On Wed, Jan 17, 2018 at 8:54 AM, Mathieu Desnoyers <[email protected]> wrote: > 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]> > Reviewed-by: Thomas Gleixner <[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: 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] > --- > Changes since v1: > - Fix prototype of sync_core_before_usermode in generic code (missing > return type). > - Add linux/processor.h include to sched/core.c. > - Add ARCH_HAS_SYNC_CORE_BEFORE_USERMODE to init/Kconfig. > - Fix linux/processor.h ifdef to target > CONFIG_ARCH_HAS_SYNC_CORE_BEFORE_USERMODE rather than > ARCH_HAS_SYNC_CORE_BEFORE_USERMODE. > - Move empty static inline in processor.h to generic patch. > --- > arch/x86/Kconfig | 1 + > arch/x86/include/asm/processor.h | 10 ++++++++++ > 2 files changed, 11 insertions(+) > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 20da391b5f32..0b44c8dd0e95 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/processor.h > b/arch/x86/include/asm/processor.h > index d3a67fba200a..3257d34dbb40 100644 > --- a/arch/x86/include/asm/processor.h > +++ b/arch/x86/include/asm/processor.h > @@ -722,6 +722,16 @@ 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, > + * 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; > + sync_core(); > +} --Andy
