Commit-ID: ac1ab12a3e6e878274e7107c8c6f326694a1c1f3 Gitweb: https://git.kernel.org/tip/ac1ab12a3e6e878274e7107c8c6f326694a1c1f3 Author: Mathieu Desnoyers <[email protected]> AuthorDate: Mon, 29 Jan 2018 15:20:16 -0500 Committer: Ingo Molnar <[email protected]> CommitDate: Mon, 5 Feb 2018 21:34:57 +0100
lockin/x86: Implement sync_core_before_usermode() Ensure that a core serializing instruction is issued before returning to user-mode. x86 implements return to user-space through sysexit, sysrel, and sysretq, which are not core serializing. Signed-off-by: Mathieu Desnoyers <[email protected]> Acked-by: Thomas Gleixner <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Cc: Andrea Parri <[email protected]> Cc: Andrew Hunter <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Arnd Bergmann <[email protected]> Cc: Avi Kivity <[email protected]> Cc: Benjamin Herrenschmidt <[email protected]> Cc: Boqun Feng <[email protected]> Cc: Dave Watson <[email protected]> Cc: David Sehr <[email protected]> Cc: Greg Hackmann <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Maged Michael <[email protected]> Cc: Michael Ellerman <[email protected]> Cc: Paul E. McKenney <[email protected]> Cc: Paul Mackerras <[email protected]> Cc: Russell King <[email protected]> Cc: Will Deacon <[email protected]> Cc: [email protected] Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/Kconfig | 1 + arch/x86/include/asm/sync_core.h | 28 ++++++++++++++++++++++++++++ 2 files changed, 29 insertions(+) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 423e4b6..31030ad 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -61,6 +61,7 @@ config X86 select ARCH_HAS_SG_CHAIN select ARCH_HAS_STRICT_KERNEL_RWX select ARCH_HAS_STRICT_MODULE_RWX + select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE select ARCH_HAS_UBSAN_SANITIZE_ALL select ARCH_HAS_ZONE_DEVICE if X86_64 select ARCH_HAVE_NMI_SAFE_CMPXCHG diff --git a/arch/x86/include/asm/sync_core.h b/arch/x86/include/asm/sync_core.h new file mode 100644 index 0000000..c67caaf --- /dev/null +++ b/arch/x86/include/asm/sync_core.h @@ -0,0 +1,28 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_X86_SYNC_CORE_H +#define _ASM_X86_SYNC_CORE_H + +#include <linux/preempt.h> +#include <asm/processor.h> +#include <asm/cpufeature.h> + +/* + * Ensure that a core serializing instruction is issued before returning + * to user-mode. x86 implements return to user-space through sysexit, + * sysrel, and sysretq, which are not core serializing. + */ +static inline void sync_core_before_usermode(void) +{ + /* With PTI, we unconditionally serialize before running user code. */ + if (static_cpu_has(X86_FEATURE_PTI)) + return; + /* + * Return from interrupt and NMI is done through iret, which is core + * serializing. + */ + if (in_irq() || in_nmi()) + return; + sync_core(); +} + +#endif /* _ASM_X86_SYNC_CORE_H */
