powerpc/64s/exception: untangle early machine check handler branch

machine_check_early_common now branches to machine_check_handle_early
which is its only caller.

Move interleaving code out of the way, and remove the branch.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190802105709.27696-16-npiggin@gmail.com

arch/powerpc/kernel/exceptions-64s.S

@@ -956,6 +956,16 @@ TRAMP_REAL_BEGIN(machine_check_fwnmi)
 
 TRAMP_KVM_SKIP(PACA_EXMC, 0x200)
 
+#define MACHINE_CHECK_HANDLER_WINDUP			\
+	/* Clear MSR_RI before setting SRR0 and SRR1. */\
+	li	r9,0;					\
+	mtmsrd	r9,1;		/* Clear MSR_RI */	\
+	/* Decrement paca->in_mce now RI is clear. */	\
+	lhz	r12,PACA_IN_MCE(r13);			\
+	subi	r12,r12,1;				\
+	sth	r12,PACA_IN_MCE(r13);			\
+	EXCEPTION_RESTORE_REGS EXC_STD
+
 EXC_COMMON_BEGIN(machine_check_early_common)
 	mtctr	r10			/* Restore ctr */
 	mfspr	r11,SPRN_SRR0
@@ -1011,74 +1021,7 @@ BEGIN_FTR_SECTION
 END_FTR_SECTION_IFSET(CPU_FTR_HVMODE)
 	li	r10,MSR_RI
 	mtmsrd	r10,1
-	b	machine_check_handle_early
 
-EXC_COMMON_BEGIN(machine_check_common)
-	/*
-	 * Machine check is different because we use a different
-	 * save area: PACA_EXMC instead of PACA_EXGEN.
-	 */
-	EXCEPTION_COMMON(PACA_EXMC, 0x200)
-	FINISH_NAP
-	RECONCILE_IRQ_STATE(r10, r11)
-	ld	r3,PACA_EXMC+EX_DAR(r13)
-	lwz	r4,PACA_EXMC+EX_DSISR(r13)
-	/* Enable MSR_RI when finished with PACA_EXMC */
-	li	r10,MSR_RI
-	mtmsrd 	r10,1
-	std	r3,_DAR(r1)
-	std	r4,_DSISR(r1)
-	bl	save_nvgprs
-	addi	r3,r1,STACK_FRAME_OVERHEAD
-	bl	machine_check_exception
-	b	ret_from_except
-
-#define MACHINE_CHECK_HANDLER_WINDUP			\
-	/* Clear MSR_RI before setting SRR0 and SRR1. */\
-	li	r9,0;					\
-	mtmsrd	r9,1;		/* Clear MSR_RI */	\
-	/* Decrement paca->in_mce now RI is clear. */	\
-	lhz	r12,PACA_IN_MCE(r13);			\
-	subi	r12,r12,1;				\
-	sth	r12,PACA_IN_MCE(r13);			\
-	EXCEPTION_RESTORE_REGS EXC_STD
-
-#ifdef CONFIG_PPC_P7_NAP
-/*
- * This is an idle wakeup. Low level machine check has already been
- * done. Queue the event then call the idle code to do the wake up.
- */
-EXC_COMMON_BEGIN(machine_check_idle_common)
-	bl	machine_check_queue_event
-
-	/*
-	 * We have not used any non-volatile GPRs here, and as a rule
-	 * most exception code including machine check does not.
-	 * Therefore PACA_NAPSTATELOST does not need to be set. Idle
-	 * wakeup will restore volatile registers.
-	 *
-	 * Load the original SRR1 into r3 for pnv_powersave_wakeup_mce.
-	 *
-	 * Then decrement MCE nesting after finishing with the stack.
-	 */
-	ld	r3,_MSR(r1)
-	ld	r4,_LINK(r1)
-
-	lhz	r11,PACA_IN_MCE(r13)
-	subi	r11,r11,1
-	sth	r11,PACA_IN_MCE(r13)
-
-	mtlr	r4
-	rlwinm	r10,r3,47-31,30,31
-	cmpwi	cr1,r10,2
-	bltlr	cr1	/* no state loss, return to idle caller */
-	b	idle_return_gpr_loss
-#endif
-	/*
-	 * Handle machine check early in real mode. We come here with
-	 * ME=1, MMU (IR=0 and DR=0) off and using MC emergency stack.
-	 */
-EXC_COMMON_BEGIN(machine_check_handle_early)
 	bl	save_nvgprs
 	addi	r3,r1,STACK_FRAME_OVERHEAD
 	bl	machine_check_early
@@ -1157,6 +1100,58 @@ END_FTR_SECTION_IFSET(CPU_FTR_CFAR)
 	EXCEPTION_PROLOG_1 EXC_STD, PACA_EXMC, 1, 0x200, 1, 1, 0
 	EXCEPTION_PROLOG_2_REAL machine_check_common, EXC_STD, 0
 
+EXC_COMMON_BEGIN(machine_check_common)
+	/*
+	 * Machine check is different because we use a different
+	 * save area: PACA_EXMC instead of PACA_EXGEN.
+	 */
+	EXCEPTION_COMMON(PACA_EXMC, 0x200)
+	FINISH_NAP
+	RECONCILE_IRQ_STATE(r10, r11)
+	ld	r3,PACA_EXMC+EX_DAR(r13)
+	lwz	r4,PACA_EXMC+EX_DSISR(r13)
+	/* Enable MSR_RI when finished with PACA_EXMC */
+	li	r10,MSR_RI
+	mtmsrd 	r10,1
+	std	r3,_DAR(r1)
+	std	r4,_DSISR(r1)
+	bl	save_nvgprs
+	addi	r3,r1,STACK_FRAME_OVERHEAD
+	bl	machine_check_exception
+	b	ret_from_except
+
+#ifdef CONFIG_PPC_P7_NAP
+/*
+ * This is an idle wakeup. Low level machine check has already been
+ * done. Queue the event then call the idle code to do the wake up.
+ */
+EXC_COMMON_BEGIN(machine_check_idle_common)
+	bl	machine_check_queue_event
+
+	/*
+	 * We have not used any non-volatile GPRs here, and as a rule
+	 * most exception code including machine check does not.
+	 * Therefore PACA_NAPSTATELOST does not need to be set. Idle
+	 * wakeup will restore volatile registers.
+	 *
+	 * Load the original SRR1 into r3 for pnv_powersave_wakeup_mce.
+	 *
+	 * Then decrement MCE nesting after finishing with the stack.
+	 */
+	ld	r3,_MSR(r1)
+	ld	r4,_LINK(r1)
+
+	lhz	r11,PACA_IN_MCE(r13)
+	subi	r11,r11,1
+	sth	r11,PACA_IN_MCE(r13)
+
+	mtlr	r4
+	rlwinm	r10,r3,47-31,30,31
+	cmpwi	cr1,r10,2
+	bltlr	cr1	/* no state loss, return to idle caller */
+	b	idle_return_gpr_loss
+#endif
+
 EXC_COMMON_BEGIN(unrecoverable_mce)
 	/*
 	 * We are going down. But there are chances that we might get hit by