Messages in this thread | | | Date | Tue, 23 Aug 2011 14:08:27 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [uml-devel] SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weird crap with vdso on uml/i386) |
| |
On 08/23/2011 10:33 AM, Linus Torvalds wrote: > > It would be *nice* if we did the swizzling automatically at setregs() > time too, but we simply don't have enough information in the kernel to > do that. Again, exactly because pt_regs doesn't have a "state" > variable, when user-space does the SETREGS call, we simply don't know > whether we are in "normal" code or in some system call entry or exit > state. So the kernel does the swizzling at GETREGS time (by virtue of > always having the registers in a "canonical" state for system call > entry), but we fundamentally *cannot* to do the unswizzle, because we > don't know what the SETREGS caller actually did. >
Again, can we steal one of the padding fields to use for that state variable? We have two 16-bit padding fields; one for cs and one for ss.
For UML, I agree, let's just not expose the vdso assuming that is possible, but for other -- possibly future -- users.
-hpa
| |