1 /* SPDX-License-Identifier: GPL-2.0-or-later */
3 * Userland implementation of gettimeofday() for 32 bits processes in a
4 * ppc64 kernel for use in the vDSO
6 * Copyright (C) 2004 Benjamin Herrenschmuidt (benh@kernel.crashing.org,
9 #include <asm/processor.h>
10 #include <asm/ppc_asm.h>
12 #include <asm/vdso_datapage.h>
13 #include <asm/asm-offsets.h>
14 #include <asm/unistd.h>
16 /* Offset for the low 32-bit part of a field of long type */
25 * Exact prototype of gettimeofday
27 * int __kernel_gettimeofday(struct timeval *tv, struct timezone *tz);
30 V_FUNCTION_BEGIN(__kernel_gettimeofday)
35 mr. r10,r3 /* r10 saves tv */
36 mr r11,r4 /* r11 saves tz */
39 LOAD_REG_IMMEDIATE(r7, 1000000) /* load up USEC_PER_SEC */
40 bl __do_get_tspec@local /* get sec/usec from tb & kernel */
41 stw r3,TVAL32_TV_SEC(r10)
42 stw r4,TVAL32_TV_USEC(r10)
44 3: cmplwi r11,0 /* check if tz is NULL */
50 lwz r4,CFG_TZ_MINUTEWEST(r9)/* fill tz */
51 lwz r5,CFG_TZ_DSTTIME(r9)
52 stw r4,TZONE_TZ_MINWEST(r11)
53 stw r5,TZONE_TZ_DSTTIME(r11)
57 V_FUNCTION_END(__kernel_gettimeofday)
60 * Exact prototype of clock_gettime()
62 * int __kernel_clock_gettime(clockid_t clock_id, struct timespec *tp);
65 V_FUNCTION_BEGIN(__kernel_clock_gettime)
67 /* Check for supported clock IDs */
68 cmpli cr0,r3,CLOCK_REALTIME
69 cmpli cr1,r3,CLOCK_MONOTONIC
70 cror cr0*4+eq,cr0*4+eq,cr1*4+eq
72 cmpli cr5,r3,CLOCK_REALTIME_COARSE
73 cmpli cr6,r3,CLOCK_MONOTONIC_COARSE
74 cror cr5*4+eq,cr5*4+eq,cr6*4+eq
76 cror cr0*4+eq,cr0*4+eq,cr5*4+eq
77 bne cr0, .Lgettime_fallback
79 mflr r12 /* r12 saves lr */
81 mr r11,r4 /* r11 saves tp */
83 LOAD_REG_IMMEDIATE(r7, NSEC_PER_SEC) /* load up NSEC_PER_SEC */
84 beq cr5, .Lcoarse_clocks
86 bl __do_get_tspec@local /* get sec/nsec from tb & kernel */
87 bne cr1, .Lfinish /* not monotonic -> all done */
93 /* now we must fixup using wall to monotonic. We need to snapshot
94 * that value and do the counter trick again. Fortunately, we still
95 * have the counter value in r8 that was returned by __do_get_xsec.
96 * At this point, r3,r4 contain our sec/nsec values, r5 and r6
97 * can be used, r7 contains NSEC_PER_SEC.
100 lwz r5,(WTOM_CLOCK_SEC+LOPART)(r9)
101 lwz r6,WTOM_CLOCK_NSEC(r9)
103 /* We now have our offset in r5,r6. We create a fake dependency
104 * on that value and re-check the counter
109 lwz r0,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
110 cmpl cr0,r8,r0 /* check if updated */
111 bne- .Lprecise_clocks
115 * For coarse clocks we get data directly from the vdso data page, so
116 * we don't need to call __do_get_tspec, but we still need to do the
120 lwz r8,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
121 andi. r0,r8,1 /* pending update ? loop */
123 add r9,r9,r0 /* r0 is already 0 */
126 * CLOCK_REALTIME_COARSE, below values are needed for MONOTONIC_COARSE
129 lwz r3,STAMP_XTIME_SEC+LOPART(r9)
130 lwz r4,STAMP_XTIME_NSEC+LOPART(r9)
133 /* CLOCK_MONOTONIC_COARSE */
134 lwz r5,(WTOM_CLOCK_SEC+LOPART)(r9)
135 lwz r6,WTOM_CLOCK_NSEC(r9)
137 /* check if counter has updated */
143 lwz r0,CFG_TB_UPDATE_COUNT+LOPART(r9)
144 cmpl cr0,r0,r8 /* check if updated */
147 /* Counter has not updated, so continue calculating proper values for
148 * sec and nsec if monotonic coarse, or just return with the proper
149 * values for realtime.
153 /* Calculate and store result. Note that this mimics the C code,
154 * which may cause funny results if nsec goes negative... is that
170 stw r3,TSPC32_TV_SEC(r11)
171 stw r4,TSPC32_TV_NSEC(r11)
182 li r0,__NR_clock_gettime
187 V_FUNCTION_END(__kernel_clock_gettime)
191 * Exact prototype of clock_getres()
193 * int __kernel_clock_getres(clockid_t clock_id, struct timespec *res);
196 V_FUNCTION_BEGIN(__kernel_clock_getres)
198 /* Check for supported clock IDs */
199 cmplwi cr0, r3, CLOCK_MAX
200 cmpwi cr1, r3, CLOCK_REALTIME_COARSE
201 cmpwi cr7, r3, CLOCK_MONOTONIC_COARSE
203 LOAD_REG_IMMEDIATE(r5, KTIME_LOW_RES)
210 lwz r5, CLOCK_HRTIMER_RES(r3)
216 stw r3,TSPC32_TV_SEC(r4)
217 stw r5,TSPC32_TV_NSEC(r4)
228 V_FUNCTION_END(__kernel_clock_getres)
232 * Exact prototype of time()
234 * time_t time(time *t);
237 V_FUNCTION_BEGIN(__kernel_time)
242 mr r11,r3 /* r11 holds t */
245 lwz r3,STAMP_XTIME_SEC+LOPART(r9)
247 cmplwi r11,0 /* check if t is NULL */
251 stw r3,0(r11) /* store result at *t */
254 V_FUNCTION_END(__kernel_time)
257 * This is the core of clock_gettime() and gettimeofday(),
258 * it returns the current time in r3 (seconds) and r4.
259 * On entry, r7 gives the resolution of r4, either USEC_PER_SEC
260 * or NSEC_PER_SEC, giving r4 in microseconds or nanoseconds.
261 * It expects the datapage ptr in r9 and doesn't clobber it.
262 * It clobbers r0, r5 and r6.
263 * On return, r8 contains the counter value that can be reused.
264 * This clobbers cr0 but not any other cr field.
268 /* Check for update count & load values. We use the low
269 * order 32 bits of the update count
271 1: lwz r8,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
272 andi. r0,r8,1 /* pending update ? loop */
274 xor r0,r8,r8 /* create dependency */
277 /* Load orig stamp (offset to TB) */
278 lwz r5,CFG_TB_ORIG_STAMP(r9)
279 lwz r6,(CFG_TB_ORIG_STAMP+4)(r9)
281 /* Get a stable TB value */
288 /* Subtract tb orig stamp and shift left 12 bits.
293 rlwimi. r0,r4,12,20,31
297 * Load scale factor & do multiplication.
298 * We only use the high 32 bits of the tb_to_xs value.
299 * Even with a 1GHz timebase clock, the high 32 bits of
300 * tb_to_xs will be at least 4 million, so the error from
301 * ignoring the low 32 bits will be no more than 0.25ppm.
302 * The error will just make the clock run very very slightly
303 * slow until the next time the kernel updates the VDSO data,
304 * at which point the clock will catch up to the kernel's value,
305 * so there is no long-term error accumulation.
307 lwz r5,CFG_TB_TO_XS(r9) /* load values */
311 beq+ 4f /* skip high part computation if 0 */
317 /* At this point, we have seconds since the xtime stamp
318 * as a 32.32 fixed-point number in r3 and r4.
319 * Load & add the xtime stamp.
321 lwz r5,STAMP_XTIME_SEC+LOPART(r9)
322 lwz r6,STAMP_SEC_FRAC(r9)
326 /* We create a fake dependency on the result in r3/r4
327 * and re-check the counter
332 lwz r0,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
333 cmplw cr0,r8,r0 /* check if updated */
336 mulhwu r4,r4,r7 /* convert to micro or nanoseconds */