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Commit b1ee8a3d authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

powerpc/64s: Dedicated system reset interrupt stack 



The system reset interrupt is used for crash/debug situations, so it is
desirable to have as little impact on the normal state of the system as
possible.

Currently it uses the current kernel stack to process the exception.
This stores into the stack which may be involved with the crash. The
stack pointer may be corrupted, or it may have overflowed.

Avoid or minimise these problems by creating a dedicated NMI stack for
the system reset interrupt to use.

Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent c4f3b52c

arch/powerpc/include/asm/exception-64s.h

+13 −0
Original line number Original line Diff line number Diff line
@@ -563,6 +563,19 @@ END_FTR_SECTION_IFSET(CPU_FTR_CTRL) 
	bl	hdlr;						\

	bl	hdlr;						\

	b	ret

	b	ret





/*

 * Exception where stack is already set in r1, r1 is saved in r10, and it

 * continues rather than returns.

 */

#define EXCEPTION_COMMON_NORET_STACK(area, trap, label, hdlr, additions) \

	EXCEPTION_PROLOG_COMMON_1();				\

	EXCEPTION_PROLOG_COMMON_2(area);			\

	EXCEPTION_PROLOG_COMMON_3(trap);			\

	/* Volatile regs are potentially clobbered here */	\

	additions;						\

	addi	r3,r1,STACK_FRAME_OVERHEAD;			\

	bl	hdlr



#define STD_EXCEPTION_COMMON(trap, label, hdlr)			\

#define STD_EXCEPTION_COMMON(trap, label, hdlr)			\

	EXCEPTION_COMMON(PACA_EXGEN, trap, label, hdlr,		\

	EXCEPTION_COMMON(PACA_EXGEN, trap, label, hdlr,		\

		ret_from_except, ADD_NVGPRS;ADD_RECONCILE)

		ret_from_except, ADD_NVGPRS;ADD_RECONCILE)

arch/powerpc/include/asm/paca.h

+2 −1
Original line number Original line Diff line number Diff line
@@ -185,7 +185,8 @@ struct paca_struct { 
	u64 exmc[13];		/* used for machine checks */

	u64 exmc[13];		/* used for machine checks */

#endif

#endif

#ifdef CONFIG_PPC_BOOK3S_64

#ifdef CONFIG_PPC_BOOK3S_64

	/* Exclusive emergency stack pointer for machine check exception. */

	/* Exclusive stacks for system reset and machine check exception. */

	void *nmi_emergency_sp;

	void *mc_emergency_sp;

	void *mc_emergency_sp;





	u16 in_nmi;			/* In nmi handler */

	u16 in_nmi;			/* In nmi handler */

arch/powerpc/kernel/asm-offsets.c

+1 −0
Original line number Original line Diff line number Diff line
@@ -234,6 +234,7 @@ int main(void) 
	OFFSET(PACAEMERGSP, paca_struct, emergency_sp);

	OFFSET(PACAEMERGSP, paca_struct, emergency_sp);

#ifdef CONFIG_PPC_BOOK3S_64

#ifdef CONFIG_PPC_BOOK3S_64

	OFFSET(PACAMCEMERGSP, paca_struct, mc_emergency_sp);

	OFFSET(PACAMCEMERGSP, paca_struct, mc_emergency_sp);

	OFFSET(PACA_NMI_EMERG_SP, paca_struct, nmi_emergency_sp);

	OFFSET(PACA_IN_MCE, paca_struct, in_mce);

	OFFSET(PACA_IN_MCE, paca_struct, in_mce);

	OFFSET(PACA_IN_NMI, paca_struct, in_nmi);

	OFFSET(PACA_IN_NMI, paca_struct, in_nmi);

#endif

#endif

arch/powerpc/kernel/exceptions-64s.S

+5 −3
Original line number Original line Diff line number Diff line
@@ -144,10 +144,12 @@ EXC_COMMON_BEGIN(system_reset_common) 
	li	r10,MSR_RI

	li	r10,MSR_RI

	mtmsrd 	r10,1

	mtmsrd 	r10,1





	EXCEPTION_COMMON(PACA_EXNMI, 0x100,

	mr	r10,r1

			system_reset, system_reset_exception, 1f,

	ld	r1,PACA_NMI_EMERG_SP(r13)

	subi	r1,r1,INT_FRAME_SIZE

	EXCEPTION_COMMON_NORET_STACK(PACA_EXNMI, 0x100,

			system_reset, system_reset_exception,

			ADD_NVGPRS;ADD_RECONCILE)

			ADD_NVGPRS;ADD_RECONCILE)

1: /* EXCEPTION_COMMON continues here */





	/*

	/*

	 * The stack is no longer in use, decrement in_nmi.

	 * The stack is no longer in use, decrement in_nmi.

arch/powerpc/kernel/setup_64.c

+5 −0
Original line number Original line Diff line number Diff line
@@ -628,6 +628,11 @@ void __init emergency_stack_init(void) 
		paca[i].emergency_sp = (void *)ti + THREAD_SIZE;

		paca[i].emergency_sp = (void *)ti + THREAD_SIZE;





#ifdef CONFIG_PPC_BOOK3S_64

#ifdef CONFIG_PPC_BOOK3S_64

		/* emergency stack for NMI exception handling. */

		ti = __va(memblock_alloc_base(THREAD_SIZE, THREAD_SIZE, limit));

		klp_init_thread_info(ti);

		paca[i].nmi_emergency_sp = (void *)ti + THREAD_SIZE;



		/* emergency stack for machine check exception handling. */

		/* emergency stack for machine check exception handling. */

		ti = __va(memblock_alloc_base(THREAD_SIZE, THREAD_SIZE, limit));

		ti = __va(memblock_alloc_base(THREAD_SIZE, THREAD_SIZE, limit));

		klp_init_thread_info(ti);

		klp_init_thread_info(ti);