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/asm-offsets.h>
13 #include <asm/unistd.h>
15 /* Offset for the low 32-bit part of a field of long type */
18 #define TSPEC_TV_SEC TSPC64_TV_SEC+LOPART
21 #define TSPEC_TV_SEC TSPC32_TV_SEC
26 * Exact prototype of gettimeofday
28 * int __kernel_gettimeofday(struct timeval *tv, struct timezone *tz);
31 V_FUNCTION_BEGIN(__kernel_gettimeofday)
36 mr r10,r3 /* r10 saves tv */
37 mr r11,r4 /* r11 saves tz */
38 bl __get_datapage@local /* get data page */
39 mr r9, r3 /* datapage ptr in r9 */
40 cmplwi r10,0 /* check if tv is NULL */
42 lis r7,1000000@ha /* load up USEC_PER_SEC */
43 addi r7,r7,1000000@l /* so we get microseconds in r4 */
44 bl __do_get_tspec@local /* get sec/usec from tb & kernel */
45 stw r3,TVAL32_TV_SEC(r10)
46 stw r4,TVAL32_TV_USEC(r10)
48 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)
60 V_FUNCTION_END(__kernel_gettimeofday)
63 * Exact prototype of clock_gettime()
65 * int __kernel_clock_gettime(clockid_t clock_id, struct timespec *tp);
68 V_FUNCTION_BEGIN(__kernel_clock_gettime)
70 /* Check for supported clock IDs */
71 cmpli cr0,r3,CLOCK_REALTIME
72 cmpli cr1,r3,CLOCK_MONOTONIC
73 cror cr0*4+eq,cr0*4+eq,cr1*4+eq
76 mflr r12 /* r12 saves lr */
78 mr r11,r4 /* r11 saves tp */
79 bl __get_datapage@local /* get data page */
80 mr r9,r3 /* datapage ptr in r9 */
81 lis r7,NSEC_PER_SEC@h /* want nanoseconds */
82 ori r7,r7,NSEC_PER_SEC@l
83 50: bl __do_get_tspec@local /* get sec/nsec from tb & kernel */
84 bne cr1,80f /* not monotonic -> all done */
90 /* now we must fixup using wall to monotonic. We need to snapshot
91 * that value and do the counter trick again. Fortunately, we still
92 * have the counter value in r8 that was returned by __do_get_xsec.
93 * At this point, r3,r4 contain our sec/nsec values, r5 and r6
94 * can be used, r7 contains NSEC_PER_SEC.
97 lwz r5,(WTOM_CLOCK_SEC+LOPART)(r9)
98 lwz r6,WTOM_CLOCK_NSEC(r9)
100 /* We now have our offset in r5,r6. We create a fake dependency
101 * on that value and re-check the counter
106 lwz r0,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
107 cmpl cr0,r8,r0 /* check if updated */
110 /* Calculate and store result. Note that this mimics the C code,
111 * which may cause funny results if nsec goes negative... is that
125 80: stw r3,TSPC32_TV_SEC(r11)
126 stw r4,TSPC32_TV_NSEC(r11)
137 li r0,__NR_clock_gettime
142 V_FUNCTION_END(__kernel_clock_gettime)
146 * Exact prototype of clock_getres()
148 * int __kernel_clock_getres(clockid_t clock_id, struct timespec *res);
151 V_FUNCTION_BEGIN(__kernel_clock_getres)
153 /* Check for supported clock IDs */
154 cmpwi cr0,r3,CLOCK_REALTIME
155 cmpwi cr1,r3,CLOCK_MONOTONIC
156 cror cr0*4+eq,cr0*4+eq,cr1*4+eq
163 lis r5,CLOCK_REALTIME_RES@h
164 ori r5,r5,CLOCK_REALTIME_RES@l
165 stw r3,TSPC32_TV_SEC(r4)
166 stw r5,TSPC32_TV_NSEC(r4)
173 li r0,__NR_clock_getres
177 V_FUNCTION_END(__kernel_clock_getres)
181 * Exact prototype of time()
183 * time_t time(time *t);
186 V_FUNCTION_BEGIN(__kernel_time)
191 mr r11,r3 /* r11 holds t */
192 bl __get_datapage@local
193 mr r9, r3 /* datapage ptr in r9 */
195 lwz r3,STAMP_XTIME+TSPEC_TV_SEC(r9)
197 cmplwi r11,0 /* check if t is NULL */
199 stw r3,0(r11) /* store result at *t */
204 V_FUNCTION_END(__kernel_time)
207 * This is the core of clock_gettime() and gettimeofday(),
208 * it returns the current time in r3 (seconds) and r4.
209 * On entry, r7 gives the resolution of r4, either USEC_PER_SEC
210 * or NSEC_PER_SEC, giving r4 in microseconds or nanoseconds.
211 * It expects the datapage ptr in r9 and doesn't clobber it.
212 * It clobbers r0, r5 and r6.
213 * On return, r8 contains the counter value that can be reused.
214 * This clobbers cr0 but not any other cr field.
218 /* Check for update count & load values. We use the low
219 * order 32 bits of the update count
221 1: lwz r8,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
222 andi. r0,r8,1 /* pending update ? loop */
224 xor r0,r8,r8 /* create dependency */
227 /* Load orig stamp (offset to TB) */
228 lwz r5,CFG_TB_ORIG_STAMP(r9)
229 lwz r6,(CFG_TB_ORIG_STAMP+4)(r9)
231 /* Get a stable TB value */
238 /* Subtract tb orig stamp and shift left 12 bits.
243 rlwimi. r0,r4,12,20,31
247 * Load scale factor & do multiplication.
248 * We only use the high 32 bits of the tb_to_xs value.
249 * Even with a 1GHz timebase clock, the high 32 bits of
250 * tb_to_xs will be at least 4 million, so the error from
251 * ignoring the low 32 bits will be no more than 0.25ppm.
252 * The error will just make the clock run very very slightly
253 * slow until the next time the kernel updates the VDSO data,
254 * at which point the clock will catch up to the kernel's value,
255 * so there is no long-term error accumulation.
257 lwz r5,CFG_TB_TO_XS(r9) /* load values */
261 beq+ 4f /* skip high part computation if 0 */
267 /* At this point, we have seconds since the xtime stamp
268 * as a 32.32 fixed-point number in r3 and r4.
269 * Load & add the xtime stamp.
271 lwz r5,STAMP_XTIME+TSPEC_TV_SEC(r9)
272 lwz r6,STAMP_SEC_FRAC(r9)
276 /* We create a fake dependency on the result in r3/r4
277 * and re-check the counter
282 lwz r0,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
283 cmplw cr0,r8,r0 /* check if updated */
286 mulhwu r4,r4,r7 /* convert to micro or nanoseconds */