diff options
Diffstat (limited to 'arch/powerpc/kernel/vdso32')
| -rw-r--r-- | arch/powerpc/kernel/vdso32/gettimeofday.S | 184 |
1 files changed, 42 insertions, 142 deletions
diff --git a/arch/powerpc/kernel/vdso32/gettimeofday.S b/arch/powerpc/kernel/vdso32/gettimeofday.S index ee038d4bf252..4ee09ee2e836 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 |