arm64: debug: remove break/step handler registration infrastructure

Remove all infrastructure for the dynamic registration previously used by
software breakpoints and stepping handlers.

Signed-off-by: Ada Couprie Diaz <ada.coupriediaz@arm.com>
Tested-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Will Deacon <will@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20250707114109.35672-6-ada.coupriediaz@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

Author: Ada Couprie Diaz

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

@@ -62,30 +62,6 @@ struct task_struct;
 #define DBG_HOOK_HANDLED	0
 #define DBG_HOOK_ERROR		1
 
-struct step_hook {
-	struct list_head node;
-	int (*fn)(struct pt_regs *regs, unsigned long esr);
-};
-
-void register_user_step_hook(struct step_hook *hook);
-void unregister_user_step_hook(struct step_hook *hook);
-
-void register_kernel_step_hook(struct step_hook *hook);
-void unregister_kernel_step_hook(struct step_hook *hook);
-
-struct break_hook {
-	struct list_head node;
-	int (*fn)(struct pt_regs *regs, unsigned long esr);
-	u16 imm;
-	u16 mask; /* These bits are ignored when comparing with imm */
-};
-
-void register_user_break_hook(struct break_hook *hook);
-void unregister_user_break_hook(struct break_hook *hook);
-
-void register_kernel_break_hook(struct break_hook *hook);
-void unregister_kernel_break_hook(struct break_hook *hook);
-
 u8 debug_monitors_arch(void);
 
 enum dbg_active_el {

arch/arm64/kernel/debug-monitors.c

@@ -159,46 +159,6 @@ NOKPROBE_SYMBOL(clear_user_regs_spsr_ss);
 #define set_regs_spsr_ss(r)	set_user_regs_spsr_ss(&(r)->user_regs)
 #define clear_regs_spsr_ss(r)	clear_user_regs_spsr_ss(&(r)->user_regs)
 
-static DEFINE_SPINLOCK(debug_hook_lock);
-static LIST_HEAD(user_step_hook);
-static LIST_HEAD(kernel_step_hook);
-
-static void register_debug_hook(struct list_head *node, struct list_head *list)
-{
-	spin_lock(&debug_hook_lock);
-	list_add_rcu(node, list);
-	spin_unlock(&debug_hook_lock);
-
-}
-
-static void unregister_debug_hook(struct list_head *node)
-{
-	spin_lock(&debug_hook_lock);
-	list_del_rcu(node);
-	spin_unlock(&debug_hook_lock);
-	synchronize_rcu();
-}
-
-void register_user_step_hook(struct step_hook *hook)
-{
-	register_debug_hook(&hook->node, &user_step_hook);
-}
-
-void unregister_user_step_hook(struct step_hook *hook)
-{
-	unregister_debug_hook(&hook->node);
-}
-
-void register_kernel_step_hook(struct step_hook *hook)
-{
-	register_debug_hook(&hook->node, &kernel_step_hook);
-}
-
-void unregister_kernel_step_hook(struct step_hook *hook)
-{
-	unregister_debug_hook(&hook->node);
-}
-
 /*
  * Call single step handlers
  * There is no Syndrome info to check for determining the handler.
@@ -264,29 +224,6 @@ static int single_step_handler(unsigned long unused, unsigned long esr,
 }
 NOKPROBE_SYMBOL(single_step_handler);
 
-static LIST_HEAD(user_break_hook);
-static LIST_HEAD(kernel_break_hook);
-
-void register_user_break_hook(struct break_hook *hook)
-{
-	register_debug_hook(&hook->node, &user_break_hook);
-}
-
-void unregister_user_break_hook(struct break_hook *hook)
-{
-	unregister_debug_hook(&hook->node);
-}
-
-void register_kernel_break_hook(struct break_hook *hook)
-{
-	register_debug_hook(&hook->node, &kernel_break_hook);
-}
-
-void unregister_kernel_break_hook(struct break_hook *hook)
-{
-	unregister_debug_hook(&hook->node);
-}
-
 static int call_break_hook(struct pt_regs *regs, unsigned long esr)
 {
 	if (user_mode(regs)) {