On Fri, 24 Jul 2015 08:48:57 -0700
Andy Lutomirski <l...@amacapital.net> wrote:
> So by the time we detect that we've hit a watchpoint, the instruction
> that tripped it is done and we don't need RF. Furthermore, after
> reading 17.3.1.1: I *think* that regs->flags withh have RF *clear* if
> we hit a watchpoint. So this might be as simple as:
>
> if ((dr6 && (0xf * DR_TRAP0) && (regs->flags & (X86_EFLAGS_RF |
Um, isn't 0xf * DR_TRAP0 same as a constant "true"?
-- Steve
> X86_EFLAGS_IF)) == X86_EFLAGS_RF && !user_mode(regs))
> for (i = 0; i < 4; i++)
> if (dr6 & (DR_TRAP0<<i)) {
> /* hit a kernel breakpoint with IF clear */
> dr7 &= ~(DR_GLOBAL_ENABLE << (i * DR_ENABLE_SHIFT));
> }
>
> I'm not saying that your code is wrong, but I think this is simpler
> and avoids poking at yet more per-cpu state from NMI context, which is
> kind of nice.
>
> If you don't like the RF games above, it would also be straightforward
> to parse dr0..dr3 for each DR_TRAP bit that's set and see if it's a
> breakpoint.
>
> --Andy
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