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Subject[PATCH 4.8 111/125] powerpc: Add check_if_tm_restore_required() to giveup_all()
4.8-stable review patch.  If anyone has any objections, please let me know.


From: Cyril Bur <>

commit b0f16b46988fde02a1e32078f66a3059d7e53bfc upstream.

giveup_all() causes FPU/VMX/VSX facilities to be disabled in a threads
MSR. If the thread performing the giveup was transactional, the kernel
must record which facilities were in use before the giveup as the
thread must have these facilities re-enabled on return to userspace.

>From process.c:
* This is called if we are on the way out to userspace and the
* TIF_RESTORE_TM flag is set. It checks if we need to reload
* FP and/or vector state and does so if necessary.
* If userspace is inside a transaction (whether active or
* suspended) and FP/VMX/VSX instructions have ever been enabled
* inside that transaction, then we have to keep them enabled
* and keep the FP/VMX/VSX state loaded while ever the transaction
* continues. The reason is that if we didn't, and subsequently
* got a FP/VMX/VSX unavailable interrupt inside a transaction,
* we don't know whether it's the same transaction, and thus we
* don't know which of the checkpointed state and the transactional
* state to use.

Calling check_if_tm_restore_required() will set TIF_RESTORE_TM and
save the MSR if needed.

Fixes: c208505 ("powerpc: create giveup_all()")
Signed-off-by: Cyril Bur <>
Signed-off-by: Michael Ellerman <>
Signed-off-by: Greg Kroah-Hartman <>

arch/powerpc/kernel/process.c | 1 +
1 file changed, 1 insertion(+)

--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -445,6 +445,7 @@ void giveup_all(struct task_struct *tsk)

+ check_if_tm_restore_required(tsk);

if (usermsr & MSR_FP)

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