FROMLIST: [PATCH v5 11/12] lib: vdso: Add support for CLOCK_BOOTTIME
authorMark Salyzyn <salyzyn@google.com>
Thu, 24 Aug 2017 20:35:24 +0000 (13:35 -0700)
committerBruno Martins <bgcngm@gmail.com>
Fri, 20 Oct 2023 16:03:36 +0000 (17:03 +0100)
commitbd9288dd83ec0b93166342dcc2eefd3b20a40b3c
treeb11ca41ed4fa6877239577229799b7e49b226486
parentc15e0471baa9f151d9e4ba6493049e05a92ec563
FROMLIST: [PATCH v5 11/12] lib: vdso: Add support for CLOCK_BOOTTIME

(cherry pick from url https://patchwork.kernel.org/patch/10044503/)

Take an effort to recode the arm64 vdso code from assembler to C
previously submitted by Andrew Pinski <apinski@cavium.com>, rework
it for use in both arm and arm64, overlapping any optimizations
for each architecture. But instead of landing it in arm64, land the
result into lib/vdso and unify both implementations to simplify
future maintenance.

Add a case for CLOCK_BOOTTIME as it is popular for measuring
relative time on systems expected to suspend() or hibernate().

Android uses CLOCK_BOOTTIME for all relative time measurements
and timeouts. Switching to vdso reduced CPU utilization and improves
accuracy. There is also a desire by some partners to switch all
logging over to CLOCK_BOOTTIME, and thus this operation alone would
contribute to a near percentile CPU load.

Signed-off-by: Mark Salyzyn <salyzyn@android.com>
Cc: James Morse <james.morse@arm.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Andy Gross <andy.gross@linaro.org>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Andrew Pinski <apinski@cavium.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Bug: 63737556
Bug: 20045882
Change-Id: I76c26b054baf7f1100e03c65d6b16fe649b883b1
arch/arm/include/asm/vdso_datapage.h
arch/arm/kernel/vdso.c
arch/arm64/include/asm/vdso_datapage.h
arch/arm64/kernel/vdso.c
lib/vdso/vgettimeofday.c