1 files changed, 15 insertions, 33 deletions

diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c
index 91fff48d0f57..73ae90ef434c 100644
--- a/arch/arm64/kernel/debug-monitors.c
+++ b/arch/arm64/kernel/debug-monitors.c
@@ -46,16 +46,14 @@ static void mdscr_write(u32 mdscr)
 {
 	unsigned long flags;
 	local_dbg_save(flags);
-	asm volatile("msr mdscr_el1, %0" :: "r" (mdscr));
+	write_sysreg(mdscr, mdscr_el1);
 	local_dbg_restore(flags);
 }
 NOKPROBE_SYMBOL(mdscr_write);
 
 static u32 mdscr_read(void)
 {
-	u32 mdscr;
-	asm volatile("mrs %0, mdscr_el1" : "=r" (mdscr));
-	return mdscr;
+	return read_sysreg(mdscr_el1);
 }
 NOKPROBE_SYMBOL(mdscr_read);
 
@@ -132,36 +130,18 @@ NOKPROBE_SYMBOL(disable_debug_monitors);
 /*
  * OS lock clearing.
  */
-static void clear_os_lock(void *unused)
+static int clear_os_lock(unsigned int cpu)
 {
-	asm volatile("msr oslar_el1, %0" : : "r" (0));
-}
-
-static int os_lock_notify(struct notifier_block *self,
-				    unsigned long action, void *data)
-{
-	if ((action & ~CPU_TASKS_FROZEN) == CPU_ONLINE)
-		clear_os_lock(NULL);
-	return NOTIFY_OK;
+	write_sysreg(0, oslar_el1);
+	isb();
+	return 0;
 }
 
-static struct notifier_block os_lock_nb = {
-	.notifier_call = os_lock_notify,
-};
-
 static int debug_monitors_init(void)
 {
-	cpu_notifier_register_begin();
-
-	/* Clear the OS lock. */
-	on_each_cpu(clear_os_lock, NULL, 1);
-	isb();
-
-	/* Register hotplug handler. */
-	__register_cpu_notifier(&os_lock_nb);
-
-	cpu_notifier_register_done();
-	return 0;
+	return cpuhp_setup_state(CPUHP_AP_ARM64_DEBUG_MONITORS_STARTING,
+				 "CPUHP_AP_ARM64_DEBUG_MONITORS_STARTING",
+				 clear_os_lock, NULL);
 }
 postcore_initcall(debug_monitors_init);
 
@@ -254,7 +234,7 @@ static int single_step_handler(unsigned long addr, unsigned int esr,
 		return 0;
 
 	if (user_mode(regs)) {
-		send_user_sigtrap(TRAP_HWBKPT);
+		send_user_sigtrap(TRAP_TRACE);
 
 		/*
 		 * ptrace will disable single step unless explicitly
@@ -382,7 +362,7 @@ NOKPROBE_SYMBOL(aarch32_break_handler);
 static int __init debug_traps_init(void)
 {
 	hook_debug_fault_code(DBG_ESR_EVT_HWSS, single_step_handler, SIGTRAP,
-			      TRAP_HWBKPT, "single-step handler");
+			      TRAP_TRACE, "single-step handler");
 	hook_debug_fault_code(DBG_ESR_EVT_BRK, brk_handler, SIGTRAP,
 			      TRAP_BRKPT, "ptrace BRK handler");
 	return 0;
@@ -435,8 +415,10 @@ NOKPROBE_SYMBOL(kernel_active_single_step);
 /* ptrace API */
 void user_enable_single_step(struct task_struct *task)
 {
-	set_ti_thread_flag(task_thread_info(task), TIF_SINGLESTEP);
-	set_regs_spsr_ss(task_pt_regs(task));
+	struct thread_info *ti = task_thread_info(task);
+
+	if (!test_and_set_ti_thread_flag(ti, TIF_SINGLESTEP))
+		set_regs_spsr_ss(task_pt_regs(task));
 }
 NOKPROBE_SYMBOL(user_enable_single_step);