----- On Nov 10, 2017, at 5:02 PM, Andy Lutomirski [email protected] wrote: > On Fri, Nov 10, 2017 at 1:37 PM, Mathieu Desnoyers > <[email protected]> wrote: >> Introduce an architecture function that ensures the current CPU >> issues a core serializing instruction before returning to usermode. >> >> This is needed to fix an existing core serialization bug on >> thread migration, and also needed by the membarrier "sync_core" command. >> >> Architectures defining the sync_core_before_usermode() static inline >> need to define ARCH_HAS_SYNC_CORE_BEFORE_USERMODE. >> >> Signed-off-by: Mathieu Desnoyers <[email protected]> >> CC: Peter Zijlstra <[email protected]> >> CC: Andy Lutomirski <[email protected]> >> CC: Paul E. McKenney <[email protected]> >> CC: Boqun Feng <[email protected]> >> CC: Andrew Hunter <[email protected]> >> CC: Maged Michael <[email protected]> >> CC: Avi Kivity <[email protected]> >> CC: Benjamin Herrenschmidt <[email protected]> >> CC: Paul Mackerras <[email protected]> >> CC: Michael Ellerman <[email protected]> >> CC: Dave Watson <[email protected]> >> CC: Thomas Gleixner <[email protected]> >> CC: Ingo Molnar <[email protected]> >> CC: "H. Peter Anvin" <[email protected]> >> CC: Andrea Parri <[email protected]> >> CC: Russell King <[email protected]> >> CC: Greg Hackmann <[email protected]> >> CC: Will Deacon <[email protected]> >> CC: David Sehr <[email protected]> >> CC: Linus Torvalds <[email protected]> >> CC: [email protected] >> CC: [email protected] >> --- >> arch/x86/Kconfig | 1 + >> arch/x86/include/asm/processor.h | 10 ++++++++++ >> include/linux/processor.h | 6 ++++++ >> 3 files changed, 17 insertions(+) >> >> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig >> index 01f78c1d40b5..54fbb8960d94 100644 >> --- a/arch/x86/Kconfig >> +++ b/arch/x86/Kconfig >> @@ -62,6 +62,7 @@ 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/processor.h >> b/arch/x86/include/asm/processor.h >> index bdac19ab2488..6ce996a7c730 100644 >> --- a/arch/x86/include/asm/processor.h >> +++ b/arch/x86/include/asm/processor.h >> @@ -706,6 +706,16 @@ static inline void sync_core(void) >> #endif >> } >> >> +/* >> + * Ensure that a core serializing instruction is issued before returning >> + * to user-mode. x86 implements return to user-space through sysexit and >> + * sysretq, which are not core serializing. >> + */ >> +static inline void sync_core_before_usermode(void) >> +{ >> + sync_core(); >> +} > > Make this if (!in_interrupt()) sync_core(); please. We can optimize > it better later on.
Sure, done. It will be part of the next version of that patch. Thanks! Mathieu -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
