4ef702c10b
For some time each panic() called with interrupts disabled triggered the !irqs_disabled() WARN_ON in smp_call_function(), producing ugly backtraces and confusing users. This is a common situation with machine checks for example which tend to call panic with interrupts disabled, but will also hit in other situations e.g. panic during early boot. In fact it means that panic cannot be called in many circumstances, which would be bad. This all started with the new fancy queued smp_call_function, which is then used by the shutdown path to shut down the other CPUs. On closer examination it turned out that the fancy RCU smp_call_function() does lots of things not suitable in a panic situation anyways, like allocating memory and relying on complex system state. I originally tried to patch this over by checking for panic there, but it was quite complicated and the original patch was also not very popular. This also didn't fix some of the underlying complexity problems. The new code in post 2.6.29 tries to patch around this by checking for oops_in_progress, but that is not enough to make this fully safe and I don't think that's a real solution because panic has to be reliable. So instead use an own vector to reboot. This makes the reboot code extremly straight forward, which is definitely a big plus in a panic situation where it is important to avoid relying on too much kernel state. The new simple code is also safe to be called from interupts off region because it is very very simple. There can be situations where it is important that panic is reliable. For example on a fatal machine check the panic is needed to get the system up again and running as quickly as possible. So it's important that panic is reliable and all function it calls simple. This is why I came up with this simple vector scheme. It's very hard to beat in simplicity. Vectors are not particularly precious anymore since all big systems are using per CPU vectors. Another possibility would have been to use an NMI similar to kdump, but there is still the problem that NMIs don't work reliably on some systems due to BIOS issues. NMIs would have been able to stop CPUs running with interrupts off too. In the sake of universal reliability I opted for using a non NMI vector for now. I put the reboot vector into the highest priority bucket of the APIC vectors and moved the 64bit UV_BAU message down instead into the next lower priority. [ Impact: bug fix, fixes an old regression ] Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
68 lines
2.4 KiB
C
68 lines
2.4 KiB
C
/*
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* This file is designed to contain the BUILD_INTERRUPT specifications for
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* all of the extra named interrupt vectors used by the architecture.
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* Usually this is the Inter Process Interrupts (IPIs)
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*/
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/*
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* The following vectors are part of the Linux architecture, there
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* is no hardware IRQ pin equivalent for them, they are triggered
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* through the ICC by us (IPIs)
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*/
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#ifdef CONFIG_SMP
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BUILD_INTERRUPT(reschedule_interrupt,RESCHEDULE_VECTOR)
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BUILD_INTERRUPT(call_function_interrupt,CALL_FUNCTION_VECTOR)
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BUILD_INTERRUPT(call_function_single_interrupt,CALL_FUNCTION_SINGLE_VECTOR)
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BUILD_INTERRUPT(irq_move_cleanup_interrupt,IRQ_MOVE_CLEANUP_VECTOR)
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BUILD_INTERRUPT(reboot_interrupt,REBOOT_VECTOR)
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BUILD_INTERRUPT3(invalidate_interrupt0,INVALIDATE_TLB_VECTOR_START+0,
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smp_invalidate_interrupt)
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BUILD_INTERRUPT3(invalidate_interrupt1,INVALIDATE_TLB_VECTOR_START+1,
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smp_invalidate_interrupt)
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BUILD_INTERRUPT3(invalidate_interrupt2,INVALIDATE_TLB_VECTOR_START+2,
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smp_invalidate_interrupt)
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BUILD_INTERRUPT3(invalidate_interrupt3,INVALIDATE_TLB_VECTOR_START+3,
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smp_invalidate_interrupt)
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BUILD_INTERRUPT3(invalidate_interrupt4,INVALIDATE_TLB_VECTOR_START+4,
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smp_invalidate_interrupt)
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BUILD_INTERRUPT3(invalidate_interrupt5,INVALIDATE_TLB_VECTOR_START+5,
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smp_invalidate_interrupt)
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BUILD_INTERRUPT3(invalidate_interrupt6,INVALIDATE_TLB_VECTOR_START+6,
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smp_invalidate_interrupt)
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BUILD_INTERRUPT3(invalidate_interrupt7,INVALIDATE_TLB_VECTOR_START+7,
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smp_invalidate_interrupt)
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#endif
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BUILD_INTERRUPT(generic_interrupt, GENERIC_INTERRUPT_VECTOR)
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/*
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* every pentium local APIC has two 'local interrupts', with a
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* soft-definable vector attached to both interrupts, one of
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* which is a timer interrupt, the other one is error counter
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* overflow. Linux uses the local APIC timer interrupt to get
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* a much simpler SMP time architecture:
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*/
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#ifdef CONFIG_X86_LOCAL_APIC
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BUILD_INTERRUPT(apic_timer_interrupt,LOCAL_TIMER_VECTOR)
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BUILD_INTERRUPT(error_interrupt,ERROR_APIC_VECTOR)
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BUILD_INTERRUPT(spurious_interrupt,SPURIOUS_APIC_VECTOR)
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#ifdef CONFIG_PERF_COUNTERS
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BUILD_INTERRUPT(perf_counter_interrupt, LOCAL_PERF_VECTOR)
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#endif
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#ifdef CONFIG_X86_THERMAL_VECTOR
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BUILD_INTERRUPT(thermal_interrupt,THERMAL_APIC_VECTOR)
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#endif
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#ifdef CONFIG_X86_MCE_THRESHOLD
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BUILD_INTERRUPT(threshold_interrupt,THRESHOLD_APIC_VECTOR)
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#endif
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#ifdef CONFIG_X86_NEW_MCE
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BUILD_INTERRUPT(mce_self_interrupt,MCE_SELF_VECTOR)
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#endif
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#endif
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