From fcb41a2030abe0eb716ef0798035ef9562097f42 Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Mon, 22 Apr 2013 09:29:33 +0000 Subject: powerpc: Add VDSO version of time On 04/18/2013 07:38 PM, Anton Blanchard wrote: > Since you are only reading one long you shouldn't need to check the > update count and loop, you will always see a consistent value. The > system call version of time() just does an unprotected load for example. Fixed. > With the above change and with Michael's comments covered (decent > changelog entry and Signed-off-by): > > Acked-by: Anton Blanchard Thanks for the review, below the updated patch: From: Adhemerval Zanella This patch implement the time syscall as vDSO. The performance speedups are: Baseline PPC32: 380 nsec Baseline PPC64: 350 nsec vdso PPC32: 20 nsec vsdo PPC64: 20 nsec Tested on 64 bit build with both 32 bit and 64 bit userland. Acked-by: Anton Blanchard Signed-off-by: Adhemerval Zanella Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/kernel/vdso32/gettimeofday.S | 26 ++++++++++++++++++++++++++ arch/powerpc/kernel/vdso32/vdso32.lds.S | 1 + 2 files changed, 27 insertions(+) (limited to 'arch/powerpc/kernel/vdso32') diff --git a/arch/powerpc/kernel/vdso32/gettimeofday.S b/arch/powerpc/kernel/vdso32/gettimeofday.S index 4ee09ee2e836..27e2f623210b 100644 --- a/arch/powerpc/kernel/vdso32/gettimeofday.S +++ b/arch/powerpc/kernel/vdso32/gettimeofday.S @@ -180,6 +180,32 @@ V_FUNCTION_BEGIN(__kernel_clock_getres) V_FUNCTION_END(__kernel_clock_getres) +/* + * Exact prototype of time() + * + * time_t time(time *t); + * + */ +V_FUNCTION_BEGIN(__kernel_time) + .cfi_startproc + mflr r12 + .cfi_register lr,r12 + + mr r11,r3 /* r11 holds t */ + bl __get_datapage@local + mr r9, r3 /* datapage ptr in r9 */ + + lwz r3,STAMP_XTIME+TSPEC_TV_SEC(r9) + + cmplwi r11,0 /* check if t is NULL */ + beq 2f + stw r3,0(r11) /* store result at *t */ +2: mtlr r12 + crclr cr0*4+so + blr + .cfi_endproc +V_FUNCTION_END(__kernel_time) + /* * This is the core of clock_gettime() and gettimeofday(), * it returns the current time in r3 (seconds) and r4. diff --git a/arch/powerpc/kernel/vdso32/vdso32.lds.S b/arch/powerpc/kernel/vdso32/vdso32.lds.S index 43200ba2e570..f223409629b9 100644 --- a/arch/powerpc/kernel/vdso32/vdso32.lds.S +++ b/arch/powerpc/kernel/vdso32/vdso32.lds.S @@ -150,6 +150,7 @@ VERSION #ifdef CONFIG_PPC64 __kernel_getcpu; #endif + __kernel_time; local: *; }; -- cgit v1.2.1