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

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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: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200611081203.995112-2-npiggin@gmail.com
This commit is contained in:
Nicholas Piggin 2020-06-11 18:12:02 +10:00 committed by Michael Ellerman
parent 48778464bb
commit b2dc2977cb
1 changed files with 24 additions and 3 deletions
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27
arch/powerpc/kernel/exceptions-64s.S
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@ -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