[PATCH] powerpc/tm: Save and restore AMR on treclaim and trechkpt

[Gustavo Romero]

Althought AMR is stashed on the checkpoint area, currently we don't save
it to the per thread checkpoint struct after a treclaim and so we don't
restore it either from that struct when we trechkpt. As a consequence when
the transaction is later rolled back kernel space AMR value when the
trechkpt was done appears in userspace.

That commit saves and restores AMR accordingly on treclaim and trechkpt.
Since AMR value is also used in kernel space in other functions, it also
takes care of stashing kernel live AMR into PACA before treclaim and before
trechkpt, restoring it later, just before returning from tm_reclaim and
__tm_recheckpoint.

Is also fixes two nonrelated comments about CR and MSR.

Signed-off-by: Gustavo Romero <gromero at linux.ibm.com>
---
 arch/powerpc/include/asm/paca.h      |  1 +
 arch/powerpc/include/asm/processor.h |  1 +
 arch/powerpc/kernel/asm-offsets.c    |  2 ++
 arch/powerpc/kernel/tm.S             | 31 +++++++++++++++++++++++-----
 4 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
index 9454d29ff4b4..44c605181529 100644
--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h
@@ -179,6 +179,7 @@ struct paca_struct {
 	u64 sprg_vdso;			/* Saved user-visible sprg */
 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
 	u64 tm_scratch;                 /* TM scratch area for reclaim */
+	u64 tm_amr;			/* Saved Kernel AMR for treclaim/trechkpt */
 #endif
 
 #ifdef CONFIG_PPC_POWERNV
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index ed0d633ab5aa..9f4f6cc033ac 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -220,6 +220,7 @@ struct thread_struct {
 	unsigned long	tm_tar;
 	unsigned long	tm_ppr;
 	unsigned long	tm_dscr;
+	unsigned long   tm_amr;
 
 	/*
 	 * Checkpointed FP and VSX 0-31 register set.
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 8711c2164b45..cf1a6d68a91f 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -170,12 +170,14 @@ int main(void)
 
 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
 	OFFSET(PACATMSCRATCH, paca_struct, tm_scratch);
+	OFFSET(PACATMAMR, paca_struct, tm_amr);
 	OFFSET(THREAD_TM_TFHAR, thread_struct, tm_tfhar);
 	OFFSET(THREAD_TM_TEXASR, thread_struct, tm_texasr);
 	OFFSET(THREAD_TM_TFIAR, thread_struct, tm_tfiar);
 	OFFSET(THREAD_TM_TAR, thread_struct, tm_tar);
 	OFFSET(THREAD_TM_PPR, thread_struct, tm_ppr);
 	OFFSET(THREAD_TM_DSCR, thread_struct, tm_dscr);
+	OFFSET(THREAD_TM_AMR, thread_struct, tm_amr);
 	OFFSET(PT_CKPT_REGS, thread_struct, ckpt_regs);
 	OFFSET(THREAD_CKVRSTATE, thread_struct, ckvr_state.vr);
 	OFFSET(THREAD_CKVRSAVE, thread_struct, ckvrsave);
diff --git a/arch/powerpc/kernel/tm.S b/arch/powerpc/kernel/tm.S
index 6ba0fdd1e7f8..e178ddb43619 100644
--- a/arch/powerpc/kernel/tm.S
+++ b/arch/powerpc/kernel/tm.S
@@ -152,6 +152,10 @@ _GLOBAL(tm_reclaim)
 	li	r5, 0
 	mtmsrd	r5, 1
 
+        /* Save AMR since it's used elsewhere in kernel space */
+	mfspr	r8, SPRN_AMR
+	std	r8, PACATMAMR(r13)
+
 	/*
 	 * BE CAREFUL HERE:
 	 * At this point we can't take an SLB miss since we have MSR_RI
@@ -245,7 +249,7 @@ _GLOBAL(tm_reclaim)
 	 * but is used in signal return to 'wind back' to the abort handler.
 	 */
 
-	/* ******************** CR,LR,CCR,MSR ********** */
+	/* ***************** CTR, LR, CR, XER ********** */
 	mfctr	r3
 	mflr	r4
 	mfcr	r5
@@ -256,7 +260,6 @@ _GLOBAL(tm_reclaim)
 	std	r5, _CCR(r7)
 	std	r6, _XER(r7)
 
-
 	/* ******************** TAR, DSCR ********** */
 	mfspr	r3, SPRN_TAR
 	mfspr	r4, SPRN_DSCR
@@ -264,6 +267,10 @@ _GLOBAL(tm_reclaim)
 	std	r3, THREAD_TM_TAR(r12)
 	std	r4, THREAD_TM_DSCR(r12)
 
+        /* ******************** AMR **************** */
+        mfspr	r3, SPRN_AMR
+        std	r3, THREAD_TM_AMR(r12)
+
 	/*
 	 * MSR and flags: We don't change CRs, and we don't need to alter MSR.
 	 */
@@ -308,8 +315,6 @@ _GLOBAL(tm_reclaim)
 	std	r3, THREAD_TM_TFHAR(r12)
 	std	r4, THREAD_TM_TFIAR(r12)
 
-	/* AMR is checkpointed too, but is unsupported by Linux. */
-
 	/* Restore original MSR/IRQ state & clear TM mode */
 	ld	r14, TM_FRAME_L0(r1)		/* Orig MSR */
 
@@ -330,6 +335,10 @@ _GLOBAL(tm_reclaim)
 	ld	r0, PACA_DSCR_DEFAULT(r13)
 	mtspr	SPRN_DSCR, r0
 
+        /* Restore kernel saved AMR */
+	ld	r4, PACATMAMR(r13)
+	mtspr	SPRN_AMR, r4
+
 	blr
 
 
@@ -355,6 +364,10 @@ _GLOBAL(__tm_recheckpoint)
 	 */
 	SAVE_NVGPRS(r1)
 
+	/* Save kernel AMR since it's used elsewhare in kernel space */
+	mfspr	r8, SPRN_AMR
+	std	r8, PACATMAMR(r13)
+
 	/* Load complete register state from ts_ckpt* registers */
 
 	addi	r7, r3, PT_CKPT_REGS		/* Thread's ckpt_regs */
@@ -404,7 +417,7 @@ _GLOBAL(__tm_recheckpoint)
 
 restore_gprs:
 
-	/* ******************** CR,LR,CCR,MSR ********** */
+	/* ****************** CTR, LR, XER ************* */
 	ld	r4, _CTR(r7)
 	ld	r5, _LINK(r7)
 	ld	r8, _XER(r7)
@@ -417,6 +430,10 @@ restore_gprs:
 	ld	r4, THREAD_TM_TAR(r3)
 	mtspr	SPRN_TAR,	r4
 
+	/* ******************** AMR ******************** */
+	ld	r4, THREAD_TM_AMR(r3)
+	mtspr	SPRN_AMR, r4
+
 	/* Load up the PPR and DSCR in GPRs only at this stage */
 	ld	r5, THREAD_TM_DSCR(r3)
 	ld	r6, THREAD_TM_PPR(r3)
@@ -522,6 +539,10 @@ restore_gprs:
 	ld	r0, PACA_DSCR_DEFAULT(r13)
 	mtspr	SPRN_DSCR, r0
 
+	/* Restore kernel saved AMR */
+	ld	r4, PACATMAMR(r13)
+	mtspr	SPRN_AMR, r4
+
 	blr
 
 	/* ****************************************************************** */
-- 
2.17.1