diff options
Diffstat (limited to 'arch/x86/entry')
| -rw-r--r-- | arch/x86/entry/thunk_32.S | 2 | ||||
| -rw-r--r-- | arch/x86/entry/thunk_64.S | 2 | ||||
| -rw-r--r-- | arch/x86/entry/vdso/vclock_gettime.c | 15 |
3 files changed, 15 insertions, 4 deletions
diff --git a/arch/x86/entry/thunk_32.S b/arch/x86/entry/thunk_32.S index fee6bc79b987..cb3464525b37 100644 --- a/arch/x86/entry/thunk_32.S +++ b/arch/x86/entry/thunk_32.S @@ -1,8 +1,8 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ /* * Trampoline to trace irqs off. (otherwise CALLER_ADDR1 might crash) * Copyright 2008 by Steven Rostedt, Red Hat, Inc * (inspired by Andi Kleen's thunk_64.S) - * Subject to the GNU public license, v.2. No warranty of any kind. */ #include <linux/linkage.h> #include <asm/asm.h> diff --git a/arch/x86/entry/thunk_64.S b/arch/x86/entry/thunk_64.S index be36bf4e0957..cfdca8b42c70 100644 --- a/arch/x86/entry/thunk_64.S +++ b/arch/x86/entry/thunk_64.S @@ -1,9 +1,9 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ /* * Save registers before calling assembly functions. This avoids * disturbance of register allocation in some inline assembly constructs. * Copyright 2001,2002 by Andi Kleen, SuSE Labs. * Added trace_hardirqs callers - Copyright 2007 Steven Rostedt, Red Hat, Inc. - * Subject to the GNU public license, v.2. No warranty of any kind. */ #include <linux/linkage.h> #include "calling.h" diff --git a/arch/x86/entry/vdso/vclock_gettime.c b/arch/x86/entry/vdso/vclock_gettime.c index 0f82a70c7682..4aed41f638bb 100644 --- a/arch/x86/entry/vdso/vclock_gettime.c +++ b/arch/x86/entry/vdso/vclock_gettime.c @@ -128,13 +128,24 @@ notrace static inline u64 vgetcyc(int mode) { if (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 - else if (mode == VCLOCK_PVCLOCK) + if (mode == VCLOCK_PVCLOCK) { + barrier(); return vread_pvclock(); + } #endif #ifdef CONFIG_HYPERV_TSCPAGE - else if (mode == VCLOCK_HVCLOCK) + if (mode == VCLOCK_HVCLOCK) { + barrier(); return vread_hvclock(); + } #endif return U64_MAX; } |