irq: riscv: perform irqentry in entry code

In preparation for removing HANDLE_DOMAIN_IRQ_IRQENTRY, have arch/riscv
perform all the irqentry accounting in its entry code. As arch/riscv
uses GENERIC_IRQ_MULTI_HANDLER, we can use generic_handle_arch_irq() to
do so.

Since generic_handle_arch_irq() handles the irq entry and setting the
irq regs, and happens before the irqchip code calls handle_IPI(), we can
remove the redundant irq entry and irq regs manipulation from
handle_IPI().

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Thomas Gleixner <tglx@linutronix.de>

arch/riscv/Kconfig

@@ -63,7 +63,6 @@ config RISCV
 	select GENERIC_SMP_IDLE_THREAD
 	select GENERIC_TIME_VSYSCALL if MMU && 64BIT
 	select HANDLE_DOMAIN_IRQ
-	select HANDLE_DOMAIN_IRQ_IRQENTRY
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL
 	select HAVE_ARCH_JUMP_LABEL_RELATIVE if !XIP_KERNEL

arch/riscv/kernel/entry.S

@@ -130,8 +130,7 @@ skip_context_tracking:
 
 	/* Handle interrupts */
 	move a0, sp /* pt_regs */
-	la a1, handle_arch_irq
-	REG_L a1, (a1)
+	la a1, generic_handle_arch_irq
 	jr a1
 1:
 	/*

arch/riscv/kernel/smp.c

@@ -140,12 +140,9 @@ void arch_irq_work_raise(void)
 
 void handle_IPI(struct pt_regs *regs)
 {
-	struct pt_regs *old_regs = set_irq_regs(regs);
 	unsigned long *pending_ipis = &ipi_data[smp_processor_id()].bits;
 	unsigned long *stats = ipi_data[smp_processor_id()].stats;
 
-	irq_enter();
-
 	riscv_clear_ipi();
 
 	while (true) {
@@ -156,7 +153,7 @@ void handle_IPI(struct pt_regs *regs)
 
 		ops = xchg(pending_ipis, 0);
 		if (ops == 0)
-			goto done;
+			return;
 
 		if (ops & (1 << IPI_RESCHEDULE)) {
 			stats[IPI_RESCHEDULE]++;
@@ -189,10 +186,6 @@ void handle_IPI(struct pt_regs *regs)
 		/* Order data access and bit testing. */
 		mb();
 	}
-
-done:
-	irq_exit();
-	set_irq_regs(old_regs);
 }
 
 static const char * const ipi_names[] = {