[v4,1/2] riscv: use vDSO common flow to reduce the latency of the time-related functions

Message ID	1591712089-12904-2-git-send-email-vincent.chen@sifive.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <SRS0=0zHy=7W=lists.infradead.org=linux-riscv-bounces+patchwork-linux-riscv=patchwork.kernel.org@kernel.org> DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BFC8B206D5 From: Vincent Chen <vincent.chen@sifive.com> To: palmer@dabbelt.com, paul.walmsley@sifive.com Subject: [PATCH v4 1/2] riscv: use vDSO common flow to reduce the latency of the time-related functions Date: Tue, 9 Jun 2020 22:14:48 +0800 Message-Id: <1591712089-12904-2-git-send-email-vincent.chen@sifive.com> In-Reply-To: <1591712089-12904-1-git-send-email-vincent.chen@sifive.com> References: <1591712089-12904-1-git-send-email-vincent.chen@sifive.com> summary: Content analysis details: (-0.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at https://www.dnswl.org/, no trust [2607:f8b0:4864:20:0:0:0:1043 listed in] [list.dnswl.org] 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature Precedence: list Cc: Vincent Chen <vincent.chen@sifive.com>, linux-riscv@lists.infradead.org, Palmer Dabbelt <palmerdabbelt@google.com> Sender: "linux-riscv" <linux-riscv-bounces@lists.infradead.org> Errors-To: linux-riscv-bounces+patchwork-linux-riscv=patchwork.kernel.org@lists.infradead.org
Series	riscv: introduce vDSO common flow \| expand [v4,0/2] riscv: introduce vDSO common flow [v4,1/2] riscv: use vDSO common flow to reduce the latency of the time-related functions [v4,2/2] riscv: set the permission of vdso_data to read-only

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 8244b8f7e7c3..d0419ab1fed0 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -12,6 +12,7 @@ config 32BIT config RISCV def_bool y + select ARCH_CLOCKSOURCE_INIT select ARCH_HAS_BINFMT_FLAT select ARCH_HAS_DEBUG_VIRTUAL if MMU select ARCH_HAS_DEBUG_WX @@ -31,6 +32,7 @@ config RISCV select GENERIC_ARCH_TOPOLOGY if SMP select GENERIC_ATOMIC64 if !64BIT select GENERIC_CLOCKEVENTS + select GENERIC_GETTIMEOFDAY if HAVE_GENERIC_VDSO select GENERIC_IOREMAP select GENERIC_IRQ_MULTI_HANDLER select GENERIC_IRQ_SHOW @@ -40,6 +42,7 @@ config RISCV select GENERIC_SMP_IDLE_THREAD select GENERIC_STRNCPY_FROM_USER if MMU select GENERIC_STRNLEN_USER if MMU + select GENERIC_TIME_VSYSCALL if MMU && 64BIT select HAVE_ARCH_AUDITSYSCALL select HAVE_ARCH_KASAN if MMU && 64BIT select HAVE_ARCH_KGDB @@ -52,6 +55,7 @@ config RISCV select HAVE_DMA_CONTIGUOUS if MMU select HAVE_EBPF_JIT if MMU select HAVE_FUTEX_CMPXCHG if FUTEX + select HAVE_GENERIC_VDSO if MMU && 64BIT select HAVE_PCI select HAVE_PERF_EVENTS select HAVE_PERF_REGS diff --git a/arch/riscv/include/asm/clocksource.h b/arch/riscv/include/asm/clocksource.h new file mode 100644 index 000000000000..482185566b0c --- /dev/null +++ b/arch/riscv/include/asm/clocksource.h @@ -0,0 +1,7 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_CLOCKSOURCE_H +#define _ASM_CLOCKSOURCE_H + +#include <asm/vdso/clocksource.h> + +#endif diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h index 3ddb798264f1..d6117b316e2b 100644 --- a/arch/riscv/include/asm/processor.h +++ b/arch/riscv/include/asm/processor.h @@ -8,6 +8,8 @@ #include <linux/const.h> +#include <vdso/processor.h> + #include <asm/ptrace.h> /* @@ -58,16 +60,6 @@ static inline void release_thread(struct task_struct *dead_task) extern unsigned long get_wchan(struct task_struct *p); -static inline void cpu_relax(void) -{ -#ifdef __riscv_muldiv - int dummy; - /* In lieu of a halt instruction, induce a long-latency stall. */ - __asm__ __volatile__ ("div %0, %0, zero" : "=r" (dummy)); -#endif - barrier(); -} - static inline void wait_for_interrupt(void) { __asm__ __volatile__ ("wfi"); diff --git a/arch/riscv/include/asm/vdso.h b/arch/riscv/include/asm/vdso.h index 7a7fce63c474..8454f746bbfd 100644 --- a/arch/riscv/include/asm/vdso.h +++ b/arch/riscv/include/asm/vdso.h @@ -10,8 +10,10 @@ #include <linux/types.h> +#ifndef GENERIC_TIME_VSYSCALL struct vdso_data { }; +#endif /* * The VDSO symbols are mapped into Linux so we can just use regular symbol diff --git a/arch/riscv/include/asm/vdso/clocksource.h b/arch/riscv/include/asm/vdso/clocksource.h new file mode 100644 index 000000000000..df6ea65c1dec --- /dev/null +++ b/arch/riscv/include/asm/vdso/clocksource.h @@ -0,0 +1,8 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_VDSOCLOCKSOURCE_H +#define __ASM_VDSOCLOCKSOURCE_H + +#define VDSO_ARCH_CLOCKMODES \ + VDSO_CLOCKMODE_ARCHTIMER + +#endif diff --git a/arch/riscv/include/asm/vdso/gettimeofday.h b/arch/riscv/include/asm/vdso/gettimeofday.h new file mode 100644 index 000000000000..c8e818688ec1 --- /dev/null +++ b/arch/riscv/include/asm/vdso/gettimeofday.h @@ -0,0 +1,79 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_VDSO_GETTIMEOFDAY_H +#define __ASM_VDSO_GETTIMEOFDAY_H + +#ifndef __ASSEMBLY__ + +#include <asm/unistd.h> +#include <asm/csr.h> +#include <uapi/linux/time.h> + +#define VDSO_HAS_CLOCK_GETRES 1 + +static __always_inline +int gettimeofday_fallback(struct __kernel_old_timeval *_tv, + struct timezone *_tz) +{ + register struct __kernel_old_timeval *tv asm("a0") = _tv; + register struct timezone *tz asm("a1") = _tz; + register long ret asm("a0"); + register long nr asm("a7") = __NR_gettimeofday; + + asm volatile ("ecall\n" + : "=r" (ret) + : "r"(tv), "r"(tz), "r"(nr) + : "memory"); + + return ret; +} + +static __always_inline +long clock_gettime_fallback(clockid_t _clkid, struct __kernel_timespec *_ts) +{ + register clockid_t clkid asm("a0") = _clkid; + register struct __kernel_timespec *ts asm("a1") = _ts; + register long ret asm("a0"); + register long nr asm("a7") = __NR_clock_gettime; + + asm volatile ("ecall\n" + : "=r" (ret) + : "r"(clkid), "r"(ts), "r"(nr) + : "memory"); + + return ret; +} + +static __always_inline +int clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts) +{ + register clockid_t clkid asm("a0") = _clkid; + register struct __kernel_timespec *ts asm("a1") = _ts; + register long ret asm("a0"); + register long nr asm("a7") = __NR_clock_getres; + + asm volatile ("ecall\n" + : "=r" (ret) + : "r"(clkid), "r"(ts), "r"(nr) + : "memory"); + + return ret; +} + +static __always_inline u64 __arch_get_hw_counter(s32 clock_mode) +{ + /* + * The purpose of csr_read(CSR_TIME) is to trap the system into + * M-mode to obtain the value of CSR_TIME. Hence, unlike other + * architecture, no fence instructions surround the csr_read() + */ + return csr_read(CSR_TIME); +} + +static __always_inline const struct vdso_data *__arch_get_vdso_data(void) +{ + return _vdso_data; +} + +#endif /* !__ASSEMBLY__ */ + +#endif /* __ASM_VDSO_GETTIMEOFDAY_H */ diff --git a/arch/riscv/include/asm/vdso/processor.h b/arch/riscv/include/asm/vdso/processor.h new file mode 100644 index 000000000000..82a5693b1861 --- /dev/null +++ b/arch/riscv/include/asm/vdso/processor.h @@ -0,0 +1,19 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef __ASM_VDSO_PROCESSOR_H +#define __ASM_VDSO_PROCESSOR_H + +#ifndef __ASSEMBLY__ + +static inline void cpu_relax(void) +{ +#ifdef __riscv_muldiv + int dummy; + /* In lieu of a halt instruction, induce a long-latency stall. */ + __asm__ __volatile__ ("div %0, %0, zero" : "=r" (dummy)); +#endif + barrier(); +} + +#endif /* __ASSEMBLY__ */ + +#endif /* __ASM_VDSO_PROCESSOR_H */ diff --git a/arch/riscv/include/asm/vdso/vsyscall.h b/arch/riscv/include/asm/vdso/vsyscall.h new file mode 100644 index 000000000000..82fd5d83bd60 --- /dev/null +++ b/arch/riscv/include/asm/vdso/vsyscall.h @@ -0,0 +1,27 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_VDSO_VSYSCALL_H +#define __ASM_VDSO_VSYSCALL_H + +#ifndef __ASSEMBLY__ + +#include <linux/timekeeper_internal.h> +#include <vdso/datapage.h> + +extern struct vdso_data *vdso_data; + +/* + * Update the vDSO data page to keep in sync with kernel timekeeping. + */ +static __always_inline struct vdso_data *__riscv_get_k_vdso_data(void) +{ + return vdso_data; +} + +#define __arch_get_k_vdso_data __riscv_get_k_vdso_data + +/* The asm-generic header needs to be included after the definitions above */ +#include <asm-generic/vdso/vsyscall.h> + +#endif /* !__ASSEMBLY__ */ + +#endif /* __ASM_VDSO_VSYSCALL_H */ diff --git a/arch/riscv/kernel/time.c b/arch/riscv/kernel/time.c index 6a53c02e9c73..4d3a1048ad8b 100644 --- a/arch/riscv/kernel/time.c +++ b/arch/riscv/kernel/time.c @@ -26,3 +26,12 @@ void __init time_init(void) lpj_fine = riscv_timebase / HZ; timer_probe(); } + +void clocksource_arch_init(struct clocksource *cs) +{ +#ifdef CONFIG_GENERIC_GETTIMEOFDAY + cs->vdso_clock_mode = VDSO_CLOCKMODE_ARCHTIMER; +#else + cs->vdso_clock_mode = VDSO_CLOCKMODE_NONE; +#endif +} diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c index 484d95a70907..70b6461a6387 100644 --- a/arch/riscv/kernel/vdso.c +++ b/arch/riscv/kernel/vdso.c @@ -11,8 +11,12 @@ #include <linux/slab.h> #include <linux/binfmts.h> #include <linux/err.h> - +#include <asm/page.h> +#ifdef GENERIC_TIME_VSYSCALL +#include <vdso/datapage.h> +#else #include <asm/vdso.h> +#endif extern char vdso_start[], vdso_end[]; @@ -26,7 +30,7 @@ static union { struct vdso_data data; u8 page[PAGE_SIZE]; } vdso_data_store __page_aligned_data; -static struct vdso_data *vdso_data = &vdso_data_store.data; +struct vdso_data *vdso_data = &vdso_data_store.data; static int __init vdso_init(void) { diff --git a/arch/riscv/kernel/vdso/Makefile b/arch/riscv/kernel/vdso/Makefile index 4c8b2a4a6a70..38ba55b0eb9d 100644 --- a/arch/riscv/kernel/vdso/Makefile +++ b/arch/riscv/kernel/vdso/Makefile @@ -1,12 +1,14 @@ # SPDX-License-Identifier: GPL-2.0-only # Copied from arch/tile/kernel/vdso/Makefile +# Absolute relocation type $(ARCH_REL_TYPE_ABS) needs to be defined before +# the inclusion of generic Makefile. +ARCH_REL_TYPE_ABS := R_RISCV_32|R_RISCV_64|R_RISCV_JUMP_SLOT +include $(srctree)/lib/vdso/Makefile # Symbols present in the vdso vdso-syms = rt_sigreturn ifdef CONFIG_64BIT -vdso-syms += gettimeofday -vdso-syms += clock_gettime -vdso-syms += clock_getres +vdso-syms += vgettimeofday endif vdso-syms += getcpu vdso-syms += flush_icache @@ -14,6 +16,10 @@ vdso-syms += flush_icache # Files to link into the vdso obj-vdso = $(patsubst %, %.o, $(vdso-syms)) note.o +ifneq ($(c-gettimeofday-y),) + CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y) +endif + # Build rules targets := $(obj-vdso) vdso.so vdso.so.dbg vdso.lds vdso-dummy.o obj-vdso := $(addprefix $(obj)/, $(obj-vdso)) diff --git a/arch/riscv/kernel/vdso/clock_getres.S b/arch/riscv/kernel/vdso/clock_getres.S deleted file mode 100644 index 91378a52eb22..000000000000 --- a/arch/riscv/kernel/vdso/clock_getres.S +++ /dev/null @@ -1,18 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0-only */ -/* - * Copyright (C) 2017 SiFive - */ - -#include <linux/linkage.h> -#include <asm/unistd.h> - - .text -/* int __vdso_clock_getres(clockid_t clock_id, struct timespec *res); */ -ENTRY(__vdso_clock_getres) - .cfi_startproc - /* For now, just do the syscall. */ - li a7, __NR_clock_getres - ecall - ret - .cfi_endproc -ENDPROC(__vdso_clock_getres) diff --git a/arch/riscv/kernel/vdso/clock_gettime.S b/arch/riscv/kernel/vdso/clock_gettime.S deleted file mode 100644 index 5371fd9bc01f..000000000000 --- a/arch/riscv/kernel/vdso/clock_gettime.S +++ /dev/null @@ -1,18 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0-only */ -/* - * Copyright (C) 2017 SiFive - */ - -#include <linux/linkage.h> -#include <asm/unistd.h> - - .text -/* int __vdso_clock_gettime(clockid_t clock_id, struct timespec *tp); */ -ENTRY(__vdso_clock_gettime) - .cfi_startproc - /* For now, just do the syscall. */ - li a7, __NR_clock_gettime - ecall - ret - .cfi_endproc -ENDPROC(__vdso_clock_gettime) diff --git a/arch/riscv/kernel/vdso/gettimeofday.S b/arch/riscv/kernel/vdso/gettimeofday.S deleted file mode 100644 index e6fb8af88632..000000000000 --- a/arch/riscv/kernel/vdso/gettimeofday.S +++ /dev/null @@ -1,18 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0-only */ -/* - * Copyright (C) 2017 SiFive - */ - -#include <linux/linkage.h> -#include <asm/unistd.h> - - .text -/* int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz); */ -ENTRY(__vdso_gettimeofday) - .cfi_startproc - /* For now, just do the syscall. */ - li a7, __NR_gettimeofday - ecall - ret - .cfi_endproc -ENDPROC(__vdso_gettimeofday) diff --git a/arch/riscv/kernel/vdso/vdso.lds.S b/arch/riscv/kernel/vdso/vdso.lds.S index f66a091cb890..e6f558bca71b 100644 --- a/arch/riscv/kernel/vdso/vdso.lds.S +++ b/arch/riscv/kernel/vdso/vdso.lds.S @@ -2,11 +2,13 @@ /* * Copyright (C) 2012 Regents of the University of California */ +#include <asm/page.h> OUTPUT_ARCH(riscv) SECTIONS { + PROVIDE(_vdso_data = . + PAGE_SIZE); . = SIZEOF_HEADERS; .hash : { *(.hash) } :text diff --git a/arch/riscv/kernel/vdso/vgettimeofday.c b/arch/riscv/kernel/vdso/vgettimeofday.c new file mode 100644 index 000000000000..d264943e2e47 --- /dev/null +++ b/arch/riscv/kernel/vdso/vgettimeofday.c @@ -0,0 +1,25 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copied from arch/arm64/kernel/vdso/vgettimeofday.c + * + * Copyright (C) 2018 ARM Ltd. + * Copyright (C) 2020 SiFive + */ + +#include <linux/time.h> +#include <linux/types.h> + +int __vdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts) +{ + return __cvdso_clock_gettime(clock, ts); +} + +int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz) +{ + return __cvdso_gettimeofday(tv, tz); +} + +int __vdso_clock_getres(clockid_t clock_id, struct __kernel_timespec *res) +{ + return __cvdso_clock_getres(clock_id, res); +}

[v4,1/2] riscv: use vDSO common flow to reduce the latency of the time-related functions

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