From mboxrd@z Thu Jan 1 00:00:00 1970 From: mathieu.desnoyers@efficios.com (Mathieu Desnoyers) Date: Tue, 19 Jun 2018 09:03:18 -0400 (EDT) Subject: [PATCH] arm: Hook up SYNC_CORE functionality for sys_membarrier() In-Reply-To: <20180619125849.GH13984@arm.com> References: <1529410974-18929-1-git-send-email-will.deacon@arm.com> <1431651959.17300.1529412602455.JavaMail.zimbra@efficios.com> <20180619125849.GH13984@arm.com> Message-ID: <598200491.17317.1529413398241.JavaMail.zimbra@efficios.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org ----- On Jun 19, 2018, at 8:58 AM, Will Deacon will.deacon at arm.com wrote: > Hi Mathieu, > > On Tue, Jun 19, 2018 at 08:50:02AM -0400, Mathieu Desnoyers wrote: >> ----- 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. >> */ > > Bah, you know I hate that comment ;) I should update arch-support.txt, > though. Diff below. It works for me with this update, thanks! Mathieu -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com