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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] crash on boot with 4.6.1 on fedora 24
On 05/10/2016 03:23 AM, Jan Beulich wrote: >>>> On 09.05.16 at 20:40, <boris.ostrovsky@xxxxxxxxxx> wrote: >> On 05/09/2016 01:22 PM, Kevin Moraga wrote: >>> On 05/09/2016 11:15 AM, Boris Ostrovsky wrote: >>>> On 05/09/2016 12:40 PM, Kevin Moraga wrote: >>>>> On 05/09/2016 09:53 AM, Jan Beulich wrote: >>>>>>>>> On 09.05.16 at 16:52, <kmoragas@xxxxxxxxxx> wrote: >>>>>>> On 05/09/2016 04:08 AM, Jan Beulich wrote: >>>>>>>>>>> On 09.05.16 at 00:51, <kmoragas@xxxxxxxxxx> wrote: >>>>>>>>> I'm try to compile kernel 4.4.8 (using fedora 23) to run with Xen >>>>>>>>> 4.6.0 >>>>>>>>> and Intel Skylake processor (Intel Core i7-6600U) >>>>>>>>> >>>>>>>>> This kernel is crashing almost in the same way as explained in this >>>>>>>>> thread... But my problem is mainly with Skylake. Because the same >>>>>>>>> configuration works within another machine but with another processor >>>>>>>>> (Intel Core i5-3340M). Attached are the boot logs. >>>>>>>> The address the fault occurs on (ffff8000006bdee0) is bogus, so >>>>>>>> from the register and stack dump alone I don't think we can derive >>>>>>>> much. What we'd need is access to the kernel binary used (or >>>>>>>> really the vmlinux accompanying the vmlinuz that was used), in >>>>>>>> order to see where exactly the kernel died, and hence where this >>>>>>>> bogus address originates from. As I understand it this is a kernel >>>>>>>> you built yourself - can you make said binary from exactly that >>>>>>>> build available somewhere? >>>>>>> Yes I have it. But I get the same crash on various 4.4.X and also with >>>>>>> 4.5.3. >>>>>>> >>>>>>> **https://drive.google.com/open?id=0B6Ol0ob95UxXQV9HM1BWMmhCZ0E >>>>>> Well, this doesn't contain the file I'm after (vmlinux), and taking >>>>>> apart vmlinuz would be quite cumbersome. >>>>>> >>>>>> Jan >>>>>> >>>>> Oh sorry, here is the link to vmlinux >>>>> >>>>> >> https://drive.google.com/file/d/0B6Ol0ob95UxXN0dDMWM1a29vMEk/view?usp=sharing >> >>>> This is still vmlinuz but the failure is at >>>> >>>> ffffffff81007ef3: 48 3b 1d 4e 2e ec 00 cmp >>>> 0xec2e4e(%rip),%rbx # 0xffffffff81ecad48 >>>> ffffffff81007efa: 73 51 jae 0xffffffff81007f4d >>>> ffffffff81007efc: 31 c0 xor %eax,%eax >>>> ffffffff81007efe: 48 8b 15 03 d2 c0 00 mov >>>> 0xc0d203(%rip),%rdx # 0xffffffff81c15108 >>>> ffffffff81007f05: 90 nop >>>> ffffffff81007f06: 90 nop >>>> ffffffff81007f07: 90 nop >>>> ffffffff81007f08: 4c 8b 2c da mov >>>> (%rdx,%rbx,8),%r13 <====== >>>> ffffffff81007f0c: 90 nop >>>> ffffffff81007f0d: 90 nop >>>> ffffffff81007f0e: 90 nop >>>> ffffffff81007f0f: 85 c0 test %eax,%eax >>>> ffffffff81007f11: 78 3a js 0xffffffff81007f4d >>>> ffffffff81007f13: 48 8b 05 ee 11 d2 00 mov >>>> 0xd211ee(%rip),%rax # 0xffffffff81d29108 >>>> ffffffff81007f1a: 49 39 c5 cmp %rax,%r13 >>>> ffffffff81007f1d: 73 6f jae 0xffffffff81007f8e >>>> ffffffff81007f1f: 48 8b 05 ea 11 d2 00 mov >>>> 0xd211ea(%rip),%rax # 0xffffffff81d29110 >>>> ffffffff81007f26: 4a 8b 04 e8 mov (%rax,%r13,8),%rax >>>> >>>> Any chance you could provide an un-stripped binary or System.map? >>> Here is the link for System.map >>> >>> >> https://drive.google.com/file/d/0B6Ol0ob95UxXYVE4SzdMcENsWWs/view?usp=sharing >> >> >> So my semi-educated guess at your stack is >> __early_ioremap >> -> __early_set_fixmap >> -> set_pte >> -> xen_set_pte_init >> -> mask_rw_pte >> -> pte_pfn >> -> pte_val >> -> xen_pte_val >> -> pte_mfn_to_pfn >> -> mfn_to_pfn_no_overrides >> -> ret = >> xen_safe_read_ulong(&machine_to_phys_mapping[mfn], &pfn) >> >> >> With ffffffff81007f08 being the faulted address the last one looks >> plausible: >> >> >> ffffffff81007efe: 48 8b 15 03 d2 c0 00 mov >> 0xc0d203(%rip),%rdx # 0xffffffff81c15108 >> ffffffff81007f05: 90 nop >> ffffffff81007f06: 90 nop >> ffffffff81007f07: 90 nop >> ffffffff81007f08: 4c 8b 2c da mov (%rdx,%rbx,8),%r13 >> >> since >> >> ostr@workbase> grep ffffffff81c15108 >> /tmp/System.map-4.4.8-9.pvops.qubes.x86_64 >> ffffffff81c15108 D machine_to_phys_mapping >> ostr@workbase> >> >> But %rdx is not ffffffff81c15108, it is ffff800000000000: >> >> (XEN) rax: 0000000000000000 rbx: 00000000000d7bdc rcx: ffff880002059000 >> (XEN) rdx: ffff800000000000 rsi: 80000000d7bdc063 rdi: 80000000d7bdc063 > But that's a MOV above, i.e. %rdx = [0xffffffff81c15108], which > sensibly is MACH2PHYS_VIRT_START. <facepalm> of course! > And the MFN in %rbx > would then match with the value in %cr2. Question is - where > does MFN 0xd7bdc come from (it's in a reserved range, and hence > can only be MMIO, which shouldn't be subject to M2P translation), > and why is this a problem only on Skylake (or maybe that's not > CPU related at all, but just dependent on the memory layout > produced by the firmware). > > Obviously, accesses to the sparse[!] M2P prior to a proper #PF > handler established can't end well. With no RAM present in the > range 0xc0000000-0xffffffff, the 4th 2Mb M2P page doesn't get > populated, i.e. this page walk > > (XEN) Pagetable walk from ffff8000006bdee0: > (XEN) L4[0x100] = 000000081daf9067 ffffffffffffffff > (XEN) L3[0x000] = 000000081daf7067 ffffffffffffffff > (XEN) L2[0x003] = 0000000000000000 ffffffffffffffff > > is to be expected. > > Anyway, Kevin, it would really make things a lot easier if you > provided the vmlinux matching the vmlinuz, which you should > have (assuming my understanding is correct that this is a kernel > you built yourself). After all what we may need to figure out is > the caller of __early_ioremap() in the call stack Boris deduced. I didn't finish unwrapping the stack yesterday. Here it is: setup_arch -> dmi_scan_machine -> dmi_walk_early -> early_ioremap -boris _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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