Commit 80691d35 authored by Ada Couprie Diaz's avatar Ada Couprie Diaz Committed by Will Deacon
Browse files

arm64: debug: refactor reinstall_suspended_bps() 



`reinstall_suspended_bps()` plays a key part in the stepping process
when we have hardware breakpoints and watchpoints enabled.
It checks if we need to step one, will re-enable it if it has
been handled and will return whether or not we need to proceed with
a single-step.

However, the current naming and return values make it harder to understand
the logic and goal of the function.

Rename it `try_step_suspended_breakpoints()` and change the return value
to a boolean, aligning it with similar functions used in
`do_el0_undef()` like `try_emulate_mrs()`, and making its behaviour
more obvious.

Signed-off-by: default avatarAda Couprie Diaz <ada.coupriediaz@arm.com>
Tested-by: default avatarLuis Claudio R. Goncalves <lgoncalv@redhat.com>
Reviewed-by: default avatarAnshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: default avatarWill Deacon <will@kernel.org>
Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20250707114109.35672-9-ada.coupriediaz@arm.com


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 43e2ae77

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

+3 −3
Original line number Diff line number Diff line
@@ -84,11 +84,11 @@ void kernel_rewind_single_step(struct pt_regs *regs); 
void kernel_fastforward_single_step(struct pt_regs *regs);



#ifdef CONFIG_HAVE_HW_BREAKPOINT

int reinstall_suspended_bps(struct pt_regs *regs);

bool try_step_suspended_breakpoints(struct pt_regs *regs);

#else

static inline int reinstall_suspended_bps(struct pt_regs *regs)

static inline bool try_step_suspended_breakpoints(struct pt_regs *regs)

{

	return -ENODEV;

	return false;

}

#endif

arch/arm64/kernel/debug-monitors.c

+1 −1
Original line number Diff line number Diff line
@@ -195,7 +195,7 @@ static int single_step_handler(unsigned long unused, unsigned long esr, 
	 * If we are stepping a pending breakpoint, call the hw_breakpoint

	 * handler first.

	 */

	if (!reinstall_suspended_bps(regs))

	if (try_step_suspended_breakpoints(regs))

		return 0;



	if (call_step_hook(regs, esr) == DBG_HOOK_HANDLED)

arch/arm64/kernel/hw_breakpoint.c

+12 −13
Original line number Diff line number Diff line
@@ -847,36 +847,35 @@ NOKPROBE_SYMBOL(watchpoint_handler); 
/*

 * Handle single-step exception.

 */

int reinstall_suspended_bps(struct pt_regs *regs)

bool try_step_suspended_breakpoints(struct pt_regs *regs)

{

	struct debug_info *debug_info = &current->thread.debug;

	int handled_exception = 0, *kernel_step;



	kernel_step = this_cpu_ptr(&stepping_kernel_bp);

	int *kernel_step = this_cpu_ptr(&stepping_kernel_bp);

	bool handled_exception = false;



	/*

	 * Called from single-step exception handler.

	 * Return 0 if execution can resume, 1 if a SIGTRAP should be

	 * reported.

	 * Return true if we stepped a breakpoint and can resume execution,

	 * false if we need to handle a single-step.

	 */

	if (user_mode(regs)) {

		if (debug_info->bps_disabled) {

			debug_info->bps_disabled = 0;

			toggle_bp_registers(AARCH64_DBG_REG_BCR, DBG_ACTIVE_EL0, 1);

			handled_exception = 1;

			handled_exception = true;

		}



		if (debug_info->wps_disabled) {

			debug_info->wps_disabled = 0;

			toggle_bp_registers(AARCH64_DBG_REG_WCR, DBG_ACTIVE_EL0, 1);

			handled_exception = 1;

			handled_exception = true;

		}



		if (handled_exception) {

			if (debug_info->suspended_step) {

				debug_info->suspended_step = 0;

				/* Allow exception handling to fall-through. */

				handled_exception = 0;

				handled_exception = false;

			} else {

				user_disable_single_step(current);

			}
@@ -890,17 +889,17 @@ int reinstall_suspended_bps(struct pt_regs *regs) 


		if (*kernel_step != ARM_KERNEL_STEP_SUSPEND) {

			kernel_disable_single_step();

			handled_exception = 1;

			handled_exception = true;

		} else {

			handled_exception = 0;

			handled_exception = false;

		}



		*kernel_step = ARM_KERNEL_STEP_NONE;

	}



	return !handled_exception;

	return handled_exception;

}

NOKPROBE_SYMBOL(reinstall_suspended_bps);

NOKPROBE_SYMBOL(try_step_suspended_breakpoints);



/*

 * Context-switcher for restoring suspended breakpoints.