1/* 2 * Userspace implementations of gettimeofday() and friends. 3 * 4 * Copyright (C) 2012 ARM Limited 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program. If not, see <http://www.gnu.org/licenses/>. 17 * 18 * Author: Will Deacon <will.deacon@arm.com> 19 */ 20 21#include <linux/linkage.h> 22#include <asm/asm-offsets.h> 23#include <asm/unistd.h> 24 25#define NSEC_PER_SEC_LO16 0xca00 26#define NSEC_PER_SEC_HI16 0x3b9a 27 28vdso_data .req x6 29use_syscall .req w7 30seqcnt .req w8 31 32 .macro seqcnt_acquire 339999: ldr seqcnt, [vdso_data, #VDSO_TB_SEQ_COUNT] 34 tbnz seqcnt, #0, 9999b 35 dmb ishld 36 ldr use_syscall, [vdso_data, #VDSO_USE_SYSCALL] 37 .endm 38 39 .macro seqcnt_read, cnt 40 dmb ishld 41 ldr \cnt, [vdso_data, #VDSO_TB_SEQ_COUNT] 42 .endm 43 44 .macro seqcnt_check, cnt, fail 45 cmp \cnt, seqcnt 46 b.ne \fail 47 .endm 48 49 .text 50 51/* int __kernel_gettimeofday(struct timeval *tv, struct timezone *tz); */ 52ENTRY(__kernel_gettimeofday) 53 .cfi_startproc 54 mov x2, x30 55 .cfi_register x30, x2 56 57 /* Acquire the sequence counter and get the timespec. */ 58 adr vdso_data, _vdso_data 591: seqcnt_acquire 60 cbnz use_syscall, 4f 61 62 /* If tv is NULL, skip to the timezone code. */ 63 cbz x0, 2f 64 bl __do_get_tspec 65 seqcnt_check w9, 1b 66 67 /* Convert ns to us. */ 68 mov x13, #1000 69 lsl x13, x13, x12 70 udiv x11, x11, x13 71 stp x10, x11, [x0, #TVAL_TV_SEC] 722: 73 /* If tz is NULL, return 0. */ 74 cbz x1, 3f 75 ldp w4, w5, [vdso_data, #VDSO_TZ_MINWEST] 76 stp w4, w5, [x1, #TZ_MINWEST] 773: 78 mov x0, xzr 79 ret x2 804: 81 /* Syscall fallback. */ 82 mov x8, #__NR_gettimeofday 83 svc #0 84 ret x2 85 .cfi_endproc 86ENDPROC(__kernel_gettimeofday) 87 88/* int __kernel_clock_gettime(clockid_t clock_id, struct timespec *tp); */ 89ENTRY(__kernel_clock_gettime) 90 .cfi_startproc 91 cmp w0, #CLOCK_REALTIME 92 ccmp w0, #CLOCK_MONOTONIC, #0x4, ne 93 b.ne 2f 94 95 mov x2, x30 96 .cfi_register x30, x2 97 98 /* Get kernel timespec. */ 99 adr vdso_data, _vdso_data 1001: seqcnt_acquire 101 cbnz use_syscall, 7f 102 103 bl __do_get_tspec 104 seqcnt_check w9, 1b 105 106 mov x30, x2 107 108 cmp w0, #CLOCK_MONOTONIC 109 b.ne 6f 110 111 /* Get wtm timespec. */ 112 ldp x13, x14, [vdso_data, #VDSO_WTM_CLK_SEC] 113 114 /* Check the sequence counter. */ 115 seqcnt_read w9 116 seqcnt_check w9, 1b 117 b 4f 1182: 119 cmp w0, #CLOCK_REALTIME_COARSE 120 ccmp w0, #CLOCK_MONOTONIC_COARSE, #0x4, ne 121 b.ne 8f 122 123 /* xtime_coarse_nsec is already right-shifted */ 124 mov x12, #0 125 126 /* Get coarse timespec. */ 127 adr vdso_data, _vdso_data 1283: seqcnt_acquire 129 ldp x10, x11, [vdso_data, #VDSO_XTIME_CRS_SEC] 130 131 /* Get wtm timespec. */ 132 ldp x13, x14, [vdso_data, #VDSO_WTM_CLK_SEC] 133 134 /* Check the sequence counter. */ 135 seqcnt_read w9 136 seqcnt_check w9, 3b 137 138 cmp w0, #CLOCK_MONOTONIC_COARSE 139 b.ne 6f 1404: 141 /* Add on wtm timespec. */ 142 add x10, x10, x13 143 lsl x14, x14, x12 144 add x11, x11, x14 145 146 /* Normalise the new timespec. */ 147 mov x15, #NSEC_PER_SEC_LO16 148 movk x15, #NSEC_PER_SEC_HI16, lsl #16 149 lsl x15, x15, x12 150 cmp x11, x15 151 b.lt 5f 152 sub x11, x11, x15 153 add x10, x10, #1 1545: 155 cmp x11, #0 156 b.ge 6f 157 add x11, x11, x15 158 sub x10, x10, #1 159 1606: /* Store to the user timespec. */ 161 lsr x11, x11, x12 162 stp x10, x11, [x1, #TSPEC_TV_SEC] 163 mov x0, xzr 164 ret 1657: 166 mov x30, x2 1678: /* Syscall fallback. */ 168 mov x8, #__NR_clock_gettime 169 svc #0 170 ret 171 .cfi_endproc 172ENDPROC(__kernel_clock_gettime) 173 174/* int __kernel_clock_getres(clockid_t clock_id, struct timespec *res); */ 175ENTRY(__kernel_clock_getres) 176 .cfi_startproc 177 cmp w0, #CLOCK_REALTIME 178 ccmp w0, #CLOCK_MONOTONIC, #0x4, ne 179 b.ne 1f 180 181 ldr x2, 5f 182 b 2f 1831: 184 cmp w0, #CLOCK_REALTIME_COARSE 185 ccmp w0, #CLOCK_MONOTONIC_COARSE, #0x4, ne 186 b.ne 4f 187 ldr x2, 6f 1882: 189 cbz w1, 3f 190 stp xzr, x2, [x1] 191 1923: /* res == NULL. */ 193 mov w0, wzr 194 ret 195 1964: /* Syscall fallback. */ 197 mov x8, #__NR_clock_getres 198 svc #0 199 ret 2005: 201 .quad CLOCK_REALTIME_RES 2026: 203 .quad CLOCK_COARSE_RES 204 .cfi_endproc 205ENDPROC(__kernel_clock_getres) 206 207/* 208 * Read the current time from the architected counter. 209 * Expects vdso_data to be initialised. 210 * Clobbers the temporary registers (x9 - x15). 211 * Returns: 212 * - w9 = vDSO sequence counter 213 * - (x10, x11) = (ts->tv_sec, shifted ts->tv_nsec) 214 * - w12 = cs_shift 215 */ 216ENTRY(__do_get_tspec) 217 .cfi_startproc 218 219 /* Read from the vDSO data page. */ 220 ldr x10, [vdso_data, #VDSO_CS_CYCLE_LAST] 221 ldp x13, x14, [vdso_data, #VDSO_XTIME_CLK_SEC] 222 ldp w11, w12, [vdso_data, #VDSO_CS_MULT] 223 seqcnt_read w9 224 225 /* Read the virtual counter. */ 226 isb 227 mrs x15, cntvct_el0 228 229 /* Calculate cycle delta and convert to ns. */ 230 sub x10, x15, x10 231 /* We can only guarantee 56 bits of precision. */ 232 movn x15, #0xff00, lsl #48 233 and x10, x15, x10 234 mul x10, x10, x11 235 236 /* Use the kernel time to calculate the new timespec. */ 237 mov x11, #NSEC_PER_SEC_LO16 238 movk x11, #NSEC_PER_SEC_HI16, lsl #16 239 lsl x11, x11, x12 240 add x15, x10, x14 241 udiv x14, x15, x11 242 add x10, x13, x14 243 mul x13, x14, x11 244 sub x11, x15, x13 245 246 ret 247 .cfi_endproc 248ENDPROC(__do_get_tspec) 249