* [PATCH] arm: Hook up SYNC_CORE functionality for sys_membarrier() @ 2018-06-19 12:22 Will Deacon 2018-06-19 12:50 ` Mathieu Desnoyers 0 siblings, 1 reply; 4+ messages in thread From: Will Deacon @ 2018-06-19 12:22 UTC (permalink / raw) To: linux-arm-kernel 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 <mathieu.desnoyers@efficios.com> Cc: Orion Hodson <oth@google.com> Signed-off-by: Will Deacon <will.deacon@arm.com> --- 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 select ARCH_HAS_PTE_SPECIAL if ARM_LPAE select ARCH_HAS_PHYS_TO_DMA select ARCH_HAS_SET_MEMORY -- 2.1.4 ^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH] arm: Hook up SYNC_CORE functionality for sys_membarrier() 2018-06-19 12:22 [PATCH] arm: Hook up SYNC_CORE functionality for sys_membarrier() Will Deacon @ 2018-06-19 12:50 ` Mathieu Desnoyers 2018-06-19 12:58 ` Will Deacon 0 siblings, 1 reply; 4+ messages in thread From: Mathieu Desnoyers @ 2018-06-19 12:50 UTC (permalink / raw) To: linux-arm-kernel ----- 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 <mathieu.desnoyers@efficios.com> > Cc: Orion Hodson <oth@google.com> > Signed-off-by: Will Deacon <will.deacon@arm.com> > --- > 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 ^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH] arm: Hook up SYNC_CORE functionality for sys_membarrier() 2018-06-19 12:50 ` Mathieu Desnoyers @ 2018-06-19 12:58 ` Will Deacon 2018-06-19 13:03 ` Mathieu Desnoyers 0 siblings, 1 reply; 4+ messages in thread From: Will Deacon @ 2018-06-19 12:58 UTC (permalink / raw) To: linux-arm-kernel 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 <mathieu.desnoyers@efficios.com> > > Cc: Orion Hodson <oth@google.com> > > Signed-off-by: Will Deacon <will.deacon@arm.com> > > --- > > 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. > Which instruction exactly is responsible for context synchronization on > arm32 ? It's the act of doing an exception return, so there are multiple instruction sequences to do that on 32-bit arm. Will --->8 diff --git a/Documentation/features/sched/membarrier-sync-core/arch-support.txt b/Documentation/features/sched/membarrier-sync-core/arch-support.txt index dbdf62907703..c7858dd1ea8f 100644 --- a/Documentation/features/sched/membarrier-sync-core/arch-support.txt +++ b/Documentation/features/sched/membarrier-sync-core/arch-support.txt @@ -5,10 +5,10 @@ # # Architecture requirements # -# * arm64 +# * arm/arm64 # -# Rely on eret context synchronization when returning from IPI handler, and -# when returning to user-space. +# Rely on implicit context synchronization as a result of exception return +# when returning from IPI handler, and when returning to user-space. # # * x86 # @@ -31,7 +31,7 @@ ----------------------- | alpha: | TODO | | arc: | TODO | - | arm: | TODO | + | arm: | ok | | arm64: | ok | | c6x: | TODO | | h8300: | TODO | ^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH] arm: Hook up SYNC_CORE functionality for sys_membarrier() 2018-06-19 12:58 ` Will Deacon @ 2018-06-19 13:03 ` Mathieu Desnoyers 0 siblings, 0 replies; 4+ messages in thread From: Mathieu Desnoyers @ 2018-06-19 13:03 UTC (permalink / raw) To: linux-arm-kernel ----- 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 <mathieu.desnoyers@efficios.com> >> > Cc: Orion Hodson <oth@google.com> >> > Signed-off-by: Will Deacon <will.deacon@arm.com> >> > --- >> > 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 ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2018-06-19 13:03 UTC | newest] Thread overview: 4+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2018-06-19 12:22 [PATCH] arm: Hook up SYNC_CORE functionality for sys_membarrier() Will Deacon 2018-06-19 12:50 ` Mathieu Desnoyers 2018-06-19 12:58 ` Will Deacon 2018-06-19 13:03 ` Mathieu Desnoyers
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