On Sun, 28 Apr 2019 10:41:10 -0700 Andy Lutomirski <l...@amacapital.net> wrote:
> > Note that at any given point > > in time, there can be at most four such call insn emulations pending: > > namely at most one per "process", "irq", "softirq" and "nmi" context. > > > > That’s quite an assumption. I think your list should also contain > exception, exceptions nested inside that exception, and machine > check, at the very least. I’m also wondering why irq and softirq are > treated separately. 4 has usually been the context count we choose. But I guess in theory, if we get exceptions then I could potentially be more. As for irq vs softirq, an interrupt can preempt a softirq. Interrupts are enabled while softirqs are running. When sofirqs run, softirqs are disabled to prevent nested softirqs. But interrupts are enabled again, and another interrupt may come in while a softirq is executing. > > All this makes me think that one of the other solutions we came up > with last time we discussed this might be better. +100 Perhaps adding another slot into pt_regs that gets used by int3 to store a slot to emulate a call on return? -- Steve
