1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef __VDSO_DATAPAGE_H 3 #define __VDSO_DATAPAGE_H 4 5 #ifndef __ASSEMBLY__ 6 7 #include <linux/compiler.h> 8 #include <uapi/linux/time.h> 9 #include <uapi/linux/types.h> 10 #include <uapi/asm-generic/errno-base.h> 11 12 #include <vdso/bits.h> 13 #include <vdso/clocksource.h> 14 #include <vdso/ktime.h> 15 #include <vdso/limits.h> 16 #include <vdso/math64.h> 17 #include <vdso/processor.h> 18 #include <vdso/time.h> 19 #include <vdso/time32.h> 20 #include <vdso/time64.h> 21 22 #ifdef CONFIG_ARCH_HAS_VDSO_TIME_DATA 23 #include <asm/vdso/time_data.h> 24 #else 25 struct arch_vdso_time_data {}; 26 #endif 27 28 #define VDSO_BASES (CLOCK_TAI + 1) 29 #define VDSO_HRES (BIT(CLOCK_REALTIME) | \ 30 BIT(CLOCK_MONOTONIC) | \ 31 BIT(CLOCK_BOOTTIME) | \ 32 BIT(CLOCK_TAI)) 33 #define VDSO_COARSE (BIT(CLOCK_REALTIME_COARSE) | \ 34 BIT(CLOCK_MONOTONIC_COARSE)) 35 #define VDSO_RAW (BIT(CLOCK_MONOTONIC_RAW)) 36 37 #define CS_HRES_COARSE 0 38 #define CS_RAW 1 39 #define CS_BASES (CS_RAW + 1) 40 41 /** 42 * struct vdso_timestamp - basetime per clock_id 43 * @sec: seconds 44 * @nsec: nanoseconds 45 * 46 * There is one vdso_timestamp object in vvar for each vDSO-accelerated 47 * clock_id. For high-resolution clocks, this encodes the time 48 * corresponding to vdso_time_data.cycle_last. For coarse clocks this encodes 49 * the actual time. 50 * 51 * To be noticed that for highres clocks nsec is left-shifted by 52 * vdso_time_data[x].shift. 53 */ 54 struct vdso_timestamp { 55 u64 sec; 56 u64 nsec; 57 }; 58 59 /** 60 * struct vdso_time_data - vdso datapage representation 61 * @seq: timebase sequence counter 62 * @clock_mode: clock mode 63 * @cycle_last: timebase at clocksource init 64 * @max_cycles: maximum cycles which won't overflow 64bit multiplication 65 * @mask: clocksource mask 66 * @mult: clocksource multiplier 67 * @shift: clocksource shift 68 * @basetime[clock_id]: basetime per clock_id 69 * @offset[clock_id]: time namespace offset per clock_id 70 * @tz_minuteswest: minutes west of Greenwich 71 * @tz_dsttime: type of DST correction 72 * @hrtimer_res: hrtimer resolution 73 * @__unused: unused 74 * @arch_data: architecture specific data (optional, defaults 75 * to an empty struct) 76 * 77 * vdso_time_data will be accessed by 64 bit and compat code at the same time 78 * so we should be careful before modifying this structure. 79 * 80 * The ordering of the struct members is optimized to have fast access to the 81 * often required struct members which are related to CLOCK_REALTIME and 82 * CLOCK_MONOTONIC. This information is stored in the first cache lines. 83 * 84 * @basetime is used to store the base time for the system wide time getter 85 * VVAR page. 86 * 87 * @offset is used by the special time namespace VVAR pages which are 88 * installed instead of the real VVAR page. These namespace pages must set 89 * @seq to 1 and @clock_mode to VDSO_CLOCKMODE_TIMENS to force the code into 90 * the time namespace slow path. The namespace aware functions retrieve the 91 * real system wide VVAR page, read host time and add the per clock offset. 92 * For clocks which are not affected by time namespace adjustment the 93 * offset must be zero. 94 */ 95 struct vdso_time_data { 96 u32 seq; 97 98 s32 clock_mode; 99 u64 cycle_last; 100 #ifdef CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT 101 u64 max_cycles; 102 #endif 103 u64 mask; 104 u32 mult; 105 u32 shift; 106 107 union { 108 struct vdso_timestamp basetime[VDSO_BASES]; 109 struct timens_offset offset[VDSO_BASES]; 110 }; 111 112 s32 tz_minuteswest; 113 s32 tz_dsttime; 114 u32 hrtimer_res; 115 u32 __unused; 116 117 struct arch_vdso_time_data arch_data; 118 }; 119 120 #define vdso_data vdso_time_data 121 122 /** 123 * struct vdso_rng_data - vdso RNG state information 124 * @generation: counter representing the number of RNG reseeds 125 * @is_ready: boolean signaling whether the RNG is initialized 126 */ 127 struct vdso_rng_data { 128 u64 generation; 129 u8 is_ready; 130 }; 131 132 /* 133 * We use the hidden visibility to prevent the compiler from generating a GOT 134 * relocation. Not only is going through a GOT useless (the entry couldn't and 135 * must not be overridden by another library), it does not even work: the linker 136 * cannot generate an absolute address to the data page. 137 * 138 * With the hidden visibility, the compiler simply generates a PC-relative 139 * relocation, and this is what we need. 140 */ 141 #ifndef CONFIG_GENERIC_VDSO_DATA_STORE 142 extern struct vdso_time_data _vdso_data[CS_BASES] __attribute__((visibility("hidden"))); 143 extern struct vdso_time_data _timens_data[CS_BASES] __attribute__((visibility("hidden"))); 144 extern struct vdso_rng_data _vdso_rng_data __attribute__((visibility("hidden"))); 145 #else 146 extern struct vdso_time_data vdso_u_time_data[CS_BASES] __attribute__((visibility("hidden"))); 147 extern struct vdso_rng_data vdso_u_rng_data __attribute__((visibility("hidden"))); 148 149 extern struct vdso_time_data *vdso_k_time_data; 150 extern struct vdso_rng_data *vdso_k_rng_data; 151 #endif 152 153 /** 154 * union vdso_data_store - Generic vDSO data page 155 */ 156 union vdso_data_store { 157 struct vdso_time_data data[CS_BASES]; 158 u8 page[1U << CONFIG_PAGE_SHIFT]; 159 }; 160 161 #ifdef CONFIG_GENERIC_VDSO_DATA_STORE 162 163 enum vdso_pages { 164 VDSO_TIME_PAGE_OFFSET, 165 VDSO_TIMENS_PAGE_OFFSET, 166 VDSO_RNG_PAGE_OFFSET, 167 VDSO_NR_PAGES 168 }; 169 170 #endif /* CONFIG_GENERIC_VDSO_DATA_STORE */ 171 172 /* 173 * The generic vDSO implementation requires that gettimeofday.h 174 * provides: 175 * - __arch_get_vdso_data(): to get the vdso datapage. 176 * - __arch_get_hw_counter(): to get the hw counter based on the 177 * clock_mode. 178 * - gettimeofday_fallback(): fallback for gettimeofday. 179 * - clock_gettime_fallback(): fallback for clock_gettime. 180 * - clock_getres_fallback(): fallback for clock_getres. 181 */ 182 #ifdef ENABLE_COMPAT_VDSO 183 #include <asm/vdso/compat_gettimeofday.h> 184 #else 185 #include <asm/vdso/gettimeofday.h> 186 #endif /* ENABLE_COMPAT_VDSO */ 187 188 #else /* !__ASSEMBLY__ */ 189 190 #ifdef CONFIG_VDSO_GETRANDOM 191 #define __vdso_u_rng_data PROVIDE(vdso_u_rng_data = vdso_u_data + 2 * PAGE_SIZE); 192 #else 193 #define __vdso_u_rng_data 194 #endif 195 196 #define VDSO_VVAR_SYMS \ 197 PROVIDE(vdso_u_data = . - __VDSO_PAGES * PAGE_SIZE); \ 198 PROVIDE(vdso_u_time_data = vdso_u_data); \ 199 __vdso_u_rng_data \ 200 201 202 #endif /* !__ASSEMBLY__ */ 203 204 #endif /* __VDSO_DATAPAGE_H */ 205