From mboxrd@z Thu Jan 1 00:00:00 1970 From: mathieu.desnoyers@efficios.com (Mathieu Desnoyers) Date: Tue, 19 Jun 2018 08:50:02 -0400 (EDT) Subject: [PATCH] arm: Hook up SYNC_CORE functionality for sys_membarrier() In-Reply-To: <1529410974-18929-1-git-send-email-will.deacon@arm.com> References: <1529410974-18929-1-git-send-email-will.deacon@arm.com> Message-ID: <1431651959.17300.1529412602455.JavaMail.zimbra@efficios.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org ----- On Jun 19, 2018, at 8:22 AM, Will Deacon will.deacon at arm.com wrote: > Exception return implies context synchronization, so we can hook up the > SYNC_CORE option to sys_membarrier() simply by selecting the Kconfig option, > just like we've done for arm64 already. > > Cc: Mathieu Desnoyers > Cc: Orion Hodson > Signed-off-by: Will Deacon > --- > arch/arm/Kconfig | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > index 54eeb8d00bc6..b0ac18547370 100644 > --- a/arch/arm/Kconfig > +++ b/arch/arm/Kconfig > @@ -9,6 +9,7 @@ config ARM > select ARCH_HAS_ELF_RANDOMIZE > select ARCH_HAS_FORTIFY_SOURCE > select ARCH_HAS_KCOV > + select ARCH_HAS_MEMBARRIER_SYNC_CORE In addition to this, we added this comment in arch/arm64/kernel/entry.S: + /* + * ARCH_HAS_MEMBARRIER_SYNC_CORE rely on eret context synchronization + * when returning from IPI handler, and when returning to user-space. + */ So I would expect a similar comment in arch/arm/kernel/entry-header.S, within svc_exit and svc_exit_via_fiq: /* * ARCH_HAS_MEMBARRIER_SYNC_CORE rely on [insn] context synchronization * when returning from IPI handler, and when returning to user-space. */ Which instruction exactly is responsible for context synchronization on arm32 ? Thanks, Mathieu > select ARCH_HAS_PTE_SPECIAL if ARM_LPAE > select ARCH_HAS_PHYS_TO_DMA > select ARCH_HAS_SET_MEMORY > -- > 2.1.4 -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com