1 files changed, 42 insertions, 142 deletions

diff --git a/arch/powerpc/kernel/vdso32/gettimeofday.S b/arch/powerpc/kernel/vdso32/gettimeofday.S
index ee038d4bf25..4ee09ee2e83 100644
--- a/arch/powerpc/kernel/vdso32/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso32/gettimeofday.S
@@ -19,8 +19,10 @@
 /* Offset for the low 32-bit part of a field of long type */
 #ifdef CONFIG_PPC64
 #define LOPART  4
+#define TSPEC_TV_SEC    TSPC64_TV_SEC+LOPART
 #else
 #define LOPART  0
+#define TSPEC_TV_SEC    TSPC32_TV_SEC
 #endif
 
         .text
@@ -41,23 +43,11 @@ V_FUNCTION_BEGIN(__kernel_gettimeofday)
         mr      r9, r3                  /* datapage ptr in r9 */
         cmplwi  r10,0                   /* check if tv is NULL */
         beq     3f
-        bl      __do_get_xsec@local     /* get xsec from tb & kernel */
-        bne-    2f                      /* out of line -> do syscall */
-
-        /* seconds are xsec >> 20 */
-        rlwinm  r5,r4,12,20,31
-        rlwimi  r5,r3,12,0,19
-        stw     r5,TVAL32_TV_SEC(r10)
-
-        /* get remaining xsec and convert to usec. we scale
-         * up remaining xsec by 12 bits and get the top 32 bits
-         * of the multiplication
-         */
-        rlwinm  r5,r4,12,0,19
-        lis     r6,1000000@h
-        ori     r6,r6,1000000@l
-        mulhwu  r5,r5,r6
-        stw     r5,TVAL32_TV_USEC(r10)
+        lis     r7,1000000@ha           /* load up USEC_PER_SEC */
+        addi    r7,r7,1000000@l         /* so we get microseconds in r4 */
+        bl      __do_get_tspec@local    /* get sec/usec from tb & kernel */
+        stw     r3,TVAL32_TV_SEC(r10)
+        stw     r4,TVAL32_TV_USEC(r10)
 
 3:      cmplwi  r11,0                   /* check if tz is NULL */
         beq     1f
@@ -70,14 +60,6 @@ V_FUNCTION_BEGIN(__kernel_gettimeofday)
         crclr   cr0*4+so
         li      r3,0
         blr
-
-2:
-        mtlr    r12
-        mr      r3,r10
-        mr      r4,r11
-        li      r0,__NR_gettimeofday
-        sc
-        blr
   .cfi_endproc
 V_FUNCTION_END(__kernel_gettimeofday)
 
@@ -100,7 +82,8 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime)
         mr      r11,r4                  /* r11 saves tp */
         bl      __get_datapage@local    /* get data page */
         mr      r9,r3                   /* datapage ptr in r9 */
-
+        lis     r7,NSEC_PER_SEC@h       /* want nanoseconds */
+        ori     r7,r7,NSEC_PER_SEC@l
 50:     bl      __do_get_tspec@local    /* get sec/nsec from tb & kernel */
         bne     cr1,80f                 /* not monotonic -> all done */
 
@@ -198,83 +181,12 @@ V_FUNCTION_END(__kernel_clock_getres)
 
 
 /*
- * This is the core of gettimeofday() & friends, it returns the xsec
- * value in r3 & r4 and expects the datapage ptr (non clobbered)
- * in r9. clobbers r0,r4,r5,r6,r7,r8.
- * When returning, r8 contains the counter value that can be reused
- * by the monotonic clock implementation
- */
-__do_get_xsec:
-  .cfi_startproc
-        /* Check for update count & load values. We use the low
-         * order 32 bits of the update count
-         */
-1:      lwz     r8,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
-        andi.   r0,r8,1                 /* pending update ? loop */
-        bne-    1b
-        xor     r0,r8,r8                /* create dependency */
-        add     r9,r9,r0
-
-        /* Load orig stamp (offset to TB) */
-        lwz     r5,CFG_TB_ORIG_STAMP(r9)
-        lwz     r6,(CFG_TB_ORIG_STAMP+4)(r9)
-
-        /* Get a stable TB value */
-2:      mftbu   r3
-        mftbl   r4
-        mftbu   r0
-        cmpl    cr0,r3,r0
-        bne-    2b
-
-        /* Substract tb orig stamp. If the high part is non-zero, we jump to
-         * the slow path which call the syscall.
-         * If it's ok, then we have our 32 bits tb_ticks value in r7
-         */
-        subfc   r7,r6,r4
-        subfe.  r0,r5,r3
-        bne-    3f
-
-        /* Load scale factor & do multiplication */
-        lwz     r5,CFG_TB_TO_XS(r9)     /* load values */
-        lwz     r6,(CFG_TB_TO_XS+4)(r9)
-        mulhwu  r4,r7,r5
-        mulhwu  r6,r7,r6
-        mullw   r0,r7,r5
-        addc    r6,r6,r0
-
-        /* At this point, we have the scaled xsec value in r4 + XER:CA
-         * we load & add the stamp since epoch
-         */
-        lwz     r5,CFG_STAMP_XSEC(r9)
-        lwz     r6,(CFG_STAMP_XSEC+4)(r9)
-        adde    r4,r4,r6
-        addze   r3,r5
-
-        /* We now have our result in r3,r4. We create a fake dependency
-         * on that result and re-check the counter
-         */
-        or      r6,r4,r3
-        xor     r0,r6,r6
-        add     r9,r9,r0
-        lwz     r0,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
-        cmpl    cr0,r8,r0               /* check if updated */
-        bne-    1b
-
-        /* Warning ! The caller expects CR:EQ to be set to indicate a
-         * successful calculation (so it won't fallback to the syscall
-         * method). We have overriden that CR bit in the counter check,
-         * but fortunately, the loop exit condition _is_ CR:EQ set, so
-         * we can exit safely here. If you change this code, be careful
-         * of that side effect.
-         */
-3:      blr
-  .cfi_endproc
-
-/*
- * This is the core of clock_gettime(), it returns the current
- * time in seconds and nanoseconds in r3 and r4.
+ * 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
+ * or NSEC_PER_SEC, giving r4 in microseconds or nanoseconds.
  * It expects the datapage ptr in r9 and doesn't clobber it.
- * It clobbers r0, r5, r6, r10 and returns NSEC_PER_SEC in r7.
+ * It clobbers r0, r5 and r6.
  * On return, r8 contains the counter value that can be reused.
  * This clobbers cr0 but not any other cr field.
  */
@@ -297,70 +209,58 @@ __do_get_tspec:
 2:      mftbu   r3
         mftbl   r4
         mftbu   r0
-        cmpl    cr0,r3,r0
+        cmplw   cr0,r3,r0
         bne-    2b
 
         /* Subtract tb orig stamp and shift left 12 bits.
          */
-        subfc   r7,r6,r4
+        subfc   r4,r6,r4
         subfe   r0,r5,r3
         slwi    r0,r0,12
-        rlwimi. r0,r7,12,20,31
-        slwi    r7,r7,12
+        rlwimi. r0,r4,12,20,31
+        slwi    r4,r4,12
 
-        /* Load scale factor & do multiplication */
+        /*
+         * Load scale factor & do multiplication.
+         * We only use the high 32 bits of the tb_to_xs value.
+         * Even with a 1GHz timebase clock, the high 32 bits of
+         * tb_to_xs will be at least 4 million, so the error from
+         * ignoring the low 32 bits will be no more than 0.25ppm.
+         * The error will just make the clock run very very slightly
+         * slow until the next time the kernel updates the VDSO data,
+         * at which point the clock will catch up to the kernel's value,
+         * so there is no long-term error accumulation.
+         */
         lwz     r5,CFG_TB_TO_XS(r9)     /* load values */
-        lwz     r6,(CFG_TB_TO_XS+4)(r9)
-        mulhwu  r3,r7,r6
-        mullw   r10,r7,r5
-        mulhwu  r4,r7,r5
-        addc    r10,r3,r10
+        mulhwu  r4,r4,r5
         li      r3,0
 
         beq+    4f                      /* skip high part computation if 0 */
         mulhwu  r3,r0,r5
-        mullw   r7,r0,r5
-        mulhwu  r5,r0,r6
-        mullw   r6,r0,r6
-        adde    r4,r4,r7
-        addze   r3,r3
+        mullw   r5,r0,r5
         addc    r4,r4,r5
         addze   r3,r3
-        addc    r10,r10,r6
-
-4:      addze   r4,r4                   /* add in carry */
-        lis     r7,NSEC_PER_SEC@h
-        ori     r7,r7,NSEC_PER_SEC@l
-        mulhwu  r4,r4,r7                /* convert to nanoseconds */
-
-        /* At this point, we have seconds & nanoseconds since the xtime
-         * stamp in r3+CA and r4.  Load & add the xtime stamp.
+4:
+        /* At this point, we have seconds since the xtime stamp
+         * as a 32.32 fixed-point number in r3 and r4.
+         * Load & add the xtime stamp.
          */
-#ifdef CONFIG_PPC64
-        lwz     r5,STAMP_XTIME+TSPC64_TV_SEC+LOPART(r9)
-        lwz     r6,STAMP_XTIME+TSPC64_TV_NSEC+LOPART(r9)
-#else
-        lwz     r5,STAMP_XTIME+TSPC32_TV_SEC(r9)
-        lwz     r6,STAMP_XTIME+TSPC32_TV_NSEC(r9)
-#endif
-        add     r4,r4,r6
+        lwz     r5,STAMP_XTIME+TSPEC_TV_SEC(r9)
+        lwz     r6,STAMP_SEC_FRAC(r9)
+        addc    r4,r4,r6
         adde    r3,r3,r5
 
-        /* We now have our result in r3,r4. We create a fake dependency
-         * on that result and re-check the counter
+        /* We create a fake dependency on the result in r3/r4
+         * and re-check the counter
          */
         or      r6,r4,r3
         xor     r0,r6,r6
         add     r9,r9,r0
         lwz     r0,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
-        cmpl    cr0,r8,r0               /* check if updated */
+        cmplw   cr0,r8,r0               /* check if updated */
         bne-    1b
 
-        /* check for nanosecond overflow and adjust if necessary */
-        cmpw    r4,r7
-        bltlr                           /* all done if no overflow */
-        subf    r4,r7,r4                /* adjust if overflow */
-        addi    r3,r3,1
+        mulhwu  r4,r4,r7                /* convert to micro or nanoseconds */
 
         blr
   .cfi_endproc