On Sat, Aug 28, 2021 at 11:47:03PM +0200, Thomas Gleixner wrote:
> /* Try to handle #PF, but anything else is fatal. */
> if (ret != -EFAULT)
> return -EINVAL;
> which all end up in user_insn(). user_insn() returns 0 or the negated
> trap number, which results in -EFAULT for #PF, but for #MC the negated
> trap number is -18 i.e. != -EFAULT. IOW, there is no endless loop.
>
> This used to be a problem before commit:
>
> aee8c67a4faa ("x86/fpu: Return proper error codes from user access functions")
>
> and as the changelog says the initial reason for this was #GP going into
> the fault path, but I'm pretty sure that I also discussed the #MC angle with
> Borislav back then. Should have added some more comments there
> obviously.
... or at least have that check spelled
if (ret != -X86_TRAP_PF)
return -EINVAL;
Unless I'm misreading your explanation, that is...
