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arm64: debug: remove debug exception registration infrastructure

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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>
This commit is contained in:
Ada Couprie Diaz 2025-07-07 12:41:09 +01:00 committed by Will Deacon
parent fc5e5d0477
commit a8b8cce9d9
7 changed files with 2 additions and 97 deletions
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2
arch/arm64/include/asm/debug-monitors.h
View File

@ -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 */

6
arch/arm64/include/asm/exception.h
View File

@ -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);
#ifdef CONFIG_HAVE_HW_BREAKPOINT
void do_breakpoint(unsigned long esr, struct pt_regs *regs);
void do_watchpoint(unsigned long addr, unsigned long esr,
@ -94,8 +92,4 @@ 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 */

4
arch/arm64/include/asm/system_misc.h
View File

@ -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 *);

3
arch/arm64/kernel/debug-monitors.c
View File

@ -316,9 +316,6 @@ 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)
{

4
arch/arm64/kernel/entry-common.c
View File

@ -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();
}

27
arch/arm64/kernel/traps.c
View File

@ -1100,30 +1100,3 @@ int ubsan_brk_handler(struct pt_regs *regs, unsigned long esr)
return DBG_HOOK_HANDLED;
}
#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();
}

53
arch/arm64/mm/fault.c
View File

@ -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.
*/