Commit b2dc2977 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

powerpc/64s/exception: treat NIA below __end_interrupts as soft-masked 



The scv instruction causes an interrupt which can enter the kernel with
MSR[EE]=1, thus allowing interrupts to hit at any time. These must not
be taken as normal interrupts, because they come from MSR[PR]=0 context,
and yet the kernel stack is not yet set up and r13 is not set to the
PACA).

Treat this as a soft-masked interrupt regardless of the soft masked
state. This does not affect behaviour yet, because currently all
interrupts are taken with MSR[EE]=0.

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/20200611081203.995112-2-npiggin@gmail.com
parent 48778464

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

+24 −3
Original line number Diff line number Diff line
@@ -508,8 +508,24 @@ DEFINE_FIXED_SYMBOL(\name\()_common_real) 


.macro __GEN_COMMON_BODY name

	.if IMASK

		.if ! ISTACK

		.error "No support for masked interrupt to use custom stack"

		.endif



		/* If coming from user, skip soft-mask tests. */

		andi.	r10,r12,MSR_PR

		bne	2f



		/* Kernel code running below __end_interrupts is implicitly

		 * soft-masked */

		LOAD_HANDLER(r10, __end_interrupts)

		cmpld	r11,r10

		li	r10,IMASK

		blt-	1f



		/* Test the soft mask state against our interrupt's bit */

		lbz	r10,PACAIRQSOFTMASK(r13)

		andi.	r10,r10,IMASK

1:		andi.	r10,r10,IMASK

		/* Associate vector numbers with bits in paca->irq_happened */

		.if IVEC == 0x500 || IVEC == 0xea0

		li	r10,PACA_IRQ_EE
@@ -540,7 +556,7 @@ DEFINE_FIXED_SYMBOL(\name\()_common_real) 


	.if ISTACK

	andi.	r10,r12,MSR_PR		/* See if coming from user	*/

	mr	r10,r1			/* Save r1			*/

2:	mr	r10,r1			/* Save r1			*/

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

	beq-	100f

	ld	r1,PACAKSAVE(r13)	/* kernel stack to use		*/
@@ -2838,7 +2854,8 @@ masked_interrupt: 
	ld	r10,PACA_EXGEN+EX_R10(r13)

	ld	r11,PACA_EXGEN+EX_R11(r13)

	ld	r12,PACA_EXGEN+EX_R12(r13)

	/* returns to kernel where r13 must be set up, so don't restore it */

	ld	r13,PACA_EXGEN+EX_R13(r13)

	/* May return to masked low address where r13 is not set up */

	.if \hsrr

	HRFI_TO_KERNEL

	.else
@@ -2997,6 +3014,10 @@ EXC_COMMON_BEGIN(ppc64_runlatch_on_trampoline) 


USE_FIXED_SECTION(virt_trampolines)

	/*

	 * All code below __end_interrupts is treated as soft-masked. If

	 * any code runs here with MSR[EE]=1, it must then cope with pending

	 * soft interrupt being raised (i.e., by ensuring it is replayed).

	 *

	 * The __end_interrupts marker must be past the out-of-line (OOL)

	 * handlers, so that they are copied to real address 0x100 when running

	 * a relocatable kernel. This ensures they can be reached from the short

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