Unverified Commit 7f55dbd9 authored by openeuler-ci-bot's avatar openeuler-ci-bot Committed by Gitee
Browse files

!3306 improve gettimeofday() performance in user space 

Merge Pull Request from: @ci-robot 
 
PR sync from: Yang Yingliang <yangyingliang@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/YHKNSX4KKFYDIZG6PFMBJYN2PUPIOMV4/ 
Don't trap kernel to read the counter register, do this in userspace to
improve performance.

Yang Yingliang (3):
  arm64: arch_timer: Disable CNTVCT_EL0 trap if workaround is enabled
  vdso: do cntvct workaround in the VDSO
  arm64: arch_timer: disable
    CONFIG_ARM_ARCH_TIMER_WORKAROUND_IN_USERSPACE


-- 
2.25.1
 
https://gitee.com/openeuler/kernel/issues/I8LFBU 
 
Link:https://gitee.com/openeuler/kernel/pulls/3306

 

Reviewed-by: default avatarWei Li <liwei391@huawei.com>
Reviewed-by: default avatarZhang Jianhua <chris.zjh@huawei.com>
Reviewed-by: default avatarXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
parents b91e04ba be898f9a

arch/arm64/configs/openeuler_defconfig

+1 −0
Original line number Diff line number Diff line
@@ -6406,6 +6406,7 @@ CONFIG_FSL_ERRATUM_A008585=y 
CONFIG_HISILICON_ERRATUM_161010101=y

CONFIG_ARM64_ERRATUM_858921=y

CONFIG_ARM_TIMER_SP804=y

# CONFIG_ARM_ARCH_TIMER_WORKAROUND_IN_USERSPACE is not set

# end of Clock Source drivers



CONFIG_MAILBOX=y

arch/arm64/include/asm/vdso/gettimeofday.h

+32 −0
Original line number Diff line number Diff line
@@ -94,6 +94,38 @@ static __always_inline u64 __arch_get_hw_counter(s32 clock_mode, 
	:

	: "memory");



#ifdef CONFIG_ARM_ARCH_TIMER_WORKAROUND_IN_USERSPACE

	if (vd->vdso_fix) {

		u64 new;

		int retries = 50;



		asm volatile(

		ALTERNATIVE("mrs %0, cntvct_el0",

			    __mrs_s("%0", SYS_CNTVCTSS_EL0),

			    ARM64_HAS_ECV)

		: "=r" (new)

		:

		: "memory");

		while (unlikely((new - res) >> vd->vdso_shift) && retries) {

			asm volatile(

			ALTERNATIVE("mrs %0, cntvct_el0",

				    __mrs_s("%0", SYS_CNTVCTSS_EL0),

				    ARM64_HAS_ECV)

			: "=r" (res)

			:

			: "memory");



			asm volatile(

			ALTERNATIVE("mrs %0, cntvct_el0",

				    __mrs_s("%0", SYS_CNTVCTSS_EL0),

				    ARM64_HAS_ECV)

			: "=r" (new)

			:

			: "memory");

			retries--;

		}

	}

#endif

	arch_counter_enforce_ordering(res);



	return res;

drivers/clocksource/Kconfig

+5 −0
Original line number Diff line number Diff line
@@ -732,4 +732,9 @@ config GOLDFISH_TIMER 
	help

	  Support for the timer/counter of goldfish-rtc



config ARM_ARCH_TIMER_WORKAROUND_IN_USERSPACE

	bool "Enable arch timer workaround in vdso"

	default y

	depends on ARM_ARCH_TIMER_OOL_WORKAROUND



endmenu

drivers/clocksource/arm_arch_timer.c

+27 −0
Original line number Diff line number Diff line
@@ -92,6 +92,10 @@ static enum vdso_clock_mode vdso_default = VDSO_CLOCKMODE_ARCHTIMER; 
#else

static enum vdso_clock_mode vdso_default = VDSO_CLOCKMODE_NONE;

#endif /* CONFIG_GENERIC_GETTIMEOFDAY */

#ifdef CONFIG_ARM_ARCH_TIMER_WORKAROUND_IN_USERSPACE

static bool vdso_fix;

static u16 vdso_shift;

#endif



static cpumask_t evtstrm_available = CPU_MASK_NONE;

static bool evtstrm_enable __ro_after_init = IS_ENABLED(CONFIG_ARM_ARCH_TIMER_EVTSTREAM);
@@ -599,8 +603,23 @@ void arch_timer_enable_workaround(const struct arch_timer_erratum_workaround *wa 
	 * change both the default value and the vdso itself.

	 */

	if (wa->read_cntvct_el0) {

#ifdef CONFIG_ARM_ARCH_TIMER_WORKAROUND_IN_USERSPACE

		if (!strncmp(wa->desc, "HiSilicon erratum 161010101",

			     strlen("HiSilicon erratum 161010101"))) {

			vdso_fix = true;

			vdso_shift = 5;

		} else if (!strncmp(wa->desc, "Freescale erratum a005858",

				    strlen("Freescale erratum a005858"))) {

			vdso_fix = true;

			vdso_shift = 0;

		} else {

			clocksource_counter.vdso_clock_mode = VDSO_CLOCKMODE_NONE;

			vdso_default = VDSO_CLOCKMODE_NONE;

		}

#else

		clocksource_counter.vdso_clock_mode = VDSO_CLOCKMODE_NONE;

		vdso_default = VDSO_CLOCKMODE_NONE;

#endif

	} else if (wa->disable_compat_vdso && vdso_default != VDSO_CLOCKMODE_NONE) {

		vdso_default = VDSO_CLOCKMODE_ARCHTIMER_NOCOMPAT;

		clocksource_counter.vdso_clock_mode = vdso_default;
@@ -973,7 +992,11 @@ static void arch_counter_set_user_access(void) 
	 * need to be workaround. The vdso may have been already

	 * disabled though.

	 */

#ifdef CONFIG_ARM_ARCH_TIMER_WORKAROUND_IN_USERSPACE

	if (arch_timer_this_cpu_has_cntvct_wa() && !vdso_fix)

#else

	if (arch_timer_this_cpu_has_cntvct_wa())

#endif

		pr_info("CPU%d: Trapping CNTVCT access\n", smp_processor_id());

	else

		cntkctl |= ARCH_TIMER_USR_VCT_ACCESS_EN;
@@ -1129,6 +1152,10 @@ static void __init arch_counter_register(unsigned type) 


		arch_timer_read_counter = rd;

		clocksource_counter.vdso_clock_mode = vdso_default;

#ifdef CONFIG_ARM_ARCH_TIMER_WORKAROUND_IN_USERSPACE

		clocksource_counter.vdso_fix = vdso_fix;

		clocksource_counter.vdso_shift = vdso_shift;

#endif

	} else {

		arch_timer_read_counter = arch_counter_get_cntvct_mem;

		scr = arch_counter_get_cntvct_mem;

include/linux/clocksource.h

+4 −0
Original line number Diff line number Diff line
@@ -110,6 +110,10 @@ struct clocksource { 
	int			rating;

	enum clocksource_ids	id;

	enum vdso_clock_mode	vdso_clock_mode;

#ifdef CONFIG_ARM_ARCH_TIMER_WORKAROUND_IN_USERSPACE

	u16			vdso_fix;

	u16			vdso_shift;

#endif

	unsigned long		flags;



	int			(*enable)(struct clocksource *cs);