diff options
Diffstat (limited to 'arch/x86/include/asm/vdso')
| -rw-r--r-- | arch/x86/include/asm/vdso/clocksource.h | 12 | ||||
| -rw-r--r-- | arch/x86/include/asm/vdso/gettimeofday.h | 323 | ||||
| -rw-r--r-- | arch/x86/include/asm/vdso/processor.h | 23 | ||||
| -rw-r--r-- | arch/x86/include/asm/vdso/vsyscall.h | 29 |
4 files changed, 387 insertions, 0 deletions
diff --git a/arch/x86/include/asm/vdso/clocksource.h b/arch/x86/include/asm/vdso/clocksource.h new file mode 100644 index 000000000..136e5e57c --- /dev/null +++ b/arch/x86/include/asm/vdso/clocksource.h @@ -0,0 +1,12 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_VDSO_CLOCKSOURCE_H +#define __ASM_VDSO_CLOCKSOURCE_H + +#define VDSO_ARCH_CLOCKMODES \ + VDSO_CLOCKMODE_TSC, \ + VDSO_CLOCKMODE_PVCLOCK, \ + VDSO_CLOCKMODE_HVCLOCK + +#define HAVE_VDSO_CLOCKMODE_HVCLOCK + +#endif /* __ASM_VDSO_CLOCKSOURCE_H */ diff --git a/arch/x86/include/asm/vdso/gettimeofday.h b/arch/x86/include/asm/vdso/gettimeofday.h new file mode 100644 index 000000000..1936f21ed --- /dev/null +++ b/arch/x86/include/asm/vdso/gettimeofday.h @@ -0,0 +1,323 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Fast user context implementation of clock_gettime, gettimeofday, and time. + * + * Copyright (C) 2019 ARM Limited. + * Copyright 2006 Andi Kleen, SUSE Labs. + * 32 Bit compat layer by Stefani Seibold <stefani@seibold.net> + * sponsored by Rohde & Schwarz GmbH & Co. KG Munich/Germany + */ +#ifndef __ASM_VDSO_GETTIMEOFDAY_H +#define __ASM_VDSO_GETTIMEOFDAY_H + +#ifndef __ASSEMBLY__ + +#include <uapi/linux/time.h> +#include <asm/vgtod.h> +#include <asm/vvar.h> +#include <asm/unistd.h> +#include <asm/msr.h> +#include <asm/pvclock.h> +#include <clocksource/hyperv_timer.h> + +#define __vdso_data (VVAR(_vdso_data)) +#define __timens_vdso_data (TIMENS(_vdso_data)) + +#define VDSO_HAS_TIME 1 + +#define VDSO_HAS_CLOCK_GETRES 1 + +/* + * Declare the memory-mapped vclock data pages. These come from hypervisors. + * If we ever reintroduce something like direct access to an MMIO clock like + * the HPET again, it will go here as well. + * + * A load from any of these pages will segfault if the clock in question is + * disabled, so appropriate compiler barriers and checks need to be used + * to prevent stray loads. + * + * These declarations MUST NOT be const. The compiler will assume that + * an extern const variable has genuinely constant contents, and the + * resulting code won't work, since the whole point is that these pages + * change over time, possibly while we're accessing them. + */ + +#ifdef CONFIG_PARAVIRT_CLOCK +/* + * This is the vCPU 0 pvclock page. We only use pvclock from the vDSO + * if the hypervisor tells us that all vCPUs can get valid data from the + * vCPU 0 page. + */ +extern struct pvclock_vsyscall_time_info pvclock_page + __attribute__((visibility("hidden"))); +#endif + +#ifdef CONFIG_HYPERV_TIMER +extern struct ms_hyperv_tsc_page hvclock_page + __attribute__((visibility("hidden"))); +#endif + +#ifdef CONFIG_TIME_NS +static __always_inline +const struct vdso_data *__arch_get_timens_vdso_data(const struct vdso_data *vd) +{ + return __timens_vdso_data; +} +#endif + +#ifndef BUILD_VDSO32 + +static __always_inline +long clock_gettime_fallback(clockid_t _clkid, struct __kernel_timespec *_ts) +{ + long ret; + + asm ("syscall" : "=a" (ret), "=m" (*_ts) : + "0" (__NR_clock_gettime), "D" (_clkid), "S" (_ts) : + "rcx", "r11"); + + return ret; +} + +static __always_inline +long gettimeofday_fallback(struct __kernel_old_timeval *_tv, + struct timezone *_tz) +{ + long ret; + + asm("syscall" : "=a" (ret) : + "0" (__NR_gettimeofday), "D" (_tv), "S" (_tz) : "memory"); + + return ret; +} + +static __always_inline +long clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts) +{ + long ret; + + asm ("syscall" : "=a" (ret), "=m" (*_ts) : + "0" (__NR_clock_getres), "D" (_clkid), "S" (_ts) : + "rcx", "r11"); + + return ret; +} + +#else + +static __always_inline +long clock_gettime_fallback(clockid_t _clkid, struct __kernel_timespec *_ts) +{ + long ret; + + asm ( + "mov %%ebx, %%edx \n" + "mov %[clock], %%ebx \n" + "call __kernel_vsyscall \n" + "mov %%edx, %%ebx \n" + : "=a" (ret), "=m" (*_ts) + : "0" (__NR_clock_gettime64), [clock] "g" (_clkid), "c" (_ts) + : "edx"); + + return ret; +} + +static __always_inline +long clock_gettime32_fallback(clockid_t _clkid, struct old_timespec32 *_ts) +{ + long ret; + + asm ( + "mov %%ebx, %%edx \n" + "mov %[clock], %%ebx \n" + "call __kernel_vsyscall \n" + "mov %%edx, %%ebx \n" + : "=a" (ret), "=m" (*_ts) + : "0" (__NR_clock_gettime), [clock] "g" (_clkid), "c" (_ts) + : "edx"); + + return ret; +} + +static __always_inline +long gettimeofday_fallback(struct __kernel_old_timeval *_tv, + struct timezone *_tz) +{ + long ret; + + asm( + "mov %%ebx, %%edx \n" + "mov %2, %%ebx \n" + "call __kernel_vsyscall \n" + "mov %%edx, %%ebx \n" + : "=a" (ret) + : "0" (__NR_gettimeofday), "g" (_tv), "c" (_tz) + : "memory", "edx"); + + return ret; +} + +static __always_inline long +clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts) +{ + long ret; + + asm ( + "mov %%ebx, %%edx \n" + "mov %[clock], %%ebx \n" + "call __kernel_vsyscall \n" + "mov %%edx, %%ebx \n" + : "=a" (ret), "=m" (*_ts) + : "0" (__NR_clock_getres_time64), [clock] "g" (_clkid), "c" (_ts) + : "edx"); + + return ret; +} + +static __always_inline +long clock_getres32_fallback(clockid_t _clkid, struct old_timespec32 *_ts) +{ + long ret; + + asm ( + "mov %%ebx, %%edx \n" + "mov %[clock], %%ebx \n" + "call __kernel_vsyscall \n" + "mov %%edx, %%ebx \n" + : "=a" (ret), "=m" (*_ts) + : "0" (__NR_clock_getres), [clock] "g" (_clkid), "c" (_ts) + : "edx"); + + return ret; +} + +#endif + +#ifdef CONFIG_PARAVIRT_CLOCK +static u64 vread_pvclock(void) +{ + const struct pvclock_vcpu_time_info *pvti = &pvclock_page.pvti; + u32 version; + u64 ret; + + /* + * Note: The kernel and hypervisor must guarantee that cpu ID + * number maps 1:1 to per-CPU pvclock time info. + * + * Because the hypervisor is entirely unaware of guest userspace + * preemption, it cannot guarantee that per-CPU pvclock time + * info is updated if the underlying CPU changes or that that + * version is increased whenever underlying CPU changes. + * + * On KVM, we are guaranteed that pvti updates for any vCPU are + * atomic as seen by *all* vCPUs. This is an even stronger + * guarantee than we get with a normal seqlock. + * + * On Xen, we don't appear to have that guarantee, but Xen still + * supplies a valid seqlock using the version field. + * + * We only do pvclock vdso timing at all if + * PVCLOCK_TSC_STABLE_BIT is set, and we interpret that bit to + * mean that all vCPUs have matching pvti and that the TSC is + * synced, so we can just look at vCPU 0's pvti. + */ + + do { + version = pvclock_read_begin(pvti); + + if (unlikely(!(pvti->flags & PVCLOCK_TSC_STABLE_BIT))) + return U64_MAX; + + ret = __pvclock_read_cycles(pvti, rdtsc_ordered()); + } while (pvclock_read_retry(pvti, version)); + + return ret; +} +#endif + +#ifdef CONFIG_HYPERV_TIMER +static u64 vread_hvclock(void) +{ + return hv_read_tsc_page(&hvclock_page); +} +#endif + +static inline u64 __arch_get_hw_counter(s32 clock_mode, + const struct vdso_data *vd) +{ + if (likely(clock_mode == VDSO_CLOCKMODE_TSC)) + return (u64)rdtsc_ordered(); + /* + * For any memory-mapped vclock type, we need to make sure that gcc + * doesn't cleverly hoist a load before the mode check. Otherwise we + * might end up touching the memory-mapped page even if the vclock in + * question isn't enabled, which will segfault. Hence the barriers. + */ +#ifdef CONFIG_PARAVIRT_CLOCK + if (clock_mode == VDSO_CLOCKMODE_PVCLOCK) { + barrier(); + return vread_pvclock(); + } +#endif +#ifdef CONFIG_HYPERV_TIMER + if (clock_mode == VDSO_CLOCKMODE_HVCLOCK) { + barrier(); + return vread_hvclock(); + } +#endif + return U64_MAX; +} + +static __always_inline const struct vdso_data *__arch_get_vdso_data(void) +{ + return __vdso_data; +} + +static inline bool arch_vdso_clocksource_ok(const struct vdso_data *vd) +{ + return true; +} +#define vdso_clocksource_ok arch_vdso_clocksource_ok + +/* + * Clocksource read value validation to handle PV and HyperV clocksources + * which can be invalidated asynchronously and indicate invalidation by + * returning U64_MAX, which can be effectively tested by checking for a + * negative value after casting it to s64. + */ +static inline bool arch_vdso_cycles_ok(u64 cycles) +{ + return (s64)cycles >= 0; +} +#define vdso_cycles_ok arch_vdso_cycles_ok + +/* + * x86 specific delta calculation. + * + * The regular implementation assumes that clocksource reads are globally + * monotonic. The TSC can be slightly off across sockets which can cause + * the regular delta calculation (@cycles - @last) to return a huge time + * jump. + * + * Therefore it needs to be verified that @cycles are greater than + * @last. If not then use @last, which is the base time of the current + * conversion period. + * + * This variant also removes the masking of the subtraction because the + * clocksource mask of all VDSO capable clocksources on x86 is U64_MAX + * which would result in a pointless operation. The compiler cannot + * optimize it away as the mask comes from the vdso data and is not compile + * time constant. + */ +static __always_inline +u64 vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 mult) +{ + if (cycles > last) + return (cycles - last) * mult; + return 0; +} +#define vdso_calc_delta vdso_calc_delta + +#endif /* !__ASSEMBLY__ */ + +#endif /* __ASM_VDSO_GETTIMEOFDAY_H */ diff --git a/arch/x86/include/asm/vdso/processor.h b/arch/x86/include/asm/vdso/processor.h new file mode 100644 index 000000000..57b1a7034 --- /dev/null +++ b/arch/x86/include/asm/vdso/processor.h @@ -0,0 +1,23 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2020 ARM Ltd. + */ +#ifndef __ASM_VDSO_PROCESSOR_H +#define __ASM_VDSO_PROCESSOR_H + +#ifndef __ASSEMBLY__ + +/* REP NOP (PAUSE) is a good thing to insert into busy-wait loops. */ +static __always_inline void rep_nop(void) +{ + asm volatile("rep; nop" ::: "memory"); +} + +static __always_inline void cpu_relax(void) +{ + rep_nop(); +} + +#endif /* __ASSEMBLY__ */ + +#endif /* __ASM_VDSO_PROCESSOR_H */ diff --git a/arch/x86/include/asm/vdso/vsyscall.h b/arch/x86/include/asm/vdso/vsyscall.h new file mode 100644 index 000000000..be199a9b2 --- /dev/null +++ b/arch/x86/include/asm/vdso/vsyscall.h @@ -0,0 +1,29 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_VDSO_VSYSCALL_H +#define __ASM_VDSO_VSYSCALL_H + +#ifndef __ASSEMBLY__ + +#include <linux/hrtimer.h> +#include <linux/timekeeper_internal.h> +#include <vdso/datapage.h> +#include <asm/vgtod.h> +#include <asm/vvar.h> + +DEFINE_VVAR(struct vdso_data, _vdso_data); +/* + * Update the vDSO data page to keep in sync with kernel timekeeping. + */ +static __always_inline +struct vdso_data *__x86_get_k_vdso_data(void) +{ + return _vdso_data; +} +#define __arch_get_k_vdso_data __x86_get_k_vdso_data + +/* The asm-generic header needs to be included after the definitions above */ +#include <asm-generic/vdso/vsyscall.h> + +#endif /* !__ASSEMBLY__ */ + +#endif /* __ASM_VDSO_VSYSCALL_H */ |