Commit ec0895f0 authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

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: default avatarChristophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/c39ef7f3dfa25356b01e211d539671f279086c09.1575273217.git.christophe.leroy@c-s.fr
parent 654abc69

arch/powerpc/include/asm/vdso_datapage.h

+10 −0
Original line number Diff line number Diff line
@@ -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__ */

arch/powerpc/kernel/vdso32/cacheflush.S

+4 −5
Original line number Diff line number Diff line
@@ -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)

arch/powerpc/kernel/vdso32/datapage.S

+3 −25
Original line number Diff line number Diff line
@@ -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

arch/powerpc/kernel/vdso32/gettimeofday.S

+5 −7
Original line number Diff line number Diff line
@@ -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)

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