linux-kernel - [PATCH]: arch: arm64: vdso: export the symbols for time()

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Message-Id: <20200615112422.234735-1-salyzyn@android.com>
Date:   Mon, 15 Jun 2020 04:24:05 -0700
From:   Mark Salyzyn <salyzyn@...roid.com>
To:     linux-kernel@...r.kernel.org
Cc:     kernel-team@...roid.com, Chiawei Wang <chiaweiwang@...gle.com>,
        Mark Salyzyn <salyzyn@...roid.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Enrico Weigelt <info@...ux.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alexios Zavras <alexios.zavras@...el.com>,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH]: arch: arm64: vdso: export the symbols for time()

From: Chiawei Wang <chiaweiwang@...gle.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@...gle.com>
Signed-off-by: Mark Salyzyn <salyzyn@...roid.com>
---
 arch/arm64/include/asm/vdso/compat_gettimeofday.h | 2 ++
 arch/arm64/include/asm/vdso/gettimeofday.h        | 2 ++
 arch/arm64/kernel/vdso/vdso.lds.S                 | 1 +
 arch/arm64/kernel/vdso/vgettimeofday.c            | 5 +++++
 arch/arm64/kernel/vdso32/vdso.lds.S               | 1 +
 arch/arm64/kernel/vdso32/vgettimeofday.c          | 5 +++++
 6 files changed, 16 insertions(+)

diff --git a/arch/arm64/include/asm/vdso/compat_gettimeofday.h b/arch/arm64/include/asm/vdso/compat_gettimeofday.h
index b6907ae78e53..55e841bff432 100644
--- a/arch/arm64/include/asm/vdso/compat_gettimeofday.h
+++ b/arch/arm64/include/asm/vdso/compat_gettimeofday.h
@@ -14,6 +14,8 @@
 
 #define VDSO_HAS_CLOCK_GETRES		1
 
+#define VDSO_HAS_TIME			1
+
 #define BUILD_VDSO32			1
 
 static __always_inline
diff --git a/arch/arm64/include/asm/vdso/gettimeofday.h b/arch/arm64/include/asm/vdso/gettimeofday.h
index afba6ba332f8..4d2f028284a0 100644
--- a/arch/arm64/include/asm/vdso/gettimeofday.h
+++ b/arch/arm64/include/asm/vdso/gettimeofday.h
@@ -11,6 +11,8 @@
 
 #define VDSO_HAS_CLOCK_GETRES		1
 
+#define VDSO_HAS_TIME			1
+
 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..09be63204e74 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);
 }
+
+time_t __kernel_time(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..9296385e7bb8 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);
 }
 
+time_t __vdso_time(time_t *time)
+{
+	return __cvdso_time(time);
+}
+
 /* Avoid unresolved references emitted by GCC */
 
 void __aeabi_unwind_cpp_pr0(void)
-- 
2.27.0.290.gba653c62da-goog