On Wed, Jan 17, 2018 at 10:10 AM, Mathieu Desnoyers <[email protected]> wrote: > ----- On Jan 17, 2018, at 12:53 PM, Andy Lutomirski [email protected] wrote: > >> 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; > > One issue I'm facing with this change is header dependency: > sync_core_before_usermode() is currently implemented in > arch/x86/include/asm/processor.h, but arch/x86/include/asm/cpufeature.h > is needed for static_cpu_has, and it happens to include > asm/processor.h. > > I'm facing a similar issue for adding a (in_irq() || in_nmi()) check. > > Should we move sync_core_before_usermode() to a different header, and if > so, any suggestion ?
tlbflush.h, maybe? > > Thanks, > > Mathieu > > > >> >>> + sync_core(); >>> +} >> >> --Andy > > -- > Mathieu Desnoyers > EfficiOS Inc. > http://www.efficios.com
