1 files changed, 76 insertions, 65 deletions

diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S
index c6401f9e37f1..262cd5857a56 100644
--- a/arch/powerpc/kernel/vdso64/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso64/gettimeofday.S
@@ -75,90 +75,49 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime)
 
         mflr    r12                     /* r12 saves lr */
   .cfi_register lr,r12
-        mr      r10,r3                  /* r10 saves id */
         mr      r11,r4                  /* r11 saves tp */
         bl      V_LOCAL_FUNC(__get_datapage)    /* get data page */
-        beq     cr1,50f                 /* if monotonic -> jump there */
-
-        /*
-         * CLOCK_REALTIME
-         */
-
-        bl      V_LOCAL_FUNC(__do_get_xsec)     /* get xsec from tb & kernel */
-
-        lis     r7,15                   /* r7 = 1000000 = USEC_PER_SEC */
-        ori     r7,r7,16960
-        rldicl  r5,r4,44,20             /* r5 = sec = xsec / XSEC_PER_SEC */
-        rldicr  r6,r5,20,43             /* r6 = sec * XSEC_PER_SEC */
-        std     r5,TSPC64_TV_SEC(r11)   /* store sec in tv */
-        subf    r0,r6,r4                /* r0 = xsec = (xsec - r6) */
-        mulld   r0,r0,r7                /* usec = (xsec * USEC_PER_SEC) /
-                                         * XSEC_PER_SEC
-                                         */
-        rldicl  r0,r0,44,20
-        mulli   r0,r0,1000              /* nsec = usec * 1000 */
-        std     r0,TSPC64_TV_NSEC(r11)  /* store nsec in tp */
-
-        mtlr    r12
-        crclr   cr0*4+so
-        li      r3,0
-        blr
+50:     bl      V_LOCAL_FUNC(__do_get_tspec)    /* get time from tb & kernel */
+        bne     cr1,80f                 /* if not monotonic, all done */
 
         /*
          * CLOCK_MONOTONIC
          */
 
-50:     bl      V_LOCAL_FUNC(__do_get_xsec)     /* get xsec from tb & kernel */
-
-        lis     r7,15                   /* r7 = 1000000 = USEC_PER_SEC */
-        ori     r7,r7,16960
-        rldicl  r5,r4,44,20             /* r5 = sec = xsec / XSEC_PER_SEC */
-        rldicr  r6,r5,20,43             /* r6 = sec * XSEC_PER_SEC */
-        subf    r0,r6,r4                /* r0 = xsec = (xsec - r6) */
-        mulld   r0,r0,r7                /* usec = (xsec * USEC_PER_SEC) /
-                                         * XSEC_PER_SEC
-                                         */
-        rldicl  r6,r0,44,20
-        mulli   r6,r6,1000              /* nsec = usec * 1000 */
-
         /* now we must fixup using wall to monotonic. We need to snapshot
          * that value and do the counter trick again. Fortunately, we still
-         * have the counter value in r8 that was returned by __do_get_xsec.
-         * At this point, r5,r6 contain our sec/nsec values.
-         * can be used
+         * have the counter value in r8 that was returned by __do_get_tspec.
+         * At this point, r4,r5 contain our sec/nsec values.
          */
 
-        lwa     r4,WTOM_CLOCK_SEC(r3)
-        lwa     r7,WTOM_CLOCK_NSEC(r3)
+        lwa     r6,WTOM_CLOCK_SEC(r3)
+        lwa     r9,WTOM_CLOCK_NSEC(r3)
 
-        /* We now have our result in r4,r7. We create a fake dependency
+        /* We now have our result in r6,r9. We create a fake dependency
          * on that result and re-check the counter
          */
-        or      r9,r4,r7
-        xor     r0,r9,r9
+        or      r0,r6,r9
+        xor     r0,r0,r0
         add     r3,r3,r0
         ld      r0,CFG_TB_UPDATE_COUNT(r3)
         cmpld   cr0,r0,r8               /* check if updated */
         bne-    50b
 
-        /* Calculate and store result. Note that this mimmics the C code,
-         * which may cause funny results if nsec goes negative... is that
-         * possible at all ?
+        /* Add wall->monotonic offset and check for overflow or underflow.
          */
-        add     r4,r4,r5
-        add     r7,r7,r6
-        lis     r9,NSEC_PER_SEC@h
-        ori     r9,r9,NSEC_PER_SEC@l
-        cmpl    cr0,r7,r9
-        cmpli   cr1,r7,0
+        add     r4,r4,r6
+        add     r5,r5,r9
+        cmpd    cr0,r5,r7
+        cmpdi   cr1,r5,0
         blt     1f
-        subf    r7,r9,r7
+        subf    r5,r7,r5
         addi    r4,r4,1
-1:      bge     cr1,1f
+1:      bge     cr1,80f
         addi    r4,r4,-1
-        add     r7,r7,r9
-1:      std     r4,TSPC64_TV_SEC(r11)
-        std     r7,TSPC64_TV_NSEC(r11)
+        add     r5,r5,r7
+
+80:     std     r4,TSPC64_TV_SEC(r11)
+        std     r5,TSPC64_TV_NSEC(r11)
 
         mtlr    r12
         crclr   cr0*4+so
@@ -168,10 +127,6 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime)
         /*
          * syscall fallback
          */
-98:
-        mtlr    r12
-        mr      r3,r10
-        mr      r4,r11
 99:
         li      r0,__NR_clock_gettime
         sc
@@ -253,3 +208,59 @@ V_FUNCTION_BEGIN(__do_get_xsec)
         blr
   .cfi_endproc
 V_FUNCTION_END(__do_get_xsec)
+
+/*
+ * This is the core of clock_gettime(), it returns the current
+ * time in seconds and nanoseconds in r4 and r5.
+ * It expects the datapage ptr in r3 and doesn't clobber it.
+ * It clobbers r0 and r6 and returns NSEC_PER_SEC in r7.
+ * On return, r8 contains the counter value that can be reused.
+ * This clobbers cr0 but not any other cr field.
+ */
+V_FUNCTION_BEGIN(__do_get_tspec)
+  .cfi_startproc
+        /* check for update count & load values */
+1:      ld      r8,CFG_TB_UPDATE_COUNT(r3)
+        andi.   r0,r8,1                 /* pending update ? loop */
+        bne-    1b
+        xor     r0,r8,r8                /* create dependency */
+        add     r3,r3,r0
+
+        /* Get TB & offset it. We use the MFTB macro which will generate
+         * workaround code for Cell.
+         */
+        MFTB(r7)
+        ld      r9,CFG_TB_ORIG_STAMP(r3)
+        subf    r7,r9,r7
+
+        /* Scale result */
+        ld      r5,CFG_TB_TO_XS(r3)
+        sldi    r7,r7,12                /* compute time since stamp_xtime */
+        mulhdu  r6,r7,r5                /* in units of 2^-32 seconds */
+
+        /* Add stamp since epoch */
+        ld      r4,STAMP_XTIME+TSPC64_TV_SEC(r3)
+        ld      r5,STAMP_XTIME+TSPC64_TV_NSEC(r3)
+        or      r0,r4,r5
+        or      r0,r0,r6
+        xor     r0,r0,r0
+        add     r3,r3,r0
+        ld      r0,CFG_TB_UPDATE_COUNT(r3)
+        cmpld   r0,r8                   /* check if updated */
+        bne-    1b                      /* reload if so */
+
+        /* convert to seconds & nanoseconds and add to stamp */
+        lis     r7,NSEC_PER_SEC@h
+        ori     r7,r7,NSEC_PER_SEC@l
+        mulhwu  r0,r6,r7                /* compute nanoseconds and */
+        srdi    r6,r6,32                /* seconds since stamp_xtime */
+        clrldi  r0,r0,32
+        add     r5,r5,r0                /* add nanoseconds together */
+        cmpd    r5,r7                   /* overflow? */
+        add     r4,r4,r6
+        bltlr                           /* all done if no overflow */
+        subf    r5,r7,r5                /* if overflow, adjust */
+        addi    r4,r4,1
+        blr
+  .cfi_endproc
+V_FUNCTION_END(__do_get_tspec)