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27e11a9fe2
Provide the following fixes for the __arch_get_hw_counter() implementation on arm64: - Fallback on syscall when an unstable counter is detected. - Introduce isb()s before and after the counter read to avoid speculation of the counter value and of the seq lock respectively. The second isb() is a temporary solution that will be revisited in 5.3-rc1. These fixes restore the semantics that __arch_counter_get_cntvct() had on arm64. Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> 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@arm.com Cc: will.deacon@arm.com Cc: arnd@arndb.de Cc: linux@armlinux.org.uk Cc: ralf@linux-mips.org Cc: paul.burton@mips.com Cc: daniel.lezcano@linaro.org Cc: salyzyn@android.com Cc: pcc@google.com Cc: shuah@kernel.org Cc: 0x7f454c46@gmail.com Cc: linux@rasmusvillemoes.dk Cc: huw@codeweavers.com Cc: sthotton@marvell.com Cc: andre.przywara@arm.com Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Link: https://lkml.kernel.org/r/20190625161804.38713-2-vincenzo.frascino@arm.com
104 lines
2.1 KiB
C
104 lines
2.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 2018 ARM Limited
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*/
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#ifndef __ASM_VDSO_GETTIMEOFDAY_H
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#define __ASM_VDSO_GETTIMEOFDAY_H
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#ifndef __ASSEMBLY__
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#include <asm/unistd.h>
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#include <uapi/linux/time.h>
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#define __VDSO_USE_SYSCALL ULLONG_MAX
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#define VDSO_HAS_CLOCK_GETRES 1
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static __always_inline
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int gettimeofday_fallback(struct __kernel_old_timeval *_tv,
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struct timezone *_tz)
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{
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register struct timezone *tz asm("x1") = _tz;
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register struct __kernel_old_timeval *tv asm("x0") = _tv;
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register long ret asm ("x0");
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register long nr asm("x8") = __NR_gettimeofday;
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asm volatile(
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" svc #0\n"
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: "=r" (ret)
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: "r" (tv), "r" (tz), "r" (nr)
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: "memory");
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return ret;
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}
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static __always_inline
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long clock_gettime_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
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{
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register struct __kernel_timespec *ts asm("x1") = _ts;
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register clockid_t clkid asm("x0") = _clkid;
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register long ret asm ("x0");
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register long nr asm("x8") = __NR_clock_gettime;
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asm volatile(
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" svc #0\n"
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: "=r" (ret)
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: "r" (clkid), "r" (ts), "r" (nr)
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: "memory");
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return ret;
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}
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static __always_inline
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int clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
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{
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register struct __kernel_timespec *ts asm("x1") = _ts;
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register clockid_t clkid asm("x0") = _clkid;
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register long ret asm ("x0");
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register long nr asm("x8") = __NR_clock_getres;
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asm volatile(
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" svc #0\n"
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: "=r" (ret)
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: "r" (clkid), "r" (ts), "r" (nr)
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: "memory");
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return ret;
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}
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static __always_inline u64 __arch_get_hw_counter(s32 clock_mode)
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{
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u64 res;
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/*
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* clock_mode == 0 implies that vDSO are enabled otherwise
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* fallback on syscall.
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*/
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if (clock_mode)
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return __VDSO_USE_SYSCALL;
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/*
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* This isb() is required to prevent that the counter value
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* is speculated.
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*/
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isb();
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asm volatile("mrs %0, cntvct_el0" : "=r" (res) :: "memory");
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/*
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* This isb() is required to prevent that the seq lock is
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* speculated.#
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*/
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isb();
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return res;
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}
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static __always_inline
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const struct vdso_data *__arch_get_vdso_data(void)
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{
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return _vdso_data;
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}
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#endif /* !__ASSEMBLY__ */
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#endif /* __ASM_VDSO_GETTIMEOFDAY_H */
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