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Message-Id: <4e44aca7d8c3b5ebb1453d499354ca5233d6defb.1577111367.git.christophe.leroy@c-s.fr>
Date: Mon, 23 Dec 2019 14:31:10 +0000 (UTC)
From: Christophe Leroy <christophe.leroy@....fr>
To: Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
Michael Ellerman <mpe@...erman.id.au>, arnd@...db.de,
tglx@...utronix.de, vincenzo.frascino@....com, luto@...nel.org
Cc: linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
linux-arm-kernel@...ts.infradead.org, linux-mips@...r.kernel.org,
x86@...nel.org
Subject: [RFC PATCH v2 09/10] powerpc/vdso32: inline __get_datapage()
__get_datapage() is only a few instructions to retrieve the
address of the page where the kernel stores data to the VDSO.
By inlining this function into its users, a bl/blr pair and
a mflr/mtlr pair is avoided, plus a few reg moves.
The improvement is noticeable (about 55 nsec/call on an 8xx)
vdsotest before the patch:
gettimeofday: vdso: 731 nsec/call
clock-gettime-realtime-coarse: vdso: 668 nsec/call
clock-gettime-monotonic-coarse: vdso: 745 nsec/call
vdsotest after the patch:
gettimeofday: vdso: 677 nsec/call
clock-gettime-realtime-coarse: vdso: 613 nsec/call
clock-gettime-monotonic-coarse: vdso: 690 nsec/call
Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
---
v3: define get_datapage macro in asm/vdso_datapage.h
v4: fixed build failure with old binutils
---
arch/powerpc/include/asm/vdso_datapage.h | 10 ++++++++++
arch/powerpc/kernel/vdso32/cacheflush.S | 9 ++++-----
arch/powerpc/kernel/vdso32/datapage.S | 28 +++-------------------------
arch/powerpc/kernel/vdso32/gettimeofday.S | 12 +++++-------
4 files changed, 22 insertions(+), 37 deletions(-)
diff --git a/arch/powerpc/include/asm/vdso_datapage.h b/arch/powerpc/include/asm/vdso_datapage.h
index 40f13f3626d3..ee5319a6f4e3 100644
--- a/arch/powerpc/include/asm/vdso_datapage.h
+++ b/arch/powerpc/include/asm/vdso_datapage.h
@@ -118,6 +118,16 @@ struct vdso_data {
extern struct vdso_data *vdso_data;
+#else /* __ASSEMBLY__ */
+
+.macro get_datapage ptr, tmp
+ bcl 20, 31, .+4
+ mflr \ptr
+ addi \ptr, \ptr, (__kernel_datapage_offset - (.-4))@l
+ lwz \tmp, 0(\ptr)
+ add \ptr, \tmp, \ptr
+.endm
+
#endif /* __ASSEMBLY__ */
#endif /* __KERNEL__ */
diff --git a/arch/powerpc/kernel/vdso32/cacheflush.S b/arch/powerpc/kernel/vdso32/cacheflush.S
index 7f882e7b9f43..d178ec8c279d 100644
--- a/arch/powerpc/kernel/vdso32/cacheflush.S
+++ b/arch/powerpc/kernel/vdso32/cacheflush.S
@@ -8,6 +8,7 @@
#include <asm/processor.h>
#include <asm/ppc_asm.h>
#include <asm/vdso.h>
+#include <asm/vdso_datapage.h>
#include <asm/asm-offsets.h>
.text
@@ -24,14 +25,12 @@ V_FUNCTION_BEGIN(__kernel_sync_dicache)
.cfi_startproc
mflr r12
.cfi_register lr,r12
- mr r11,r3
- bl __get_datapage@...al
+ get_datapage r10, r0
mtlr r12
- mr r10,r3
lwz r7,CFG_DCACHE_BLOCKSZ(r10)
addi r5,r7,-1
- andc r6,r11,r5 /* round low to line bdy */
+ andc r6,r3,r5 /* round low to line bdy */
subf r8,r6,r4 /* compute length */
add r8,r8,r5 /* ensure we get enough */
lwz r9,CFG_DCACHE_LOGBLOCKSZ(r10)
@@ -48,7 +47,7 @@ V_FUNCTION_BEGIN(__kernel_sync_dicache)
lwz r7,CFG_ICACHE_BLOCKSZ(r10)
addi r5,r7,-1
- andc r6,r11,r5 /* round low to line bdy */
+ andc r6,r3,r5 /* round low to line bdy */
subf r8,r6,r4 /* compute length */
add r8,r8,r5
lwz r9,CFG_ICACHE_LOGBLOCKSZ(r10)
diff --git a/arch/powerpc/kernel/vdso32/datapage.S b/arch/powerpc/kernel/vdso32/datapage.S
index 6c7401bd284e..1095d818f94a 100644
--- a/arch/powerpc/kernel/vdso32/datapage.S
+++ b/arch/powerpc/kernel/vdso32/datapage.S
@@ -10,35 +10,13 @@
#include <asm/asm-offsets.h>
#include <asm/unistd.h>
#include <asm/vdso.h>
+#include <asm/vdso_datapage.h>
.text
.global __kernel_datapage_offset;
__kernel_datapage_offset:
.long 0
-V_FUNCTION_BEGIN(__get_datapage)
- .cfi_startproc
- /* We don't want that exposed or overridable as we want other objects
- * to be able to bl directly to here
- */
- .protected __get_datapage
- .hidden __get_datapage
-
- mflr r0
- .cfi_register lr,r0
-
- bcl 20,31,data_page_branch
-data_page_branch:
- mflr r3
- mtlr r0
- addi r3, r3, __kernel_datapage_offset-data_page_branch
- lwz r0,0(r3)
- .cfi_restore lr
- add r3,r0,r3
- blr
- .cfi_endproc
-V_FUNCTION_END(__get_datapage)
-
/*
* void *__kernel_get_syscall_map(unsigned int *syscall_count) ;
*
@@ -53,7 +31,7 @@ V_FUNCTION_BEGIN(__kernel_get_syscall_map)
mflr r12
.cfi_register lr,r12
mr r4,r3
- bl __get_datapage@...al
+ get_datapage r3, r0
mtlr r12
addi r3,r3,CFG_SYSCALL_MAP32
cmpli cr0,r4,0
@@ -75,7 +53,7 @@ V_FUNCTION_BEGIN(__kernel_get_tbfreq)
.cfi_startproc
mflr r12
.cfi_register lr,r12
- bl __get_datapage@...al
+ get_datapage r3, r0
lwz r4,(CFG_TB_TICKS_PER_SEC + 4)(r3)
lwz r3,CFG_TB_TICKS_PER_SEC(r3)
mtlr r12
diff --git a/arch/powerpc/kernel/vdso32/gettimeofday.S b/arch/powerpc/kernel/vdso32/gettimeofday.S
index 3306672f57a9..d6c1d331e8cb 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>
@@ -33,8 +34,7 @@ V_FUNCTION_BEGIN(__kernel_gettimeofday)
mr r10,r3 /* r10 saves tv */
mr r11,r4 /* r11 saves tz */
- bl __get_datapage@...al /* get data page */
- mr r9, r3 /* datapage ptr in r9 */
+ get_datapage r9, r0
cmplwi r10,0 /* check if tv is NULL */
beq 3f
lis r7,1000000@ha /* load up USEC_PER_SEC */
@@ -74,8 +74,7 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime)
mflr r12 /* r12 saves lr */
.cfi_register lr,r12
mr r11,r4 /* r11 saves tp */
- bl __get_datapage@...al /* get data page */
- mr r9,r3 /* datapage ptr in r9 */
+ get_datapage r9, r0
lis r7,NSEC_PER_SEC@h /* want nanoseconds */
ori r7,r7,NSEC_PER_SEC@l
50: bl __do_get_tspec@...al /* get sec/nsec from tb & kernel */
@@ -156,7 +155,7 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
mflr r12
.cfi_register lr,r12
- bl __get_datapage@...al /* get data page */
+ get_datapage r3, r0
lwz r5, CLOCK_HRTIMER_RES(r3)
mtlr r12
li r3,0
@@ -190,8 +189,7 @@ V_FUNCTION_BEGIN(__kernel_time)
.cfi_register lr,r12
mr r11,r3 /* r11 holds t */
- bl __get_datapage@...al
- mr r9, r3 /* datapage ptr in r9 */
+ get_datapage r9, r0
lwz r3,STAMP_XTIME_SEC+LOPART(r9)
--
2.13.3
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