From 7ac8707479886c75f353bfb6a8273f423cfccb23 Mon Sep 17 00:00:00 2001 From: Vincenzo Frascino Date: Fri, 21 Jun 2019 10:52:49 +0100 Subject: x86/vdso: Switch to generic vDSO implementation The x86 vDSO library requires some adaptations to take advantage of the newly introduced generic vDSO library. Introduce the following changes: - Modification of vdso.c to be compliant with the common vdso datapage - Use of lib/vdso for gettimeofday [ tglx: Massaged changelog and cleaned up the function signature formatting ] Signed-off-by: Vincenzo Frascino Signed-off-by: Thomas Gleixner Cc: linux-arch@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-mips@vger.kernel.org Cc: linux-kselftest@vger.kernel.org Cc: Catalin Marinas Cc: Will Deacon Cc: Arnd Bergmann Cc: Russell King Cc: Ralf Baechle Cc: Paul Burton Cc: Daniel Lezcano Cc: Mark Salyzyn Cc: Peter Collingbourne Cc: Shuah Khan Cc: Dmitry Safonov <0x7f454c46@gmail.com> Cc: Rasmus Villemoes Cc: Huw Davies Cc: Shijith Thotton Cc: Andre Przywara Link: https://lkml.kernel.org/r/20190621095252.32307-23-vincenzo.frascino@arm.com --- arch/x86/include/asm/vdso/gettimeofday.h | 191 +++++++++++++++++++++++++++++++ arch/x86/include/asm/vdso/vsyscall.h | 44 +++++++ 2 files changed, 235 insertions(+) create mode 100644 arch/x86/include/asm/vdso/gettimeofday.h create mode 100644 arch/x86/include/asm/vdso/vsyscall.h (limited to 'arch/x86/include/asm/vdso') diff --git a/arch/x86/include/asm/vdso/gettimeofday.h b/arch/x86/include/asm/vdso/gettimeofday.h new file mode 100644 index 000000000000..0e2650fc191b --- /dev/null +++ b/arch/x86/include/asm/vdso/gettimeofday.h @@ -0,0 +1,191 @@ +/* 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 + * sponsored by Rohde & Schwarz GmbH & Co. KG Munich/Germany + */ +#ifndef __ASM_VDSO_GETTIMEOFDAY_H +#define __ASM_VDSO_GETTIMEOFDAY_H + +#ifndef __ASSEMBLY__ + +#include +#include +#include +#include +#include +#include +#include + +#define __vdso_data (VVAR(_vdso_data)) + +#define VDSO_HAS_TIME 1 + +#ifdef CONFIG_PARAVIRT_CLOCK +extern u8 pvclock_page[PAGE_SIZE] + __attribute__((visibility("hidden"))); +#endif + +#ifdef CONFIG_HYPERV_TSCPAGE +extern u8 hvclock_page[PAGE_SIZE] + __attribute__((visibility("hidden"))); +#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; +} + +#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 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; +} + +#endif + +#ifdef CONFIG_PARAVIRT_CLOCK +static const struct pvclock_vsyscall_time_info *get_pvti0(void) +{ + return (const struct pvclock_vsyscall_time_info *)&pvclock_page; +} + +static u64 vread_pvclock(void) +{ + const struct pvclock_vcpu_time_info *pvti = &get_pvti0()->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_TSCPAGE +static u64 vread_hvclock(void) +{ + const struct ms_hyperv_tsc_page *tsc_pg = + (const struct ms_hyperv_tsc_page *)&hvclock_page; + + return hv_read_tsc_page(tsc_pg); +} +#endif + +static inline u64 __arch_get_hw_counter(s32 clock_mode) +{ + if (clock_mode == VCLOCK_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 == VCLOCK_PVCLOCK) { + barrier(); + return vread_pvclock(); + } +#endif +#ifdef CONFIG_HYPERV_TSCPAGE + if (clock_mode == VCLOCK_HVCLOCK) { + barrier(); + return vread_hvclock(); + } +#endif + return U64_MAX; +} + +static __always_inline const struct vdso_data *__arch_get_vdso_data(void) +{ + return __vdso_data; +} + +#endif /* !__ASSEMBLY__ */ + +#endif /* __ASM_VDSO_GETTIMEOFDAY_H */ diff --git a/arch/x86/include/asm/vdso/vsyscall.h b/arch/x86/include/asm/vdso/vsyscall.h new file mode 100644 index 000000000000..0026ab2123ce --- /dev/null +++ b/arch/x86/include/asm/vdso/vsyscall.h @@ -0,0 +1,44 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_VDSO_VSYSCALL_H +#define __ASM_VDSO_VSYSCALL_H + +#ifndef __ASSEMBLY__ + +#include +#include +#include +#include +#include + +int vclocks_used __read_mostly; + +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 + +static __always_inline +int __x86_get_clock_mode(struct timekeeper *tk) +{ + int vclock_mode = tk->tkr_mono.clock->archdata.vclock_mode; + + /* Mark the new vclock used. */ + BUILD_BUG_ON(VCLOCK_MAX >= 32); + WRITE_ONCE(vclocks_used, READ_ONCE(vclocks_used) | (1 << vclock_mode)); + + return vclock_mode; +} +#define __arch_get_clock_mode __x86_get_clock_mode + +/* The asm-generic header needs to be included after the definitions above */ +#include + +#endif /* !__ASSEMBLY__ */ + +#endif /* __ASM_VDSO_VSYSCALL_H */ -- cgit