Messages in this thread Patch in this message | | | From | Mathieu Desnoyers <> | Subject | [RFC PATCH for 4.15 05/10] x86: Introduce sync_core_before_usermode | Date | Fri, 10 Nov 2017 16:37:12 -0500 |
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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 <mathieu.desnoyers@efficios.com> CC: Peter Zijlstra <peterz@infradead.org> CC: Andy Lutomirski <luto@kernel.org> CC: Paul E. McKenney <paulmck@linux.vnet.ibm.com> CC: Boqun Feng <boqun.feng@gmail.com> CC: Andrew Hunter <ahh@google.com> CC: Maged Michael <maged.michael@gmail.com> CC: Avi Kivity <avi@scylladb.com> CC: Benjamin Herrenschmidt <benh@kernel.crashing.org> CC: Paul Mackerras <paulus@samba.org> CC: Michael Ellerman <mpe@ellerman.id.au> CC: Dave Watson <davejwatson@fb.com> CC: Thomas Gleixner <tglx@linutronix.de> CC: Ingo Molnar <mingo@redhat.com> CC: "H. Peter Anvin" <hpa@zytor.com> CC: Andrea Parri <parri.andrea@gmail.com> CC: Russell King <linux@armlinux.org.uk> CC: Greg Hackmann <ghackmann@google.com> CC: Will Deacon <will.deacon@arm.com> CC: David Sehr <sehr@google.com> CC: Linus Torvalds <torvalds@linux-foundation.org> CC: x86@kernel.org CC: linux-arch@vger.kernel.org --- 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(); +} + extern void select_idle_routine(const struct cpuinfo_x86 *c); extern void amd_e400_c1e_apic_setup(void); diff --git a/include/linux/processor.h b/include/linux/processor.h index dbc952eec869..7d12e6fa050e 100644 --- a/include/linux/processor.h +++ b/include/linux/processor.h @@ -68,4 +68,10 @@ do { \ #endif +#ifndef ARCH_HAS_SYNC_CORE_BEFORE_USERMODE +static inline sync_core_before_usermode(void) +{ +} +#endif + #endif /* _LINUX_PROCESSOR_H */ -- 2.11.0
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