On 04/13/2015 02:18 PM, Anshuman Khandual wrote: > On 04/10/2015 04:03 PM, Ulrich Weigand wrote: >> Anshuman Khandual <khand...@linux.vnet.ibm.com> wrote on 10.04.2015 >> 11:10:35: > > I believed it stores the check pointed MSR value which was in the register > before the transaction started. But then how it is different from the > ckpt_regs.msr, I am not sure. Mikey or Michael should be able to clarify > more on this. I can see "orig_msr" getting used in many places to hold the > check pointed value of MSR.
tm_orig_msr is used during process context switch only. ckpt_regs gets used in the signal context where we save all userspace context. So ptrace would look into the saved MSR value correctly inside ckpt_regs.msr slot. I believe thats the check pointed MSR value we are interested in from the ptrace perspective not the tm_orig_msr which just gets used during process context switch. >> I may be misreading kernel code, but it seems the kernel does not >> actually >> use the ckpt_regs.msr slot at all, and therefore the corresponding slot >> of >> the NT_PPC_TM_CGPR regset is likewise undefined/unused. Would it not be >> more consistent to use that slot to pass the checkpointed MSR? > > Hmm. Its a valid point. Would like to get some more clarity on this from > Mikey whether that slot can be used for check pointed MSR value or not. > Then why did we have these two slots to hold the same check pointed MSR > value in the first place at all. Getting confused a bit. Using ckpt_regs.msr during process context switch instead of tm_orig_msr seems to be working fine and all the basic TM tests pass, in which case we can drop tm_orig_msr from thread_struct. Will post a patch on this and see whats the response from others. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
