arm64: mops: Handle MOPS exceptions from EL1

We will soon be using MOPS instructions in the kernel, so wire up the
exception handler to handle exceptions from EL1 caused by the copy/set
operation being stopped and resumed on a different type of CPU.

Add a helper for advancing the single step state machine, similarly to
what the EL0 exception handler does.

Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
Link: https://lore.kernel.org/r/20240930161051.3777828-3-kristina.martsenko@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Author: kristina-martsenko

arch/arm64/include/asm/debug-monitors.h

@@ -105,6 +105,7 @@ void kernel_enable_single_step(struct pt_regs *regs);
 void kernel_disable_single_step(void);
 int kernel_active_single_step(void);
 void kernel_rewind_single_step(struct pt_regs *regs);
+void kernel_fastforward_single_step(struct pt_regs *regs);
 
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 int reinstall_suspended_bps(struct pt_regs *regs);

arch/arm64/include/asm/exception.h

@@ -73,6 +73,7 @@ void do_el0_svc_compat(struct pt_regs *regs);
 void do_el0_fpac(struct pt_regs *regs, unsigned long esr);
 void do_el1_fpac(struct pt_regs *regs, unsigned long esr);
 void do_el0_mops(struct pt_regs *regs, unsigned long esr);
+void do_el1_mops(struct pt_regs *regs, unsigned long esr);
 void do_serror(struct pt_regs *regs, unsigned long esr);
 void do_signal(struct pt_regs *regs);
 

arch/arm64/kernel/debug-monitors.c

@@ -441,6 +441,11 @@ void kernel_rewind_single_step(struct pt_regs *regs)
 	set_regs_spsr_ss(regs);
 }
 
+void kernel_fastforward_single_step(struct pt_regs *regs)
+{
+	clear_regs_spsr_ss(regs);
+}
+
 /* ptrace API */
 void user_enable_single_step(struct task_struct *task)
 {

arch/arm64/kernel/entry-common.c

@@ -463,6 +463,15 @@ static void noinstr el1_bti(struct pt_regs *regs, unsigned long esr)
 	exit_to_kernel_mode(regs);
 }
 
+static void noinstr el1_mops(struct pt_regs *regs, unsigned long esr)
+{
+	enter_from_kernel_mode(regs);
+	local_daif_inherit(regs);
+	do_el1_mops(regs, esr);
+	local_daif_mask();
+	exit_to_kernel_mode(regs);
+}
+
 static void noinstr el1_dbg(struct pt_regs *regs, unsigned long esr)
 {
 	unsigned long far = read_sysreg(far_el1);
@@ -505,6 +514,9 @@ asmlinkage void noinstr el1h_64_sync_handler(struct pt_regs *regs)
 	case ESR_ELx_EC_BTI:
 		el1_bti(regs, esr);
 		break;
+	case ESR_ELx_EC_MOPS:
+		el1_mops(regs, esr);
+		break;
 	case ESR_ELx_EC_BREAKPT_CUR:
 	case ESR_ELx_EC_SOFTSTP_CUR:
 	case ESR_ELx_EC_WATCHPT_CUR:

arch/arm64/kernel/traps.c

@@ -531,6 +531,13 @@ void do_el0_mops(struct pt_regs *regs, unsigned long esr)
 	user_fastforward_single_step(current);
 }
 
+void do_el1_mops(struct pt_regs *regs, unsigned long esr)
+{
+	arm64_mops_reset_regs(&regs->user_regs, esr);
+
+	kernel_fastforward_single_step(regs);
+}
+
 #define __user_cache_maint(insn, address, res)			\
 	if (address >= TASK_SIZE_MAX) {				\
 		res = -EFAULT;					\