Commit eaff68b3 authored by Ada Couprie Diaz's avatar Ada Couprie Diaz Committed by Will Deacon
Browse files

arm64: entry: Add entry and exit functions for debug exceptions 



Move the `debug_exception_enter()` and `debug_exception_exit()`
functions from mm/fault.c, as they are needed to split
the debug exceptions entry paths from the current unified one.

Make them externally visible in include/asm/exception.h until
the caller in mm/fault.c is cleaned up.

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/20250707114109.35672-7-ada.coupriediaz@arm.com


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent d4e0b126

arch/arm64/include/asm/exception.h

+4 −0
Original line number Diff line number Diff line
@@ -80,4 +80,8 @@ 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 */

arch/arm64/kernel/entry-common.c

+22 −0
Original line number Diff line number Diff line
@@ -441,6 +441,28 @@ static __always_inline void fpsimd_syscall_exit(void) 
	__this_cpu_write(fpsimd_last_state.to_save, FP_STATE_CURRENT);

}



/*

 * In debug exception context, we explicitly disable preemption despite

 * having interrupts disabled.

 * This serves two purposes: it makes it much less likely that we would

 * 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)

{

	preempt_disable();



	/* This code is a bit fragile.  Test it. */

	RCU_LOCKDEP_WARN(!rcu_is_watching(), "exception_enter didn't work");

}

NOKPROBE_SYMBOL(debug_exception_enter);



void debug_exception_exit(struct pt_regs *regs)

{

	preempt_enable_no_resched();

}

NOKPROBE_SYMBOL(debug_exception_exit);



UNHANDLED(el1t, 64, sync)

UNHANDLED(el1t, 64, irq)

UNHANDLED(el1t, 64, fiq)

arch/arm64/mm/fault.c

+0 −22
Original line number Diff line number Diff line
@@ -966,28 +966,6 @@ void __init hook_debug_fault_code(int nr, 
	debug_fault_info[nr].name	= name;

}



/*

 * In debug exception context, we explicitly disable preemption despite

 * having interrupts disabled.

 * This serves two purposes: it makes it much less likely that we would

 * accidentally schedule in exception context and it will force a warning

 * if we somehow manage to schedule by accident.

 */

static void debug_exception_enter(struct pt_regs *regs)

{

	preempt_disable();



	/* This code is a bit fragile.  Test it. */

	RCU_LOCKDEP_WARN(!rcu_is_watching(), "exception_enter didn't work");

}

NOKPROBE_SYMBOL(debug_exception_enter);



static void debug_exception_exit(struct pt_regs *regs)

{

	preempt_enable_no_resched();

}

NOKPROBE_SYMBOL(debug_exception_exit);



void do_debug_exception(unsigned long addr_if_watchpoint, unsigned long esr,

			struct pt_regs *regs)

{