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Commit 0499c51f authored by Mark Salyzyn's avatar Mark Salyzyn Committed by Gagan Malvi
Browse files

FROMLIST: lib: vdso: add support for time 

(cherry pick from url https://patchwork.kernel.org/patch/10053549/

)

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.

Signed-off-by: default avatarMark Salyzyn <salyzyn@android.com>
Bug: 63737556
Bug: 20045882
Change-Id: I0bb3c6bafe57f9ed69350e2dd54edaae58316e8f

Signed-off-by: default avatarstarlight5234 <ifist2834@gmail.com>
Signed-off-by: default avatarTheSync <repo-sync@outlook.com>
parent 2424b07c

arch/arm/kernel/vdso.c

+1 −0
Original line number Diff line number Diff line
@@ -174,6 +174,7 @@ 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 */

	}

}

arch/arm/vdso/vdso.lds.S

+1 −0
Original line number Diff line number Diff line
@@ -83,6 +83,7 @@ VERSION 
		__vdso_clock_gettime;

		__vdso_gettimeofday;

		__vdso_clock_getres;

		__vdso_time;

	local: *;

	};

}

arch/arm64/kernel/vdso/compiler.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */

arch/arm64/kernel/vdso/vdso.lds.S

+1 −0
Original line number Diff line number Diff line
@@ -88,6 +88,7 @@ VERSION 
		__kernel_gettimeofday;

		__kernel_clock_gettime;

		__kernel_clock_getres;

		__kernel_time;

	local: *;

	};

}

lib/vdso/vgettimeofday.c

+10 −0
Original line number Diff line number Diff line
@@ -385,3 +385,13 @@ 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;

}