| Message ID | 1529410974-18929-1-git-send-email-will.deacon@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
----- On Jun 19, 2018, at 8:22 AM, Will Deacon will.deacon@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
----- On Jun 19, 2018, at 8:58 AM, Will Deacon will.deacon@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@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
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
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(+)