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| author |  Nicholas Piggin <npiggin@gmail.com>
| 2022-09-26 15:43:01 +1000 |
|---|---|---|
| committer |  Michael Ellerman <mpe@ellerman.id.au>
| 2022-09-28 19:22:11 +1000 |
| commit | e485f6c751e0a969327336c635ca602feea117f0 (patch) | |
| tree | 61f8e345236e656ddf174cf266d873b0f82556bb /arch/powerpc/kernel/interrupt_64.S | |
| parent | powerpc/64: mark irqs hard disabled in boot paca (diff) | |
| download | linux-e485f6c751e0a969327336c635ca602feea117f0.tar.gz linux-e485f6c751e0a969327336c635ca602feea117f0.tar.bz2 linux-e485f6c751e0a969327336c635ca602feea117f0.zip | |
powerpc/64/interrupt: Fix return to masked context after hard-mask irq becomes pending
If a synchronous interrupt (e.g., hash fault) is taken inside an
irqs-disabled region which has MSR[EE]=1, then an asynchronous interrupt
that is PACA_IRQ_MUST_HARD_MASK (e.g., PMI) is taken inside the
synchronous interrupt handler, then the synchronous interrupt will
return with MSR[EE]=1 and the asynchronous interrupt fires again.
If the asynchronous interrupt is a PMI and the original context does not
have PMIs disabled (only Linux IRQs), the asynchronous interrupt will
fire despite having the PMI marked soft pending. This can confuse the
perf code and cause warnings.
This patch changes the interrupt return so that irqs-disabled MSR[EE]=1
contexts will be returned to with MSR[EE]=0 if a PACA_IRQ_MUST_HARD_MASK
interrupt has become pending in the meantime.
The longer explanation for what happens:
1. local_irq_disable()
2. Hash fault interrupt fires, do_hash_fault handler runs
3. interrupt_enter_prepare() sets IRQS_ALL_DISABLED
4. interrupt_enter_prepare() sets MSR[EE]=1
5. PMU interrupt fires, masked handler runs
6. Masked handler marks PMI pending
7. Masked handler returns with PACA_IRQ_HARD_DIS set, MSR[EE]=0
8. do_hash_fault interrupt return handler runs
9. interrupt_exit_kernel_prepare() clears PACA_IRQ_HARD_DIS
10. interrupt returns with MSR[EE]=1
11. PMU interrupt fires, perf handler runs
Fixes: 4423eb5ae32e ("powerpc/64/interrupt: make normal synchronous interrupts enable MSR[EE] if possible")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220926054305.2671436-4-npiggin@gmail.com
Diffstat (limited to 'arch/powerpc/kernel/interrupt_64.S')
| -rw-r--r-- | arch/powerpc/kernel/interrupt_64.S | 34 |
1 files changed, 31 insertions, 3 deletions
diff --git a/arch/powerpc/kernel/interrupt_64.S b/arch/powerpc/kernel/interrupt_64.S index 90dbd6a8d4da..1dfa67e9199a 100644 --- a/arch/powerpc/kernel/interrupt_64.S +++ b/arch/powerpc/kernel/interrupt_64.S @@ -526,15 +526,43 @@ _ASM_NOKPROBE_SYMBOL(interrupt_return_\srr\()_kernel) ld r11,SOFTE(r1) cmpwi r11,IRQS_ENABLED stb r11,PACAIRQSOFTMASK(r13) - bne 1f + beq .Linterrupt_return_\srr\()_soft_enabled + + /* + * Returning to soft-disabled context. + * Check if a MUST_HARD_MASK interrupt has become pending, in which + * case we need to disable MSR[EE] in the return context. + */ + ld r12,_MSR(r1) + andi. r10,r12,MSR_EE + beq .Lfast_kernel_interrupt_return_\srr\() // EE already disabled + lbz r11,PACAIRQHAPPENED(r13) + andi. r10,r11,PACA_IRQ_MUST_HARD_MASK + beq 1f // No HARD_MASK pending + + /* Must clear MSR_EE from _MSR */ +#ifdef CONFIG_PPC_BOOK3S + li r10,0 + /* Clear valid before changing _MSR */ + .ifc \srr,srr + stb r10,PACASRR_VALID(r13) + .else + stb r10,PACAHSRR_VALID(r13) + .endif +#endif + xori r12,r12,MSR_EE + std r12,_MSR(r1) + b .Lfast_kernel_interrupt_return_\srr\() + +.Linterrupt_return_\srr\()_soft_enabled: #ifdef CONFIG_PPC_BOOK3S lbz r11,PACAIRQHAPPENED(r13) andi. r11,r11,(~PACA_IRQ_HARD_DIS)@l bne- interrupt_return_\srr\()_kernel_restart #endif - li r11,0 - stb r11,PACAIRQHAPPENED(r13) # clear out possible HARD_DIS 1: + li r11,0 + stb r11,PACAIRQHAPPENED(r13) // clear the possible HARD_DIS .Lfast_kernel_interrupt_return_\srr\(): cmpdi cr1,r3,0 |