powerpc: tm: Always use fp_state and vr_state to store live registers

There is currently an inconsistency as to how the entire CPU register
state is saved and restored when a thread uses transactional memory
(TM).

Using transactional memory results in the CPU having duplicated
(almost) all of its register state. This duplication results in a set
of registers which can be considered 'live', those being currently
modified by the instructions being executed and another set that is
frozen at a point in time.

On context switch, both sets of state have to be saved and (later)
restored. These two states are often called a variety of different
things. Common terms for the state which only exists after the CPU has
entered a transaction (performed a TBEGIN instruction) in hardware are
'transactional' or 'speculative'.

Between a TBEGIN and a TEND or TABORT (or an event that causes the
hardware to abort), regardless of the use of TSUSPEND the
transactional state can be referred to as the live state.

The second state is often to referred to as the 'checkpointed' state
and is a duplication of the live state when the TBEGIN instruction is
executed. This state is kept in the hardware and will be rolled back
to on transaction failure.

Currently all the registers stored in pt_regs are ALWAYS the live
registers, that is, when a thread has transactional registers their
values are stored in pt_regs and the checkpointed state is in
ckpt_regs. A strange opposite is true for fp_state/vr_state. When a
thread is non transactional fp_state/vr_state holds the live
registers. When a thread has initiated a transaction fp_state/vr_state
holds the checkpointed state and transact_fp/transact_vr become the
structure which holds the live state (at this point it is a
transactional state).

This method creates confusion as to where the live state is, in some
circumstances it requires extra work to determine where to put the
live state and prevents the use of common functions designed (probably
before TM) to save the live state.

With this patch pt_regs, fp_state and vr_state all represent the
same thing and the other structures [pending rename] are for
checkpointed state.

Acked-by: Simon Guo <wei.guo.simon@gmail.com>
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 24 insertions, 30 deletions

diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index befa10af0c17..af58af520472 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -221,28 +221,25 @@ static long setup_tm_sigcontexts(struct sigcontext __user *sc,
 	 */
 	regs->msr &= ~MSR_TS_MASK;
 
-	flush_fp_to_thread(tsk);
-
 #ifdef CONFIG_ALTIVEC
 	err |= __put_user(v_regs, &sc->v_regs);
 	err |= __put_user(tm_v_regs, &tm_sc->v_regs);
 
 	/* save altivec registers */
 	if (tsk->thread.used_vr) {
-		flush_altivec_to_thread(tsk);
 		/* Copy 33 vec registers (vr0..31 and vscr) to the stack */
-		err |= __copy_to_user(v_regs, &tsk->thread.vr_state,
+		err |= __copy_to_user(v_regs, &tsk->thread.transact_vr,
 				      33 * sizeof(vector128));
 		/* If VEC was enabled there are transactional VRs valid too,
 		 * else they're a copy of the checkpointed VRs.
 		 */
 		if (msr & MSR_VEC)
 			err |= __copy_to_user(tm_v_regs,
-					      &tsk->thread.transact_vr,
+					      &tsk->thread.vr_state,
 					      33 * sizeof(vector128));
 		else
 			err |= __copy_to_user(tm_v_regs,
-					      &tsk->thread.vr_state,
+					      &tsk->thread.transact_vr,
 					      33 * sizeof(vector128));
 
 		/* set MSR_VEC in the MSR value in the frame to indicate
@@ -254,13 +251,13 @@ static long setup_tm_sigcontexts(struct sigcontext __user *sc,
 	 * use altivec.
 	 */
 	if (cpu_has_feature(CPU_FTR_ALTIVEC))
-		tsk->thread.vrsave = mfspr(SPRN_VRSAVE);
-	err |= __put_user(tsk->thread.vrsave, (u32 __user *)&v_regs[33]);
+		tsk->thread.transact_vrsave = mfspr(SPRN_VRSAVE);
+	err |= __put_user(tsk->thread.transact_vrsave, (u32 __user *)&v_regs[33]);
 	if (msr & MSR_VEC)
-		err |= __put_user(tsk->thread.transact_vrsave,
+		err |= __put_user(tsk->thread.vrsave,
 				  (u32 __user *)&tm_v_regs[33]);
 	else
-		err |= __put_user(tsk->thread.vrsave,
+		err |= __put_user(tsk->thread.transact_vrsave,
 				  (u32 __user *)&tm_v_regs[33]);
 
 #else /* CONFIG_ALTIVEC */
@@ -269,11 +266,11 @@ static long setup_tm_sigcontexts(struct sigcontext __user *sc,
 #endif /* CONFIG_ALTIVEC */
 
 	/* copy fpr regs and fpscr */
-	err |= copy_fpr_to_user(&sc->fp_regs, tsk);
+	err |= copy_transact_fpr_to_user(&sc->fp_regs, tsk);
 	if (msr & MSR_FP)
-		err |= copy_transact_fpr_to_user(&tm_sc->fp_regs, tsk);
-	else
 		err |= copy_fpr_to_user(&tm_sc->fp_regs, tsk);
+	else
+		err |= copy_transact_fpr_to_user(&tm_sc->fp_regs, tsk);
 
 #ifdef CONFIG_VSX
 	/*
@@ -282,16 +279,15 @@ static long setup_tm_sigcontexts(struct sigcontext __user *sc,
 	 * VMX data.
 	 */
 	if (tsk->thread.used_vsr) {
-		flush_vsx_to_thread(tsk);
 		v_regs += ELF_NVRREG;
 		tm_v_regs += ELF_NVRREG;
 
-		err |= copy_vsx_to_user(v_regs, tsk);
+		err |= copy_transact_vsx_to_user(v_regs, tsk);
 
 		if (msr & MSR_VSX)
-			err |= copy_transact_vsx_to_user(tm_v_regs, tsk);
-		else
 			err |= copy_vsx_to_user(tm_v_regs, tsk);
+		else
+			err |= copy_transact_vsx_to_user(tm_v_regs, tsk);
 
 		/* set MSR_VSX in the MSR value in the frame to
 		 * indicate that sc->vs_reg) contains valid data.
@@ -501,9 +497,9 @@ static long restore_tm_sigcontexts(struct task_struct *tsk,
 		return -EFAULT;
 	/* Copy 33 vec registers (vr0..31 and vscr) from the stack */
 	if (v_regs != NULL && tm_v_regs != NULL && (msr & MSR_VEC) != 0) {
-		err |= __copy_from_user(&tsk->thread.vr_state, v_regs,
+		err |= __copy_from_user(&tsk->thread.transact_vr, v_regs,
 					33 * sizeof(vector128));
-		err |= __copy_from_user(&tsk->thread.transact_vr, tm_v_regs,
+		err |= __copy_from_user(&tsk->thread.vr_state, tm_v_regs,
 					33 * sizeof(vector128));
 		current->thread.used_vr = true;
 	}
@@ -513,9 +509,9 @@ static long restore_tm_sigcontexts(struct task_struct *tsk,
 	}
 	/* Always get VRSAVE back */
 	if (v_regs != NULL && tm_v_regs != NULL) {
-		err |= __get_user(tsk->thread.vrsave,
-				  (u32 __user *)&v_regs[33]);
 		err |= __get_user(tsk->thread.transact_vrsave,
+				  (u32 __user *)&v_regs[33]);
+		err |= __get_user(tsk->thread.vrsave,
 				  (u32 __user *)&tm_v_regs[33]);
 	}
 	else {
@@ -526,8 +522,8 @@ static long restore_tm_sigcontexts(struct task_struct *tsk,
 		mtspr(SPRN_VRSAVE, tsk->thread.vrsave);
 #endif /* CONFIG_ALTIVEC */
 	/* restore floating point */
-	err |= copy_fpr_from_user(tsk, &sc->fp_regs);
-	err |= copy_transact_fpr_from_user(tsk, &tm_sc->fp_regs);
+	err |= copy_fpr_from_user(tsk, &tm_sc->fp_regs);
+	err |= copy_transact_fpr_from_user(tsk, &sc->fp_regs);
 #ifdef CONFIG_VSX
 	/*
 	 * Get additional VSX data. Update v_regs to point after the
@@ -537,8 +533,8 @@ static long restore_tm_sigcontexts(struct task_struct *tsk,
 	if (v_regs && ((msr & MSR_VSX) != 0)) {
 		v_regs += ELF_NVRREG;
 		tm_v_regs += ELF_NVRREG;
-		err |= copy_vsx_from_user(tsk, v_regs);
-		err |= copy_transact_vsx_from_user(tsk, tm_v_regs);
+		err |= copy_vsx_from_user(tsk, tm_v_regs);
+		err |= copy_transact_vsx_from_user(tsk, v_regs);
 		tsk->thread.used_vsr = true;
 	} else {
 		for (i = 0; i < 32 ; i++) {
@@ -553,17 +549,15 @@ static long restore_tm_sigcontexts(struct task_struct *tsk,
 	/* This loads the checkpointed FP/VEC state, if used */
 	tm_recheckpoint(&tsk->thread, msr);
 
-	/* This loads the speculative FP/VEC state, if used */
+	msr_check_and_set(msr & (MSR_FP | MSR_VEC));
 	if (msr & MSR_FP) {
-		do_load_up_transact_fpu(&tsk->thread);
+		load_fp_state(&tsk->thread.fp_state);
 		regs->msr |= (MSR_FP | tsk->thread.fpexc_mode);
 	}
-#ifdef CONFIG_ALTIVEC
 	if (msr & MSR_VEC) {
-		do_load_up_transact_altivec(&tsk->thread);
+		load_vr_state(&tsk->thread.vr_state);
 		regs->msr |= MSR_VEC;
 	}
-#endif
 
 	return err;
 }