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Diffstat (limited to 'include/vdso/datapage.h')
| -rw-r--r-- | include/vdso/datapage.h | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/include/vdso/datapage.h b/include/vdso/datapage.h new file mode 100644 index 000000000..73eb622e7 --- /dev/null +++ b/include/vdso/datapage.h @@ -0,0 +1,142 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __VDSO_DATAPAGE_H +#define __VDSO_DATAPAGE_H + +#ifndef __ASSEMBLY__ + +#include <linux/compiler.h> +#include <uapi/linux/time.h> +#include <uapi/linux/types.h> +#include <uapi/asm-generic/errno-base.h> + +#include <vdso/bits.h> +#include <vdso/clocksource.h> +#include <vdso/ktime.h> +#include <vdso/limits.h> +#include <vdso/math64.h> +#include <vdso/processor.h> +#include <vdso/time.h> +#include <vdso/time32.h> +#include <vdso/time64.h> + +#ifdef CONFIG_ARCH_HAS_VDSO_DATA +#include <asm/vdso/data.h> +#else +struct arch_vdso_data {}; +#endif + +#define VDSO_BASES (CLOCK_TAI + 1) +#define VDSO_HRES (BIT(CLOCK_REALTIME) | \ + BIT(CLOCK_MONOTONIC) | \ + BIT(CLOCK_BOOTTIME) | \ + BIT(CLOCK_TAI)) +#define VDSO_COARSE (BIT(CLOCK_REALTIME_COARSE) | \ + BIT(CLOCK_MONOTONIC_COARSE)) +#define VDSO_RAW (BIT(CLOCK_MONOTONIC_RAW)) + +#define CS_HRES_COARSE 0 +#define CS_RAW 1 +#define CS_BASES (CS_RAW + 1) + +/** + * struct vdso_timestamp - basetime per clock_id + * @sec: seconds + * @nsec: nanoseconds + * + * There is one vdso_timestamp object in vvar for each vDSO-accelerated + * clock_id. For high-resolution clocks, this encodes the time + * corresponding to vdso_data.cycle_last. For coarse clocks this encodes + * the actual time. + * + * To be noticed that for highres clocks nsec is left-shifted by + * vdso_data.cs[x].shift. + */ +struct vdso_timestamp { + u64 sec; + u64 nsec; +}; + +/** + * struct vdso_data - vdso datapage representation + * @seq: timebase sequence counter + * @clock_mode: clock mode + * @cycle_last: timebase at clocksource init + * @mask: clocksource mask + * @mult: clocksource multiplier + * @shift: clocksource shift + * @basetime[clock_id]: basetime per clock_id + * @offset[clock_id]: time namespace offset per clock_id + * @tz_minuteswest: minutes west of Greenwich + * @tz_dsttime: type of DST correction + * @hrtimer_res: hrtimer resolution + * @__unused: unused + * @arch_data: architecture specific data (optional, defaults + * to an empty struct) + * + * vdso_data will be accessed by 64 bit and compat code at the same time + * so we should be careful before modifying this structure. + * + * @basetime is used to store the base time for the system wide time getter + * VVAR page. + * + * @offset is used by the special time namespace VVAR pages which are + * installed instead of the real VVAR page. These namespace pages must set + * @seq to 1 and @clock_mode to VDSO_CLOCKMODE_TIMENS to force the code into + * the time namespace slow path. The namespace aware functions retrieve the + * real system wide VVAR page, read host time and add the per clock offset. + * For clocks which are not affected by time namespace adjustment the + * offset must be zero. + */ +struct vdso_data { + u32 seq; + + s32 clock_mode; + u64 cycle_last; + u64 mask; + u32 mult; + u32 shift; + + union { + struct vdso_timestamp basetime[VDSO_BASES]; + struct timens_offset offset[VDSO_BASES]; + }; + + s32 tz_minuteswest; + s32 tz_dsttime; + u32 hrtimer_res; + u32 __unused; + + struct arch_vdso_data arch_data; +}; + +/* + * We use the hidden visibility to prevent the compiler from generating a GOT + * relocation. Not only is going through a GOT useless (the entry couldn't and + * must not be overridden by another library), it does not even work: the linker + * cannot generate an absolute address to the data page. + * + * With the hidden visibility, the compiler simply generates a PC-relative + * relocation, and this is what we need. + */ +extern struct vdso_data _vdso_data[CS_BASES] __attribute__((visibility("hidden"))); +extern struct vdso_data _timens_data[CS_BASES] __attribute__((visibility("hidden"))); + +/* + * The generic vDSO implementation requires that gettimeofday.h + * provides: + * - __arch_get_vdso_data(): to get the vdso datapage. + * - __arch_get_hw_counter(): to get the hw counter based on the + * clock_mode. + * - gettimeofday_fallback(): fallback for gettimeofday. + * - clock_gettime_fallback(): fallback for clock_gettime. + * - clock_getres_fallback(): fallback for clock_getres. + */ +#ifdef ENABLE_COMPAT_VDSO +#include <asm/vdso/compat_gettimeofday.h> +#else +#include <asm/vdso/gettimeofday.h> +#endif /* ENABLE_COMPAT_VDSO */ + +#endif /* !__ASSEMBLY__ */ + +#endif /* __VDSO_DATAPAGE_H */ |