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 #define VDSO_BASES (CLOCK_TAI + 1) 23 #define VDSO_HRES (BIT(CLOCK_REALTIME) | \ 24 BIT(CLOCK_MONOTONIC) | \ 25 BIT(CLOCK_BOOTTIME) | \ 26 BIT(CLOCK_TAI)) 27 #define VDSO_COARSE (BIT(CLOCK_REALTIME_COARSE) | \ 28 BIT(CLOCK_MONOTONIC_COARSE)) 29 #define VDSO_RAW (BIT(CLOCK_MONOTONIC_RAW)) 30 31 #define CS_HRES_COARSE 0 32 #define CS_RAW 1 33 #define CS_BASES (CS_RAW + 1) 34 35 /** 36 * struct vdso_timestamp - basetime per clock_id 37 * @sec: seconds 38 * @nsec: nanoseconds 39 * 40 * There is one vdso_timestamp object in vvar for each vDSO-accelerated 41 * clock_id. For high-resolution clocks, this encodes the time 42 * corresponding to vdso_data.cycle_last. For coarse clocks this encodes 43 * the actual time. 44 * 45 * To be noticed that for highres clocks nsec is left-shifted by 46 * vdso_data.cs[x].shift. 47 */ 48 struct vdso_timestamp { 49 u64 sec; 50 u64 nsec; 51 }; 52 53 /** 54 * struct vdso_data - vdso datapage representation 55 * @seq: timebase sequence counter 56 * @clock_mode: clock mode 57 * @cycle_last: timebase at clocksource init 58 * @mask: clocksource mask 59 * @mult: clocksource multiplier 60 * @shift: clocksource shift 61 * @basetime[clock_id]: basetime per clock_id 62 * @offset[clock_id]: time namespace offset per clock_id 63 * @tz_minuteswest: minutes west of Greenwich 64 * @tz_dsttime: type of DST correction 65 * @hrtimer_res: hrtimer resolution 66 * @__unused: unused 67 * 68 * vdso_data will be accessed by 64 bit and compat code at the same time 69 * so we should be careful before modifying this structure. 70 * 71 * @basetime is used to store the base time for the system wide time getter 72 * VVAR page. 73 * 74 * @offset is used by the special time namespace VVAR pages which are 75 * installed instead of the real VVAR page. These namespace pages must set 76 * @seq to 1 and @clock_mode to VLOCK_TIMENS to force the code into the 77 * time namespace slow path. The namespace aware functions retrieve the 78 * real system wide VVAR page, read host time and add the per clock offset. 79 * For clocks which are not affected by time namespace adjustment the 80 * offset must be zero. 81 */ 82 struct vdso_data { 83 u32 seq; 84 85 s32 clock_mode; 86 u64 cycle_last; 87 u64 mask; 88 u32 mult; 89 u32 shift; 90 91 union { 92 struct vdso_timestamp basetime[VDSO_BASES]; 93 struct timens_offset offset[VDSO_BASES]; 94 }; 95 96 s32 tz_minuteswest; 97 s32 tz_dsttime; 98 u32 hrtimer_res; 99 u32 __unused; 100 }; 101 102 /* 103 * We use the hidden visibility to prevent the compiler from generating a GOT 104 * relocation. Not only is going through a GOT useless (the entry couldn't and 105 * must not be overridden by another library), it does not even work: the linker 106 * cannot generate an absolute address to the data page. 107 * 108 * With the hidden visibility, the compiler simply generates a PC-relative 109 * relocation, and this is what we need. 110 */ 111 extern struct vdso_data _vdso_data[CS_BASES] __attribute__((visibility("hidden"))); 112 113 /* 114 * The generic vDSO implementation requires that gettimeofday.h 115 * provides: 116 * - __arch_get_vdso_data(): to get the vdso datapage. 117 * - __arch_get_hw_counter(): to get the hw counter based on the 118 * clock_mode. 119 * - gettimeofday_fallback(): fallback for gettimeofday. 120 * - clock_gettime_fallback(): fallback for clock_gettime. 121 * - clock_getres_fallback(): fallback for clock_getres. 122 */ 123 #ifdef ENABLE_COMPAT_VDSO 124 #include <asm/vdso/compat_gettimeofday.h> 125 #else 126 #include <asm/vdso/gettimeofday.h> 127 #endif /* ENABLE_COMPAT_VDSO */ 128 129 #endif /* !__ASSEMBLY__ */ 130 131 #endif /* __VDSO_DATAPAGE_H */ 132