linux-kernel - [PATCH v3 2/3] arm64: vdso: Use ARCH_TIMER

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Date:   Wed, 26 Dec 2018 11:45:08 -0500
From:   Pavel Tatashin <pasha.tatashin@...een.com>
To:     catalin.marinas@....com, will.deacon@....com,
        akpm@...ux-foundation.org, rppt@...ux.vnet.ibm.com,
        mhocko@...e.com, ard.biesheuvel@...aro.org, andrew.murray@....com,
        james.morse@....com, marc.zyngier@....com, sboyd@...nel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        pasha.tatashin@...een.com
Subject: [PATCH v3 2/3] arm64: vdso: Use ARCH_TIMER_NBITS to calculate mask

get_clock_shifted_nsec macro in vdso/gettimeofday.S has another place
where the size of clocksource precision is hardcoded. Use
ARCH_TIMER_NBITS to generate mask value.

Signed-off-by: Pavel Tatashin <pasha.tatashin@...een.com>
---
 arch/arm64/kernel/asm-offsets.c       | 1 +
 arch/arm64/kernel/vdso/gettimeofday.S | 3 +--
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index 65b8afc84466..32e1b935dd6c 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -107,6 +107,7 @@ int main(void)
   DEFINE(CLOCK_MONOTONIC_COARSE,CLOCK_MONOTONIC_COARSE);
   DEFINE(CLOCK_COARSE_RES,	LOW_RES_NSEC);
   DEFINE(NSEC_PER_SEC,		NSEC_PER_SEC);
+  DEFINE(CLOCKSOURCE_MASK,	CLOCKSOURCE_MASK(ARCH_TIMER_NBITS));
   BLANK();
   DEFINE(VDSO_CS_CYCLE_LAST,	offsetof(struct vdso_data, cs_cycle_last));
   DEFINE(VDSO_RAW_TIME_SEC,	offsetof(struct vdso_data, raw_time_sec));
diff --git a/arch/arm64/kernel/vdso/gettimeofday.S b/arch/arm64/kernel/vdso/gettimeofday.S
index c39872a7b03c..5a7580d0118e 100644
--- a/arch/arm64/kernel/vdso/gettimeofday.S
+++ b/arch/arm64/kernel/vdso/gettimeofday.S
@@ -69,8 +69,7 @@ x_tmp		.req	x8
 	mrs	x_tmp, cntvct_el0
 	/* Calculate cycle delta and convert to ns. */
 	sub	\res, x_tmp, \cycle_last
-	/* We can only guarantee 56 bits of precision. */
-	movn	x_tmp, #0xff00, lsl #48
+	mov     x_tmp, #CLOCKSOURCE_MASK
 	and	\res, x_tmp, \res
 	mul	\res, \res, \mult
 	.endm
-- 
2.20.1