[PATCH v3 13/13] arm64: debug: remove debug exception registration infrastructure
From: Ada Couprie Diaz <hidden>
Date: 2025-06-09 19:22:53
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
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. Signed-off-by: Ada Couprie Diaz <redacted> --- arch/arm64/include/asm/debug-monitors.h | 2 - arch/arm64/include/asm/exception.h | 6 --- arch/arm64/include/asm/system_misc.h | 4 -- arch/arm64/kernel/debug-monitors.c | 3 -- arch/arm64/kernel/entry-common.c | 4 +- arch/arm64/kernel/traps.c | 26 +----------- arch/arm64/mm/fault.c | 53 ------------------------- 7 files changed, 3 insertions(+), 95 deletions(-)
diff --git a/arch/arm64/include/asm/debug-monitors.h b/arch/arm64/include/asm/debug-monitors.h
index 586290e95d87..4dfc37dd1d96 100644
--- a/arch/arm64/include/asm/debug-monitors.h
+++ b/arch/arm64/include/asm/debug-monitors.h@@ -94,7 +94,5 @@ static inline bool try_step_suspended_breakpoints(struct pt_regs *regs) bool try_handle_aarch32_break(struct pt_regs *regs); -void debug_traps_init(void); - #endif /* __ASSEMBLY */ #endif /* __ASM_DEBUG_MONITORS_H */
diff --git a/arch/arm64/include/asm/exception.h b/arch/arm64/include/asm/exception.h
index 1c41b6e3d3be..f7f772d75860 100644
--- a/arch/arm64/include/asm/exception.h
+++ b/arch/arm64/include/asm/exception.h@@ -59,8 +59,6 @@ void do_el0_bti(struct pt_regs *regs); void do_el1_bti(struct pt_regs *regs, unsigned long esr); void do_el0_gcs(struct pt_regs *regs, unsigned long esr); void do_el1_gcs(struct pt_regs *regs, unsigned long esr); -void do_debug_exception(unsigned long addr_if_watchpoint, unsigned long esr, - struct pt_regs *regs); void do_breakpoint(unsigned long esr, struct pt_regs *regs); void do_softstep(unsigned long esr, struct pt_regs *regs); void do_watchpoint(unsigned long addr, unsigned long esr,
@@ -86,8 +84,4 @@ void do_serror(struct pt_regs *regs, unsigned long esr); void do_signal(struct pt_regs *regs); void __noreturn panic_bad_stack(struct pt_regs *regs, unsigned long esr, unsigned long far); - -void debug_exception_enter(struct pt_regs *regs); -void debug_exception_exit(struct pt_regs *regs); - #endif /* __ASM_EXCEPTION_H */
diff --git a/arch/arm64/include/asm/system_misc.h b/arch/arm64/include/asm/system_misc.h
index c34344256762..344b1c1a4bbb 100644
--- a/arch/arm64/include/asm/system_misc.h
+++ b/arch/arm64/include/asm/system_misc.h@@ -25,10 +25,6 @@ void arm64_notify_die(const char *str, struct pt_regs *regs, int signo, int sicode, unsigned long far, unsigned long err); -void hook_debug_fault_code(int nr, int (*fn)(unsigned long, unsigned long, - struct pt_regs *), - int sig, int code, const char *name); - struct mm_struct; extern void __show_regs(struct pt_regs *);
diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c
index 5490a4f32e85..172be6b367f8 100644
--- a/arch/arm64/kernel/debug-monitors.c
+++ b/arch/arm64/kernel/debug-monitors.c@@ -333,9 +333,6 @@ bool try_handle_aarch32_break(struct pt_regs *regs) } NOKPROBE_SYMBOL(try_handle_aarch32_break); -void __init debug_traps_init(void) -{} - /* Re-enable single step for syscall restarting. */ void user_rewind_single_step(struct task_struct *task) {
diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
index 90ee140052c5..879beba5c78b 100644
--- a/arch/arm64/kernel/entry-common.c
+++ b/arch/arm64/kernel/entry-common.c@@ -448,7 +448,7 @@ static __always_inline void fpsimd_syscall_exit(void) * accidentally schedule in exception context and it will force a warning * if we somehow manage to schedule by accident. */ -void debug_exception_enter(struct pt_regs *regs) +static void debug_exception_enter(struct pt_regs *regs) { preempt_disable();
@@ -457,7 +457,7 @@ void debug_exception_enter(struct pt_regs *regs) } NOKPROBE_SYMBOL(debug_exception_enter); -void debug_exception_exit(struct pt_regs *regs) +static void debug_exception_exit(struct pt_regs *regs) { preempt_enable_no_resched(); }
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 654c8ea46ec6..d6c5268e6947 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c@@ -1101,29 +1101,5 @@ int ubsan_brk_handler(struct pt_regs *regs, unsigned long esr) } #endif -/* - * Initial handler for AArch64 BRK exceptions - * This handler only used until debug_traps_init(). - */ -int __init early_brk64(unsigned long addr, unsigned long esr, - struct pt_regs *regs) -{ -#ifdef CONFIG_CFI_CLANG - if (esr_is_cfi_brk(esr)) - return cfi_brk_handler(regs, esr) != DBG_HOOK_HANDLED; -#endif -#ifdef CONFIG_KASAN_SW_TAGS - if ((esr_brk_comment(esr) & ~KASAN_BRK_MASK) == KASAN_BRK_IMM) - return kasan_brk_handler(regs, esr) != DBG_HOOK_HANDLED; -#endif -#ifdef CONFIG_UBSAN_TRAP - if (esr_is_ubsan_brk(esr)) - return ubsan_brk_handler(regs, esr) != DBG_HOOK_HANDLED; -#endif - return bug_brk_handler(regs, esr) != DBG_HOOK_HANDLED; -} - void __init trap_init(void) -{ - debug_traps_init(); -} +{}
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);
@@ -938,53 +932,6 @@ 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. */
--
2.43.0