Messages in this thread | | | Date | Mon, 7 Aug 2017 17:18:11 +0100 | From | "Maciej W. Rozycki" <> | Subject | Re: [PATCH 4/7] signal/mips: Document a conflict with SI_USER with SIGFPE |
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On Tue, 18 Jul 2017, Eric W. Biederman wrote:
> diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c > index b68b4d0726d3..6c9cca9c5341 100644 > --- a/arch/mips/kernel/traps.c > +++ b/arch/mips/kernel/traps.c > @@ -735,7 +735,7 @@ void force_fcr31_sig(unsigned long fcr31, void __user *fault_addr, > else if (fcr31 & FPU_CSR_INE_X) > si.si_code = FPE_FLTRES; > else > - si.si_code = __SI_FAULT; > + si.si_code = FPE_FIXME;
This is an "impossible" state to reach unless your hardware is on fire. One or more of the FCSR Cause bits will have been set (in `fcr31') or the FPE exception would not have happened.
Of course there could be a simulator bug, or we could have breakage somewhere causing `process_fpemu_return' to be called with SIGFPE and inconsistent `fcr31'. So we need to handle it somehow.
So what would be the right value of `si_code' to use here for such an unexpected exception condition? I think `BUG()' would be too big a hammer here. Or wouldn't it?
Maciej
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