1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef __VDSO_DATAPAGE_H 3 #define __VDSO_DATAPAGE_H 4 5 #ifdef __KERNEL__ 6 7 #ifndef __ASSEMBLY__ 8 9 #include <linux/bits.h> 10 #include <linux/time.h> 11 #include <linux/types.h> 12 13 #define VDSO_BASES (CLOCK_TAI + 1) 14 #define VDSO_HRES (BIT(CLOCK_REALTIME) | \ 15 BIT(CLOCK_MONOTONIC) | \ 16 BIT(CLOCK_BOOTTIME) | \ 17 BIT(CLOCK_TAI)) 18 #define VDSO_COARSE (BIT(CLOCK_REALTIME_COARSE) | \ 19 BIT(CLOCK_MONOTONIC_COARSE)) 20 #define VDSO_RAW (BIT(CLOCK_MONOTONIC_RAW)) 21 22 #define CS_HRES_COARSE 0 23 #define CS_RAW 1 24 #define CS_BASES (CS_RAW + 1) 25 26 /** 27 * struct vdso_timestamp - basetime per clock_id 28 * @sec: seconds 29 * @nsec: nanoseconds 30 * 31 * There is one vdso_timestamp object in vvar for each vDSO-accelerated 32 * clock_id. For high-resolution clocks, this encodes the time 33 * corresponding to vdso_data.cycle_last. For coarse clocks this encodes 34 * the actual time. 35 * 36 * To be noticed that for highres clocks nsec is left-shifted by 37 * vdso_data.cs[x].shift. 38 */ 39 struct vdso_timestamp { 40 u64 sec; 41 u64 nsec; 42 }; 43 44 /** 45 * struct vdso_data - vdso datapage representation 46 * @seq: timebase sequence counter 47 * @clock_mode: clock mode 48 * @cycle_last: timebase at clocksource init 49 * @mask: clocksource mask 50 * @mult: clocksource multiplier 51 * @shift: clocksource shift 52 * @basetime[clock_id]: basetime per clock_id 53 * @tz_minuteswest: minutes west of Greenwich 54 * @tz_dsttime: type of DST correction 55 * @hrtimer_res: hrtimer resolution 56 * @__unused: unused 57 * 58 * vdso_data will be accessed by 64 bit and compat code at the same time 59 * so we should be careful before modifying this structure. 60 */ 61 struct vdso_data { 62 u32 seq; 63 64 s32 clock_mode; 65 u64 cycle_last; 66 u64 mask; 67 u32 mult; 68 u32 shift; 69 70 struct vdso_timestamp basetime[VDSO_BASES]; 71 72 s32 tz_minuteswest; 73 s32 tz_dsttime; 74 u32 hrtimer_res; 75 u32 __unused; 76 }; 77 78 /* 79 * We use the hidden visibility to prevent the compiler from generating a GOT 80 * relocation. Not only is going through a GOT useless (the entry couldn't and 81 * must not be overridden by another library), it does not even work: the linker 82 * cannot generate an absolute address to the data page. 83 * 84 * With the hidden visibility, the compiler simply generates a PC-relative 85 * relocation, and this is what we need. 86 */ 87 extern struct vdso_data _vdso_data[CS_BASES] __attribute__((visibility("hidden"))); 88 89 #endif /* !__ASSEMBLY__ */ 90 91 #endif /* __KERNEL__ */ 92 93 #endif /* __VDSO_DATAPAGE_H */ 94