On 03/10/2015 04:25 PM, Michael Ellerman wrote: > On Tue, 2015-03-10 at 20:34 +1100, Benjamin Herrenschmidt wrote: >> On Tue, 2015-03-10 at 18:36 +1100, Michael Ellerman wrote: >>> We currently have a "special" syscall for switching endianness. This is >>> syscall number 0x1ebe, which is handled explicitly in the 64-bit syscall >>> exception entry. >>> >>> That has a few problems, firstly the syscall number is outside of the >>> usual range, which confuses various tools. For example strace doesn't >>> recognise the syscalls at all. >>> >>> Secondly it's handled explicitly as a special case in the syscall >>> exception entry, which is complicated enough without it. >>> >>> As a first step toward removing the special syscall, we need to add a >>> regular syscall that implements the same functionality. >>> >>> The logic is simple, it simply toggles the MSR_LE bit in the userspace >>> MSR. This is the same as the special syscall, with the caveat that the >>> special syscall clobbers fewer registers. >> >> You can set _TIF_RESTOREALL to force a restore of all the registers on >> the way back which should do the job. > > Right, I'd forgotten we talked about that. > > I'll try that tomorrow.
The test fails when we add set_thread_flag(TIF_RESTOREALL) after the MSR flip. Though the test passes with the original patch. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
