powerpc/64s: move NMI soft-mask handling to C

Saving and restoring soft-mask state can now be done in C using the
interrupt handler wrapper functions.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210130130852.2952424-41-npiggin@gmail.com

arch/powerpc/include/asm/interrupt.h

@@ -95,6 +95,10 @@ static inline void interrupt_async_exit_prepare(struct pt_regs *regs, struct int
 
 struct interrupt_nmi_state {
 #ifdef CONFIG_PPC64
+#ifdef CONFIG_PPC_BOOK3S_64
+	u8 irq_soft_mask;
+	u8 irq_happened;
+#endif
 	u8 ftrace_enabled;
 #endif
 };
@@ -102,6 +106,20 @@ struct interrupt_nmi_state {
 static inline void interrupt_nmi_enter_prepare(struct pt_regs *regs, struct interrupt_nmi_state *state)
 {
 #ifdef CONFIG_PPC64
+#ifdef CONFIG_PPC_BOOK3S_64
+	state->irq_soft_mask = local_paca->irq_soft_mask;
+	state->irq_happened = local_paca->irq_happened;
+
+	/*
+	 * Set IRQS_ALL_DISABLED unconditionally so irqs_disabled() does
+	 * the right thing, and set IRQ_HARD_DIS. We do not want to reconcile
+	 * because that goes through irq tracing which we don't want in NMI.
+	 */
+	local_paca->irq_soft_mask = IRQS_ALL_DISABLED;
+	local_paca->irq_happened |= PACA_IRQ_HARD_DIS;
+
+	/* Don't do any per-CPU operations until interrupt state is fixed */
+#endif
 	/* Allow DEC and PMI to be traced when they are soft-NMI */
 	if (TRAP(regs) != 0x900 && TRAP(regs) != 0xf00 && TRAP(regs) != 0x260) {
 		state->ftrace_enabled = this_cpu_get_ftrace_enabled();
@@ -129,6 +147,13 @@ static inline void interrupt_nmi_exit_prepare(struct pt_regs *regs, struct inter
 #ifdef CONFIG_PPC64
 	if (TRAP(regs) != 0x900 && TRAP(regs) != 0xf00 && TRAP(regs) != 0x260)
 		this_cpu_set_ftrace_enabled(state->ftrace_enabled);
+
+#ifdef CONFIG_PPC_BOOK3S_64
+	/* Check we didn't change the pending interrupt mask. */
+	WARN_ON_ONCE((state->irq_happened | PACA_IRQ_HARD_DIS) != local_paca->irq_happened);
+	local_paca->irq_happened = state->irq_happened;
+	local_paca->irq_soft_mask = state->irq_soft_mask;
+#endif
 #endif
 }
 

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

@@ -1008,20 +1008,6 @@ EXC_COMMON_BEGIN(system_reset_common)
 	ld	r1,PACA_NMI_EMERG_SP(r13)
 	subi	r1,r1,INT_FRAME_SIZE
 	__GEN_COMMON_BODY system_reset
-	/*
-	 * Set IRQS_ALL_DISABLED unconditionally so irqs_disabled() does
-	 * the right thing. We do not want to reconcile because that goes
-	 * through irq tracing which we don't want in NMI.
-	 *
-	 * Save PACAIRQHAPPENED to RESULT (otherwise unused), and set HARD_DIS
-	 * as we are running with MSR[EE]=0.
-	 */
-	li	r10,IRQS_ALL_DISABLED
-	stb	r10,PACAIRQSOFTMASK(r13)
-	lbz	r10,PACAIRQHAPPENED(r13)
-	std	r10,RESULT(r1)
-	ori	r10,r10,PACA_IRQ_HARD_DIS
-	stb	r10,PACAIRQHAPPENED(r13)
 
 	addi	r3,r1,STACK_FRAME_OVERHEAD
 	bl	system_reset_exception
@@ -1037,14 +1023,6 @@ EXC_COMMON_BEGIN(system_reset_common)
 	subi	r10,r10,1
 	sth	r10,PACA_IN_NMI(r13)
 
-	/*
-	 * Restore soft mask settings.
-	 */
-	ld	r10,RESULT(r1)
-	stb	r10,PACAIRQHAPPENED(r13)
-	ld	r10,SOFTE(r1)
-	stb	r10,PACAIRQSOFTMASK(r13)
-
 	kuap_kernel_restore r9, r10
 	EXCEPTION_RESTORE_REGS
 	RFI_TO_USER_OR_KERNEL
@@ -1190,30 +1168,11 @@ END_FTR_SECTION_IFSET(CPU_FTR_HVMODE)
 	li	r10,MSR_RI
 	mtmsrd	r10,1
 
-	/*
-	 * Set IRQS_ALL_DISABLED and save PACAIRQHAPPENED (see
-	 * system_reset_common)
-	 */
-	li	r10,IRQS_ALL_DISABLED
-	stb	r10,PACAIRQSOFTMASK(r13)
-	lbz	r10,PACAIRQHAPPENED(r13)
-	std	r10,RESULT(r1)
-	ori	r10,r10,PACA_IRQ_HARD_DIS
-	stb	r10,PACAIRQHAPPENED(r13)
-
 	addi	r3,r1,STACK_FRAME_OVERHEAD
 	bl	machine_check_early
 	std	r3,RESULT(r1)	/* Save result */
 	ld	r12,_MSR(r1)
 
-	/*
-	 * Restore soft mask settings.
-	 */
-	ld	r10,RESULT(r1)
-	stb	r10,PACAIRQHAPPENED(r13)
-	ld	r10,SOFTE(r1)
-	stb	r10,PACAIRQSOFTMASK(r13)
-
 #ifdef CONFIG_PPC_P7_NAP
 	/*
 	 * Check if thread was in power saving mode. We come here when any
@@ -2818,17 +2777,6 @@ EXC_COMMON_BEGIN(soft_nmi_common)
 	subi	r1,r1,INT_FRAME_SIZE
 	__GEN_COMMON_BODY soft_nmi
 
-	/*
-	 * Set IRQS_ALL_DISABLED and save PACAIRQHAPPENED (see
-	 * system_reset_common)
-	 */
-	li	r10,IRQS_ALL_DISABLED
-	stb	r10,PACAIRQSOFTMASK(r13)
-	lbz	r10,PACAIRQHAPPENED(r13)
-	std	r10,RESULT(r1)
-	ori	r10,r10,PACA_IRQ_HARD_DIS
-	stb	r10,PACAIRQHAPPENED(r13)
-
 	addi	r3,r1,STACK_FRAME_OVERHEAD
 	bl	soft_nmi_interrupt
 
@@ -2836,14 +2784,6 @@ EXC_COMMON_BEGIN(soft_nmi_common)
 	li	r9,0
 	mtmsrd	r9,1
 
-	/*
-	 * Restore soft mask settings.
-	 */
-	ld	r10,RESULT(r1)
-	stb	r10,PACAIRQHAPPENED(r13)
-	ld	r10,SOFTE(r1)
-	stb	r10,PACAIRQSOFTMASK(r13)
-
 	kuap_kernel_restore r9, r10
 	EXCEPTION_RESTORE_REGS hsrr=0
 	RFI_TO_KERNEL