On Tue, Mar 24, 2015 at 4:42 PM, Dave Hansen <[email protected]> wrote: > On 03/24/2015 03:28 PM, Andy Lutomirski wrote: >> Your function appears to be getting it for write (I assume that's what >> the unlazy_fpu is for), so I'd rather have it called >> tsk_get_xsave_field_for_write or something like that. > > It should be entirely read-only. > > For MPX (the only user of get_xsave_addr() iirc), we are only worried > about getting the status codes (and addresses) out of the bndstatus > register and making sure that the kernel-recorded bounds directory > address matches the bndcfgu (configuration) register. > > We don't ever write to the registers.
So why are you unlazying it? IIUC, the xstae for current can be in one of three logical states: 1. Live in CPU regs. The in-memory copy is garbage and the state is in CPU regs. 2. Lazy. The in-memory copy and the CPU regs match. Writing to either copy is illegal. 3. In memory only. Writing to the in-memory copy is safe. IIUC, you want to read the xstate, do you're okay with #2 or #3. This would be tsk_get_xsave_field_for_read in my terminology. If you want to write the xstate, you'd need to be in state #3, which would be tsk_get_xsave_field_for_write. IIUC, unlazy_fpu just moves from from state 2 to 3. I could be totally wrong for any number of reasons, though. --Andy -- Andy Lutomirski AMA Capital Management, LLC -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
