riscv: misaligned: factorize trap handling

BugLink: https://bugs.launchpad.net/bugs/2115252

[ Upstream commit fd94de9f9e7aac11ec659e386b9db1203d502023 ]

Since both load/store and user/kernel should use almost the same path and
that we are going to add some code around that, factorize it.

Signed-off-by: Clément Léger <cleger@rivosinc.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20250422162324.956065-2-cleger@rivosinc.com
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Stable-dep-of: 453805f0a28f ("riscv: misaligned: enable IRQs while handling misaligned accesses")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

Author: clementleger

arch/riscv/kernel/traps.c

@@ -198,47 +198,53 @@ asmlinkage __visible __trap_section void do_trap_insn_illegal(struct pt_regs *re
 DO_ERROR_INFO(do_trap_load_fault,
 	SIGSEGV, SEGV_ACCERR, "load access fault");
 
-asmlinkage __visible __trap_section void do_trap_load_misaligned(struct pt_regs *regs)
+enum misaligned_access_type {
+	MISALIGNED_STORE,
+	MISALIGNED_LOAD,
+};
+static const struct {
+	const char *type_str;
+	int (*handler)(struct pt_regs *regs);
+} misaligned_handler[] = {
+	[MISALIGNED_STORE] = {
+		.type_str = "Oops - store (or AMO) address misaligned",
+		.handler = handle_misaligned_store,
+	},
+	[MISALIGNED_LOAD] = {
+		.type_str = "Oops - load address misaligned",
+		.handler = handle_misaligned_load,
+	},
+};
+
+static void do_trap_misaligned(struct pt_regs *regs, enum misaligned_access_type type)
 {
-	if (user_mode(regs)) {
+	irqentry_state_t state;
+
+	if (user_mode(regs))
 		irqentry_enter_from_user_mode(regs);
+	else
+		state = irqentry_nmi_enter(regs);
 
-		if (handle_misaligned_load(regs))
-			do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc,
-			      "Oops - load address misaligned");
+	if (misaligned_handler[type].handler(regs))
+		do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc,
+			      misaligned_handler[type].type_str);
 
+	if (user_mode(regs))
 		irqentry_exit_to_user_mode(regs);
-	} else {
-		irqentry_state_t state = irqentry_nmi_enter(regs);
-
-		if (handle_misaligned_load(regs))
-			do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc,
-			      "Oops - load address misaligned");
-
+	else
 		irqentry_nmi_exit(regs, state);
-	}
 }
 
-asmlinkage __visible __trap_section void do_trap_store_misaligned(struct pt_regs *regs)
+asmlinkage __visible __trap_section void do_trap_load_misaligned(struct pt_regs *regs)
 {
-	if (user_mode(regs)) {
-		irqentry_enter_from_user_mode(regs);
-
-		if (handle_misaligned_store(regs))
-			do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc,
-				"Oops - store (or AMO) address misaligned");
-
-		irqentry_exit_to_user_mode(regs);
-	} else {
-		irqentry_state_t state = irqentry_nmi_enter(regs);
-
-		if (handle_misaligned_store(regs))
-			do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc,
-				"Oops - store (or AMO) address misaligned");
+	do_trap_misaligned(regs, MISALIGNED_LOAD);
+}
 
-		irqentry_nmi_exit(regs, state);
-	}
+asmlinkage __visible __trap_section void do_trap_store_misaligned(struct pt_regs *regs)
+{
+	do_trap_misaligned(regs, MISALIGNED_STORE);
 }
+
 DO_ERROR_INFO(do_trap_store_fault,
 	SIGSEGV, SEGV_ACCERR, "store (or AMO) access fault");
 DO_ERROR_INFO(do_trap_ecall_s,