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    Subject[tip:timers/vdso] x86/vdso: Add clock_getres() entry point
    Commit-ID:  f66501dc53e72079045a6a17e023b41316ede220
    Gitweb: https://git.kernel.org/tip/f66501dc53e72079045a6a17e023b41316ede220
    Author: Vincenzo Frascino <vincenzo.frascino@arm.com>
    AuthorDate: Fri, 21 Jun 2019 10:52:50 +0100
    Committer: Thomas Gleixner <tglx@linutronix.de>
    CommitDate: Sat, 22 Jun 2019 21:21:10 +0200

    x86/vdso: Add clock_getres() entry point

    The generic vDSO library provides an implementation of clock_getres()
    that can be leveraged by each architecture.

    Add the clock_getres() VDSO entry point on x86.

    [ tglx: Massaged changelog and cleaned up the function signature formatting ]

    Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Cc: linux-arch@vger.kernel.org
    Cc: linux-arm-kernel@lists.infradead.org
    Cc: linux-mips@vger.kernel.org
    Cc: linux-kselftest@vger.kernel.org
    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Cc: Will Deacon <will.deacon@arm.com>
    Cc: Arnd Bergmann <arnd@arndb.de>
    Cc: Russell King <linux@armlinux.org.uk>
    Cc: Ralf Baechle <ralf@linux-mips.org>
    Cc: Paul Burton <paul.burton@mips.com>
    Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
    Cc: Mark Salyzyn <salyzyn@android.com>
    Cc: Peter Collingbourne <pcc@google.com>
    Cc: Shuah Khan <shuah@kernel.org>
    Cc: Dmitry Safonov <0x7f454c46@gmail.com>
    Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
    Cc: Huw Davies <huw@codeweavers.com>
    Cc: Shijith Thotton <sthotton@marvell.com>
    Cc: Andre Przywara <andre.przywara@arm.com>
    Link: https://lkml.kernel.org/r/20190621095252.32307-24-vincenzo.frascino@arm.com

    ---
    arch/x86/entry/vdso/vclock_gettime.c | 17 +++++++++++++++++
    arch/x86/entry/vdso/vdso.lds.S | 2 ++
    arch/x86/entry/vdso/vdso32/vdso32.lds.S | 1 +
    arch/x86/include/asm/vdso/gettimeofday.h | 31 +++++++++++++++++++++++++++++++
    4 files changed, 51 insertions(+)

    diff --git a/arch/x86/entry/vdso/vclock_gettime.c b/arch/x86/entry/vdso/vclock_gettime.c
    index f01a3f0787ca..1a648b509d46 100644
    --- a/arch/x86/entry/vdso/vclock_gettime.c
    +++ b/arch/x86/entry/vdso/vclock_gettime.c
    @@ -36,6 +36,7 @@ time_t time(time_t *t) __attribute__((weak, alias("__vdso_time")));
    #if defined(CONFIG_X86_64) && !defined(BUILD_VDSO32_64)
    /* both 64-bit and x32 use these */
    extern int __vdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts);
    +extern int __vdso_clock_getres(clockid_t clock, struct __kernel_timespec *res);

    int __vdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
    {
    @@ -45,9 +46,18 @@ int __vdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
    int clock_gettime(clockid_t, struct __kernel_timespec *)
    __attribute__((weak, alias("__vdso_clock_gettime")));

    +int __vdso_clock_getres(clockid_t clock,
    + struct __kernel_timespec *res)
    +{
    + return __cvdso_clock_getres(clock, res);
    +}
    +int clock_getres(clockid_t, struct __kernel_timespec *)
    + __attribute__((weak, alias("__vdso_clock_getres")));
    +
    #else
    /* i386 only */
    extern int __vdso_clock_gettime(clockid_t clock, struct old_timespec32 *ts);
    +extern int __vdso_clock_getres(clockid_t clock, struct old_timespec32 *res);

    int __vdso_clock_gettime(clockid_t clock, struct old_timespec32 *ts)
    {
    @@ -57,4 +67,11 @@ int __vdso_clock_gettime(clockid_t clock, struct old_timespec32 *ts)
    int clock_gettime(clockid_t, struct old_timespec32 *)
    __attribute__((weak, alias("__vdso_clock_gettime")));

    +int __vdso_clock_getres(clockid_t clock, struct old_timespec32 *res)
    +{
    + return __cvdso_clock_getres_time32(clock, res);
    +}
    +
    +int clock_getres(clockid_t, struct old_timespec32 *)
    + __attribute__((weak, alias("__vdso_clock_getres")));
    #endif
    diff --git a/arch/x86/entry/vdso/vdso.lds.S b/arch/x86/entry/vdso/vdso.lds.S
    index d3a2dce4cfa9..36b644e16272 100644
    --- a/arch/x86/entry/vdso/vdso.lds.S
    +++ b/arch/x86/entry/vdso/vdso.lds.S
    @@ -25,6 +25,8 @@ VERSION {
    __vdso_getcpu;
    time;
    __vdso_time;
    + clock_getres;
    + __vdso_clock_getres;
    local: *;
    };
    }
    diff --git a/arch/x86/entry/vdso/vdso32/vdso32.lds.S b/arch/x86/entry/vdso/vdso32/vdso32.lds.S
    index 422764a81d32..991b26cc855b 100644
    --- a/arch/x86/entry/vdso/vdso32/vdso32.lds.S
    +++ b/arch/x86/entry/vdso/vdso32/vdso32.lds.S
    @@ -26,6 +26,7 @@ VERSION
    __vdso_clock_gettime;
    __vdso_gettimeofday;
    __vdso_time;
    + __vdso_clock_getres;
    };

    LINUX_2.5 {
    diff --git a/arch/x86/include/asm/vdso/gettimeofday.h b/arch/x86/include/asm/vdso/gettimeofday.h
    index 0e2650fc191b..f92752d6cbcf 100644
    --- a/arch/x86/include/asm/vdso/gettimeofday.h
    +++ b/arch/x86/include/asm/vdso/gettimeofday.h
    @@ -24,6 +24,8 @@

    #define VDSO_HAS_TIME 1

    +#define VDSO_HAS_CLOCK_GETRES 1
    +
    #ifdef CONFIG_PARAVIRT_CLOCK
    extern u8 pvclock_page[PAGE_SIZE]
    __attribute__((visibility("hidden")));
    @@ -60,6 +62,18 @@ long gettimeofday_fallback(struct __kernel_old_timeval *_tv,
    return ret;
    }

    +static __always_inline
    +long clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
    +{
    + long ret;
    +
    + asm ("syscall" : "=a" (ret), "=m" (*_ts) :
    + "0" (__NR_clock_getres), "D" (_clkid), "S" (_ts) :
    + "rcx", "r11");
    +
    + return ret;
    +}
    +
    #else

    static __always_inline
    @@ -97,6 +111,23 @@ long gettimeofday_fallback(struct __kernel_old_timeval *_tv,
    return ret;
    }

    +static __always_inline long
    +clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
    +{
    + long ret;
    +
    + asm (
    + "mov %%ebx, %%edx \n"
    + "mov %[clock], %%ebx \n"
    + "call __kernel_vsyscall \n"
    + "mov %%edx, %%ebx \n"
    + : "=a" (ret), "=m" (*_ts)
    + : "0" (__NR_clock_getres_time64), [clock] "g" (_clkid), "c" (_ts)
    + : "edx");
    +
    + return ret;
    +}
    +
    #endif

    #ifdef CONFIG_PARAVIRT_CLOCK
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