powerpc/vdso32: miscellaneous optimisations

Various optimisations by inverting branches and removing
redundant instructions.
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/b4e79f963845545bcce1459cd6fcfe46bdde7863.1575273217.git.christophe.leroy@c-s.fr

arch/powerpc/kernel/vdso32/datapage.S

@@ -30,11 +30,10 @@ V_FUNCTION_BEGIN(__kernel_get_syscall_map)
   .cfi_startproc
 	mflr	r12
   .cfi_register lr,r12
-	mr	r4,r3
+	mr.	r4,r3
 	get_datapage	r3, r0
 	mtlr	r12
 	addi	r3,r3,CFG_SYSCALL_MAP32
-	cmpli	cr0,r4,0
 	beqlr
 	li	r0,NR_syscalls
 	stw	r0,0(r4)

arch/powerpc/kernel/vdso32/getcpu.S

@@ -25,10 +25,10 @@ V_FUNCTION_BEGIN(__kernel_getcpu)
 	rlwinm  r7,r5,16,31-15,31-0
 	beq	cr0,1f
 	stw	r6,0(r3)
-1:	beq	cr1,2f
-	stw	r7,0(r4)
-2:	crclr	cr0*4+so
+1:	crclr	cr0*4+so
 	li	r3,0			/* always success */
+	beqlr	cr1
+	stw	r7,0(r4)
 	blr
   .cfi_endproc
 V_FUNCTION_END(__kernel_getcpu)

arch/powerpc/kernel/vdso32/gettimeofday.S

@@ -32,10 +32,9 @@ V_FUNCTION_BEGIN(__kernel_gettimeofday)
 	mflr	r12
   .cfi_register lr,r12
 
-	mr	r10,r3			/* r10 saves tv */
+	mr.	r10,r3			/* r10 saves tv */
 	mr	r11,r4			/* r11 saves tz */
 	get_datapage	r9, r0
-	cmplwi	r10,0			/* check if tv is NULL */
 	beq	3f
 	LOAD_REG_IMMEDIATE(r7, 1000000)	/* load up USEC_PER_SEC */
 	bl	__do_get_tspec@local	/* get sec/usec from tb & kernel */
@@ -43,15 +42,16 @@ V_FUNCTION_BEGIN(__kernel_gettimeofday)
 	stw	r4,TVAL32_TV_USEC(r10)
 
 3:	cmplwi	r11,0			/* check if tz is NULL */
-	beq	1f
+	mtlr	r12
+	crclr	cr0*4+so
+	li	r3,0
+	beqlr
+
 	lwz	r4,CFG_TZ_MINUTEWEST(r9)/* fill tz */
 	lwz	r5,CFG_TZ_DSTTIME(r9)
 	stw	r4,TZONE_TZ_MINWEST(r11)
 	stw	r5,TZONE_TZ_DSTTIME(r11)
 
-1:	mtlr	r12
-	crclr	cr0*4+so
-	li	r3,0
 	blr
   .cfi_endproc
 V_FUNCTION_END(__kernel_gettimeofday)
@@ -245,10 +245,10 @@ V_FUNCTION_BEGIN(__kernel_time)
 	lwz	r3,STAMP_XTIME_SEC+LOPART(r9)
 
 	cmplwi	r11,0			/* check if t is NULL */
-	beq	2f
-	stw	r3,0(r11)		/* store result at *t */
-2:	mtlr	r12
+	mtlr	r12
 	crclr	cr0*4+so
+	beqlr
+	stw	r3,0(r11)		/* store result at *t */
 	blr
   .cfi_endproc
 V_FUNCTION_END(__kernel_time)