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

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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: Ada Couprie Diaz <ada.coupriediaz@arm.com>
Tested-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Will Deacon <will@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20250707114109.35672-7-ada.coupriediaz@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Ada Couprie Diaz
2025-07-07 12:41:02 +01:00
committed by Will Deacon
parent d4e0b12620
commit eaff68b328
3 changed files with 26 additions and 22 deletions
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4
arch/arm64/include/asm/exception.h
View File

@@ -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 */

22
arch/arm64/kernel/entry-common.c
View File

@@ -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)

22
arch/arm64/mm/fault.c
View File

@@ -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)
{