439 lines
10 KiB
C
439 lines
10 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Generic userspace implementations of gettimeofday() and similar.
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*/
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#include <vdso/datapage.h>
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#include <vdso/helpers.h>
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#ifndef vdso_calc_delta
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/*
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* Default implementation which works for all sane clocksources. That
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* obviously excludes x86/TSC.
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*/
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static __always_inline
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u64 vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 mult)
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{
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return ((cycles - last) & mask) * mult;
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}
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#endif
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#ifndef vdso_shift_ns
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static __always_inline u64 vdso_shift_ns(u64 ns, u32 shift)
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{
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return ns >> shift;
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}
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#endif
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#ifndef __arch_vdso_hres_capable
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static inline bool __arch_vdso_hres_capable(void)
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{
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return true;
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}
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#endif
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#ifndef vdso_clocksource_ok
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static inline bool vdso_clocksource_ok(const struct vdso_data *vd)
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{
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return vd->clock_mode != VDSO_CLOCKMODE_NONE;
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}
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#endif
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#ifndef vdso_cycles_ok
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static inline bool vdso_cycles_ok(u64 cycles)
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{
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return true;
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}
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#endif
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#ifdef CONFIG_TIME_NS
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static int do_hres_timens(const struct vdso_data *vdns, clockid_t clk,
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struct __kernel_timespec *ts)
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{
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const struct vdso_data *vd = __arch_get_timens_vdso_data();
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const struct timens_offset *offs = &vdns->offset[clk];
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const struct vdso_timestamp *vdso_ts;
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u64 cycles, last, ns;
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u32 seq;
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s64 sec;
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if (clk != CLOCK_MONOTONIC_RAW)
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vd = &vd[CS_HRES_COARSE];
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else
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vd = &vd[CS_RAW];
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vdso_ts = &vd->basetime[clk];
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do {
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seq = vdso_read_begin(vd);
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if (unlikely(!vdso_clocksource_ok(vd)))
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return -1;
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cycles = __arch_get_hw_counter(vd->clock_mode, vd);
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if (unlikely(!vdso_cycles_ok(cycles)))
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return -1;
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ns = vdso_ts->nsec;
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last = vd->cycle_last;
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ns += vdso_calc_delta(cycles, last, vd->mask, vd->mult);
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ns = vdso_shift_ns(ns, vd->shift);
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sec = vdso_ts->sec;
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} while (unlikely(vdso_read_retry(vd, seq)));
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/* Add the namespace offset */
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sec += offs->sec;
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ns += offs->nsec;
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/*
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* Do this outside the loop: a race inside the loop could result
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* in __iter_div_u64_rem() being extremely slow.
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*/
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ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
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ts->tv_nsec = ns;
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return 0;
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}
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#else
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static __always_inline const struct vdso_data *__arch_get_timens_vdso_data(void)
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{
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return NULL;
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}
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static int do_hres_timens(const struct vdso_data *vdns, clockid_t clk,
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struct __kernel_timespec *ts)
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{
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return -EINVAL;
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}
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#endif
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static __always_inline int do_hres(const struct vdso_data *vd, clockid_t clk,
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struct __kernel_timespec *ts)
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{
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const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
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u64 cycles, last, sec, ns;
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u32 seq;
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/* Allows to compile the high resolution parts out */
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if (!__arch_vdso_hres_capable())
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return -1;
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do {
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/*
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* Open coded to handle VDSO_CLOCKMODE_TIMENS. Time namespace
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* enabled tasks have a special VVAR page installed which
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* has vd->seq set to 1 and vd->clock_mode set to
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* VDSO_CLOCKMODE_TIMENS. For non time namespace affected tasks
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* this does not affect performance because if vd->seq is
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* odd, i.e. a concurrent update is in progress the extra
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* check for vd->clock_mode is just a few extra
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* instructions while spin waiting for vd->seq to become
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* even again.
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*/
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while (unlikely((seq = READ_ONCE(vd->seq)) & 1)) {
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if (IS_ENABLED(CONFIG_TIME_NS) &&
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vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
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return do_hres_timens(vd, clk, ts);
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cpu_relax();
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}
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smp_rmb();
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if (unlikely(!vdso_clocksource_ok(vd)))
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return -1;
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cycles = __arch_get_hw_counter(vd->clock_mode, vd);
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if (unlikely(!vdso_cycles_ok(cycles)))
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return -1;
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ns = vdso_ts->nsec;
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last = vd->cycle_last;
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ns += vdso_calc_delta(cycles, last, vd->mask, vd->mult);
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ns = vdso_shift_ns(ns, vd->shift);
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sec = vdso_ts->sec;
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} while (unlikely(vdso_read_retry(vd, seq)));
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/*
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* Do this outside the loop: a race inside the loop could result
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* in __iter_div_u64_rem() being extremely slow.
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*/
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ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
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ts->tv_nsec = ns;
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return 0;
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}
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#ifdef CONFIG_TIME_NS
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static int do_coarse_timens(const struct vdso_data *vdns, clockid_t clk,
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struct __kernel_timespec *ts)
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{
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const struct vdso_data *vd = __arch_get_timens_vdso_data();
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const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
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const struct timens_offset *offs = &vdns->offset[clk];
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u64 nsec;
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s64 sec;
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s32 seq;
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do {
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seq = vdso_read_begin(vd);
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sec = vdso_ts->sec;
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nsec = vdso_ts->nsec;
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} while (unlikely(vdso_read_retry(vd, seq)));
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/* Add the namespace offset */
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sec += offs->sec;
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nsec += offs->nsec;
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/*
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* Do this outside the loop: a race inside the loop could result
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* in __iter_div_u64_rem() being extremely slow.
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*/
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ts->tv_sec = sec + __iter_div_u64_rem(nsec, NSEC_PER_SEC, &nsec);
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ts->tv_nsec = nsec;
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return 0;
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}
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#else
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static int do_coarse_timens(const struct vdso_data *vdns, clockid_t clk,
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struct __kernel_timespec *ts)
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{
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return -1;
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}
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#endif
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static __always_inline int do_coarse(const struct vdso_data *vd, clockid_t clk,
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struct __kernel_timespec *ts)
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{
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const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
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u32 seq;
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do {
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/*
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* Open coded to handle VDSO_CLOCK_TIMENS. See comment in
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* do_hres().
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*/
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while ((seq = READ_ONCE(vd->seq)) & 1) {
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if (IS_ENABLED(CONFIG_TIME_NS) &&
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vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
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return do_coarse_timens(vd, clk, ts);
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cpu_relax();
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}
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smp_rmb();
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ts->tv_sec = vdso_ts->sec;
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ts->tv_nsec = vdso_ts->nsec;
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} while (unlikely(vdso_read_retry(vd, seq)));
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return 0;
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}
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static __always_inline int
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__cvdso_clock_gettime_common(const struct vdso_data *vd, clockid_t clock,
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struct __kernel_timespec *ts)
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{
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u32 msk;
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/* Check for negative values or invalid clocks */
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if (unlikely((u32) clock >= MAX_CLOCKS))
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return -1;
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/*
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* Convert the clockid to a bitmask and use it to check which
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* clocks are handled in the VDSO directly.
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*/
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msk = 1U << clock;
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if (likely(msk & VDSO_HRES))
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vd = &vd[CS_HRES_COARSE];
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else if (msk & VDSO_COARSE)
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return do_coarse(&vd[CS_HRES_COARSE], clock, ts);
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else if (msk & VDSO_RAW)
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vd = &vd[CS_RAW];
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else
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return -1;
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return do_hres(vd, clock, ts);
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}
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static __maybe_unused int
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__cvdso_clock_gettime_data(const struct vdso_data *vd, clockid_t clock,
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struct __kernel_timespec *ts)
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{
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int ret = __cvdso_clock_gettime_common(vd, clock, ts);
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if (unlikely(ret))
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return clock_gettime_fallback(clock, ts);
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return 0;
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}
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static __maybe_unused int
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__cvdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
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{
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return __cvdso_clock_gettime_data(__arch_get_vdso_data(), clock, ts);
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}
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#ifdef BUILD_VDSO32
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static __maybe_unused int
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__cvdso_clock_gettime32_data(const struct vdso_data *vd, clockid_t clock,
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struct old_timespec32 *res)
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{
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struct __kernel_timespec ts;
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int ret;
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ret = __cvdso_clock_gettime_common(vd, clock, &ts);
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if (unlikely(ret))
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return clock_gettime32_fallback(clock, res);
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/* For ret == 0 */
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res->tv_sec = ts.tv_sec;
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res->tv_nsec = ts.tv_nsec;
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return ret;
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}
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static __maybe_unused int
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__cvdso_clock_gettime32(clockid_t clock, struct old_timespec32 *res)
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{
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return __cvdso_clock_gettime32_data(__arch_get_vdso_data(), clock, res);
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}
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#endif /* BUILD_VDSO32 */
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static __maybe_unused int
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__cvdso_gettimeofday_data(const struct vdso_data *vd,
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struct __kernel_old_timeval *tv, struct timezone *tz)
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{
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if (likely(tv != NULL)) {
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struct __kernel_timespec ts;
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if (do_hres(&vd[CS_HRES_COARSE], CLOCK_REALTIME, &ts))
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return gettimeofday_fallback(tv, tz);
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tv->tv_sec = ts.tv_sec;
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tv->tv_usec = (u32)ts.tv_nsec / NSEC_PER_USEC;
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}
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if (unlikely(tz != NULL)) {
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if (IS_ENABLED(CONFIG_TIME_NS) &&
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vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
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vd = __arch_get_timens_vdso_data();
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tz->tz_minuteswest = vd[CS_HRES_COARSE].tz_minuteswest;
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tz->tz_dsttime = vd[CS_HRES_COARSE].tz_dsttime;
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}
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return 0;
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}
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static __maybe_unused int
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__cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
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{
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return __cvdso_gettimeofday_data(__arch_get_vdso_data(), tv, tz);
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}
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#ifdef VDSO_HAS_TIME
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static __maybe_unused __kernel_old_time_t
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__cvdso_time_data(const struct vdso_data *vd, __kernel_old_time_t *time)
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{
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__kernel_old_time_t t;
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if (IS_ENABLED(CONFIG_TIME_NS) &&
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vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
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vd = __arch_get_timens_vdso_data();
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t = READ_ONCE(vd[CS_HRES_COARSE].basetime[CLOCK_REALTIME].sec);
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if (time)
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*time = t;
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return t;
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}
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static __maybe_unused __kernel_old_time_t __cvdso_time(__kernel_old_time_t *time)
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{
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return __cvdso_time_data(__arch_get_vdso_data(), time);
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}
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#endif /* VDSO_HAS_TIME */
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#ifdef VDSO_HAS_CLOCK_GETRES
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static __maybe_unused
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int __cvdso_clock_getres_common(const struct vdso_data *vd, clockid_t clock,
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struct __kernel_timespec *res)
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{
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u32 msk;
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u64 ns;
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/* Check for negative values or invalid clocks */
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if (unlikely((u32) clock >= MAX_CLOCKS))
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return -1;
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if (IS_ENABLED(CONFIG_TIME_NS) &&
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vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
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vd = __arch_get_timens_vdso_data();
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/*
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* Convert the clockid to a bitmask and use it to check which
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* clocks are handled in the VDSO directly.
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*/
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msk = 1U << clock;
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if (msk & (VDSO_HRES | VDSO_RAW)) {
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/*
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* Preserves the behaviour of posix_get_hrtimer_res().
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*/
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ns = READ_ONCE(vd[CS_HRES_COARSE].hrtimer_res);
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} else if (msk & VDSO_COARSE) {
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/*
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* Preserves the behaviour of posix_get_coarse_res().
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*/
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ns = LOW_RES_NSEC;
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} else {
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return -1;
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}
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if (likely(res)) {
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res->tv_sec = 0;
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res->tv_nsec = ns;
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}
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return 0;
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}
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static __maybe_unused
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int __cvdso_clock_getres_data(const struct vdso_data *vd, clockid_t clock,
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struct __kernel_timespec *res)
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{
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int ret = __cvdso_clock_getres_common(vd, clock, res);
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if (unlikely(ret))
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return clock_getres_fallback(clock, res);
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return 0;
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}
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static __maybe_unused
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int __cvdso_clock_getres(clockid_t clock, struct __kernel_timespec *res)
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{
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return __cvdso_clock_getres_data(__arch_get_vdso_data(), clock, res);
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}
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#ifdef BUILD_VDSO32
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static __maybe_unused int
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__cvdso_clock_getres_time32_data(const struct vdso_data *vd, clockid_t clock,
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struct old_timespec32 *res)
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{
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struct __kernel_timespec ts;
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int ret;
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ret = __cvdso_clock_getres_common(vd, clock, &ts);
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if (unlikely(ret))
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return clock_getres32_fallback(clock, res);
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if (likely(res)) {
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res->tv_sec = ts.tv_sec;
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res->tv_nsec = ts.tv_nsec;
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}
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return ret;
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}
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static __maybe_unused int
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__cvdso_clock_getres_time32(clockid_t clock, struct old_timespec32 *res)
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{
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return __cvdso_clock_getres_time32_data(__arch_get_vdso_data(),
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clock, res);
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}
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#endif /* BUILD_VDSO32 */
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#endif /* VDSO_HAS_CLOCK_GETRES */
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