Hi, On 13/02/17 14:40, Dmitry V. Levin wrote: > On Mon, Jan 09, 2017 at 08:54:52PM +0300, Dmitry V. Levin wrote: >> On Mon, Jan 09, 2017 at 05:31:37PM +0000, James Cowgill wrote: >>> On 06/01/17 00:51, Dmitry V. Levin wrote: >>>> On Tue, Jan 03, 2017 at 06:02:44PM +0000, James Cowgill wrote: >>>>> On 20/12/16 00:36, Steve McIntyre wrote: >>>>>> On Tue, Dec 20, 2016 at 03:16:17AM +0300, Dmitry V. Levin wrote: >>>>>>> On Tue, Dec 20, 2016 at 12:50:29AM +0100, Nahim El Atmani wrote: >>>>>>>> On Mon, 19 Dec 2016 18:30:29 +0000, Steve McIntyre wrote: >>>>>>>>> I'm seeing test suite failures on mips[1], mipsel[2] and mips64el[3] >>>>>>>>> on Debian machines. >>>>>>>>> >>>>>>>>> The 32-bit builds are both showing issues with fault injection. I >>>>>>>>> can't follow what the code is meant to be doing here, so no >>>>>>>>> ideas on what's wrong. :-( >>>>>>>> >>>>>>>> As Dmitry said earlier: >>>>>>>> >>>>>>>> On Tue, 15 Nov 2016 15:43:59 +0300, Dmitry V. Levin wrote: >>>>>>>>> Well, the mips kernel does not implement substitution of syscall >>>>>>>>> numbers >>>>>>>> >>>>>>>> So it looks like the test has failed to SKIP on this target. >>>>>>> >>>>>>> As I'm not 100% sure there is no kernel support for mips, I decided >>>>>>> not to skip the test on mips until somebody investigates. >>>>>> >>>>>> Ah, OK. James Cowgill is my friendly local mips expert - let's see >>>>>> what he thinks... :-) >>>>> >>>>> I've had a look and I think there is a kernel bug here - specifically >>>>> affecting 32-bit programs run on 64-bit kernels (like all the Debian >>>>> buildds and the porterbox are). An extra PTRACE_SYSCALL stop is >>>>> happening which confuses everything. I'll look some more tomorrow. >>>> >>>> Indeed, it seems to be a kernel bug in scall64-o32.S and scall64-n32.S. >>>> >>>> According to current arch/mips/kernel/scall64-o32.S:trace_a_syscall >>>> (the same applies to arch/mips/kernel/scall64-n32.S), >>>> >>>> if the syscall number after the first syscall_trace_enter call is out >>>> of range, there is a jump to not_o32_scall which in turn jumps to >>>> arch/mips/kernel/scall64-64.S:handle_sys64 (or to handle_sysn32 which >>>> then jumps on to handle_sys64). >>>> >>>> Handle_sys64, unsurprisingly, does all over again, starting with >>>> a syscall_trace_enter call, which appears to be the second one >>>> and causes that extra syscall stop you observe with 32-bit tracees >>>> running on 64-bit kernels. >>> >>> Just going through all the MIPS testsuite bugs again: >>> >>> fault_injection* >>> The kernel bug above (no patch yet). >> >> I couldn't find an easy fix for this kernel bug. Any ideas? > > OK, there is not going to be any fix for this kernel bug in v4.10, > so I'd rather disable scno tampering tests when MIPS ABI is o32 > but the kernel is n64. > > Is there any simple way for MIPS o32 userspace to find out whether > the kernel is not a native MIPS o32? Something less hackish > than manually invoking a MIPS n64 syscall?
uname -m is a bit less hackish: 32-bit kernel: $(uname -m) = mips 64-bit kernel: $(uname -m) = mips64 Note there is no difference between big and little endian here. Thanks, James
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