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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@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/c39ef7f3dfa25356b01e211d539671f279086c09.1575273217.git.christophe.leroy@c-s.fr
This commit is contained in:
Christophe Leroy 2019-12-02 07:57:30 +00:00 committed by Michael Ellerman
parent 654abc69ef
commit ec0895f08f
4 changed files with 22 additions and 37 deletions
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10
arch/powerpc/include/asm/vdso_datapage.h
View File

@ -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__ */

9
arch/powerpc/kernel/vdso32/cacheflush.S
View File

@ -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@local
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)

28
arch/powerpc/kernel/vdso32/datapage.S
View File

@ -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@local
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@local
get_datapage r3, r0
lwz r4,(CFG_TB_TICKS_PER_SEC + 4)(r3)
lwz r3,CFG_TB_TICKS_PER_SEC(r3)
mtlr r12

12
arch/powerpc/kernel/vdso32/gettimeofday.S
View File

@ -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@local /* 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 */
@ -80,8 +80,7 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime)
mflr r12 /* r12 saves lr */
.cfi_register lr,r12
mr r11,r4 /* r11 saves tp */
bl __get_datapage@local /* 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
beq cr5, .Lcoarse_clocks
@ -206,7 +205,7 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
mflr r12
.cfi_register lr,r12
bl __get_datapage@local /* get data page */
get_datapage r3, r0
lwz r5, CLOCK_HRTIMER_RES(r3)
mtlr r12
li r3,0
@ -240,8 +239,7 @@ V_FUNCTION_BEGIN(__kernel_time)
.cfi_register lr,r12
mr r11,r3 /* r11 holds t */
bl __get_datapage@local
mr r9, r3 /* datapage ptr in r9 */
get_datapage r9, r0
lwz r3,STAMP_XTIME_SEC+LOPART(r9)