| Message ID | 20200615143838.143137-1-salyzyn@android.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] : arch: arm64: vdso: export the symbols for time() | expand |
On Mon, Jun 15, 2020 at 07:38:24AM -0700, Mark Salyzyn wrote: > From: Chiawei Wang <chiaweiwang@google.com> > > __cvdso_time() can be found in vDSO implementation, > but the symbols for time() are not exported. > > Export the symbols and run bionic-benchmarks. > > BEFORE: > bionic-benchmarks32 --bionic_extra BM_time_time > ----------------------------------------------------- > Benchmark Time CPU Iterations > ----------------------------------------------------- > BM_time_time 83.6 ns 83.5 ns 8385964 > > bionic-benchmarks64 --bionic_extra BM_time_time > ----------------------------------------------------- > Benchmark Time CPU Iterations > ----------------------------------------------------- > BM_time_time 63.5 ns 63.4 ns 11037509 > > AFTER: > bionic-benchmarks32 --bionic_extra BM_time_time > ----------------------------------------------------- > Benchmark Time CPU Iterations > ----------------------------------------------------- > BM_time_time 8.57 ns 8.56 ns 81887312 > > bionic-benchmarks64 --bionic_extra BM_time_time > ----------------------------------------------------- > Benchmark Time CPU Iterations > ----------------------------------------------------- > BM_time_time 7.52 ns 7.51 ns 93253809 > > Signed-off-by: Chiawei Wang <chiaweiwang@google.com> > Signed-off-by: Mark Salyzyn <salyzyn@android.com> > Cc: linux-kernel@vger.kernel.org > Cc: kernel-team@android.com > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Will Deacon <will@kernel.org> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> > Cc: Enrico Weigelt <info@metux.net> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Cc: Alexios Zavras <alexios.zavras@intel.com> > Cc: linux-arm-kernel@lists.infradead.org I don't understand this: neither arm nor arm64 offer the time() syscall afaict, so the C library should be implementing it in terms of clock_gettime() anyway, which _is_ implemented in the vDSO. What's am I missing? Will
On Tue, Jun 23, 2020 at 09:47:57AM -0700, Mark Salyzyn wrote: > time() in bionic libc will go an use vDSO interface to pick up this > low-resolution timer. But my point is it should _already_ be using the vDSO implementation of clock_gettime(), which should be plenty fast enough. Will
diff --git a/arch/arm64/include/asm/vdso/compat_gettimeofday.h b/arch/arm64/include/asm/vdso/compat_gettimeofday.h index b6907ae78e53..d0a5655785bd 100644 --- a/arch/arm64/include/asm/vdso/compat_gettimeofday.h +++ b/arch/arm64/include/asm/vdso/compat_gettimeofday.h @@ -14,8 +14,20 @@ #define VDSO_HAS_CLOCK_GETRES 1 +#define VDSO_HAS_TIME 1 + #define BUILD_VDSO32 1 +extern int __vdso_clock_gettime(clockid_t clock, + struct old_timespec32 *ts); +extern int __vdso_clock_gettime64(clockid_t clock, + struct __kernel_timespec *ts); +extern int __vdso_gettimeofday(struct __kernel_old_timeval *tv, + struct timezone *tz); +extern int __vdso_clock_getres(clockid_t clock_id, + struct old_timespec32 *res); +extern __kernel_old_time_t time(__kernel_old_time_t *time); + static __always_inline int gettimeofday_fallback(struct __kernel_old_timeval *_tv, struct timezone *_tz) diff --git a/arch/arm64/include/asm/vdso/gettimeofday.h b/arch/arm64/include/asm/vdso/gettimeofday.h index afba6ba332f8..e0dcf0dce6c0 100644 --- a/arch/arm64/include/asm/vdso/gettimeofday.h +++ b/arch/arm64/include/asm/vdso/gettimeofday.h @@ -11,6 +11,16 @@ #define VDSO_HAS_CLOCK_GETRES 1 +#define VDSO_HAS_TIME 1 + +extern int __kernel_clock_gettime(clockid_t clock, + struct __kernel_timespec *ts); +extern int __kernel_gettimeofday(struct __kernel_old_timeval *tv, + struct timezone *tz); +extern int __kernel_clock_getres(clockid_t clock_id, + struct __kernel_timespec *res); +extern __kernel_old_time_t __vdso_time(__kernel_old_time_t *time); + static __always_inline int gettimeofday_fallback(struct __kernel_old_timeval *_tv, struct timezone *_tz) diff --git a/arch/arm64/kernel/vdso/vdso.lds.S b/arch/arm64/kernel/vdso/vdso.lds.S index 7ad2d3a0cd48..61dddb0af1a5 100644 --- a/arch/arm64/kernel/vdso/vdso.lds.S +++ b/arch/arm64/kernel/vdso/vdso.lds.S @@ -77,6 +77,7 @@ VERSION __kernel_gettimeofday; __kernel_clock_gettime; __kernel_clock_getres; + __kernel_time; local: *; }; } diff --git a/arch/arm64/kernel/vdso/vgettimeofday.c b/arch/arm64/kernel/vdso/vgettimeofday.c index 4236cf34d7d9..9a9058ba1f89 100644 --- a/arch/arm64/kernel/vdso/vgettimeofday.c +++ b/arch/arm64/kernel/vdso/vgettimeofday.c @@ -23,3 +23,8 @@ int __kernel_clock_getres(clockid_t clock_id, { return __cvdso_clock_getres(clock_id, res); } + +__kernel_old_time_t __vdso_time(__kernel_old_time_t *time) +{ + return __cvdso_time(time); +} diff --git a/arch/arm64/kernel/vdso32/vdso.lds.S b/arch/arm64/kernel/vdso32/vdso.lds.S index a3944927eaeb..2222c78451b4 100644 --- a/arch/arm64/kernel/vdso32/vdso.lds.S +++ b/arch/arm64/kernel/vdso32/vdso.lds.S @@ -69,6 +69,7 @@ VERSION __kernel_rt_sigreturn_arm; __kernel_rt_sigreturn_thumb; __vdso_clock_gettime64; + __vdso_time; local: *; }; } diff --git a/arch/arm64/kernel/vdso32/vgettimeofday.c b/arch/arm64/kernel/vdso32/vgettimeofday.c index 5acff29c5991..7eb988fa06d8 100644 --- a/arch/arm64/kernel/vdso32/vgettimeofday.c +++ b/arch/arm64/kernel/vdso32/vgettimeofday.c @@ -30,6 +30,11 @@ int __vdso_clock_getres(clockid_t clock_id, return __cvdso_clock_getres_time32(clock_id, res); } +__kernel_old_time_t time(__kernel_old_time_t *time) +{ + return __cvdso_time(time); +} + /* Avoid unresolved references emitted by GCC */ void __aeabi_unwind_cpp_pr0(void)