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-rw-r--r--arch/powerpc/kernel/vdso32/gettimeofday.S298
1 files changed, 298 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/vdso32/gettimeofday.S b/arch/powerpc/kernel/vdso32/gettimeofday.S
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+++ b/arch/powerpc/kernel/vdso32/gettimeofday.S
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+/*
+ * 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 <asm/processor.h>
+#include <asm/ppc_asm.h>
+#include <asm/vdso.h>
+#include <asm/asm-offsets.h>
+#include <asm/unistd.h>
+
+/* 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
+/*
+ * 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 */
+ cmplwi r10,0 /* check if tv is NULL */
+ beq 3f
+ 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
+ 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)
+
+/*
+ * Exact prototype of clock_gettime()
+ *
+ * int __kernel_clock_gettime(clockid_t clock_id, struct timespec *tp);
+ *
+ */
+V_FUNCTION_BEGIN(__kernel_clock_gettime)
+ .cfi_startproc
+ /* Check for supported clock IDs */
+ cmpli cr0,r3,CLOCK_REALTIME
+ cmpli cr1,r3,CLOCK_MONOTONIC
+ cror cr0*4+eq,cr0*4+eq,cr1*4+eq
+ bne cr0,99f
+
+ mflr r12 /* r12 saves lr */
+ .cfi_register lr,r12
+ 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 */
+
+ /*
+ * CLOCK_MONOTONIC
+ */
+
+ /* 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, r3,r4 contain our sec/nsec values, r5 and r6
+ * can be used, r7 contains NSEC_PER_SEC.
+ */
+
+ lwz r5,WTOM_CLOCK_SEC(r9)
+ lwz r6,WTOM_CLOCK_NSEC(r9)
+
+ /* We now have our offset in r5,r6. We create a fake dependency
+ * on that value and re-check the counter
+ */
+ or r0,r6,r5
+ xor r0,r0,r0
+ add r9,r9,r0
+ lwz r0,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
+ cmpl cr0,r8,r0 /* check if updated */
+ bne- 50b
+
+ /* Calculate and store result. Note that this mimics the C code,
+ * which may cause funny results if nsec goes negative... is that
+ * possible at all ?
+ */
+ add r3,r3,r5
+ add r4,r4,r6
+ cmpw cr0,r4,r7
+ cmpwi cr1,r4,0
+ blt 1f
+ subf r4,r7,r4
+ addi r3,r3,1
+1: bge cr1,80f
+ addi r3,r3,-1
+ add r4,r4,r7
+
+80: stw r3,TSPC32_TV_SEC(r11)
+ stw r4,TSPC32_TV_NSEC(r11)
+
+ mtlr r12
+ crclr cr0*4+so
+ li r3,0
+ blr
+
+ /*
+ * syscall fallback
+ */
+99:
+ li r0,__NR_clock_gettime
+ sc
+ blr
+ .cfi_endproc
+V_FUNCTION_END(__kernel_clock_gettime)
+
+
+/*
+ * Exact prototype of clock_getres()
+ *
+ * int __kernel_clock_getres(clockid_t clock_id, struct timespec *res);
+ *
+ */
+V_FUNCTION_BEGIN(__kernel_clock_getres)
+ .cfi_startproc
+ /* Check for supported clock IDs */
+ cmpwi cr0,r3,CLOCK_REALTIME
+ cmpwi cr1,r3,CLOCK_MONOTONIC
+ cror cr0*4+eq,cr0*4+eq,cr1*4+eq
+ bne cr0,99f
+
+ li r3,0
+ cmpli cr0,r4,0
+ crclr cr0*4+so
+ beqlr
+ lis r5,CLOCK_REALTIME_RES@h
+ ori r5,r5,CLOCK_REALTIME_RES@l
+ stw r3,TSPC32_TV_SEC(r4)
+ stw r5,TSPC32_TV_NSEC(r4)
+ blr
+
+ /*
+ * syscall fallback
+ */
+99:
+ li r0,__NR_clock_getres
+ sc
+ blr
+ .cfi_endproc
+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
+ * 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 and r6.
+ * On return, r8 contains the counter value that can be reused.
+ * This clobbers cr0 but not any other cr field.
+ */
+__do_get_tspec:
+ .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 */
+#ifdef CONFIG_8xx
+2: mftbu r3
+ mftbl r4
+ mftbu r0
+#else
+2: mfspr r3, SPRN_TBRU
+ mfspr r4, SPRN_TBRL
+ mfspr r0, SPRN_TBRU
+#endif
+ cmplw cr0,r3,r0
+ bne- 2b
+
+ /* Subtract tb orig stamp and shift left 12 bits.
+ */
+ subfc r4,r6,r4
+ subfe r0,r5,r3
+ slwi r0,r0,12
+ rlwimi. r0,r4,12,20,31
+ slwi r4,r4,12
+
+ /*
+ * 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 */
+ mulhwu r4,r4,r5
+ li r3,0
+
+ beq+ 4f /* skip high part computation if 0 */
+ mulhwu r3,r0,r5
+ mullw r5,r0,r5
+ addc r4,r4,r5
+ addze r3,r3
+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.
+ */
+ lwz r5,STAMP_XTIME+TSPEC_TV_SEC(r9)
+ lwz r6,STAMP_SEC_FRAC(r9)
+ addc r4,r4,r6
+ adde r3,r3,r5
+
+ /* 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)
+ cmplw cr0,r8,r0 /* check if updated */
+ bne- 1b
+
+ mulhwu r4,r4,r7 /* convert to micro or nanoseconds */
+
+ blr
+ .cfi_endproc