linux-kernel - [PATCH 01/19] vdso: Consolidate vdso_calc

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Message-Id: <20240308131512.44324-2-adrian.hunter@intel.com>
Date: Fri,  8 Mar 2024 15:14:54 +0200
From: Adrian Hunter <adrian.hunter@...el.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Michael Ellerman <mpe@...erman.id.au>,
	Nicholas Piggin <npiggin@...il.com>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	"Aneesh Kumar K.V" <aneesh.kumar@...nel.org>,
	"Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>,
	Heiko Carstens <hca@...ux.ibm.com>,
	Vasily Gorbik <gor@...ux.ibm.com>,
	Alexander Gordeev <agordeev@...ux.ibm.com>,
	Christian Borntraeger <borntraeger@...ux.ibm.com>,
	Sven Schnelle <svens@...ux.ibm.com>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	Andy Lutomirski <luto@...nel.org>,
	Vincenzo Frascino <vincenzo.frascino@....com>,
	John Stultz <jstultz@...gle.com>,
	Stephen Boyd <sboyd@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Randy Dunlap <rdunlap@...radead.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Arnd Bergmann <arnd@...db.de>,
	Anna-Maria Behnsen <anna-maria@...utronix.de>,
	linuxppc-dev@...ts.ozlabs.org,
	linux-kernel@...r.kernel.org,
	linux-s390@...r.kernel.org
Subject: [PATCH 01/19] vdso: Consolidate vdso_calc_delta()

Consolidate vdso_calc_delta(), in preparation for further simplification.

Suggested-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
---
 arch/powerpc/include/asm/vdso/gettimeofday.h | 17 ++---------------
 arch/s390/include/asm/vdso/gettimeofday.h    |  7 ++-----
 lib/vdso/gettimeofday.c                      |  4 ++++
 3 files changed, 8 insertions(+), 20 deletions(-)

diff --git a/arch/powerpc/include/asm/vdso/gettimeofday.h b/arch/powerpc/include/asm/vdso/gettimeofday.h
index f0a4cf01e85c..f4da8e18cdf3 100644
--- a/arch/powerpc/include/asm/vdso/gettimeofday.h
+++ b/arch/powerpc/include/asm/vdso/gettimeofday.h
@@ -14,6 +14,8 @@
 
 #define VDSO_HAS_TIME			1
 
+#define VDSO_DELTA_NOMASK		1
+
 static __always_inline int do_syscall_2(const unsigned long _r0, const unsigned long _r3,
 					const unsigned long _r4)
 {
@@ -105,21 +107,6 @@ static inline bool vdso_clocksource_ok(const struct vdso_data *vd)
 }
 #define vdso_clocksource_ok vdso_clocksource_ok
 
-/*
- * powerpc specific delta calculation.
- *
- * This variant removes the masking of the subtraction because the
- * clocksource mask of all VDSO capable clocksources on powerpc is U64_MAX
- * which would result in a pointless operation. The compiler cannot
- * optimize it away as the mask comes from the vdso data and is not compile
- * time constant.
- */
-static __always_inline u64 vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 mult)
-{
-	return (cycles - last) * mult;
-}
-#define vdso_calc_delta vdso_calc_delta
-
 #ifndef __powerpc64__
 static __always_inline u64 vdso_shift_ns(u64 ns, unsigned long shift)
 {
diff --git a/arch/s390/include/asm/vdso/gettimeofday.h b/arch/s390/include/asm/vdso/gettimeofday.h
index db84942eb78f..7937765ccfa5 100644
--- a/arch/s390/include/asm/vdso/gettimeofday.h
+++ b/arch/s390/include/asm/vdso/gettimeofday.h
@@ -6,16 +6,13 @@
 
 #define VDSO_HAS_CLOCK_GETRES 1
 
+#define VDSO_DELTA_NOMASK 1
+
 #include <asm/syscall.h>
 #include <asm/timex.h>
 #include <asm/unistd.h>
 #include <linux/compiler.h>
 
-#define vdso_calc_delta __arch_vdso_calc_delta
-static __always_inline u64 __arch_vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 mult)
-{
-	return (cycles - last) * mult;
-}
 
 static __always_inline const struct vdso_data *__arch_get_vdso_data(void)
 {
diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index ce2f69552003..042b95e8164d 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -13,7 +13,11 @@
 static __always_inline
 u64 vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 mult)
 {
+#ifdef VDSO_DELTA_NOMASK
+	return (cycles - last) * mult;
+#else
 	return ((cycles - last) & mask) * mult;
+#endif
 }
 #endif
 
-- 
2.34.1