Subject: [RFC PATCH 08/12] [WIP] powerpc/tm: Fix *unavailable_tm exceptions

From: Cyril Bur <[email-masked]>
Date: Tue, 20 Feb 2018 11:22:37 +1100

---
 arch/powerpc/kernel/process.c | 11 ++++++++++-
 arch/powerpc/kernel/traps.c   |  3 ---
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 574b05fe7d66..8a32fd062a2b 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -500,11 +500,20 @@ void giveup_all(struct task_struct *tsk)
 
 	usermsr = tsk->thread.regs->msr;
 
+	/*
+	 * The *_unavailable_tm() functions might call this in a
+	 * transaction but with not FP or VEC or VSX meaning that the
+	 * if condition below will be true, this is bad since we will
+	 * have preformed a reclaim but not set the TIF flag which
+	 * must be set in order to trigger the recheckpoint.
+	 *
+	 * possibleTODO: Move setting the TIF flag into reclaim code
+	 */
+	check_if_tm_restore_required(tsk);
 	if ((usermsr & msr_all_available) == 0)
 		return;
 
 	msr_check_and_set(msr_all_available);
-	check_if_tm_restore_required(tsk);
 
 	WARN_ON((usermsr & MSR_VSX) && !((usermsr & MSR_FP) && (usermsr & MSR_VEC)));
 
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 1e48d157196a..dccfcaf4f603 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -1728,7 +1728,6 @@ void fp_unavailable_tm(struct pt_regs *regs)
 	 * If VMX is in use, the VRs now hold checkpointed values,
 	 * so we don't want to load the VRs from the thread_struct.
 	 */
-	tm_recheckpoint(&current->thread);
 }
 
 void altivec_unavailable_tm(struct pt_regs *regs)
@@ -1742,7 +1741,6 @@ void altivec_unavailable_tm(struct pt_regs *regs)
 		 regs->nip, regs->msr);
 	tm_reclaim_current(TM_CAUSE_FAC_UNAV);
 	current->thread.load_vec = 1;
-	tm_recheckpoint(&current->thread);
 	current->thread.used_vr = 1;
 }
 
@@ -1767,7 +1765,6 @@ void vsx_unavailable_tm(struct pt_regs *regs)
 	current->thread.load_vec = 1;
 	current->thread.load_fp = 1;
 
-	tm_recheckpoint(&current->thread);
 }
 #endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
 
-- 
2.16.2