Commit b7d9ccec authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

powerpc/64s/exception: machine check move unrecoverable handling out of line 



Similarly to the previous change, all callers of the unrecoverable
handler run relocated so can reach it with a direct branch. This makes
it easy to move out of line, which makes the "normal" path less
cluttered and easier to follow.

MSR[ME] manipulation still requires the rfi, so that is moved out of
line to its own function.

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/20190802105709.27696-15-npiggin@gmail.com
parent 296e753f

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

+44 −43
Original line number Diff line number Diff line
@@ -992,9 +992,9 @@ EXC_COMMON_BEGIN(machine_check_early_common) 
	bne	1f

	/* First machine check entry */

	ld	r1,PACAMCEMERGSP(r13)	/* Use MC emergency stack */

1:	subi	r1,r1,INT_FRAME_SIZE	/* alloc stack frame */

	/* Limit nested MCE to level 4 to avoid stack overflow */

	bge	cr1,2f			/* Check if we hit limit of 4 */

1:	/* Limit nested MCE to level 4 to avoid stack overflow */

	bgt	cr1,unrecoverable_mce	/* Check if we hit limit of 4 */

	subi	r1,r1,INT_FRAME_SIZE	/* alloc stack frame */



	EXCEPTION_PROLOG_COMMON_1()

	/* We don't touch AMR here, we never go to virtual mode */
@@ -1013,21 +1013,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_HVMODE) 
	mtmsrd	r10,1

	b	machine_check_handle_early



2:

	/* Stack overflow. Stay on emergency stack and panic.

	 * Keep the ME bit off while panic-ing, so that if we hit

	 * another machine check we checkstop.

	 */

	addi	r1,r1,INT_FRAME_SIZE	/* go back to previous stack frame */

	ld	r11,PACAKMSR(r13)

	LOAD_HANDLER(r12, unrecover_mce)

	li	r10,MSR_ME

	andc	r11,r11,r10		/* Turn off MSR_ME */

	mtspr	SPRN_SRR0,r12

	mtspr	SPRN_SRR1,r11

	RFI_TO_KERNEL

	b	.	/* prevent speculative execution */



EXC_COMMON_BEGIN(machine_check_common)

	/*

	 * Machine check is different because we use a different
@@ -1141,32 +1126,15 @@ END_FTR_SECTION_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206) 
	 * If yes, then stay on emergency stack and panic.

	 */

	andi.	r11,r12,MSR_RI

	bne	2f

1:	mfspr	r11,SPRN_SRR0

	LOAD_HANDLER(r10,unrecover_mce)

	mtspr	SPRN_SRR0,r10

	ld	r10,PACAKMSR(r13)

	/*

	 * We are going down. But there are chances that we might get hit by

	 * another MCE during panic path and we may run into unstable state

	 * with no way out. Hence, turn ME bit off while going down, so that

	 * when another MCE is hit during panic path, system will checkstop

	 * and hypervisor will get restarted cleanly by SP.

	 */

	li	r3,MSR_ME

	andc	r10,r10,r3		/* Turn off MSR_ME */

	mtspr	SPRN_SRR1,r10

	RFI_TO_KERNEL

	b	.

2:

	beq	unrecoverable_mce



	/*

	 * Check if we have successfully handled/recovered from error, if not

	 * then stay on emergency stack and panic.

	 */

	ld	r3,RESULT(r1)	/* Load result */

	cmpdi	r3,0		/* see if we handled MCE successfully */



	beq	1b		/* if !handled then panic */

	beq	unrecoverable_mce /* if !handled then panic */



	/*

	 * Return from MC interrupt.
@@ -1189,17 +1157,35 @@ END_FTR_SECTION_IFSET(CPU_FTR_CFAR) 
	EXCEPTION_PROLOG_1 EXC_STD, PACA_EXMC, 1, 0x200, 1, 1, 0

	EXCEPTION_PROLOG_2_REAL machine_check_common, EXC_STD, 0



EXC_COMMON_BEGIN(unrecover_mce)

EXC_COMMON_BEGIN(unrecoverable_mce)

	/*

	 * We are going down. But there are chances that we might get hit by

	 * another MCE during panic path and we may run into unstable state

	 * with no way out. Hence, turn ME bit off while going down, so that

	 * when another MCE is hit during panic path, system will checkstop

	 * and hypervisor will get restarted cleanly by SP.

	 */

BEGIN_FTR_SECTION

	li	r10,0 /* clear MSR_RI */

	mtmsrd	r10,1

	bl	disable_machine_check

END_FTR_SECTION_IFSET(CPU_FTR_HVMODE)

	ld	r10,PACAKMSR(r13)

	li	r3,MSR_ME

	andc	r10,r10,r3

	mtmsrd	r10



	/* Invoke machine_check_exception to print MCE event and panic. */

	addi	r3,r1,STACK_FRAME_OVERHEAD

	bl	machine_check_exception



	/*

	 * We will not reach here. Even if we did, there is no way out. Call

	 * unrecoverable_exception and die.

	 * We will not reach here. Even if we did, there is no way out.

	 * Call unrecoverable_exception and die.

	 */

1:	addi	r3,r1,STACK_FRAME_OVERHEAD

	addi	r3,r1,STACK_FRAME_OVERHEAD

	bl	unrecoverable_exception

	b	1b

	b	.





EXC_REAL_BEGIN(data_access, 0x300, 0x80)
@@ -2282,6 +2268,21 @@ enable_machine_check: 
1:	mtlr	r0

	blr



/* MSR[RI] should be clear because this uses SRR[01] */

disable_machine_check:

	mflr	r0

	bcl	20,31,$+4

0:	mflr	r3

	addi	r3,r3,(1f - 0b)

	mtspr	SPRN_SRR0,r3

	mfmsr	r3

	li	r4,MSR_ME

	andc	r3,r3,r4

	mtspr	SPRN_SRR1,r3

	RFI_TO_KERNEL

1:	mtlr	r0

	blr



/*

 * Hash table stuff

 */

CRA Git | Maintained and supported by SUSTech CRA and CCSE