arm64: debug: remove debug exception registration infrastructure

Now that debug exceptions are handled individually and without the need
for dynamic registration, remove the unused registration infrastructure.

This removes the external caller for `debug_exception_enter()` and
`debug_exception_exit()`.
Make them static again and remove them from the header.

Remove `early_brk64()` as it has been made redundant by
(arm64: debug: split brk64 exception entry) and is not used anymore.
Note : in `early_brk64()` `bug_brk_handler()` is called unconditionally
as a fall-through, but now `call_break_hook()` only calls it if the
immediate matches.
This does not change the behaviour in early boot, as if
`bug_brk_handler()` was called on a non-BUG immediate it would return
DBG_HOOK_ERROR anyway, which `call_break_hook()` will do if no immediate
matches.

Remove `trap_init()`, as it would be empty and a weak definition already
exists in `init/main.c`.

Signed-off-by: Ada Couprie Diaz <ada.coupriediaz@arm.com>
Tested-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
Reviewed-by: Will Deacon <will@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20250707114109.35672-14-ada.coupriediaz@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

1 files changed, 0 insertions, 53 deletions

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index d451d7d834f1..bc7f554dea9f 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -53,18 +53,12 @@ struct fault_info {
 };
 
 static const struct fault_info fault_info[];
-static struct fault_info debug_fault_info[];
 
 static inline const struct fault_info *esr_to_fault_info(unsigned long esr)
 {
 	return fault_info + (esr & ESR_ELx_FSC);
 }
 
-static inline const struct fault_info *esr_to_debug_fault_info(unsigned long esr)
-{
-	return debug_fault_info + DBG_ESR_EVT(esr);
-}
-
 static void data_abort_decode(unsigned long esr)
 {
 	unsigned long iss2 = ESR_ELx_ISS2(esr);
@@ -939,53 +933,6 @@ void do_sp_pc_abort(unsigned long addr, unsigned long esr, struct pt_regs *regs)
 NOKPROBE_SYMBOL(do_sp_pc_abort);
 
 /*
- * __refdata because early_brk64 is __init, but the reference to it is
- * clobbered at arch_initcall time.
- * See traps.c and debug-monitors.c:debug_traps_init().
- */
-static struct fault_info __refdata debug_fault_info[] = {
-	{ do_bad,	SIGTRAP,	TRAP_HWBKPT,	"hardware breakpoint"	},
-	{ do_bad,	SIGTRAP,	TRAP_HWBKPT,	"hardware single-step"	},
-	{ do_bad,	SIGTRAP,	TRAP_HWBKPT,	"hardware watchpoint"	},
-	{ do_bad,	SIGKILL,	SI_KERNEL,	"unknown 3"		},
-	{ do_bad,	SIGTRAP,	TRAP_BRKPT,	"aarch32 BKPT"		},
-	{ do_bad,	SIGKILL,	SI_KERNEL,	"aarch32 vector catch"	},
-	{ early_brk64,	SIGTRAP,	TRAP_BRKPT,	"aarch64 BRK"		},
-	{ do_bad,	SIGKILL,	SI_KERNEL,	"unknown 7"		},
-};
-
-void __init hook_debug_fault_code(int nr,
-				  int (*fn)(unsigned long, unsigned long, struct pt_regs *),
-				  int sig, int code, const char *name)
-{
-	BUG_ON(nr < 0 || nr >= ARRAY_SIZE(debug_fault_info));
-
-	debug_fault_info[nr].fn		= fn;
-	debug_fault_info[nr].sig	= sig;
-	debug_fault_info[nr].code	= code;
-	debug_fault_info[nr].name	= name;
-}
-
-void do_debug_exception(unsigned long addr_if_watchpoint, unsigned long esr,
-			struct pt_regs *regs)
-{
-	const struct fault_info *inf = esr_to_debug_fault_info(esr);
-	unsigned long pc = instruction_pointer(regs);
-
-	debug_exception_enter(regs);
-
-	if (user_mode(regs) && !is_ttbr0_addr(pc))
-		arm64_apply_bp_hardening();
-
-	if (inf->fn(addr_if_watchpoint, esr, regs)) {
-		arm64_notify_die(inf->name, regs, inf->sig, inf->code, pc, esr);
-	}
-
-	debug_exception_exit(regs);
-}
-NOKPROBE_SYMBOL(do_debug_exception);
-
-/*
  * Used during anonymous page fault handling.
  */
 struct folio *vma_alloc_zeroed_movable_folio(struct vm_area_struct *vma,