Message-ID: <1fd47b0d-f77f-8d07-c039-6ac9072834fc@samsung.com>
Date:   Fri, 28 Jun 2019 15:09:18 +0200
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     Vincenzo Frascino <vincenzo.frascino@....com>,
        linux-arch@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-mips@...r.kernel.org,
        linux-kselftest@...r.kernel.org
Cc:     Shuah Khan <shuah@...nel.org>,
        Andre Przywara <andre.przywara@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Huw Davies <huw@...eweavers.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Will Deacon <will.deacon@....com>,
        Russell King <linux@...linux.org.uk>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Mark Salyzyn <salyzyn@...roid.com>,
        Paul Burton <paul.burton@...s.com>,
        Dmitry Safonov <0x7f454c46@...il.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Thomas Gleixner <tglx@...utronix.de>,
        Shijith Thotton <sthotton@...vell.com>,
        Peter Collingbourne <pcc@...gle.com>,
        Sylwester Nawrocki <s.nawrocki@...sung.com>
Subject: Re: [PATCH v7 04/25] arm64: Substitute gettimeofday with C
 implementation

Dear All,

On 2019-06-21 11:52, Vincenzo Frascino wrote:
> To take advantage of the commonly defined vdso interface for
> gettimeofday the architectural code requires an adaptation.
>
> Re-implement the gettimeofday vdso in C in order to use lib/vdso.
>
> With the new implementation arm64 gains support for CLOCK_BOOTTIME
> and CLOCK_TAI.
>
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Will Deacon <will.deacon@....com>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@....com>
> Tested-by: Shijith Thotton <sthotton@...vell.com>
> Tested-by: Andre Przywara <andre.przywara@....com>
> Signed-off-by: Catalin Marinas <catalin.marinas@....com>

This patch causes serious regression on Samsung Exynos5433 SoC based 
TM2(e) boards. The time in userspace is always set to begin of the epoch:

# date 062813152019
Fri Jun 28 13:15:00 UTC 2019
# date
Thu Jan  1 00:00:00 UTC 1970
# date
Thu Jan  1 00:00:00 UTC 1970

I've noticed that since the patch landed in Linux next-20190625 and 
bisect indeed pointed to this patch.

> ---
>   arch/arm64/Kconfig                         |   2 +
>   arch/arm64/include/asm/vdso/gettimeofday.h |  86 ++++++
>   arch/arm64/include/asm/vdso/vsyscall.h     |  53 ++++
>   arch/arm64/include/asm/vdso_datapage.h     |  48 ---
>   arch/arm64/kernel/asm-offsets.c            |  33 +-
>   arch/arm64/kernel/vdso.c                   |  51 +---
>   arch/arm64/kernel/vdso/Makefile            |  34 ++-
>   arch/arm64/kernel/vdso/gettimeofday.S      | 334 ---------------------
>   arch/arm64/kernel/vdso/vgettimeofday.c     |  28 ++
>   9 files changed, 223 insertions(+), 446 deletions(-)
>   create mode 100644 arch/arm64/include/asm/vdso/gettimeofday.h
>   create mode 100644 arch/arm64/include/asm/vdso/vsyscall.h
>   delete mode 100644 arch/arm64/include/asm/vdso_datapage.h
>   delete mode 100644 arch/arm64/kernel/vdso/gettimeofday.S
>   create mode 100644 arch/arm64/kernel/vdso/vgettimeofday.c
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 697ea0510729..952c9f8cf3b8 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -107,6 +107,7 @@ config ARM64
>   	select GENERIC_STRNCPY_FROM_USER
>   	select GENERIC_STRNLEN_USER
>   	select GENERIC_TIME_VSYSCALL
> +	select GENERIC_GETTIMEOFDAY
>   	select HANDLE_DOMAIN_IRQ
>   	select HARDIRQS_SW_RESEND
>   	select HAVE_PCI
> @@ -160,6 +161,7 @@ config ARM64
>   	select HAVE_SYSCALL_TRACEPOINTS
>   	select HAVE_KPROBES
>   	select HAVE_KRETPROBES
> +	select HAVE_GENERIC_VDSO
>   	select IOMMU_DMA if IOMMU_SUPPORT
>   	select IRQ_DOMAIN
>   	select IRQ_FORCED_THREADING
> diff --git a/arch/arm64/include/asm/vdso/gettimeofday.h b/arch/arm64/include/asm/vdso/gettimeofday.h
> new file mode 100644
> index 000000000000..bc3cb6738051
> --- /dev/null
> +++ b/arch/arm64/include/asm/vdso/gettimeofday.h
> @@ -0,0 +1,86 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2018 ARM Limited
> + */
> +#ifndef __ASM_VDSO_GETTIMEOFDAY_H
> +#define __ASM_VDSO_GETTIMEOFDAY_H
> +
> +#ifndef __ASSEMBLY__
> +
> +#include <asm/unistd.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 timezone *tz asm("x1") = _tz;
> +	register struct __kernel_old_timeval *tv asm("x0") = _tv;
> +	register long ret asm ("x0");
> +	register long nr asm("x8") = __NR_gettimeofday;
> +
> +	asm volatile(
> +	"       svc #0\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 struct __kernel_timespec *ts asm("x1") = _ts;
> +	register clockid_t clkid asm("x0") = _clkid;
> +	register long ret asm ("x0");
> +	register long nr asm("x8") = __NR_clock_gettime;
> +
> +	asm volatile(
> +	"       svc #0\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 struct __kernel_timespec *ts asm("x1") = _ts;
> +	register clockid_t clkid asm("x0") = _clkid;
> +	register long ret asm ("x0");
> +	register long nr asm("x8") = __NR_clock_getres;
> +
> +	asm volatile(
> +	"       svc #0\n"
> +	: "=r" (ret)
> +	: "r" (clkid), "r" (ts), "r" (nr)
> +	: "memory");
> +
> +	return ret;
> +}
> +
> +static __always_inline u64 __arch_get_hw_counter(s32 clock_mode)
> +{
> +	u64 res;
> +
> +	asm volatile("mrs %0, cntvct_el0" : "=r" (res) :: "memory");
> +
> +	return res;
> +}
> +
> +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/arm64/include/asm/vdso/vsyscall.h b/arch/arm64/include/asm/vdso/vsyscall.h
> new file mode 100644
> index 000000000000..0c731bfc7c8c
> --- /dev/null
> +++ b/arch/arm64/include/asm/vdso/vsyscall.h
> @@ -0,0 +1,53 @@
> +/* 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>
> +
> +#define VDSO_PRECISION_MASK	~(0xFF00ULL<<48)
> +
> +extern struct vdso_data *vdso_data;
> +
> +/*
> + * Update the vDSO data page to keep in sync with kernel timekeeping.
> + */
> +static __always_inline
> +struct vdso_data *__arm64_get_k_vdso_data(void)
> +{
> +	return vdso_data;
> +}
> +#define __arch_get_k_vdso_data __arm64_get_k_vdso_data
> +
> +static __always_inline
> +int __arm64_get_clock_mode(struct timekeeper *tk)
> +{
> +	u32 use_syscall = !tk->tkr_mono.clock->archdata.vdso_direct;
> +
> +	return use_syscall;
> +}
> +#define __arch_get_clock_mode __arm64_get_clock_mode
> +
> +static __always_inline
> +int __arm64_use_vsyscall(struct vdso_data *vdata)
> +{
> +	return !vdata[CS_HRES_COARSE].clock_mode;
> +}
> +#define __arch_use_vsyscall __arm64_use_vsyscall
> +
> +static __always_inline
> +void __arm64_update_vsyscall(struct vdso_data *vdata, struct timekeeper *tk)
> +{
> +	vdata[CS_HRES_COARSE].mask	= VDSO_PRECISION_MASK;
> +	vdata[CS_RAW].mask		= VDSO_PRECISION_MASK;
> +}
> +#define __arch_update_vsyscall __arm64_update_vsyscall
> +
> +/* 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/arm64/include/asm/vdso_datapage.h b/arch/arm64/include/asm/vdso_datapage.h
> deleted file mode 100644
> index f89263c8e11a..000000000000
> --- a/arch/arm64/include/asm/vdso_datapage.h
> +++ /dev/null
> @@ -1,48 +0,0 @@
> -/*
> - * Copyright (C) 2012 ARM Limited
> - *
> - * This program is free software; you can redistribute it and/or modify
> - * it under the terms of the GNU General Public License version 2 as
> - * published by the Free Software Foundation.
> - *
> - * 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.
> - *
> - * You should have received a copy of the GNU General Public License
> - * along with this program.  If not, see <http://www.gnu.org/licenses/>.
> - */
> -#ifndef __ASM_VDSO_DATAPAGE_H
> -#define __ASM_VDSO_DATAPAGE_H
> -
> -#ifdef __KERNEL__
> -
> -#ifndef __ASSEMBLY__
> -
> -struct vdso_data {
> -	__u64 cs_cycle_last;	/* Timebase at clocksource init */
> -	__u64 raw_time_sec;	/* Raw time */
> -	__u64 raw_time_nsec;
> -	__u64 xtime_clock_sec;	/* Kernel time */
> -	__u64 xtime_clock_nsec;
> -	__u64 xtime_coarse_sec;	/* Coarse time */
> -	__u64 xtime_coarse_nsec;
> -	__u64 wtm_clock_sec;	/* Wall to monotonic time */
> -	__u64 wtm_clock_nsec;
> -	__u32 tb_seq_count;	/* Timebase sequence counter */
> -	/* cs_* members must be adjacent and in this order (ldp accesses) */
> -	__u32 cs_mono_mult;	/* NTP-adjusted clocksource multiplier */
> -	__u32 cs_shift;		/* Clocksource shift (mono = raw) */
> -	__u32 cs_raw_mult;	/* Raw clocksource multiplier */
> -	__u32 tz_minuteswest;	/* Whacky timezone stuff */
> -	__u32 tz_dsttime;
> -	__u32 use_syscall;
> -	__u32 hrtimer_res;
> -};
> -
> -#endif /* !__ASSEMBLY__ */
> -
> -#endif /* __KERNEL__ */
> -
> -#endif /* __ASM_VDSO_DATAPAGE_H */
> diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
> index 947e39896e28..9e4b7ccbab2f 100644
> --- a/arch/arm64/kernel/asm-offsets.c
> +++ b/arch/arm64/kernel/asm-offsets.c
> @@ -25,13 +25,13 @@
>   #include <linux/kvm_host.h>
>   #include <linux/preempt.h>
>   #include <linux/suspend.h>
> +#include <vdso/datapage.h>
>   #include <asm/cpufeature.h>
>   #include <asm/fixmap.h>
>   #include <asm/thread_info.h>
>   #include <asm/memory.h>
>   #include <asm/smp_plat.h>
>   #include <asm/suspend.h>
> -#include <asm/vdso_datapage.h>
>   #include <linux/kbuild.h>
>   #include <linux/arm-smccc.h>
>   
> @@ -100,17 +100,28 @@ int main(void)
>     DEFINE(CLOCK_COARSE_RES,	LOW_RES_NSEC);
>     DEFINE(NSEC_PER_SEC,		NSEC_PER_SEC);
>     BLANK();
> -  DEFINE(VDSO_CS_CYCLE_LAST,	offsetof(struct vdso_data, cs_cycle_last));
> -  DEFINE(VDSO_RAW_TIME_SEC,	offsetof(struct vdso_data, raw_time_sec));
> -  DEFINE(VDSO_XTIME_CLK_SEC,	offsetof(struct vdso_data, xtime_clock_sec));
> -  DEFINE(VDSO_XTIME_CRS_SEC,	offsetof(struct vdso_data, xtime_coarse_sec));
> -  DEFINE(VDSO_XTIME_CRS_NSEC,	offsetof(struct vdso_data, xtime_coarse_nsec));
> -  DEFINE(VDSO_WTM_CLK_SEC,	offsetof(struct vdso_data, wtm_clock_sec));
> -  DEFINE(VDSO_TB_SEQ_COUNT,	offsetof(struct vdso_data, tb_seq_count));
> -  DEFINE(VDSO_CS_MONO_MULT,	offsetof(struct vdso_data, cs_mono_mult));
> -  DEFINE(VDSO_CS_SHIFT,		offsetof(struct vdso_data, cs_shift));
> +  DEFINE(VDSO_SEQ,		offsetof(struct vdso_data, seq));
> +  DEFINE(VDSO_CLK_MODE,		offsetof(struct vdso_data, clock_mode));
> +  DEFINE(VDSO_CYCLE_LAST,	offsetof(struct vdso_data, cycle_last));
> +  DEFINE(VDSO_MASK,		offsetof(struct vdso_data, mask));
> +  DEFINE(VDSO_MULT,		offsetof(struct vdso_data, mult));
> +  DEFINE(VDSO_SHIFT,		offsetof(struct vdso_data, shift));
> +  DEFINE(VDSO_REALTIME_SEC,	offsetof(struct vdso_data, basetime[CLOCK_REALTIME].sec));
> +  DEFINE(VDSO_REALTIME_NSEC,	offsetof(struct vdso_data, basetime[CLOCK_REALTIME].nsec));
> +  DEFINE(VDSO_MONO_SEC,		offsetof(struct vdso_data, basetime[CLOCK_MONOTONIC].sec));
> +  DEFINE(VDSO_MONO_NSEC,	offsetof(struct vdso_data, basetime[CLOCK_MONOTONIC].nsec));
> +  DEFINE(VDSO_MONO_RAW_SEC,	offsetof(struct vdso_data, basetime[CLOCK_MONOTONIC_RAW].sec));
> +  DEFINE(VDSO_MONO_RAW_NSEC,	offsetof(struct vdso_data, basetime[CLOCK_MONOTONIC_RAW].nsec));
> +  DEFINE(VDSO_BOOTTIME_SEC,	offsetof(struct vdso_data, basetime[CLOCK_BOOTTIME].sec));
> +  DEFINE(VDSO_BOOTTIME_NSEC,	offsetof(struct vdso_data, basetime[CLOCK_BOOTTIME].nsec));
> +  DEFINE(VDSO_TAI_SEC,		offsetof(struct vdso_data, basetime[CLOCK_TAI].sec));
> +  DEFINE(VDSO_TAI_NSEC,		offsetof(struct vdso_data, basetime[CLOCK_TAI].nsec));
> +  DEFINE(VDSO_RT_COARSE_SEC,	offsetof(struct vdso_data, basetime[CLOCK_REALTIME_COARSE].sec));
> +  DEFINE(VDSO_RT_COARSE_NSEC,	offsetof(struct vdso_data, basetime[CLOCK_REALTIME_COARSE].nsec));
> +  DEFINE(VDSO_MONO_COARSE_SEC,	offsetof(struct vdso_data, basetime[CLOCK_MONOTONIC_COARSE].sec));
> +  DEFINE(VDSO_MONO_COARSE_NSEC,	offsetof(struct vdso_data, basetime[CLOCK_MONOTONIC_COARSE].nsec));
>     DEFINE(VDSO_TZ_MINWEST,	offsetof(struct vdso_data, tz_minuteswest));
> -  DEFINE(VDSO_USE_SYSCALL,	offsetof(struct vdso_data, use_syscall));
> +  DEFINE(VDSO_TZ_DSTTIME,	offsetof(struct vdso_data, tz_dsttime));
>     BLANK();
>     DEFINE(TVAL_TV_SEC,		offsetof(struct timeval, tv_sec));
>     DEFINE(TSPEC_TV_SEC,		offsetof(struct timespec, tv_sec));
> diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
> index 8074cbd3a3a8..23c38303a52a 100644
> --- a/arch/arm64/kernel/vdso.c
> +++ b/arch/arm64/kernel/vdso.c
> @@ -31,11 +31,13 @@
>   #include <linux/slab.h>
>   #include <linux/timekeeper_internal.h>
>   #include <linux/vmalloc.h>
> +#include <vdso/datapage.h>
> +#include <vdso/helpers.h>
> +#include <vdso/vsyscall.h>
>   
>   #include <asm/cacheflush.h>
>   #include <asm/signal32.h>
>   #include <asm/vdso.h>
> -#include <asm/vdso_datapage.h>
>   
>   extern char vdso_start[], vdso_end[];
>   static unsigned long vdso_pages __ro_after_init;
> @@ -44,10 +46,10 @@ static unsigned long vdso_pages __ro_after_init;
>    * The vDSO data page.
>    */
>   static union {
> -	struct vdso_data	data;
> +	struct vdso_data	data[CS_BASES];
>   	u8			page[PAGE_SIZE];
>   } vdso_data_store __page_aligned_data;
> -struct vdso_data *vdso_data = &vdso_data_store.data;
> +struct vdso_data *vdso_data = vdso_data_store.data;
>   
>   #ifdef CONFIG_COMPAT
>   /*
> @@ -280,46 +282,3 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
>   	up_write(&mm->mmap_sem);
>   	return PTR_ERR(ret);
>   }
> -
> -/*
> - * Update the vDSO data page to keep in sync with kernel timekeeping.
> - */
> -void update_vsyscall(struct timekeeper *tk)
> -{
> -	u32 use_syscall = !tk->tkr_mono.clock->archdata.vdso_direct;
> -
> -	++vdso_data->tb_seq_count;
> -	smp_wmb();
> -
> -	vdso_data->use_syscall			= use_syscall;
> -	vdso_data->xtime_coarse_sec		= tk->xtime_sec;
> -	vdso_data->xtime_coarse_nsec		= tk->tkr_mono.xtime_nsec >>
> -							tk->tkr_mono.shift;
> -	vdso_data->wtm_clock_sec		= tk->wall_to_monotonic.tv_sec;
> -	vdso_data->wtm_clock_nsec		= tk->wall_to_monotonic.tv_nsec;
> -
> -	/* Read without the seqlock held by clock_getres() */
> -	WRITE_ONCE(vdso_data->hrtimer_res, hrtimer_resolution);
> -
> -	if (!use_syscall) {
> -		/* tkr_mono.cycle_last == tkr_raw.cycle_last */
> -		vdso_data->cs_cycle_last	= tk->tkr_mono.cycle_last;
> -		vdso_data->raw_time_sec         = tk->raw_sec;
> -		vdso_data->raw_time_nsec        = tk->tkr_raw.xtime_nsec;
> -		vdso_data->xtime_clock_sec	= tk->xtime_sec;
> -		vdso_data->xtime_clock_nsec	= tk->tkr_mono.xtime_nsec;
> -		vdso_data->cs_mono_mult		= tk->tkr_mono.mult;
> -		vdso_data->cs_raw_mult		= tk->tkr_raw.mult;
> -		/* tkr_mono.shift == tkr_raw.shift */
> -		vdso_data->cs_shift		= tk->tkr_mono.shift;
> -	}
> -
> -	smp_wmb();
> -	++vdso_data->tb_seq_count;
> -}
> -
> -void update_vsyscall_tz(void)
> -{
> -	vdso_data->tz_minuteswest	= sys_tz.tz_minuteswest;
> -	vdso_data->tz_dsttime		= sys_tz.tz_dsttime;
> -}
> diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
> index fa230ff09aa1..3acfc813e966 100644
> --- a/arch/arm64/kernel/vdso/Makefile
> +++ b/arch/arm64/kernel/vdso/Makefile
> @@ -6,7 +6,12 @@
>   # Heavily based on the vDSO Makefiles for other archs.
>   #
>   
> -obj-vdso := gettimeofday.o note.o sigreturn.o
> +# Absolute relocation type $(ARCH_REL_TYPE_ABS) needs to be defined before
> +# the inclusion of generic Makefile.
> +ARCH_REL_TYPE_ABS := R_AARCH64_JUMP_SLOT|R_AARCH64_GLOB_DAT|R_AARCH64_ABS64
> +include $(srctree)/lib/vdso/Makefile
> +
> +obj-vdso := vgettimeofday.o note.o sigreturn.o
>   
>   # Build rules
>   targets := $(obj-vdso) vdso.so vdso.so.dbg
> @@ -15,6 +20,24 @@ obj-vdso := $(addprefix $(obj)/, $(obj-vdso))
>   ldflags-y := -shared -nostdlib -soname=linux-vdso.so.1 --hash-style=sysv \
>   		--build-id -n -T
>   
> +ccflags-y := -fno-common -fno-builtin -fno-stack-protector
> +ccflags-y += -DDISABLE_BRANCH_PROFILING
> +
> +VDSO_LDFLAGS := -Bsymbolic
> +
> +CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os
> +KBUILD_CFLAGS			+= $(DISABLE_LTO)
> +KASAN_SANITIZE			:= n
> +UBSAN_SANITIZE			:= n
> +OBJECT_FILES_NON_STANDARD	:= y
> +KCOV_INSTRUMENT			:= n
> +
> +ifeq ($(c-gettimeofday-y),)
> +CFLAGS_vgettimeofday.o = -O2 -mcmodel=tiny
> +else
> +CFLAGS_vgettimeofday.o = -O2 -mcmodel=tiny -include $(c-gettimeofday-y)
> +endif
> +
>   # Disable gcov profiling for VDSO code
>   GCOV_PROFILE := n
>   
> @@ -28,6 +51,7 @@ $(obj)/vdso.o : $(obj)/vdso.so
>   # Link rule for the .so file, .lds has to be first
>   $(obj)/vdso.so.dbg: $(obj)/vdso.lds $(obj-vdso) FORCE
>   	$(call if_changed,ld)
> +	$(call if_changed,vdso_check)
>   
>   # Strip rule for the .so file
>   $(obj)/%.so: OBJCOPYFLAGS := -S
> @@ -42,13 +66,9 @@ quiet_cmd_vdsosym = VDSOSYM $@
>   include/generated/vdso-offsets.h: $(obj)/vdso.so.dbg FORCE
>   	$(call if_changed,vdsosym)
>   
> -# Assembly rules for the .S files
> -$(obj-vdso): %.o: %.S FORCE
> -	$(call if_changed_dep,vdsoas)
> -
>   # Actual build commands
> -quiet_cmd_vdsoas = VDSOA   $@
> -      cmd_vdsoas = $(CC) $(a_flags) -c -o $@ $<
> +quiet_cmd_vdsocc = VDSOCC   $@
> +      cmd_vdsocc = $(CC) $(a_flags) $(c_flags) -c -o $@ $<
>   
>   # Install commands for the unstripped file
>   quiet_cmd_vdso_install = INSTALL $@
> diff --git a/arch/arm64/kernel/vdso/gettimeofday.S b/arch/arm64/kernel/vdso/gettimeofday.S
> deleted file mode 100644
> index 856fee6d3512..000000000000
> --- a/arch/arm64/kernel/vdso/gettimeofday.S
> +++ /dev/null
> @@ -1,334 +0,0 @@
> -/*
> - * Userspace implementations of gettimeofday() and friends.
> - *
> - * Copyright (C) 2012 ARM Limited
> - *
> - * This program is free software; you can redistribute it and/or modify
> - * it under the terms of the GNU General Public License version 2 as
> - * published by the Free Software Foundation.
> - *
> - * 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.
> - *
> - * You should have received a copy of the GNU General Public License
> - * along with this program.  If not, see <http://www.gnu.org/licenses/>.
> - *
> - * Author: Will Deacon <will.deacon@....com>
> - */
> -
> -#include <linux/linkage.h>
> -#include <asm/asm-offsets.h>
> -#include <asm/unistd.h>
> -
> -#define NSEC_PER_SEC_LO16	0xca00
> -#define NSEC_PER_SEC_HI16	0x3b9a
> -
> -vdso_data	.req	x6
> -seqcnt		.req	w7
> -w_tmp		.req	w8
> -x_tmp		.req	x8
> -
> -/*
> - * Conventions for macro arguments:
> - * - An argument is write-only if its name starts with "res".
> - * - All other arguments are read-only, unless otherwise specified.
> - */
> -
> -	.macro	seqcnt_acquire
> -9999:	ldr	seqcnt, [vdso_data, #VDSO_TB_SEQ_COUNT]
> -	tbnz	seqcnt, #0, 9999b
> -	dmb	ishld
> -	.endm
> -
> -	.macro	seqcnt_check fail
> -	dmb	ishld
> -	ldr	w_tmp, [vdso_data, #VDSO_TB_SEQ_COUNT]
> -	cmp	w_tmp, seqcnt
> -	b.ne	\fail
> -	.endm
> -
> -	.macro	syscall_check fail
> -	ldr	w_tmp, [vdso_data, #VDSO_USE_SYSCALL]
> -	cbnz	w_tmp, \fail
> -	.endm
> -
> -	.macro get_nsec_per_sec res
> -	mov	\res, #NSEC_PER_SEC_LO16
> -	movk	\res, #NSEC_PER_SEC_HI16, lsl #16
> -	.endm
> -
> -	/*
> -	 * Returns the clock delta, in nanoseconds left-shifted by the clock
> -	 * shift.
> -	 */
> -	.macro	get_clock_shifted_nsec res, cycle_last, mult
> -	/* Read the virtual counter. */
> -	isb
> -	mrs	x_tmp, cntvct_el0
> -	/* Calculate cycle delta and convert to ns. */
> -	sub	\res, x_tmp, \cycle_last
> -	/* We can only guarantee 56 bits of precision. */
> -	movn	x_tmp, #0xff00, lsl #48
> -	and	\res, x_tmp, \res
> -	mul	\res, \res, \mult
> -	/*
> -	 * Fake address dependency from the value computed from the counter
> -	 * register to subsequent data page accesses so that the sequence
> -	 * locking also orders the read of the counter.
> -	 */
> -	and	x_tmp, \res, xzr
> -	add	vdso_data, vdso_data, x_tmp
> -	.endm
> -
> -	/*
> -	 * Returns in res_{sec,nsec} the REALTIME timespec, based on the
> -	 * "wall time" (xtime) and the clock_mono delta.
> -	 */
> -	.macro	get_ts_realtime res_sec, res_nsec, \
> -			clock_nsec, xtime_sec, xtime_nsec, nsec_to_sec
> -	add	\res_nsec, \clock_nsec, \xtime_nsec
> -	udiv	x_tmp, \res_nsec, \nsec_to_sec
> -	add	\res_sec, \xtime_sec, x_tmp
> -	msub	\res_nsec, x_tmp, \nsec_to_sec, \res_nsec
> -	.endm
> -
> -	/*
> -	 * Returns in res_{sec,nsec} the timespec based on the clock_raw delta,
> -	 * used for CLOCK_MONOTONIC_RAW.
> -	 */
> -	.macro	get_ts_clock_raw res_sec, res_nsec, clock_nsec, nsec_to_sec
> -	udiv	\res_sec, \clock_nsec, \nsec_to_sec
> -	msub	\res_nsec, \res_sec, \nsec_to_sec, \clock_nsec
> -	.endm
> -
> -	/* sec and nsec are modified in place. */
> -	.macro add_ts sec, nsec, ts_sec, ts_nsec, nsec_to_sec
> -	/* Add timespec. */
> -	add	\sec, \sec, \ts_sec
> -	add	\nsec, \nsec, \ts_nsec
> -
> -	/* Normalise the new timespec. */
> -	cmp	\nsec, \nsec_to_sec
> -	b.lt	9999f
> -	sub	\nsec, \nsec, \nsec_to_sec
> -	add	\sec, \sec, #1
> -9999:
> -	cmp	\nsec, #0
> -	b.ge	9998f
> -	add	\nsec, \nsec, \nsec_to_sec
> -	sub	\sec, \sec, #1
> -9998:
> -	.endm
> -
> -	.macro clock_gettime_return, shift=0
> -	.if \shift == 1
> -	lsr	x11, x11, x12
> -	.endif
> -	stp	x10, x11, [x1, #TSPEC_TV_SEC]
> -	mov	x0, xzr
> -	ret
> -	.endm
> -
> -	.macro jump_slot jumptable, index, label
> -	.if (. - \jumptable) != 4 * (\index)
> -	.error "Jump slot index mismatch"
> -	.endif
> -	b	\label
> -	.endm
> -
> -	.text
> -
> -/* int __kernel_gettimeofday(struct timeval *tv, struct timezone *tz); */
> -ENTRY(__kernel_gettimeofday)
> -	.cfi_startproc
> -	adr	vdso_data, _vdso_data
> -	/* If tv is NULL, skip to the timezone code. */
> -	cbz	x0, 2f
> -
> -	/* Compute the time of day. */
> -1:	seqcnt_acquire
> -	syscall_check fail=4f
> -	ldr	x10, [vdso_data, #VDSO_CS_CYCLE_LAST]
> -	/* w11 = cs_mono_mult, w12 = cs_shift */
> -	ldp	w11, w12, [vdso_data, #VDSO_CS_MONO_MULT]
> -	ldp	x13, x14, [vdso_data, #VDSO_XTIME_CLK_SEC]
> -
> -	get_nsec_per_sec res=x9
> -	lsl	x9, x9, x12
> -
> -	get_clock_shifted_nsec res=x15, cycle_last=x10, mult=x11
> -	seqcnt_check fail=1b
> -	get_ts_realtime res_sec=x10, res_nsec=x11, \
> -		clock_nsec=x15, xtime_sec=x13, xtime_nsec=x14, nsec_to_sec=x9
> -
> -	/* Convert ns to us. */
> -	mov	x13, #1000
> -	lsl	x13, x13, x12
> -	udiv	x11, x11, x13
> -	stp	x10, x11, [x0, #TVAL_TV_SEC]
> -2:
> -	/* If tz is NULL, return 0. */
> -	cbz	x1, 3f
> -	ldp	w4, w5, [vdso_data, #VDSO_TZ_MINWEST]
> -	stp	w4, w5, [x1, #TZ_MINWEST]
> -3:
> -	mov	x0, xzr
> -	ret
> -4:
> -	/* Syscall fallback. */
> -	mov	x8, #__NR_gettimeofday
> -	svc	#0
> -	ret
> -	.cfi_endproc
> -ENDPROC(__kernel_gettimeofday)
> -
> -#define JUMPSLOT_MAX CLOCK_MONOTONIC_COARSE
> -
> -/* int __kernel_clock_gettime(clockid_t clock_id, struct timespec *tp); */
> -ENTRY(__kernel_clock_gettime)
> -	.cfi_startproc
> -	cmp	w0, #JUMPSLOT_MAX
> -	b.hi	syscall
> -	adr	vdso_data, _vdso_data
> -	adr	x_tmp, jumptable
> -	add	x_tmp, x_tmp, w0, uxtw #2
> -	br	x_tmp
> -
> -	ALIGN
> -jumptable:
> -	jump_slot jumptable, CLOCK_REALTIME, realtime
> -	jump_slot jumptable, CLOCK_MONOTONIC, monotonic
> -	b	syscall
> -	b	syscall
> -	jump_slot jumptable, CLOCK_MONOTONIC_RAW, monotonic_raw
> -	jump_slot jumptable, CLOCK_REALTIME_COARSE, realtime_coarse
> -	jump_slot jumptable, CLOCK_MONOTONIC_COARSE, monotonic_coarse
> -
> -	.if (. - jumptable) != 4 * (JUMPSLOT_MAX + 1)
> -	.error	"Wrong jumptable size"
> -	.endif
> -
> -	ALIGN
> -realtime:
> -	seqcnt_acquire
> -	syscall_check fail=syscall
> -	ldr	x10, [vdso_data, #VDSO_CS_CYCLE_LAST]
> -	/* w11 = cs_mono_mult, w12 = cs_shift */
> -	ldp	w11, w12, [vdso_data, #VDSO_CS_MONO_MULT]
> -	ldp	x13, x14, [vdso_data, #VDSO_XTIME_CLK_SEC]
> -
> -	/* All computations are done with left-shifted nsecs. */
> -	get_nsec_per_sec res=x9
> -	lsl	x9, x9, x12
> -
> -	get_clock_shifted_nsec res=x15, cycle_last=x10, mult=x11
> -	seqcnt_check fail=realtime
> -	get_ts_realtime res_sec=x10, res_nsec=x11, \
> -		clock_nsec=x15, xtime_sec=x13, xtime_nsec=x14, nsec_to_sec=x9
> -	clock_gettime_return, shift=1
> -
> -	ALIGN
> -monotonic:
> -	seqcnt_acquire
> -	syscall_check fail=syscall
> -	ldr	x10, [vdso_data, #VDSO_CS_CYCLE_LAST]
> -	/* w11 = cs_mono_mult, w12 = cs_shift */
> -	ldp	w11, w12, [vdso_data, #VDSO_CS_MONO_MULT]
> -	ldp	x13, x14, [vdso_data, #VDSO_XTIME_CLK_SEC]
> -	ldp	x3, x4, [vdso_data, #VDSO_WTM_CLK_SEC]
> -
> -	/* All computations are done with left-shifted nsecs. */
> -	lsl	x4, x4, x12
> -	get_nsec_per_sec res=x9
> -	lsl	x9, x9, x12
> -
> -	get_clock_shifted_nsec res=x15, cycle_last=x10, mult=x11
> -	seqcnt_check fail=monotonic
> -	get_ts_realtime res_sec=x10, res_nsec=x11, \
> -		clock_nsec=x15, xtime_sec=x13, xtime_nsec=x14, nsec_to_sec=x9
> -
> -	add_ts sec=x10, nsec=x11, ts_sec=x3, ts_nsec=x4, nsec_to_sec=x9
> -	clock_gettime_return, shift=1
> -
> -	ALIGN
> -monotonic_raw:
> -	seqcnt_acquire
> -	syscall_check fail=syscall
> -	ldr	x10, [vdso_data, #VDSO_CS_CYCLE_LAST]
> -	/* w11 = cs_raw_mult, w12 = cs_shift */
> -	ldp	w12, w11, [vdso_data, #VDSO_CS_SHIFT]
> -	ldp	x13, x14, [vdso_data, #VDSO_RAW_TIME_SEC]
> -
> -	/* All computations are done with left-shifted nsecs. */
> -	get_nsec_per_sec res=x9
> -	lsl	x9, x9, x12
> -
> -	get_clock_shifted_nsec res=x15, cycle_last=x10, mult=x11
> -	seqcnt_check fail=monotonic_raw
> -	get_ts_clock_raw res_sec=x10, res_nsec=x11, \
> -		clock_nsec=x15, nsec_to_sec=x9
> -
> -	add_ts sec=x10, nsec=x11, ts_sec=x13, ts_nsec=x14, nsec_to_sec=x9
> -	clock_gettime_return, shift=1
> -
> -	ALIGN
> -realtime_coarse:
> -	seqcnt_acquire
> -	ldp	x10, x11, [vdso_data, #VDSO_XTIME_CRS_SEC]
> -	seqcnt_check fail=realtime_coarse
> -	clock_gettime_return
> -
> -	ALIGN
> -monotonic_coarse:
> -	seqcnt_acquire
> -	ldp	x10, x11, [vdso_data, #VDSO_XTIME_CRS_SEC]
> -	ldp	x13, x14, [vdso_data, #VDSO_WTM_CLK_SEC]
> -	seqcnt_check fail=monotonic_coarse
> -
> -	/* Computations are done in (non-shifted) nsecs. */
> -	get_nsec_per_sec res=x9
> -	add_ts sec=x10, nsec=x11, ts_sec=x13, ts_nsec=x14, nsec_to_sec=x9
> -	clock_gettime_return
> -
> -	ALIGN
> -syscall: /* Syscall fallback. */
> -	mov	x8, #__NR_clock_gettime
> -	svc	#0
> -	ret
> -	.cfi_endproc
> -ENDPROC(__kernel_clock_gettime)
> -
> -/* int __kernel_clock_getres(clockid_t clock_id, struct timespec *res); */
> -ENTRY(__kernel_clock_getres)
> -	.cfi_startproc
> -	cmp	w0, #CLOCK_REALTIME
> -	ccmp	w0, #CLOCK_MONOTONIC, #0x4, ne
> -	ccmp	w0, #CLOCK_MONOTONIC_RAW, #0x4, ne
> -	b.ne	1f
> -
> -	adr	vdso_data, _vdso_data
> -	ldr	w2, [vdso_data, #CLOCK_REALTIME_RES]
> -	b	2f
> -1:
> -	cmp	w0, #CLOCK_REALTIME_COARSE
> -	ccmp	w0, #CLOCK_MONOTONIC_COARSE, #0x4, ne
> -	b.ne	4f
> -	ldr	x2, 5f
> -2:
> -	cbz	x1, 3f
> -	stp	xzr, x2, [x1]
> -
> -3:	/* res == NULL. */
> -	mov	w0, wzr
> -	ret
> -
> -4:	/* Syscall fallback. */
> -	mov	x8, #__NR_clock_getres
> -	svc	#0
> -	ret
> -5:
> -	.quad	CLOCK_COARSE_RES
> -	.cfi_endproc
> -ENDPROC(__kernel_clock_getres)
> diff --git a/arch/arm64/kernel/vdso/vgettimeofday.c b/arch/arm64/kernel/vdso/vgettimeofday.c
> new file mode 100644
> index 000000000000..3c58f19dbdf4
> --- /dev/null
> +++ b/arch/arm64/kernel/vdso/vgettimeofday.c
> @@ -0,0 +1,28 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * ARM64 userspace implementations of gettimeofday() and similar.
> + *
> + * Copyright (C) 2018 ARM Limited
> + *
> + */
> +#include <linux/time.h>
> +#include <linux/types.h>
> +
> +int __kernel_clock_gettime(clockid_t clock,
> +			   struct __kernel_timespec *ts)
> +{
> +	return __cvdso_clock_gettime(clock, ts);
> +}
> +
> +int __kernel_gettimeofday(struct __kernel_old_timeval *tv,
> +			  struct timezone *tz)
> +{
> +	return __cvdso_gettimeofday(tv, tz);
> +}
> +
> +int __kernel_clock_getres(clockid_t clock_id,
> +			  struct __kernel_timespec *res)
> +{
> +	return __cvdso_clock_getres(clock_id, res);
> +}
> +

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland

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