x86: Replace ist_enter() with nmi_enter()

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A few exceptions (like #DB and #BP) can happen at any location in the code,
this then means that tracers should treat events from these exceptions as
NMI-like. The interrupted context could be holding locks with interrupts
disabled for instance.

Similarly, #MC is an actual NMI-like exception.

All of them use ist_enter() which only concerns itself with RCU, but does
not do any of the other setup that NMIs need. This means things like:

	printk()
	  raw_spin_lock_irq(&logbuf_lock);
	  <#DB/#BP/#MC>
	     printk()
	       raw_spin_lock_irq(&logbuf_lock);

are entirely possible (well, not really since printk tries hard to
play nice, but the concept stands).

So replace ist_enter() with nmi_enter(). Also observe that any nmi_enter()
caller must be both notrace and NOKPROBE, or in the noinstr text section.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Link: https://lkml.kernel.org/r/20200505134101.525508608@linutronix.de

...

This commit is contained in:

Peter Zijlstra 2020-02-19 09:46:43 +01:00 • committed by Thomas Gleixner

parent 5567d11c21

commit 0d00449c7a

5 changed files with 24 additions and 65 deletions

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3

arch/x86/include/asm/traps.h

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arch/x86/kernel/cpu/mce/core.c

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arch/x86/kernel/cpu/mce/p5.c

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arch/x86/kernel/cpu/mce/winchip.c

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arch/x86/kernel/traps.c

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