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From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	 nathanl@linux.ibm.com, arnd@arndb.de, tglx@linutronix.de,
	vincenzo.frascino@arm.com, luto@kernel.org
Cc: x86@kernel.org, linuxppc-dev@lists.ozlabs.org,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org
Subject: [RFC PATCH v4 07/11] powerpc/vdso: provide vdso data pointer from the ASM caller.
Date: Thu, 16 Jan 2020 17:58:31 +0000 (UTC)
Message-ID: <027645df415c27a91921247df46976beed6f2133.1579196675.git.christophe.leroy@c-s.fr> (raw)
In-Reply-To: <cover.1579196675.git.christophe.leroy@c-s.fr>

__arch_get_vdso_data() clobbers the link register, requiring
the caller to save it.

As the ASM calling function already has to set a stack frame and
saves the link register before calling the C vdso function,
retriving the vdso data pointer there is lighter.

The improvement is significant:

Before:
gettimeofday:    vdso: 1212 nsec/call
clock-getres-realtime-coarse:    vdso: 714 nsec/call
clock-gettime-realtime-coarse:    vdso: 784 nsec/call
clock-getres-realtime:    vdso: 714 nsec/call

After:
gettimeofday:    vdso: 1094 nsec/call
getcpu:    vdso: not tested
clock-getres-realtime-coarse:    vdso: 545 nsec/call
clock-gettime-realtime-coarse:    vdso: 584 nsec/call
clock-getres-realtime:    vdso: 545 nsec/call

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/include/asm/vdso/gettimeofday.h | 10 +---------
 arch/powerpc/kernel/vdso32/gettimeofday.S    |  3 +++
 arch/powerpc/kernel/vdso32/vgettimeofday.c   | 19 +++++++++++--------
 arch/powerpc/kernel/vdso64/gettimeofday.S    |  3 +++
 arch/powerpc/kernel/vdso64/vgettimeofday.c   | 19 +++++++++++--------
 5 files changed, 29 insertions(+), 25 deletions(-)

diff --git a/arch/powerpc/include/asm/vdso/gettimeofday.h b/arch/powerpc/include/asm/vdso/gettimeofday.h
index c2cafd85d3cb..0a247f9b9af9 100644
--- a/arch/powerpc/include/asm/vdso/gettimeofday.h
+++ b/arch/powerpc/include/asm/vdso/gettimeofday.h
@@ -6,7 +6,6 @@
 
 #include <asm/time.h>
 #include <asm/unistd.h>
-#include <asm/vdso_datapage.h>
 #include <uapi/linux/time.h>
 
 #define VDSO_HAS_CLOCK_GETRES		1
@@ -73,14 +72,7 @@ static __always_inline u64 __arch_get_hw_counter(s32 clock_mode)
 	return get_tb();
 }
 
-void *__get_datapage(void);
-
-static __always_inline const struct vdso_data *__arch_get_vdso_data(void)
-{
-	struct vdso_arch_data *vdso_data = __get_datapage();
-
-	return vdso_data->data;
-}
+const struct vdso_data *__arch_get_vdso_data(void);
 
 /*
  * powerpc specific delta calculation.
diff --git a/arch/powerpc/kernel/vdso32/gettimeofday.S b/arch/powerpc/kernel/vdso32/gettimeofday.S
index ba0bd64b3da3..0d43878e462c 100644
--- a/arch/powerpc/kernel/vdso32/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso32/gettimeofday.S
@@ -9,6 +9,7 @@
 #include <asm/processor.h>
 #include <asm/ppc_asm.h>
 #include <asm/vdso.h>
+#include <asm/vdso_datapage.h>
 #include <asm/asm-offsets.h>
 #include <asm/unistd.h>
 
@@ -18,6 +19,7 @@
 	stwu	r1, -16(r1)
 	mflr	r0
 	stw	r0, 20(r1)
+	get_datapage	r5, VDSO_DATA_OFFSET
 	bl	\funct
 	lwz	r0, 20(r1)
 	cmpwi	r3, 0
@@ -79,6 +81,7 @@ V_FUNCTION_BEGIN(__kernel_time)
 	stwu	r1, -16(r1)
 	mflr	r0
 	stw	r0, 20(r1)
+	get_datapage	r4, VDSO_DATA_OFFSET
 	bl	__c_kernel_time
 	lwz	r0, 20(r1)
 	crclr	cr0*4+so
diff --git a/arch/powerpc/kernel/vdso32/vgettimeofday.c b/arch/powerpc/kernel/vdso32/vgettimeofday.c
index 4ed1bf2ae30e..9bdc3c435846 100644
--- a/arch/powerpc/kernel/vdso32/vgettimeofday.c
+++ b/arch/powerpc/kernel/vdso32/vgettimeofday.c
@@ -5,22 +5,25 @@
 #include <linux/time.h>
 #include <linux/types.h>
 
-int __c_kernel_clock_gettime(clockid_t clock, struct old_timespec32 *ts)
+int __c_kernel_clock_gettime(clockid_t clock, struct old_timespec32 *ts,
+			     const struct vdso_data *vd)
 {
-	return __cvdso_clock_gettime32(clock, ts);
+	return __cvdso_clock_gettime32_data(vd, clock, ts);
 }
 
-int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
+int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz,
+			    const struct vdso_data *vd)
 {
-	return __cvdso_gettimeofday(tv, tz);
+	return __cvdso_gettimeofday_data(vd, tv, tz);
 }
 
-int __c_kernel_clock_getres(clockid_t clock_id, struct old_timespec32 *res)
+int __c_kernel_clock_getres(clockid_t clock_id, struct old_timespec32 *res,
+			    const struct vdso_data *vd)
 {
-	return __cvdso_clock_getres_time32(clock_id, res);
+	return __cvdso_clock_getres_time32_data(vd, clock_id, res);
 }
 
-time_t __c_kernel_time(time_t *time)
+time_t __c_kernel_time(time_t *time, const struct vdso_data *vd)
 {
-	return __cvdso_time(time);
+	return __cvdso_time_data(vd, time);
 }
diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S
index 22f4f1f73bbc..f61c53eb6600 100644
--- a/arch/powerpc/kernel/vdso64/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso64/gettimeofday.S
@@ -9,6 +9,7 @@
 #include <asm/processor.h>
 #include <asm/ppc_asm.h>
 #include <asm/vdso.h>
+#include <asm/vdso_datapage.h>
 #include <asm/asm-offsets.h>
 #include <asm/unistd.h>
 
@@ -18,6 +19,7 @@
 	mflr	r0
 	std	r0, 16(r1)
 	stdu	r1, -128(r1)
+	get_datapage	r5, VDSO_DATA_OFFSET
 	bl	\funct
 	addi	r1, r1, 128
 	ld	r0, 16(r1)
@@ -79,6 +81,7 @@ V_FUNCTION_BEGIN(__kernel_time)
 	mflr	r0
 	std	r0, 16(r1)
 	stdu	r1, -128(r1)
+	get_datapage	r4, VDSO_DATA_OFFSET
 	bl	__c_kernel_time
 	addi	r1, r1, 128
 	ld	r0, 16(r1)
diff --git a/arch/powerpc/kernel/vdso64/vgettimeofday.c b/arch/powerpc/kernel/vdso64/vgettimeofday.c
index 407c6a7ed4e2..cd80867c501c 100644
--- a/arch/powerpc/kernel/vdso64/vgettimeofday.c
+++ b/arch/powerpc/kernel/vdso64/vgettimeofday.c
@@ -5,22 +5,25 @@
 #include <linux/time.h>
 #include <linux/types.h>
 
-int __c_kernel_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
+int __c_kernel_clock_gettime(clockid_t clock, struct __kernel_timespec *ts,
+			     const struct vdso_data *vd)
 {
-	return __cvdso_clock_gettime(clock, ts);
+	return __cvdso_clock_gettime_data(vd, clock, ts);
 }
 
-int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
+int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz,
+			    const struct vdso_data *vd)
 {
-	return __cvdso_gettimeofday(tv, tz);
+	return __cvdso_gettimeofday_data(vd, tv, tz);
 }
 
-int __c_kernel_clock_getres(clockid_t clock_id, struct __kernel_timespec *res)
+int __c_kernel_clock_getres(clockid_t clock_id, struct __kernel_timespec *res,
+			    const struct vdso_data *vd)
 {
-	return __cvdso_clock_getres(clock_id, res);
+	return __cvdso_clock_getres_data(vd, clock_id, res);
 }
 
-time_t __c_kernel_time(time_t *time)
+time_t __c_kernel_time(time_t *time, const struct vdso_data *vd)
 {
-	return __cvdso_time(time);
+	return __cvdso_time_data(vd, time);
 }
-- 
2.13.3


  parent reply index

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-16 17:58 [RFC PATCH v4 00/11] powerpc: switch VDSO to C implementation Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 01/11] powerpc/64: Don't provide time functions in compat VDSO32 Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 02/11] powerpc/vdso: Switch VDSO to generic C implementation Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 03/11] lib: vdso: only read hrtimer_res when needed in __cvdso_clock_getres() Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 04/11] powerpc/vdso: simplify __get_datapage() Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 05/11] lib: vdso: allow arches to provide vdso data pointer Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 06/11] powerpc/vdso: provide inline alternative to __get_datapage() Christophe Leroy
2020-01-16 17:58 ` Christophe Leroy [this message]
2020-01-16 17:58 ` [RFC PATCH v4 08/11] lib: vdso: allow fixed clock mode Christophe Leroy
2020-01-16 20:13   ` Thomas Gleixner
2020-01-16 20:19     ` Andy Lutomirski
2020-01-16 21:07       ` Thomas Gleixner
2020-01-16 17:58 ` [RFC PATCH v4 09/11] powerpc/vdso: override __arch_vdso_capable() Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 10/11] lib: vdso: Allow arches to override the ns shift operation Christophe Leroy
2020-01-16 19:47   ` Andy Lutomirski
2020-01-16 19:57     ` Thomas Gleixner
2020-01-16 20:20       ` Andy Lutomirski
2020-01-16 17:58 ` [RFC PATCH v4 11/11] powerpc/32: provide vdso_shift_ns() Christophe Leroy
2020-01-17  8:58 ` [RFC PATCH v4 00/11] powerpc: switch VDSO to C implementation Segher Boessenkool
2020-01-17  9:26   ` Christophe Leroy

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