diff options
Diffstat (limited to 'arch/powerpc/kernel/vdso32/gettimeofday.S')
| -rw-r--r-- | arch/powerpc/kernel/vdso32/gettimeofday.S | 272 |
1 files changed, 124 insertions, 148 deletions
diff --git a/arch/powerpc/kernel/vdso32/gettimeofday.S b/arch/powerpc/kernel/vdso32/gettimeofday.S index 05909f75430..6b2b69616e7 100644 --- a/arch/powerpc/kernel/vdso32/gettimeofday.S +++ b/arch/powerpc/kernel/vdso32/gettimeofday.S @@ -16,6 +16,15 @@ #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 @@ -32,25 +41,15 @@ V_FUNCTION_BEGIN(__kernel_gettimeofday) 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 */ + 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) @@ -61,14 +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) @@ -88,101 +79,54 @@ 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 __get_datapage@local /* get data page */ mr r9,r3 /* datapage ptr in r9 */ - beq cr1,50f /* if monotonic -> jump there */ - - /* - * CLOCK_REALTIME - */ - - bl __do_get_xsec@local /* get xsec from tb & kernel */ - bne- 98f /* out of line -> do syscall */ - - /* seconds are xsec >> 20 */ - rlwinm r5,r4,12,20,31 - rlwimi r5,r3,12,0,19 - stw r5,TSPC32_TV_SEC(r11) - - /* get remaining xsec and convert to nsec. we scale - * up remaining xsec by 12 bits and get the top 32 bits - * of the multiplication, then we multiply by 1000 - */ - rlwinm r5,r4,12,0,19 - lis r6,1000000@h - ori r6,r6,1000000@l - mulhwu r5,r5,r6 - mulli r5,r5,1000 - stw r5,TSPC32_TV_NSEC(r11) - mtlr r12 - crclr cr0*4+so - li r3,0 - blr + 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 */ -50: bl __do_get_xsec@local /* get xsec from tb & kernel */ - bne- 98f /* out of line -> do syscall */ - - /* seconds are xsec >> 20 */ - rlwinm r6,r4,12,20,31 - rlwimi r6,r3,12,0,19 - - /* get remaining xsec and convert to nsec. we scale - * up remaining xsec by 12 bits and get the top 32 bits - * of the multiplication, then we multiply by 1000 - */ - rlwinm r7,r4,12,0,19 - lis r5,1000000@h - ori r5,r5,1000000@l - mulhwu r7,r7,r5 - mulli r7,r7,1000 - /* 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, r6,r7 contain our sec/nsec values, r3,r4 and r5 - * can be used + * At this point, r3,r4 contain our sec/nsec values, r5 and r6 + * can be used, r7 contains NSEC_PER_SEC. */ - lwz r3,WTOM_CLOCK_SEC(r9) - lwz r4,WTOM_CLOCK_NSEC(r9) + lwz r5,WTOM_CLOCK_SEC(r9) + lwz r6,WTOM_CLOCK_NSEC(r9) - /* We now have our result in r3,r4. We create a fake dependency - * on that result and re-check the counter + /* We now have our offset in r5,r6. We create a fake dependency + * on that value and re-check the counter */ - or r5,r4,r3 - xor r0,r5,r5 + or r0,r6,r5 + xor r0,r0,r0 add r9,r9,r0 -#ifdef CONFIG_PPC64 - lwz r0,(CFG_TB_UPDATE_COUNT+4)(r9) -#else - lwz r0,(CFG_TB_UPDATE_COUNT)(r9) -#endif + lwz r0,(CFG_TB_UPDATE_COUNT+LOPART)(r9) cmpl cr0,r8,r0 /* check if updated */ bne- 50b - /* Calculate and store result. Note that this mimmics the C code, + /* 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,r6 - add r4,r4,r7 - lis r5,NSEC_PER_SEC@h - ori r5,r5,NSEC_PER_SEC@l - cmpl cr0,r4,r5 - cmpli cr1,r4,0 + add r3,r3,r5 + add r4,r4,r6 + cmpw cr0,r4,r7 + cmpwi cr1,r4,0 blt 1f - subf r4,r5,r4 + subf r4,r7,r4 addi r3,r3,1 -1: bge cr1,1f +1: bge cr1,80f addi r3,r3,-1 - add r4,r4,r5 -1: stw r3,TSPC32_TV_SEC(r11) + add r4,r4,r7 + +80: stw r3,TSPC32_TV_SEC(r11) stw r4,TSPC32_TV_NSEC(r11) mtlr r12 @@ -193,10 +137,6 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) /* * syscall fallback */ -98: - mtlr r12 - mr r3,r10 - mr r4,r11 99: li r0,__NR_clock_gettime sc @@ -241,22 +181,47 @@ 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 + * 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_xsec: +__do_get_tspec: .cfi_startproc /* Check for update count & load values. We use the low * order 32 bits of the update count */ -#ifdef CONFIG_PPC64 -1: lwz r8,(CFG_TB_UPDATE_COUNT+4)(r9) -#else -1: lwz r8,(CFG_TB_UPDATE_COUNT)(r9) -#endif +1: lwz r8,(CFG_TB_UPDATE_COUNT+LOPART)(r9) andi. r0,r8,1 /* pending update ? loop */ bne- 1b xor r0,r8,r8 /* create dependency */ @@ -267,56 +232,67 @@ __do_get_xsec: lwz r6,(CFG_TB_ORIG_STAMP+4)(r9) /* Get a stable TB value */ +#ifdef CONFIG_8xx 2: mftbu r3 mftbl r4 mftbu r0 - cmpl cr0,r3,r0 +#else +2: mfspr r3, SPRN_TBRU + mfspr r4, SPRN_TBRL + mfspr r0, SPRN_TBRU +#endif + cmplw 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 + /* Subtract tb orig stamp and shift left 12 bits. */ - subfc r7,r6,r4 - subfe. r0,r5,r3 - bne- 3f + 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 */ + /* + * 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 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 + 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,CFG_STAMP_XSEC(r9) - lwz r6,(CFG_STAMP_XSEC+4)(r9) - adde r4,r4,r6 - addze r3,r5 + 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 -#ifdef CONFIG_PPC64 - lwz r0,(CFG_TB_UPDATE_COUNT+4)(r9) -#else - lwz r0,(CFG_TB_UPDATE_COUNT)(r9) -#endif - cmpl cr0,r8,r0 /* check if updated */ + lwz r0,(CFG_TB_UPDATE_COUNT+LOPART)(r9) + cmplw 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 + mulhwu r4,r4,r7 /* convert to micro or nanoseconds */ + + blr .cfi_endproc |