Re: [PATCH v7 04/25] arm64: Substitute gettimeofday with C implementation

Marek Szyprowski
2019-06-28T13:09:26Z

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@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
> Tested-by: Shijith Thotton <sthotton@marvell.com>
> Tested-by: Andre Przywara <andre.przywara@arm.com>
> Signed-off-by: Catalin Marinas <catalin.marinas@arm.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@arm.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