/* * 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 #include #include #include #include /* 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 */ 2: mftbu r3 mftbl r4 mftbu r0 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