1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * Copyright (C) 2018 ARM Limited 4 */ 5 #ifndef __ASM_VDSO_GETTIMEOFDAY_H 6 #define __ASM_VDSO_GETTIMEOFDAY_H 7 8 #ifndef __ASSEMBLY__ 9 10 #include <asm/barrier.h> 11 #include <asm/unistd.h> 12 #include <asm/errno.h> 13 14 #include <asm/vdso/compat_barrier.h> 15 16 #define VDSO_HAS_CLOCK_GETRES 1 17 18 #define BUILD_VDSO32 1 19 20 static __always_inline 21 int gettimeofday_fallback(struct __kernel_old_timeval *_tv, 22 struct timezone *_tz) 23 { 24 register struct timezone *tz asm("r1") = _tz; 25 register struct __kernel_old_timeval *tv asm("r0") = _tv; 26 register long ret asm ("r0"); 27 register long nr asm("r7") = __NR_compat_gettimeofday; 28 29 asm volatile( 30 " swi #0\n" 31 : "=r" (ret) 32 : "r" (tv), "r" (tz), "r" (nr) 33 : "memory"); 34 35 return ret; 36 } 37 38 static __always_inline 39 long clock_gettime_fallback(clockid_t _clkid, struct __kernel_timespec *_ts) 40 { 41 register struct __kernel_timespec *ts asm("r1") = _ts; 42 register clockid_t clkid asm("r0") = _clkid; 43 register long ret asm ("r0"); 44 register long nr asm("r7") = __NR_compat_clock_gettime64; 45 46 asm volatile( 47 " swi #0\n" 48 : "=r" (ret) 49 : "r" (clkid), "r" (ts), "r" (nr) 50 : "memory"); 51 52 return ret; 53 } 54 55 static __always_inline 56 long clock_gettime32_fallback(clockid_t _clkid, struct old_timespec32 *_ts) 57 { 58 register struct old_timespec32 *ts asm("r1") = _ts; 59 register clockid_t clkid asm("r0") = _clkid; 60 register long ret asm ("r0"); 61 register long nr asm("r7") = __NR_compat_clock_gettime; 62 63 asm volatile( 64 " swi #0\n" 65 : "=r" (ret) 66 : "r" (clkid), "r" (ts), "r" (nr) 67 : "memory"); 68 69 return ret; 70 } 71 72 static __always_inline 73 int clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts) 74 { 75 register struct __kernel_timespec *ts asm("r1") = _ts; 76 register clockid_t clkid asm("r0") = _clkid; 77 register long ret asm ("r0"); 78 register long nr asm("r7") = __NR_compat_clock_getres_time64; 79 80 asm volatile( 81 " swi #0\n" 82 : "=r" (ret) 83 : "r" (clkid), "r" (ts), "r" (nr) 84 : "memory"); 85 86 return ret; 87 } 88 89 static __always_inline 90 int clock_getres32_fallback(clockid_t _clkid, struct old_timespec32 *_ts) 91 { 92 register struct old_timespec32 *ts asm("r1") = _ts; 93 register clockid_t clkid asm("r0") = _clkid; 94 register long ret asm ("r0"); 95 register long nr asm("r7") = __NR_compat_clock_getres; 96 97 asm volatile( 98 " swi #0\n" 99 : "=r" (ret) 100 : "r" (clkid), "r" (ts), "r" (nr) 101 : "memory"); 102 103 return ret; 104 } 105 106 static __always_inline u64 __arch_get_hw_counter(s32 clock_mode, 107 const struct vdso_data *vd) 108 { 109 u64 res; 110 111 /* 112 * Core checks for mode already, so this raced against a concurrent 113 * update. Return something. Core will do another round and then 114 * see the mode change and fallback to the syscall. 115 */ 116 if (clock_mode != VDSO_CLOCKMODE_ARCHTIMER) 117 return 0; 118 119 /* 120 * This isb() is required to prevent that the counter value 121 * is speculated. 122 */ 123 isb(); 124 asm volatile("mrrc p15, 1, %Q0, %R0, c14" : "=r" (res)); 125 /* 126 * This isb() is required to prevent that the seq lock is 127 * speculated. 128 */ 129 isb(); 130 131 return res; 132 } 133 134 static __always_inline const struct vdso_data *__arch_get_vdso_data(void) 135 { 136 const struct vdso_data *ret; 137 138 /* 139 * This simply puts &_vdso_data into ret. The reason why we don't use 140 * `ret = _vdso_data` is that the compiler tends to optimise this in a 141 * very suboptimal way: instead of keeping &_vdso_data in a register, 142 * it goes through a relocation almost every time _vdso_data must be 143 * accessed (even in subfunctions). This is both time and space 144 * consuming: each relocation uses a word in the code section, and it 145 * has to be loaded at runtime. 146 * 147 * This trick hides the assignment from the compiler. Since it cannot 148 * track where the pointer comes from, it will only use one relocation 149 * where __arch_get_vdso_data() is called, and then keep the result in 150 * a register. 151 */ 152 asm volatile("mov %0, %1" : "=r"(ret) : "r"(_vdso_data)); 153 154 return ret; 155 } 156 157 #ifdef CONFIG_TIME_NS 158 static __always_inline const struct vdso_data *__arch_get_timens_vdso_data(void) 159 { 160 const struct vdso_data *ret; 161 162 /* See __arch_get_vdso_data(). */ 163 asm volatile("mov %0, %1" : "=r"(ret) : "r"(_timens_data)); 164 165 return ret; 166 } 167 #endif 168 169 static inline bool vdso_clocksource_ok(const struct vdso_data *vd) 170 { 171 return vd->clock_mode == VDSO_CLOCKMODE_ARCHTIMER; 172 } 173 #define vdso_clocksource_ok vdso_clocksource_ok 174 175 #endif /* !__ASSEMBLY__ */ 176 177 #endif /* __ASM_VDSO_GETTIMEOFDAY_H */ 178