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powerpc/64s/exception: Soft NMI interrupt should not use ret_from_except 

The soft NMI handler does not reconcile interrupt state, so it should
not return via the normal ret_from_except path. Return like other NMIs,
using the EXCEPTION_RESTORE_REGS macro.

This becomes important when the scv interrupt is implemented, which
must handle soft-masked interrupts that have r13 set to something
other than the PACA -- returning to kernel in this case must restore
r13.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200225173541.1549955-23-npiggin@gmail.com
This commit is contained in:
Nicholas Piggin 2020-02-26 03:35:31 +10:00 committed by Michael Ellerman
parent b44fc96d7b
commit 71c3b05a80
1 changed files with 29 additions and 1 deletions
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30
arch/powerpc/kernel/exceptions-64s.S
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@ -2731,6 +2731,7 @@ EXC_VIRT_NONE(0x5800, 0x100)
INT_DEFINE_BEGIN(soft_nmi)
IVEC=0x900
ISTACK=0
IRECONCILE=0 /* Soft-NMI may fire under local_irq_disable */
INT_DEFINE_END(soft_nmi)
/*
@ -2749,9 +2750,36 @@ EXC_COMMON_BEGIN(soft_nmi_common)
subi r1,r1,INT_FRAME_SIZE
__GEN_COMMON_BODY soft_nmi
bl save_nvgprs
/*
* Set IRQS_ALL_DISABLED and save PACAIRQHAPPENED (see
* system_reset_common)
*/
li r10,IRQS_ALL_DISABLED
stb r10,PACAIRQSOFTMASK(r13)
lbz r10,PACAIRQHAPPENED(r13)
std r10,_DAR(r1)
ori r10,r10,PACA_IRQ_HARD_DIS
stb r10,PACAIRQHAPPENED(r13)
addi r3,r1,STACK_FRAME_OVERHEAD
bl soft_nmi_interrupt
b ret_from_except
/* Clear MSR_RI before setting SRR0 and SRR1. */
li r9,0
mtmsrd r9,1
/*
* Restore soft mask settings.
*/
ld r10,_DAR(r1)
stb r10,PACAIRQHAPPENED(r13)
ld r10,SOFTE(r1)
stb r10,PACAIRQSOFTMASK(r13)
kuap_restore_amr r10
EXCEPTION_RESTORE_REGS hsrr=0
RFI_TO_KERNEL
#endif /* CONFIG_PPC_WATCHDOG */