projects / lttng-modules.git / blame
| Commit | Line | Data |
|---|---|---|
| 92e2c5fe MD |
1 | /* SPDX-License-Identifier: (GPL-2.0-only) |
| 2 | * | |
| 3 | * wrapper/ibt.h | |
| 4 | * | |
| 5 | * Copyright (C) 2024 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
| 6 | */ | |
| 7 | ||
| 8 | #ifndef _LTTNG_WRAPPER_IBT_H | |
| 9 | #define _LTTNG_WRAPPER_IBT_H | |
| 10 | ||
| 11 | struct irq_ibt_state { | |
| 12 | u64 msr; | |
| 13 | unsigned long flags; | |
| 14 | }; | |
| 15 | ||
| 16 | /* | |
| 17 | * Save (disable) and restore interrupts around MSR bit change and indirect | |
| 18 | * function call to make sure this thread is not migrated to another CPU which | |
| 19 | * would not have the MSR bit cleared. | |
| 20 | */ | |
| 21 | ||
| 22 | #ifdef CONFIG_X86_KERNEL_IBT | |
| 23 | # include <asm/cpufeature.h> | |
| 24 | # include <asm/msr.h> | |
| 25 | static inline __attribute__((always_inline)) | |
| 26 | struct irq_ibt_state wrapper_irq_ibt_save(void) | |
| 27 | { | |
| 28 | struct irq_ibt_state state = { 0, 0 }; | |
| 29 | u64 msr; | |
| 30 | ||
| 31 | if (!cpu_feature_enabled(X86_FEATURE_IBT)) | |
| 32 | goto end; | |
| 33 | local_irq_save(state.flags); | |
| 34 | rdmsrl(MSR_IA32_S_CET, msr); | |
| 35 | wrmsrl(MSR_IA32_S_CET, msr & ~CET_ENDBR_EN); | |
| 36 | state.msr = msr; | |
| 37 | end: | |
| 38 | return state; | |
| 39 | } | |
| 40 | ||
| 41 | static inline __attribute__((always_inline)) | |
| 42 | void wrapper_irq_ibt_restore(struct irq_ibt_state state) | |
| 43 | { | |
| 44 | u64 msr; | |
| 45 | ||
| 46 | if (!cpu_feature_enabled(X86_FEATURE_IBT)) | |
| 47 | return; | |
| 48 | rdmsrl(MSR_IA32_S_CET, msr); | |
| 49 | msr &= ~CET_ENDBR_EN; | |
| 50 | msr |= (state.msr & CET_ENDBR_EN); | |
| 51 | wrmsrl(MSR_IA32_S_CET, msr); | |
| 52 | local_irq_restore(state.flags); | |
| 53 | } | |
| 54 | #else | |
| 55 | static inline struct irq_ibt_state wrapper_irq_ibt_save(void) { struct irq_ibt_state state = { 0, 0 }; return state; } | |
| 56 | static inline void wrapper_irq_ibt_restore(struct irq_ibt_state state) { } | |
| 57 | #endif | |
| 58 | ||
| 59 | #endif /* _LTTNG_WRAPPER_IBT_H */ |