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authorAdhemerval Zanella <azanella@linux.vnet.ibm.com>2013-04-22 09:29:33 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2013-04-23 16:05:05 +1000
commitfcb41a2030abe0eb716ef0798035ef9562097f42 (patch)
tree4b063cc1cb872fb9609fd90485c7b602b9fdc57f /arch/powerpc/kernel/vdso32
parentaf81d7878c641629f2693ae3fdaf74b4af14dfca (diff)
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 <anton@samba.org> Thanks for the review, below the updated patch: From: Adhemerval Zanella <azanella@linux.vnet.ibm.com> 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 <anton@samba.org> Signed-off-by: Adhemerval Zanella <azanella@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/kernel/vdso32')
-rw-r--r--arch/powerpc/kernel/vdso32/gettimeofday.S26
-rw-r--r--arch/powerpc/kernel/vdso32/vdso32.lds.S1
2 files changed, 27 insertions, 0 deletions
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
@@ -181,6 +181,32 @@ 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.
* On entry, r7 gives the resolution of r4, either USEC_PER_SEC
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: *;
};