xor.o +lib-$(CONFIG_RISCV_ISA_V) += riscv_v_helpers.o diff --git a/arch/riscv/lib/riscv_v_helpers.c b/arch/riscv/lib/riscv_v_helpers.c new file mode 100644 index 000000000000..be38a93cedae --- /dev/null +++ b/arch/riscv/lib/riscv_v_helpers.c @@ -0,0 +1,45 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2023 SiFive + * Author: Andy Chiu + */ +#include +#include + +#include +#include + +#ifdef CONFIG_MMU +#include +#endif + +#ifdef CONFIG_MMU +size_t riscv_v_usercopy_threshold = CONFIG_RISCV_ISA_V_UCOPY_THRESHOLD; +int __asm_vector_usercopy(void *dst, void *src, size_t n); +int fallback_scalar_usercopy(void *dst, void *src, size_t n); +asmlinkage int enter_vector_usercopy(void *dst, void *src, size_t n) +{ + size_t remain, copied; + + /* skip has_vector() check because it has been done by the asm */ + if (!may_use_simd()) + goto fallback; + + kernel_vector_begin(); + remain = __asm_vector_usercopy(dst, src, n); + kernel_vector_end(); + + if (remain) { + copied = n - remain; + dst += copied; + src += copied; + n = remain; + goto fallback; + } + + return remain; + +fallback: + return fallback_scalar_usercopy(dst, src, n); +} +#endif diff --git a/arch/riscv/lib/uaccess.S b/arch/riscv/lib/uaccess.S index 3ab438f30d13..a1e4a3c42925 100644 --- a/arch/riscv/lib/uaccess.S +++ b/arch/riscv/lib/uaccess.S @@ -3,6 +3,8 @@ #include #include #include +#include +#include .macro fixup op reg addr lbl 100: @@ -11,6 +13,13 @@ .endm SYM_FUNC_START(__asm_copy_to_user) +#ifdef CONFIG_RISCV_ISA_V + ALTERNATIVE("j fallback_scalar_usercopy", "nop", 0, RISCV_ISA_EXT_v, CONFIG_RISCV_ISA_V) + REG_L t0, riscv_v_usercopy_threshold + bltu a2, t0, fallback_scalar_usercopy + tail enter_vector_usercopy +#endif +SYM_FUNC_START(fallback_scalar_usercopy) /* Enable access to user memory */ li t6, SR_SUM @@ -181,6 +190,7 @@ SYM_FUNC_START(__asm_copy_to_user) sub a0, t5, a0 ret SYM_FUNC_END(__asm_copy_to_user) +SYM_FUNC_END(fallback_scalar_usercopy) EXPORT_SYMBOL(__asm_copy_to_user) SYM_FUNC_ALIAS(__asm_copy_from_user, __asm_copy_to_user) EXPORT_SYMBOL(__asm_copy_from_user) diff --git a/arch/riscv/lib/uaccess_vector.S b/arch/riscv/lib/uaccess_vector.S new file mode 100644 index 000000000000..51ab5588e9ff --- /dev/null +++ b/arch/riscv/lib/uaccess_vector.S @@ -0,0 +1,53 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ + +#include +#include +#include +#include +#include + +#define pDst a0 +#define pSrc a1 +#define iNum a2 + +#define iVL a3 + +#define ELEM_LMUL_SETTING m8 +#define vData v0 + + .macro fixup op reg addr lbl +100: + \op \reg, \addr + _asm_extable 100b, \lbl + .endm + +SYM_FUNC_START(__asm_vector_usercopy) + /* Enable access to user memory */ + li t6, SR_SUM + csrs CSR_STATUS, t6 + +loop: + vsetvli iVL, iNum, e8, ELEM_LMUL_SETTING, ta, ma + fixup vle8.v vData, (pSrc), 10f + sub iNum, iNum, iVL + add pSrc, pSrc, iVL + fixup vse8.v vData, (pDst), 11f + add pDst, pDst, iVL + bnez iNum, loop + + /* Exception fixup for vector load is shared with normal exit */ +10: + /* Disable access to user memory */ + csrc CSR_STATUS, t6 + mv a0, iNum + ret + + /* Exception fixup code for vector store. */ +11: + /* Undo the subtraction after vle8.v */ + add iNum, iNum, iVL + /* Make sure the scalar fallback skip already processed bytes */ + csrr t2, CSR_VSTART + sub iNum, iNum, t2 + j 10b +SYM_FUNC_END(__asm_vector_usercopy) From a93fdaf183125fea81f66b9bd756ef5a0c30859e Mon Sep 17 00:00:00 2001 From: Andy Chiu Date: Mon, 15 Jan 2024 05:59:25 +0000 Subject: [PATCH 06/10] riscv: fpu: drop SR_SD bit checking MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit SR_SD summarizes the dirty status of FS/VS/XS. However, the current code structure does not fully utilize it because each extension specific code is divided into an individual segment. So remove the SR_SD check for now. Signed-off-by: Andy Chiu Reviewed-by: Song Shuai Reviewed-by: Guo Ren Tested-by: Björn Töpel Tested-by: Lad Prabhakar Link: https://lore.kernel.org/r/20240115055929.4736-7-andy.chiu@sifive.com Signed-off-by: Palmer Dabbelt --- arch/riscv/include/asm/switch_to.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/arch/riscv/include/asm/switch_to.h b/arch/riscv/include/asm/switch_to.h index f90d8e42f3c7..7efdb0584d47 100644 --- a/arch/riscv/include/asm/switch_to.h +++ b/arch/riscv/include/asm/switch_to.h @@ -53,8 +53,7 @@ static inline void __switch_to_fpu(struct task_struct *prev, struct pt_regs *regs; regs = task_pt_regs(prev); - if (unlikely(regs->status & SR_SD)) - fstate_save(prev, regs); + fstate_save(prev, regs); fstate_restore(next, task_pt_regs(next)); } From d6c78f1ca3e8ec3fd1afa1bc567cdf083e7af9fe Mon Sep 17 00:00:00 2001 From: Andy Chiu Date: Mon, 15 Jan 2024 05:59:26 +0000 Subject: [PATCH 07/10] riscv: vector: do not pass task_struct into riscv_v_vstate_{save,restore}() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit riscv_v_vstate_{save,restore}() can operate only on the knowlege of struct __riscv_v_ext_state, and struct pt_regs. Let the caller decides which should be passed into the function. Meanwhile, the kernel-mode Vector is going to introduce another vstate, so this also makes functions potentially able to be reused. Signed-off-by: Andy Chiu Acked-by: Conor Dooley Tested-by: Björn Töpel Tested-by: Lad Prabhakar Link: https://lore.kernel.org/r/20240115055929.4736-8-andy.chiu@sifive.com Signed-off-by: Palmer Dabbelt --- arch/riscv/include/asm/entry-common.h | 2 +- arch/riscv/include/asm/vector.h | 14 +++++--------- arch/riscv/kernel/kernel_mode_vector.c | 2 +- arch/riscv/kernel/ptrace.c | 2 +- arch/riscv/kernel/signal.c | 2 +- 5 files changed, 9 insertions(+), 13 deletions(-) diff --git a/arch/riscv/include/asm/entry-common.h b/arch/riscv/include/asm/entry-common.h index 19023c430a9b..2293e535f865 100644 --- a/arch/riscv/include/asm/entry-common.h +++ b/arch/riscv/include/asm/entry-common.h @@ -16,7 +16,7 @@ static inline void arch_exit_to_user_mode_prepare(struct pt_regs *regs, * We are already called with irq disabled, so go without * keeping track of riscv_v_flags. */ - riscv_v_vstate_restore(current, regs); + riscv_v_vstate_restore(¤t->thread.vstate, regs); } } diff --git a/arch/riscv/include/asm/vector.h b/arch/riscv/include/asm/vector.h index 961c4e3d1b62..d75079520629 100644 --- a/arch/riscv/include/asm/vector.h +++ b/arch/riscv/include/asm/vector.h @@ -171,23 +171,19 @@ static inline void riscv_v_vstate_discard(struct pt_regs *regs) __riscv_v_vstate_dirty(regs); } -static inline void riscv_v_vstate_save(struct task_struct *task, +static inline void riscv_v_vstate_save(struct __riscv_v_ext_state *vstate, struct pt_regs *regs) { if ((regs->status & SR_VS) == SR_VS_DIRTY) { - struct __riscv_v_ext_state *vstate = &task->thread.vstate; - __riscv_v_vstate_save(vstate, vstate->datap); __riscv_v_vstate_clean(regs); } } -static inline void riscv_v_vstate_restore(struct task_struct *task, +static inline void riscv_v_vstate_restore(struct __riscv_v_ext_state *vstate, struct pt_regs *regs) { if ((regs->status & SR_VS) != SR_VS_OFF) { - struct __riscv_v_ext_state *vstate = &task->thread.vstate; - __riscv_v_vstate_restore(vstate, vstate->datap); __riscv_v_vstate_clean(regs); } @@ -208,7 +204,7 @@ static inline void __switch_to_vector(struct task_struct *prev, struct pt_regs *regs; regs = task_pt_regs(prev); - riscv_v_vstate_save(prev, regs); + riscv_v_vstate_save(&prev->thread.vstate, regs); riscv_v_vstate_set_restore(next, task_pt_regs(next)); } @@ -226,8 +222,8 @@ static inline bool riscv_v_vstate_query(struct pt_regs *regs) { return false; } static inline bool riscv_v_vstate_ctrl_user_allowed(void) { return false; } #define riscv_v_vsize (0) #define riscv_v_vstate_discard(regs) do {} while (0) -#define riscv_v_vstate_save(task, regs) do {} while (0) -#define riscv_v_vstate_restore(task, regs) do {} while (0) +#define riscv_v_vstate_save(vstate, regs) do {} while (0) +#define riscv_v_vstate_restore(vstate, regs) do {} while (0) #define __switch_to_vector(__prev, __next) do {} while (0) #define riscv_v_vstate_off(regs) do {} while (0) #define riscv_v_vstate_on(regs) do {} while (0) diff --git a/arch/riscv/kernel/kernel_mode_vector.c b/arch/riscv/kernel/kernel_mode_vector.c index 8422c881f452..241a8f834e1c 100644 --- a/arch/riscv/kernel/kernel_mode_vector.c +++ b/arch/riscv/kernel/kernel_mode_vector.c @@ -97,7 +97,7 @@ void kernel_vector_begin(void) get_cpu_vector_context(); - riscv_v_vstate_save(current, task_pt_regs(current)); + riscv_v_vstate_save(¤t->thread.vstate, task_pt_regs(current)); riscv_v_enable(); } diff --git a/arch/riscv/kernel/ptrace.c b/arch/riscv/kernel/ptrace.c index 7b93bcbdf9fa..e8515aa9d80b 100644 --- a/arch/riscv/kernel/ptrace.c +++ b/arch/riscv/kernel/ptrace.c @@ -101,7 +101,7 @@ static int riscv_vr_get(struct task_struct *target, */ if (target == current) { get_cpu_vector_context(); - riscv_v_vstate_save(current, task_pt_regs(current)); + riscv_v_vstate_save(¤t->thread.vstate, task_pt_regs(current)); put_cpu_vector_context(); } diff --git a/arch/riscv/kernel/signal.c b/arch/riscv/kernel/signal.c index aca4a12c8416..5d69f4db9e8f 100644 --- a/arch/riscv/kernel/signal.c +++ b/arch/riscv/kernel/signal.c @@ -87,7 +87,7 @@ static long save_v_state(struct pt_regs *regs, void __user **sc_vec) WARN_ON(unlikely(!IS_ALIGNED((unsigned long)datap, 16))); get_cpu_vector_context(); - riscv_v_vstate_save(current, regs); + riscv_v_vstate_save(¤t->thread.vstate, regs); put_cpu_vector_context(); /* Copy everything of vstate but datap. */ From 5b6048f2ff710196c85ce14373febe8be5115bbe Mon Sep 17 00:00:00 2001 From: Andy Chiu Date: Mon, 15 Jan 2024 05:59:27 +0000 Subject: [PATCH 08/10] riscv: vector: use a mask to write vstate_ctrl MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit riscv_v_ctrl_set() should only touch bits within PR_RISCV_V_VSTATE_CTRL_MASK. So, use the mask when we really set task's vstate_ctrl. Signed-off-by: Andy Chiu Tested-by: Björn Töpel Tested-by: Lad Prabhakar Link: https://lore.kernel.org/r/20240115055929.4736-9-andy.chiu@sifive.com Signed-off-by: Palmer Dabbelt --- arch/riscv/kernel/vector.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/riscv/kernel/vector.c b/arch/riscv/kernel/vector.c index 66e8c6ab09d2..c1f28bc89ec6 100644 --- a/arch/riscv/kernel/vector.c +++ b/arch/riscv/kernel/vector.c @@ -122,7 +122,8 @@ static inline void riscv_v_ctrl_set(struct task_struct *tsk, int cur, int nxt, ctrl |= VSTATE_CTRL_MAKE_NEXT(nxt); if (inherit) ctrl |= PR_RISCV_V_VSTATE_CTRL_INHERIT; - tsk->thread.vstate_ctrl = ctrl; + tsk->thread.vstate_ctrl &= ~PR_RISCV_V_VSTATE_CTRL_MASK; + tsk->thread.vstate_ctrl |= ctrl; } bool riscv_v_vstate_ctrl_user_allowed(void) From bd446f5df5afab212917f6732ba6442a5e8de85e Mon Sep 17 00:00:00 2001 From: Andy Chiu Date: Mon, 15 Jan 2024 05:59:28 +0000 Subject: [PATCH 09/10] riscv: vector: use kmem_cache to manage vector context MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The allocation size of thread.vstate.datap is always riscv_v_vsize. So it is possbile to use kmem_cache_* to manage the allocation. This gives users more information regarding allocation of vector context via /proc/slabinfo. And it potentially reduces the latency of the first-use trap because of the allocation caches. Signed-off-by: Andy Chiu Tested-by: Björn Töpel Tested-by: Lad Prabhakar Link: https://lore.kernel.org/r/20240115055929.4736-10-andy.chiu@sifive.com Signed-off-by: Palmer Dabbelt --- arch/riscv/include/asm/vector.h | 4 ++++ arch/riscv/kernel/process.c | 7 ++++++- arch/riscv/kernel/vector.c | 19 ++++++++++++++++++- 3 files changed, 28 insertions(+), 2 deletions(-) diff --git a/arch/riscv/include/asm/vector.h b/arch/riscv/include/asm/vector.h index d75079520629..7b316050f24f 100644 --- a/arch/riscv/include/asm/vector.h +++ b/arch/riscv/include/asm/vector.h @@ -26,6 +26,8 @@ void kernel_vector_begin(void); void kernel_vector_end(void); void get_cpu_vector_context(void); void put_cpu_vector_context(void); +void riscv_v_thread_free(struct task_struct *tsk); +void __init riscv_v_setup_ctx_cache(void); static inline u32 riscv_v_flags(void) { @@ -227,6 +229,8 @@ static inline bool riscv_v_vstate_ctrl_user_allowed(void) { return false; } #define __switch_to_vector(__prev, __next) do {} while (0) #define riscv_v_vstate_off(regs) do {} while (0) #define riscv_v_vstate_on(regs) do {} while (0) +#define riscv_v_thread_free(tsk) do {} while (0) +#define riscv_v_setup_ctx_cache() do {} while (0) #endif /* CONFIG_RISCV_ISA_V */ diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c index 36993f408de4..862d59c3872e 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -179,7 +179,7 @@ void arch_release_task_struct(struct task_struct *tsk) { /* Free the vector context of datap. */ if (has_vector()) - kfree(tsk->thread.vstate.datap); + riscv_v_thread_free(tsk); } int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) @@ -228,3 +228,8 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) p->thread.sp = (unsigned long)childregs; /* kernel sp */ return 0; } + +void __init arch_task_cache_init(void) +{ + riscv_v_setup_ctx_cache(); +} diff --git a/arch/riscv/kernel/vector.c b/arch/riscv/kernel/vector.c index c1f28bc89ec6..f7b4aeb9e457 100644 --- a/arch/riscv/kernel/vector.c +++ b/arch/riscv/kernel/vector.c @@ -21,6 +21,7 @@ #include static bool riscv_v_implicit_uacc = IS_ENABLED(CONFIG_RISCV_ISA_V_DEFAULT_ENABLE); +static struct kmem_cache *riscv_v_user_cachep; unsigned long riscv_v_vsize __read_mostly; EXPORT_SYMBOL_GPL(riscv_v_vsize); @@ -47,6 +48,16 @@ int riscv_v_setup_vsize(void) return 0; } +void __init riscv_v_setup_ctx_cache(void) +{ + if (!has_vector()) + return; + + riscv_v_user_cachep = kmem_cache_create_usercopy("riscv_vector_ctx", + riscv_v_vsize, 16, SLAB_PANIC, + 0, riscv_v_vsize, NULL); +} + static bool insn_is_vector(u32 insn_buf) { u32 opcode = insn_buf & __INSN_OPCODE_MASK; @@ -84,7 +95,7 @@ static int riscv_v_thread_zalloc(void) { void *datap; - datap = kzalloc(riscv_v_vsize, GFP_KERNEL); + datap = kmem_cache_zalloc(riscv_v_user_cachep, GFP_KERNEL); if (!datap) return -ENOMEM; @@ -94,6 +105,12 @@ static int riscv_v_thread_zalloc(void) return 0; } +void riscv_v_thread_free(struct task_struct *tsk) +{ + if (tsk->thread.vstate.datap) + kmem_cache_free(riscv_v_user_cachep, tsk->thread.vstate.datap); +} + #define VSTATE_CTRL_GET_CUR(x) ((x) & PR_RISCV_V_VSTATE_CTRL_CUR_MASK) #define VSTATE_CTRL_GET_NEXT(x) (((x) & PR_RISCV_V_VSTATE_CTRL_NEXT_MASK) >> 2) #define VSTATE_CTRL_MAKE_NEXT(x) (((x) << 2) & PR_RISCV_V_VSTATE_CTRL_NEXT_MASK) From 2080ff9493072a94e42b1856d59f5f1bffb761b7 Mon Sep 17 00:00:00 2001 From: Andy Chiu Date: Mon, 15 Jan 2024 05:59:29 +0000 Subject: [PATCH 10/10] riscv: vector: allow kernel-mode Vector with preemption MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add kernel_vstate to keep track of kernel-mode Vector registers when trap introduced context switch happens. Also, provide riscv_v_flags to let context save/restore routine track context status. Context tracking happens whenever the core starts its in-kernel Vector executions. An active (dirty) kernel task's V contexts will be saved to memory whenever a trap-introduced context switch happens. Or, when a softirq, which happens to nest on top of it, uses Vector. Context retoring happens when the execution transfer back to the original Kernel context where it first enable preempt_v. Also, provide a config CONFIG_RISCV_ISA_V_PREEMPTIVE to give users an option to disable preemptible kernel-mode Vector at build time. Users with constraint memory may want to disable this config as preemptible kernel-mode Vector needs extra space for tracking of per thread's kernel-mode V context. Or, users might as well want to disable it if all kernel-mode Vector code is time sensitive and cannot tolerate context switch overhead. Signed-off-by: Andy Chiu Tested-by: Björn Töpel Tested-by: Lad Prabhakar Link: https://lore.kernel.org/r/20240115055929.4736-11-andy.chiu@sifive.com Signed-off-by: Palmer Dabbelt --- arch/riscv/Kconfig | 14 +++ arch/riscv/include/asm/asm-prototypes.h | 5 + arch/riscv/include/asm/processor.h | 30 +++++- arch/riscv/include/asm/simd.h | 26 ++++- arch/riscv/include/asm/vector.h | 58 ++++++++++- arch/riscv/kernel/entry.S | 8 ++ arch/riscv/kernel/kernel_mode_vector.c | 133 ++++++++++++++++++++++-- arch/riscv/kernel/process.c | 3 + arch/riscv/kernel/vector.c | 31 ++++-- 9 files changed, 286 insertions(+), 22 deletions(-) diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 3c5ba05e8a2d..0a03d72706b5 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -533,6 +533,20 @@ config RISCV_ISA_V_UCOPY_THRESHOLD Prefer using vectorized copy_to_user()/copy_from_user() when the workload size exceeds this value. +config RISCV_ISA_V_PREEMPTIVE + bool "Run kernel-mode Vector with kernel preemption" + depends on PREEMPTION + depends on RISCV_ISA_V + default y + help + Usually, in-kernel SIMD routines are run with preemption disabled. + Functions which envoke long running SIMD thus must yield core's + vector unit to prevent blocking other tasks for too long. + + This config allows kernel to run SIMD without explicitly disable + preemption. Enabling this config will result in higher memory + consumption due to the allocation of per-task's kernel Vector context. + config TOOLCHAIN_HAS_ZBB bool default y diff --git a/arch/riscv/include/asm/asm-prototypes.h b/arch/riscv/include/asm/asm-prototypes.h index be438932f321..cd627ec289f1 100644 --- a/arch/riscv/include/asm/asm-prototypes.h +++ b/arch/riscv/include/asm/asm-prototypes.h @@ -30,6 +30,11 @@ void xor_regs_5_(unsigned long bytes, unsigned long *__restrict p1, const unsigned long *__restrict p4, const unsigned long *__restrict p5); +#ifdef CONFIG_RISCV_ISA_V_PREEMPTIVE +asmlinkage void riscv_v_context_nesting_start(struct pt_regs *regs); +asmlinkage void riscv_v_context_nesting_end(struct pt_regs *regs); +#endif /* CONFIG_RISCV_ISA_V_PREEMPTIVE */ + #endif /* CONFIG_RISCV_ISA_V */ #define DECLARE_DO_ERROR_INFO(name) asmlinkage void name(struct pt_regs *regs) diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h index 55ace554f202..b02119ff08fc 100644 --- a/arch/riscv/include/asm/processor.h +++ b/arch/riscv/include/asm/processor.h @@ -80,8 +80,35 @@ struct pt_regs; * - bit 0: indicates whether the in-kernel Vector context is active. The * activation of this state disables the preemption. On a non-RT kernel, it * also disable bh. + * - bits 8: is used for tracking preemptible kernel-mode Vector, when + * RISCV_ISA_V_PREEMPTIVE is enabled. Calling kernel_vector_begin() does not + * disable the preemption if the thread's kernel_vstate.datap is allocated. + * Instead, the kernel set this bit field. Then the trap entry/exit code + * knows if we are entering/exiting the context that owns preempt_v. + * - 0: the task is not using preempt_v + * - 1: the task is actively using preempt_v. But whether does the task own + * the preempt_v context is decided by bits in RISCV_V_CTX_DEPTH_MASK. + * - bit 16-23 are RISCV_V_CTX_DEPTH_MASK, used by context tracking routine + * when preempt_v starts: + * - 0: the task is actively using, and own preempt_v context. + * - non-zero: the task was using preempt_v, but then took a trap within. + * Thus, the task does not own preempt_v. Any use of Vector will have to + * save preempt_v, if dirty, and fallback to non-preemptible kernel-mode + * Vector. + * - bit 30: The in-kernel preempt_v context is saved, and requries to be + * restored when returning to the context that owns the preempt_v. + * - bit 31: The in-kernel preempt_v context is dirty, as signaled by the + * trap entry code. Any context switches out-of current task need to save + * it to the task's in-kernel V context. Also, any traps nesting on-top-of + * preempt_v requesting to use V needs a save. */ -#define RISCV_KERNEL_MODE_V 0x1 +#define RISCV_V_CTX_DEPTH_MASK 0x00ff0000 + +#define RISCV_V_CTX_UNIT_DEPTH 0x00010000 +#define RISCV_KERNEL_MODE_V 0x00000001 +#define RISCV_PREEMPT_V 0x00000100 +#define RISCV_PREEMPT_V_DIRTY 0x80000000 +#define RISCV_PREEMPT_V_NEED_RESTORE 0x40000000 /* CPU-specific state of a task */ struct thread_struct { @@ -95,6 +122,7 @@ struct thread_struct { u32 vstate_ctrl; struct __riscv_v_ext_state vstate; unsigned long align_ctl; + struct __riscv_v_ext_state kernel_vstate; }; /* Whitelist the fstate from the task_struct for hardened usercopy */ diff --git a/arch/riscv/include/asm/simd.h b/arch/riscv/include/asm/simd.h index 4d699e16c9a9..54efbf523d49 100644 --- a/arch/riscv/include/asm/simd.h +++ b/arch/riscv/include/asm/simd.h @@ -12,6 +12,7 @@ #include #include #include +#include #include @@ -28,12 +29,27 @@ 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. - * - * Kernel-mode Vector temporarily disables bh. So we must not return - * true on irq_disabled(). Otherwise we would fail the lockdep check - * calling local_bh_enable() */ - return !in_hardirq() && !in_nmi() && !irqs_disabled() && !(riscv_v_flags() & RISCV_KERNEL_MODE_V); + if (in_hardirq() || in_nmi()) + return false; + + /* + * Nesting is acheived in preempt_v by spreading the control for + * preemptible and non-preemptible kernel-mode Vector into two fields. + * Always try to match with prempt_v if kernel V-context exists. Then, + * fallback to check non preempt_v if nesting happens, or if the config + * is not set. + */ + if (IS_ENABLED(CONFIG_RISCV_ISA_V_PREEMPTIVE) && current->thread.kernel_vstate.datap) { + if (!riscv_preempt_v_started(current)) + return true; + } + /* + * Non-preemptible kernel-mode Vector temporarily disables bh. So we + * must not return true on irq_disabled(). Otherwise we would fail the + * lockdep check calling local_bh_enable() + */ + return !irqs_disabled() && !(riscv_v_flags() & RISCV_KERNEL_MODE_V); } #else /* ! CONFIG_RISCV_ISA_V */ diff --git a/arch/riscv/include/asm/vector.h b/arch/riscv/include/asm/vector.h index 7b316050f24f..0cd6f0a027d1 100644 --- a/arch/riscv/include/asm/vector.h +++ b/arch/riscv/include/asm/vector.h @@ -28,10 +28,11 @@ void get_cpu_vector_context(void); void put_cpu_vector_context(void); void riscv_v_thread_free(struct task_struct *tsk); void __init riscv_v_setup_ctx_cache(void); +void riscv_v_thread_alloc(struct task_struct *tsk); static inline u32 riscv_v_flags(void) { - return current->thread.riscv_v_flags; + return READ_ONCE(current->thread.riscv_v_flags); } static __always_inline bool has_vector(void) @@ -200,14 +201,62 @@ static inline void riscv_v_vstate_set_restore(struct task_struct *task, } } +#ifdef CONFIG_RISCV_ISA_V_PREEMPTIVE +static inline bool riscv_preempt_v_dirty(struct task_struct *task) +{ + return !!(task->thread.riscv_v_flags & RISCV_PREEMPT_V_DIRTY); +} + +static inline bool riscv_preempt_v_restore(struct task_struct *task) +{ + return !!(task->thread.riscv_v_flags & RISCV_PREEMPT_V_NEED_RESTORE); +} + +static inline void riscv_preempt_v_clear_dirty(struct task_struct *task) +{ + barrier(); + task->thread.riscv_v_flags &= ~RISCV_PREEMPT_V_DIRTY; +} + +static inline void riscv_preempt_v_set_restore(struct task_struct *task) +{ + barrier(); + task->thread.riscv_v_flags |= RISCV_PREEMPT_V_NEED_RESTORE; +} + +static inline bool riscv_preempt_v_started(struct task_struct *task) +{ + return !!(task->thread.riscv_v_flags & RISCV_PREEMPT_V); +} + +#else /* !CONFIG_RISCV_ISA_V_PREEMPTIVE */ +static inline bool riscv_preempt_v_dirty(struct task_struct *task) { return false; } +static inline bool riscv_preempt_v_restore(struct task_struct *task) { return false; } +static inline bool riscv_preempt_v_started(struct task_struct *task) { return false; } +#define riscv_preempt_v_clear_dirty(tsk) do {} while (0) +#define riscv_preempt_v_set_restore(tsk) do {} while (0) +#endif /* CONFIG_RISCV_ISA_V_PREEMPTIVE */ + static inline void __switch_to_vector(struct task_struct *prev, struct task_struct *next) { struct pt_regs *regs; - regs = task_pt_regs(prev); - riscv_v_vstate_save(&prev->thread.vstate, regs); - riscv_v_vstate_set_restore(next, task_pt_regs(next)); + if (riscv_preempt_v_started(prev)) { + if (riscv_preempt_v_dirty(prev)) { + __riscv_v_vstate_save(&prev->thread.kernel_vstate, + prev->thread.kernel_vstate.datap); + riscv_preempt_v_clear_dirty(prev); + } + } else { + regs = task_pt_regs(prev); + riscv_v_vstate_save(&prev->thread.vstate, regs); + } + + if (riscv_preempt_v_started(next)) + riscv_preempt_v_set_restore(next); + else + riscv_v_vstate_set_restore(next, task_pt_regs(next)); } void riscv_v_vstate_ctrl_init(struct task_struct *tsk); @@ -231,6 +280,7 @@ static inline bool riscv_v_vstate_ctrl_user_allowed(void) { return false; } #define riscv_v_vstate_on(regs) do {} while (0) #define riscv_v_thread_free(tsk) do {} while (0) #define riscv_v_setup_ctx_cache() do {} while (0) +#define riscv_v_thread_alloc(tsk) do {} while (0) #endif /* CONFIG_RISCV_ISA_V */ diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index 54ca4564a926..9d1a305d5508 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -83,6 +83,10 @@ SYM_CODE_START(handle_exception) /* Load the kernel shadow call stack pointer if coming from userspace */ scs_load_current_if_task_changed s5 +#ifdef CONFIG_RISCV_ISA_V_PREEMPTIVE + move a0, sp + call riscv_v_context_nesting_start +#endif move a0, sp /* pt_regs */ la ra, ret_from_exception @@ -138,6 +142,10 @@ SYM_CODE_START_NOALIGN(ret_from_exception) */ csrw CSR_SCRATCH, tp 1: +#ifdef CONFIG_RISCV_ISA_V_PREEMPTIVE + move a0, sp + call riscv_v_context_nesting_end +#endif REG_L a0, PT_STATUS(sp) /* * The current load reservation is effectively part of the processor's diff --git a/arch/riscv/kernel/kernel_mode_vector.c b/arch/riscv/kernel/kernel_mode_vector.c index 241a8f834e1c..6afe80c7f03a 100644 --- a/arch/riscv/kernel/kernel_mode_vector.c +++ b/arch/riscv/kernel/kernel_mode_vector.c @@ -14,10 +14,13 @@ #include #include #include +#ifdef CONFIG_RISCV_ISA_V_PREEMPTIVE +#include +#endif static inline void riscv_v_flags_set(u32 flags) { - current->thread.riscv_v_flags = flags; + WRITE_ONCE(current->thread.riscv_v_flags, flags); } static inline void riscv_v_start(u32 flags) @@ -27,12 +30,14 @@ static inline void riscv_v_start(u32 flags) orig = riscv_v_flags(); BUG_ON((orig & flags) != 0); riscv_v_flags_set(orig | flags); + barrier(); } static inline void riscv_v_stop(u32 flags) { int orig; + barrier(); orig = riscv_v_flags(); BUG_ON((orig & flags) == 0); riscv_v_flags_set(orig & ~flags); @@ -75,6 +80,117 @@ void put_cpu_vector_context(void) preempt_enable(); } +#ifdef CONFIG_RISCV_ISA_V_PREEMPTIVE +static __always_inline u32 *riscv_v_flags_ptr(void) +{ + return ¤t->thread.riscv_v_flags; +} + +static inline void riscv_preempt_v_set_dirty(void) +{ + *riscv_v_flags_ptr() |= RISCV_PREEMPT_V_DIRTY; +} + +static inline void riscv_preempt_v_reset_flags(void) +{ + *riscv_v_flags_ptr() &= ~(RISCV_PREEMPT_V_DIRTY | RISCV_PREEMPT_V_NEED_RESTORE); +} + +static inline void riscv_v_ctx_depth_inc(void) +{ + *riscv_v_flags_ptr() += RISCV_V_CTX_UNIT_DEPTH; +} + +static inline void riscv_v_ctx_depth_dec(void) +{ + *riscv_v_flags_ptr() -= RISCV_V_CTX_UNIT_DEPTH; +} + +static inline u32 riscv_v_ctx_get_depth(void) +{ + return *riscv_v_flags_ptr() & RISCV_V_CTX_DEPTH_MASK; +} + +static int riscv_v_stop_kernel_context(void) +{ + if (riscv_v_ctx_get_depth() != 0 || !riscv_preempt_v_started(current)) + return 1; + + riscv_preempt_v_clear_dirty(current); + riscv_v_stop(RISCV_PREEMPT_V); + return 0; +} + +static int riscv_v_start_kernel_context(bool *is_nested) +{ + struct __riscv_v_ext_state *kvstate, *uvstate; + + kvstate = ¤t->thread.kernel_vstate; + if (!kvstate->datap) + return -ENOENT; + + if (riscv_preempt_v_started(current)) { + WARN_ON(riscv_v_ctx_get_depth() == 0); + *is_nested = true; + get_cpu_vector_context(); + if (riscv_preempt_v_dirty(current)) { + __riscv_v_vstate_save(kvstate, kvstate->datap); + riscv_preempt_v_clear_dirty(current); + } + riscv_preempt_v_set_restore(current); + return 0; + } + + /* Transfer the ownership of V from user to kernel, then save */ + riscv_v_start(RISCV_PREEMPT_V | RISCV_PREEMPT_V_DIRTY); + if ((task_pt_regs(current)->status & SR_VS) == SR_VS_DIRTY) { + uvstate = ¤t->thread.vstate; + __riscv_v_vstate_save(uvstate, uvstate->datap); + } + riscv_preempt_v_clear_dirty(current); + return 0; +} + +/* low-level V context handling code, called with irq disabled */ +asmlinkage void riscv_v_context_nesting_start(struct pt_regs *regs) +{ + int depth; + + if (!riscv_preempt_v_started(current)) + return; + + depth = riscv_v_ctx_get_depth(); + if (depth == 0 && (regs->status & SR_VS) == SR_VS_DIRTY) + riscv_preempt_v_set_dirty(); + + riscv_v_ctx_depth_inc(); +} + +asmlinkage void riscv_v_context_nesting_end(struct pt_regs *regs) +{ + struct __riscv_v_ext_state *vstate = ¤t->thread.kernel_vstate; + u32 depth; + + WARN_ON(!irqs_disabled()); + + if (!riscv_preempt_v_started(current)) + return; + + riscv_v_ctx_depth_dec(); + depth = riscv_v_ctx_get_depth(); + if (depth == 0) { + if (riscv_preempt_v_restore(current)) { + __riscv_v_vstate_restore(vstate, vstate->datap); + __riscv_v_vstate_clean(regs); + riscv_preempt_v_reset_flags(); + } + } +} +#else +#define riscv_v_start_kernel_context(nested) (-ENOENT) +#define riscv_v_stop_kernel_context() (-ENOENT) +#endif /* CONFIG_RISCV_ISA_V_PREEMPTIVE */ + /* * kernel_vector_begin(): obtain the CPU vector registers for use by the calling * context @@ -90,14 +206,20 @@ void put_cpu_vector_context(void) */ void kernel_vector_begin(void) { + bool nested = false; + if (WARN_ON(!has_vector())) return; BUG_ON(!may_use_simd()); - get_cpu_vector_context(); + if (riscv_v_start_kernel_context(&nested)) { + get_cpu_vector_context(); + riscv_v_vstate_save(¤t->thread.vstate, task_pt_regs(current)); + } - riscv_v_vstate_save(¤t->thread.vstate, task_pt_regs(current)); + if (!nested) + riscv_v_vstate_set_restore(current, task_pt_regs(current)); riscv_v_enable(); } @@ -117,10 +239,9 @@ void kernel_vector_end(void) if (WARN_ON(!has_vector())) return; - riscv_v_vstate_set_restore(current, task_pt_regs(current)); - riscv_v_disable(); - put_cpu_vector_context(); + if (riscv_v_stop_kernel_context()) + 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 862d59c3872e..92922dbd5b5c 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -188,6 +188,7 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) *dst = *src; /* clear entire V context, including datap for a new task */ memset(&dst->thread.vstate, 0, sizeof(struct __riscv_v_ext_state)); + memset(&dst->thread.kernel_vstate, 0, sizeof(struct __riscv_v_ext_state)); clear_tsk_thread_flag(dst, TIF_RISCV_V_DEFER_RESTORE); return 0; @@ -224,6 +225,8 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) p->thread.s[0] = 0; } p->thread.riscv_v_flags = 0; + if (has_vector()) + riscv_v_thread_alloc(p); p->thread.ra = (unsigned long)ret_from_fork; p->thread.sp = (unsigned long)childregs; /* kernel sp */ return 0; diff --git a/arch/riscv/kernel/vector.c b/arch/riscv/kernel/vector.c index f7b4aeb9e457..6727d1d3b8f2 100644 --- a/arch/riscv/kernel/vector.c +++ b/arch/riscv/kernel/vector.c @@ -22,6 +22,9 @@ static bool riscv_v_implicit_uacc = IS_ENABLED(CONFIG_RISCV_ISA_V_DEFAULT_ENABLE); static struct kmem_cache *riscv_v_user_cachep; +#ifdef CONFIG_RISCV_ISA_V_PREEMPTIVE +static struct kmem_cache *riscv_v_kernel_cachep; +#endif unsigned long riscv_v_vsize __read_mostly; EXPORT_SYMBOL_GPL(riscv_v_vsize); @@ -56,6 +59,11 @@ void __init riscv_v_setup_ctx_cache(void) riscv_v_user_cachep = kmem_cache_create_usercopy("riscv_vector_ctx", riscv_v_vsize, 16, SLAB_PANIC, 0, riscv_v_vsize, NULL); +#ifdef CONFIG_RISCV_ISA_V_PREEMPTIVE + riscv_v_kernel_cachep = kmem_cache_create("riscv_vector_kctx", + riscv_v_vsize, 16, + SLAB_PANIC, NULL); +#endif } static bool insn_is_vector(u32 insn_buf) @@ -91,24 +99,35 @@ static bool insn_is_vector(u32 insn_buf) return false; } -static int riscv_v_thread_zalloc(void) +static int riscv_v_thread_zalloc(struct kmem_cache *cache, + struct __riscv_v_ext_state *ctx) { void *datap; - datap = kmem_cache_zalloc(riscv_v_user_cachep, GFP_KERNEL); + datap = kmem_cache_zalloc(cache, GFP_KERNEL); if (!datap) return -ENOMEM; - current->thread.vstate.datap = datap; - memset(¤t->thread.vstate, 0, offsetof(struct __riscv_v_ext_state, - datap)); + ctx->datap = datap; + memset(ctx, 0, offsetof(struct __riscv_v_ext_state, datap)); return 0; } +void riscv_v_thread_alloc(struct task_struct *tsk) +{ +#ifdef CONFIG_RISCV_ISA_V_PREEMPTIVE + riscv_v_thread_zalloc(riscv_v_kernel_cachep, &tsk->thread.kernel_vstate); +#endif +} + void riscv_v_thread_free(struct task_struct *tsk) { if (tsk->thread.vstate.datap) kmem_cache_free(riscv_v_user_cachep, tsk->thread.vstate.datap); +#ifdef CONFIG_RISCV_ISA_V_PREEMPTIVE + if (tsk->thread.kernel_vstate.datap) + kmem_cache_free(riscv_v_kernel_cachep, tsk->thread.kernel_vstate.datap); +#endif } #define VSTATE_CTRL_GET_CUR(x) ((x) & PR_RISCV_V_VSTATE_CTRL_CUR_MASK) @@ -180,7 +199,7 @@ bool riscv_v_first_use_handler(struct pt_regs *regs) * context where VS has been off. So, try to allocate the user's V * context and resume execution. */ - if (riscv_v_thread_zalloc()) { + if (riscv_v_thread_zalloc(riscv_v_user_cachep, ¤t->thread.vstate)) { force_sig(SIGBUS); return true; }