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_DATA 23 #include <asm/vdso/data.h> 24 #else 25 struct arch_vdso_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_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_data.cs[x].shift. 53 */ 54 struct vdso_timestamp { 55 u64 sec; 56 u64 nsec; 57 }; 58 59 /** 60 * struct vdso_data - vdso datapage representation 61 * @seq: timebase sequence counter 62 * @clock_mode: clock mode 63 * @cycle_last: timebase at clocksource init 64 * @mask: clocksource mask 65 * @mult: clocksource multiplier 66 * @shift: clocksource shift 67 * @basetime[clock_id]: basetime per clock_id 68 * @offset[clock_id]: time namespace offset per clock_id 69 * @tz_minuteswest: minutes west of Greenwich 70 * @tz_dsttime: type of DST correction 71 * @hrtimer_res: hrtimer resolution 72 * @__unused: unused 73 * @arch_data: architecture specific data (optional, defaults 74 * to an empty struct) 75 * 76 * vdso_data will be accessed by 64 bit and compat code at the same time 77 * so we should be careful before modifying this structure. 78 * 79 * @basetime is used to store the base time for the system wide time getter 80 * VVAR page. 81 * 82 * @offset is used by the special time namespace VVAR pages which are 83 * installed instead of the real VVAR page. These namespace pages must set 84 * @seq to 1 and @clock_mode to VDSO_CLOCKMODE_TIMENS to force the code into 85 * the time namespace slow path. The namespace aware functions retrieve the 86 * real system wide VVAR page, read host time and add the per clock offset. 87 * For clocks which are not affected by time namespace adjustment the 88 * offset must be zero. 89 */ 90 struct vdso_data { 91 u32 seq; 92 93 s32 clock_mode; 94 u64 cycle_last; 95 u64 mask; 96 u32 mult; 97 u32 shift; 98 99 union { 100 struct vdso_timestamp basetime[VDSO_BASES]; 101 struct timens_offset offset[VDSO_BASES]; 102 }; 103 104 s32 tz_minuteswest; 105 s32 tz_dsttime; 106 u32 hrtimer_res; 107 u32 __unused; 108 109 struct arch_vdso_data arch_data; 110 }; 111 112 /* 113 * We use the hidden visibility to prevent the compiler from generating a GOT 114 * relocation. Not only is going through a GOT useless (the entry couldn't and 115 * must not be overridden by another library), it does not even work: the linker 116 * cannot generate an absolute address to the data page. 117 * 118 * With the hidden visibility, the compiler simply generates a PC-relative 119 * relocation, and this is what we need. 120 */ 121 extern struct vdso_data _vdso_data[CS_BASES] __attribute__((visibility("hidden"))); 122 extern struct vdso_data _timens_data[CS_BASES] __attribute__((visibility("hidden"))); 123 124 /** 125 * union vdso_data_store - Generic vDSO data page 126 */ 127 union vdso_data_store { 128 struct vdso_data data[CS_BASES]; 129 u8 page[1U << CONFIG_PAGE_SHIFT]; 130 }; 131 132 /* 133 * The generic vDSO implementation requires that gettimeofday.h 134 * provides: 135 * - __arch_get_vdso_data(): to get the vdso datapage. 136 * - __arch_get_hw_counter(): to get the hw counter based on the 137 * clock_mode. 138 * - gettimeofday_fallback(): fallback for gettimeofday. 139 * - clock_gettime_fallback(): fallback for clock_gettime. 140 * - clock_getres_fallback(): fallback for clock_getres. 141 */ 142 #ifdef ENABLE_COMPAT_VDSO 143 #include <asm/vdso/compat_gettimeofday.h> 144 #else 145 #include <asm/vdso/gettimeofday.h> 146 #endif /* ENABLE_COMPAT_VDSO */ 147 148 #endif /* !__ASSEMBLY__ */ 149 150 #endif /* __VDSO_DATAPAGE_H */ 151