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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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6241c4dc6e
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/20190625161804.38713-3-vincenzo.frascino@arm.com
127 lines
3.0 KiB
C
127 lines
3.0 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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#include <asm/vdso/compat_barrier.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("r1") = _tz;
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register struct __kernel_old_timeval *tv asm("r0") = _tv;
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register long ret asm ("r0");
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register long nr asm("r7") = __NR_compat_gettimeofday;
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asm volatile(
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" swi #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("r1") = _ts;
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register clockid_t clkid asm("r0") = _clkid;
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register long ret asm ("r0");
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register long nr asm("r7") = __NR_compat_clock_gettime64;
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asm volatile(
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" swi #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("r1") = _ts;
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register clockid_t clkid asm("r0") = _clkid;
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register long ret asm ("r0");
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register long nr asm("r7") = __NR_compat_clock_getres_time64;
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/* The checks below are required for ABI consistency with arm */
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if ((_clkid >= MAX_CLOCKS) && (_ts == NULL))
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return -EINVAL;
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asm volatile(
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" swi #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("mrrc p15, 1, %Q0, %R0, c14" : "=r" (res));
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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 const struct vdso_data *__arch_get_vdso_data(void)
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{
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const struct vdso_data *ret;
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/*
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* This simply puts &_vdso_data into ret. The reason why we don't use
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* `ret = _vdso_data` is that the compiler tends to optimise this in a
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* very suboptimal way: instead of keeping &_vdso_data in a register,
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* it goes through a relocation almost every time _vdso_data must be
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* accessed (even in subfunctions). This is both time and space
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* consuming: each relocation uses a word in the code section, and it
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* has to be loaded at runtime.
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*
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* This trick hides the assignment from the compiler. Since it cannot
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* track where the pointer comes from, it will only use one relocation
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* where __arch_get_vdso_data() is called, and then keep the result in
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* a register.
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*/
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asm volatile("mov %0, %1" : "=r"(ret) : "r"(_vdso_data));
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return ret;
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}
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#endif /* !__ASSEMBLY__ */
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#endif /* __ASM_VDSO_GETTIMEOFDAY_H */
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