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Subject[RFC PATCH v3 10/12] powerpc/vdso: provide vdso data pointer from the ASM caller.
Date
__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: 1027 nsec/call
clock-getres-realtime-coarse: vdso: 699 nsec/call
clock-gettime-realtime-coarse: vdso: 784 nsec/call
clock-gettime-realtime: vdso: 1231 nsec/call

After:
gettimeofday: vdso: 908 nsec/call
clock-getres-realtime-coarse: vdso: 545 nsec/call
clock-gettime-realtime-coarse: vdso: 617 nsec/call
clock-gettime-realtime: vdso: 1078 nsec/call

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
arch/powerpc/include/asm/vdso/gettimeofday.h | 12 ++----------
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, 30 insertions(+), 26 deletions(-)

diff --git a/arch/powerpc/include/asm/vdso/gettimeofday.h b/arch/powerpc/include/asm/vdso/gettimeofday.h
index 343c81a7e951..d1e702e0ea86 100644
--- a/arch/powerpc/include/asm/vdso/gettimeofday.h
+++ b/arch/powerpc/include/asm/vdso/gettimeofday.h
@@ -6,13 +6,14 @@

#include <asm/time.h>
#include <asm/unistd.h>
-#include <asm/vdso_datapage.h>
#include <uapi/linux/time.h>

#define VDSO_HAS_CLOCK_GETRES 1

#define VDSO_HAS_TIME 1

+#define VDSO_GETS_VD_PTR_FROM_ARCH 1
+
static __always_inline int do_syscall_2(const unsigned long _r0, const unsigned long _r3,
const unsigned long _r4)
{
@@ -80,15 +81,6 @@ 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;
-}
-
/*
* 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..7fdccf896a9c 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(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(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(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(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..4917d7a92a0c 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(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(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(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(vd, time);
}
--
2.13.3
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