1 files changed, 139 insertions, 0 deletions

diff --git a/arch/ppc64/kernel/vdso32/gettimeofday.S b/arch/ppc64/kernel/vdso32/gettimeofday.S
new file mode 100644
index 000000000000..ca7f415195c4
--- /dev/null
+++ b/arch/ppc64/kernel/vdso32/gettimeofday.S
@@ -0,0 +1,139 @@
+/*
+ * Userland implementation of gettimeofday() for 32 bits processes in a
+ * ppc64 kernel for use in the vDSO
+ *
+ * Copyright (C) 2004 Benjamin Herrenschmuidt (benh@kernel.crashing.org), IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+#include <linux/config.h>
+#include <asm/processor.h>
+#include <asm/ppc_asm.h>
+#include <asm/vdso.h>
+#include <asm/offsets.h>
+#include <asm/unistd.h>
+
+        .text
+/*
+ * Exact prototype of gettimeofday
+ *
+ * int __kernel_gettimeofday(struct timeval *tv, struct timezone *tz);
+ *
+ */
+V_FUNCTION_BEGIN(__kernel_gettimeofday)
+  .cfi_startproc
+        mflr    r12
+  .cfi_register lr,r12
+
+        mr      r10,r3                  /* r10 saves tv */
+        mr      r11,r4                  /* r11 saves tz */
+        bl      __get_datapage@local    /* get data page */
+        mr      r9, r3                  /* datapage ptr in r9 */
+        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)
+
+        cmpli   cr0,r11,0               /* check if tz is NULL */
+        beq     1f
+        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
+        blr
+
+2:      mr      r3,r10
+        mr      r4,r11
+        li      r0,__NR_gettimeofday
+        sc
+        b       1b
+  .cfi_endproc
+V_FUNCTION_END(__kernel_gettimeofday)
+
+/*
+ * This is the core of gettimeofday(), it returns the xsec
+ * value in r3 & r4 and expects the datapage ptr (non clobbered)
+ * in r9. clobbers r0,r4,r5,r6,r7,r8
+*/
+__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+4)(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   r6,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
+         */
+        xor     r0,r4,r4
+        add     r9,r9,r0
+        lwz     r0,(CFG_TB_UPDATE_COUNT+4)(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