From a7f71a2c8903f8599312f75233946287c558d9f6 Mon Sep 17 00:00:00 2001 From: Vincenzo Frascino Date: Fri, 21 Jun 2019 10:52:37 +0100 Subject: arm64: compat: Add vDSO Provide the arm64 compat (AArch32) vDSO in kernel/vdso32 in a similar way to what happens in kernel/vdso. The compat vDSO leverages on an adaptation of the arm architecture code with few changes: - Use of lib/vdso for gettimeofday - Implement a syscall based fallback - Introduce clock_getres() for the compat library - Implement trampolines - Implement elf note To build the compat vDSO a 32 bit compiler is required and needs to be specified via CONFIG_CROSS_COMPILE_COMPAT_VDSO. The code is not yet enabled as other prerequisites are missing. Signed-off-by: Vincenzo Frascino Signed-off-by: Thomas Gleixner Tested-by: Shijith Thotton Tested-by: Andre Przywara 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 Link: https://lkml.kernel.org/r/20190621095252.32307-11-vincenzo.frascino@arm.com --- arch/arm64/include/asm/vdso/compat_barrier.h | 51 ++++++++++ arch/arm64/include/asm/vdso/compat_gettimeofday.h | 108 ++++++++++++++++++++++ 2 files changed, 159 insertions(+) create mode 100644 arch/arm64/include/asm/vdso/compat_barrier.h create mode 100644 arch/arm64/include/asm/vdso/compat_gettimeofday.h (limited to 'arch/arm64/include/asm/vdso') diff --git a/arch/arm64/include/asm/vdso/compat_barrier.h b/arch/arm64/include/asm/vdso/compat_barrier.h new file mode 100644 index 000000000000..ea24ea856b07 --- /dev/null +++ b/arch/arm64/include/asm/vdso/compat_barrier.h @@ -0,0 +1,51 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2018 ARM Limited + */ +#ifndef __COMPAT_BARRIER_H +#define __COMPAT_BARRIER_H + +#ifndef __ASSEMBLY__ +/* + * Warning: This code is meant to be used with + * ENABLE_COMPAT_VDSO only. + */ +#ifndef ENABLE_COMPAT_VDSO +#error This header is meant to be used with ENABLE_COMPAT_VDSO only +#endif + +#ifdef dmb +#undef dmb +#endif + +#if __LINUX_ARM_ARCH__ >= 7 +#define dmb(option) __asm__ __volatile__ ("dmb " #option : : : "memory") +#elif __LINUX_ARM_ARCH__ == 6 +#define dmb(x) __asm__ __volatile__ ("mcr p15, 0, %0, c7, c10, 5" \ + : : "r" (0) : "memory") +#else +#define dmb(x) __asm__ __volatile__ ("" : : : "memory") +#endif + +#if __LINUX_ARM_ARCH__ >= 8 +#define aarch32_smp_mb() dmb(ish) +#define aarch32_smp_rmb() dmb(ishld) +#define aarch32_smp_wmb() dmb(ishst) +#else +#define aarch32_smp_mb() dmb(ish) +#define aarch32_smp_rmb() aarch32_smp_mb() +#define aarch32_smp_wmb() dmb(ishst) +#endif + + +#undef smp_mb +#undef smp_rmb +#undef smp_wmb + +#define smp_mb() aarch32_smp_mb() +#define smp_rmb() aarch32_smp_rmb() +#define smp_wmb() aarch32_smp_wmb() + +#endif /* !__ASSEMBLY__ */ + +#endif /* __COMPAT_BARRIER_H */ diff --git a/arch/arm64/include/asm/vdso/compat_gettimeofday.h b/arch/arm64/include/asm/vdso/compat_gettimeofday.h new file mode 100644 index 000000000000..93dbd935b66d --- /dev/null +++ b/arch/arm64/include/asm/vdso/compat_gettimeofday.h @@ -0,0 +1,108 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2018 ARM Limited + */ +#ifndef __ASM_VDSO_GETTIMEOFDAY_H +#define __ASM_VDSO_GETTIMEOFDAY_H + +#ifndef __ASSEMBLY__ + +#include +#include + +#include + +#define VDSO_HAS_CLOCK_GETRES 1 + +static __always_inline +int gettimeofday_fallback(struct __kernel_old_timeval *_tv, + struct timezone *_tz) +{ + register struct timezone *tz asm("r1") = _tz; + register struct __kernel_old_timeval *tv asm("r0") = _tv; + register long ret asm ("r0"); + register long nr asm("r7") = __NR_compat_gettimeofday; + + asm volatile( + " swi #0\n" + : "=r" (ret) + : "r" (tv), "r" (tz), "r" (nr) + : "memory"); + + return ret; +} + +static __always_inline +long clock_gettime_fallback(clockid_t _clkid, struct __kernel_timespec *_ts) +{ + register struct __kernel_timespec *ts asm("r1") = _ts; + register clockid_t clkid asm("r0") = _clkid; + register long ret asm ("r0"); + register long nr asm("r7") = __NR_compat_clock_gettime64; + + asm volatile( + " swi #0\n" + : "=r" (ret) + : "r" (clkid), "r" (ts), "r" (nr) + : "memory"); + + return ret; +} + +static __always_inline +int clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts) +{ + register struct __kernel_timespec *ts asm("r1") = _ts; + register clockid_t clkid asm("r0") = _clkid; + register long ret asm ("r0"); + register long nr asm("r7") = __NR_compat_clock_getres_time64; + + /* The checks below are required for ABI consistency with arm */ + if ((_clkid >= MAX_CLOCKS) && (_ts == NULL)) + return -EINVAL; + + asm volatile( + " swi #0\n" + : "=r" (ret) + : "r" (clkid), "r" (ts), "r" (nr) + : "memory"); + + return ret; +} + +static __always_inline u64 __arch_get_hw_counter(s32 clock_mode) +{ + u64 res; + + isb(); + asm volatile("mrrc p15, 1, %Q0, %R0, c14" : "=r" (res)); + + return res; +} + +static __always_inline const struct vdso_data *__arch_get_vdso_data(void) +{ + const struct vdso_data *ret; + + /* + * This simply puts &_vdso_data into ret. The reason why we don't use + * `ret = _vdso_data` is that the compiler tends to optimise this in a + * very suboptimal way: instead of keeping &_vdso_data in a register, + * it goes through a relocation almost every time _vdso_data must be + * accessed (even in subfunctions). This is both time and space + * consuming: each relocation uses a word in the code section, and it + * has to be loaded at runtime. + * + * This trick hides the assignment from the compiler. Since it cannot + * track where the pointer comes from, it will only use one relocation + * where __arch_get_vdso_data() is called, and then keep the result in + * a register. + */ + asm volatile("mov %0, %1" : "=r"(ret) : "r"(_vdso_data)); + + return ret; +} + +#endif /* !__ASSEMBLY__ */ + +#endif /* __ASM_VDSO_GETTIMEOFDAY_H */ -- cgit v1.2.3