----- 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 ? Thanks, Mathieu > >> + sync_core(); >> +} > > --Andy -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
