Commit f7bff6e7 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

powerpc/64/interrupt: avoid BUG/WARN recursion in interrupt entry 



BUG/WARN are handled with a program interrupt which can turn into an
infinite recursion when there are bugs in interrupt handler entry
(which can be irritated by bugs in other parts of the code).

There is one feeble attempt to avoid this recursion, but it misses
several cases. Make a tidier macro for this and switch most bugs in
the interrupt entry wrapper over to use it.

Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220926054305.2671436-7-npiggin@gmail.com
parent c39fb71a

arch/powerpc/include/asm/interrupt.h

+20 −13
Original line number Diff line number Diff line
@@ -74,6 +74,19 @@ 
#include <asm/kprobes.h>

#include <asm/runlatch.h>



#ifdef CONFIG_PPC64

/*

 * WARN/BUG is handled with a program interrupt so minimise checks here to

 * avoid recursion and maximise the chance of getting the first oops handled.

 */

#define INT_SOFT_MASK_BUG_ON(regs, cond)				\

do {									\

	if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG) &&		\

	    (user_mode(regs) || (TRAP(regs) != INTERRUPT_PROGRAM)))	\

		BUG_ON(cond);						\

} while (0)

#endif



#ifdef CONFIG_PPC_BOOK3S_64

extern char __end_soft_masked[];

bool search_kernel_soft_mask_table(unsigned long addr);
@@ -170,8 +183,7 @@ static inline void interrupt_enter_prepare(struct pt_regs *regs) 
	 * context.

	 */

	if (!(local_paca->irq_happened & PACA_IRQ_HARD_DIS)) {

		if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))

			BUG_ON(!(regs->msr & MSR_EE));

		INT_SOFT_MASK_BUG_ON(regs, !(regs->msr & MSR_EE));

		__hard_irq_enable();

	} else {

		__hard_RI_enable();
@@ -194,20 +206,15 @@ static inline void interrupt_enter_prepare(struct pt_regs *regs) 
		 * CT_WARN_ON comes here via program_check_exception,

		 * so avoid recursion.

		 */

		if (TRAP(regs) != INTERRUPT_PROGRAM) {

		if (TRAP(regs) != INTERRUPT_PROGRAM)

			CT_WARN_ON(ct_state() != CONTEXT_KERNEL &&

				   ct_state() != CONTEXT_IDLE);

			if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))

				BUG_ON(is_implicit_soft_masked(regs));

		}



		/* Move this under a debugging check */

		if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG) &&

				arch_irq_disabled_regs(regs))

			BUG_ON(search_kernel_restart_table(regs->nip));

		INT_SOFT_MASK_BUG_ON(regs, is_implicit_soft_masked(regs));

		INT_SOFT_MASK_BUG_ON(regs, arch_irq_disabled_regs(regs) &&

					   search_kernel_restart_table(regs->nip));

	}

	if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))

		BUG_ON(!arch_irq_disabled_regs(regs) && !(regs->msr & MSR_EE));

	INT_SOFT_MASK_BUG_ON(regs, !arch_irq_disabled_regs(regs) &&

				   !(regs->msr & MSR_EE));

#endif



	booke_restore_dbcr0();