diff options
Diffstat (limited to 'arch/powerpc/kernel/vdso32/gettimeofday.S')
| -rw-r--r-- | arch/powerpc/kernel/vdso32/gettimeofday.S | 339 |
1 files changed, 339 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/vdso32/gettimeofday.S b/arch/powerpc/kernel/vdso32/gettimeofday.S new file mode 100644 index 000000000..e7f8f9f1b --- /dev/null +++ b/arch/powerpc/kernel/vdso32/gettimeofday.S @@ -0,0 +1,339 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * 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. + */ +#include <asm/processor.h> +#include <asm/ppc_asm.h> +#include <asm/vdso.h> +#include <asm/vdso_datapage.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 +#else +#define LOPART 0 +#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 */ + get_datapage r9, r0 + beq 3f + LOAD_REG_IMMEDIATE(r7, 1000000) /* load up USEC_PER_SEC */ + 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 */ + mtlr r12 + crclr cr0*4+so + li r3,0 + beqlr + + 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) + + 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 + + cmpli cr5,r3,CLOCK_REALTIME_COARSE + cmpli cr6,r3,CLOCK_MONOTONIC_COARSE + cror cr5*4+eq,cr5*4+eq,cr6*4+eq + + cror cr0*4+eq,cr0*4+eq,cr5*4+eq + bne cr0, .Lgettime_fallback + + mflr r12 /* r12 saves lr */ + .cfi_register lr,r12 + mr r11,r4 /* r11 saves tp */ + get_datapage r9, r0 + LOAD_REG_IMMEDIATE(r7, NSEC_PER_SEC) /* load up NSEC_PER_SEC */ + beq cr5, .Lcoarse_clocks +.Lprecise_clocks: + bl __do_get_tspec@local /* get sec/nsec from tb & kernel */ + bne cr1, .Lfinish /* 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+LOPART)(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- .Lprecise_clocks + b .Lfinish_monotonic + + /* + * For coarse clocks we get data directly from the vdso data page, so + * we don't need to call __do_get_tspec, but we still need to do the + * counter trick. + */ +.Lcoarse_clocks: + lwz r8,(CFG_TB_UPDATE_COUNT+LOPART)(r9) + andi. r0,r8,1 /* pending update ? loop */ + bne- .Lcoarse_clocks + add r9,r9,r0 /* r0 is already 0 */ + + /* + * CLOCK_REALTIME_COARSE, below values are needed for MONOTONIC_COARSE + * too + */ + lwz r3,STAMP_XTIME_SEC+LOPART(r9) + lwz r4,STAMP_XTIME_NSEC+LOPART(r9) + bne cr6,1f + + /* CLOCK_MONOTONIC_COARSE */ + lwz r5,(WTOM_CLOCK_SEC+LOPART)(r9) + lwz r6,WTOM_CLOCK_NSEC(r9) + + /* check if counter has updated */ + or r0,r6,r5 +1: or r0,r0,r3 + or r0,r0,r4 + xor r0,r0,r0 + add r3,r3,r0 + lwz r0,CFG_TB_UPDATE_COUNT+LOPART(r9) + cmpl cr0,r0,r8 /* check if updated */ + bne- .Lcoarse_clocks + + /* Counter has not updated, so continue calculating proper values for + * sec and nsec if monotonic coarse, or just return with the proper + * values for realtime. + */ + bne cr6, .Lfinish + + /* 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 ? + */ +.Lfinish_monotonic: + 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, .Lfinish + addi r3,r3,-1 + add r4,r4,r7 + +.Lfinish: + stw r3,TSPC32_TV_SEC(r11) + stw r4,TSPC32_TV_NSEC(r11) + + mtlr r12 + crclr cr0*4+so + li r3,0 + blr + + /* + * syscall fallback + */ +.Lgettime_fallback: + li r0,__NR_clock_gettime + .cfi_restore lr + 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 */ + cmplwi cr0, r3, CLOCK_MAX + cmpwi cr1, r3, CLOCK_REALTIME_COARSE + cmpwi cr7, r3, CLOCK_MONOTONIC_COARSE + bgt cr0, 99f + LOAD_REG_IMMEDIATE(r5, KTIME_LOW_RES) + beq cr1, 1f + beq cr7, 1f + + mflr r12 + .cfi_register lr,r12 + get_datapage r3, r0 + lwz r5, CLOCK_HRTIMER_RES(r3) + mtlr r12 +1: li r3,0 + cmpli cr0,r4,0 + crclr cr0*4+so + beqlr + 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 */ + get_datapage r9, r0 + + lwz r3,STAMP_XTIME_SEC+LOPART(r9) + + cmplwi r11,0 /* check if t is NULL */ + mtlr r12 + crclr cr0*4+so + beqlr + stw r3,0(r11) /* store result at *t */ + 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_SEC+LOPART(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 |