arm64: debug: Remove redundant user_mode(regs) checks from debug handlers

Now that the debug hook dispatching code takes the triggering exception
level into account, there's no need for the hooks themselves to poke
around with user_mode(regs).
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm64/kernel/kgdb.c

@@ -244,9 +244,6 @@ int kgdb_arch_handle_exception(int exception_vector, int signo,
 
 static int kgdb_brk_fn(struct pt_regs *regs, unsigned int esr)
 {
-	if (user_mode(regs))
-		return DBG_HOOK_ERROR;
-
 	kgdb_handle_exception(1, SIGTRAP, 0, regs);
 	return DBG_HOOK_HANDLED;
 }
@@ -254,9 +251,6 @@ NOKPROBE_SYMBOL(kgdb_brk_fn)
 
 static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int esr)
 {
-	if (user_mode(regs))
-		return DBG_HOOK_ERROR;
-
 	compiled_break = 1;
 	kgdb_handle_exception(1, SIGTRAP, 0, regs);
 
@@ -266,7 +260,7 @@ NOKPROBE_SYMBOL(kgdb_compiled_brk_fn);
 
 static int kgdb_step_brk_fn(struct pt_regs *regs, unsigned int esr)
 {
-	if (user_mode(regs) || !kgdb_single_step)
+	if (!kgdb_single_step)
 		return DBG_HOOK_ERROR;
 
 	kgdb_handle_exception(1, SIGTRAP, 0, regs);

arch/arm64/kernel/probes/kprobes.c

@@ -445,9 +445,6 @@ kprobe_single_step_handler(struct pt_regs *regs, unsigned int esr)
 	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 	int retval;
 
-	if (user_mode(regs))
-		return DBG_HOOK_ERROR;
-
 	/* return error if this is not our step */
 	retval = kprobe_ss_hit(kcb, instruction_pointer(regs));
 
@@ -468,9 +465,6 @@ static struct step_hook kprobes_step_hook = {
 static int __kprobes
 kprobe_breakpoint_handler(struct pt_regs *regs, unsigned int esr)
 {
-	if (user_mode(regs))
-		return DBG_HOOK_ERROR;
-
 	kprobe_handler(regs);
 	return DBG_HOOK_HANDLED;
 }

arch/arm64/kernel/probes/uprobes.c

@@ -171,7 +171,7 @@ int arch_uprobe_exception_notify(struct notifier_block *self,
 static int uprobe_breakpoint_handler(struct pt_regs *regs,
 		unsigned int esr)
 {
-	if (user_mode(regs) && uprobe_pre_sstep_notifier(regs))
+	if (uprobe_pre_sstep_notifier(regs))
 		return DBG_HOOK_HANDLED;
 
 	return DBG_HOOK_ERROR;
@@ -182,13 +182,9 @@ static int uprobe_single_step_handler(struct pt_regs *regs,
 {
 	struct uprobe_task *utask = current->utask;
 
-	if (user_mode(regs)) {
-		WARN_ON(utask &&
-			(instruction_pointer(regs) != utask->xol_vaddr + 4));
-
+	WARN_ON(utask && (instruction_pointer(regs) != utask->xol_vaddr + 4));
 	if (uprobe_post_sstep_notifier(regs))
 		return DBG_HOOK_HANDLED;
-	}
 
 	return DBG_HOOK_ERROR;
 }

arch/arm64/kernel/traps.c

@@ -947,9 +947,6 @@ int is_valid_bugaddr(unsigned long addr)
 
 static int bug_handler(struct pt_regs *regs, unsigned int esr)
 {
-	if (user_mode(regs))
-		return DBG_HOOK_ERROR;
-
 	switch (report_bug(regs->pc, regs)) {
 	case BUG_TRAP_TYPE_BUG:
 		die("Oops - BUG", regs, 0);
@@ -988,9 +985,6 @@ static int kasan_handler(struct pt_regs *regs, unsigned int esr)
 	u64 addr = regs->regs[0];
 	u64 pc = regs->pc;
 
-	if (user_mode(regs))
-		return DBG_HOOK_ERROR;
-
 	kasan_report(addr, size, write, pc);
 
 	/*