| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.8 111/125] powerpc: Add check_if_tm_restore_required() to giveup_all() | Date | Sat, 29 Oct 2016 09:50:29 -0400 |
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4.8-stable review patch. If anyone has any objections, please let me know.
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From: Cyril Bur <cyrilbur@gmail.com>
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 <cyrilbur@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- 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) return; msr_check_and_set(msr_all_available); + check_if_tm_restore_required(tsk); #ifdef CONFIG_PPC_FPU if (usermsr & MSR_FP)
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