From: Mark Salyzyn <saly...@google.com>
Add time() vdso support to match up with existing support in the x86's
vdso. Currently benefitting arm and arm64 which uses the common
vgettimeofday.c implementation. On arm provides about a ~14 fold
improvement in speed over the straight syscall, and about a ~5 fold
improvement in speed over an alternate library implementation that
relies on the vdso call to gettimeofday to fulfill the request.
We can provide __vdso_time even if we can not provide a speed
enhanced __vdso_gettimeofday. (arm, virtual counters).
Signed-off-by: Mark Salyzyn <saly...@android.com>
Tested-by: Mark Salyzyn <saly...@android.com>
Cc: James Morse <james.mo...@arm.com>
Cc: Russell King <li...@armlinux.org.uk>
Cc: Catalin Marinas <catalin.mari...@arm.com>
Cc: Will Deacon <will.dea...@arm.com>
Cc: Andy Lutomirski <l...@amacapital.net>
Cc: Dmitry Safonov <dsafo...@virtuozzo.com>
Cc: John Stultz <john.stu...@linaro.org>
Cc: Mark Rutland <mark.rutl...@arm.com>
Cc: Laura Abbott <labb...@redhat.com>
Cc: Kees Cook <keesc...@chromium.org>
Cc: Ard Biesheuvel <ard.biesheu...@linaro.org>
Cc: Andy Gross <andy.gr...@linaro.org>
Cc: Kevin Brodsky <kevin.brod...@arm.com>
Cc: Andrew Pinski <apin...@cavium.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-ker...@lists.infradead.org
Cc: Jeremy Linton <jeremy.lin...@arm.com>
Cc: android-ker...@android.com
---
arch/arm/kernel/vdso.c | 1 +
arch/arm/vdso/vdso.lds.S | 1 +
arch/arm64/kernel/vdso/compiler.h | 1 +
arch/arm64/kernel/vdso/vdso.lds.S | 1 +
lib/vdso/vgettimeofday.c | 10 ++++++++++
5 files changed, 14 insertions(+)
diff --git a/arch/arm/kernel/vdso.c b/arch/arm/kernel/vdso.c
index 51d8dcbd9952..6721854c5ae6 100644
--- a/arch/arm/kernel/vdso.c
+++ b/arch/arm/kernel/vdso.c
@@ -192,6 +192,7 @@ static void __init patch_vdso(void *ehdr)
vdso_nullpatch_one(&einfo, "__vdso_gettimeofday");
vdso_nullpatch_one(&einfo, "__vdso_clock_gettime");
vdso_nullpatch_one(&einfo, "__vdso_clock_getres");
+ /* do not zero out __vdso_time, no cntvct_ok dependency */
}
}
diff --git a/arch/arm/vdso/vdso.lds.S b/arch/arm/vdso/vdso.lds.S
index 1d81e8c3acf6..1eb577091d1f 100644
--- a/arch/arm/vdso/vdso.lds.S
+++ b/arch/arm/vdso/vdso.lds.S
@@ -83,6 +83,7 @@ VERSION
__vdso_clock_gettime;
__vdso_gettimeofday;
__vdso_clock_getres;
+ __vdso_time;
local: *;
};
}
diff --git a/arch/arm64/kernel/vdso/compiler.h
b/arch/arm64/kernel/vdso/compiler.h
index 921a7191b497..fb27545640f2 100644
--- a/arch/arm64/kernel/vdso/compiler.h
+++ b/arch/arm64/kernel/vdso/compiler.h
@@ -65,5 +65,6 @@ static __always_inline notrace u64
arch_vdso_read_counter(void)
#define __vdso_clock_gettime __kernel_clock_gettime
#define __vdso_gettimeofday __kernel_gettimeofday
#define __vdso_clock_getres __kernel_clock_getres
+#define __vdso_time __kernel_time
#endif /* __VDSO_COMPILER_H */
diff --git a/arch/arm64/kernel/vdso/vdso.lds.S
b/arch/arm64/kernel/vdso/vdso.lds.S
index beca249bc2f3..9de0ffc369c5 100644
--- a/arch/arm64/kernel/vdso/vdso.lds.S
+++ b/arch/arm64/kernel/vdso/vdso.lds.S
@@ -88,6 +88,7 @@ VERSION
__kernel_gettimeofday;
__kernel_clock_gettime;
__kernel_clock_getres;
+ __kernel_time;
local: *;
};
}
diff --git a/lib/vdso/vgettimeofday.c b/lib/vdso/vgettimeofday.c
index 54e519c99c4b..dfced9608cd3 100644
--- a/lib/vdso/vgettimeofday.c
+++ b/lib/vdso/vgettimeofday.c
@@ -386,3 +386,13 @@ int __vdso_clock_getres(clockid_t clock, struct timespec
*res)
return 0;
}
+
+notrace time_t __vdso_time(time_t *t)
+{
+ const struct vdso_data *vd = __get_datapage();
+ time_t result = READ_ONCE(vd->xtime_coarse_sec);
+
+ if (t)
+ *t = result;
+ return result;
+}
--
2.19.0.605.g01d371f741-goog
