On Tue, Jul 11, 2017 at 3:35 AM, Kirill A. Shutemov <kirill@xxxxxxxxxxxxx> wrote: > On Mon, Jul 10, 2017 at 05:30:38PM -0700, Andy Lutomirski wrote: >> On Mon, Jul 10, 2017 at 2:24 PM, Kirill A. Shutemov >> <kirill@xxxxxxxxxxxxx> wrote: >> > On Mon, Jul 10, 2017 at 01:07:13PM -0700, Andy Lutomirski wrote: >> >> Can you give the disassembly of the backtrace lines? Blaming the >> >> .endr doesn't make much sense to me. >> > >> > I don't have backtrace. It's before printk() is functional. I only see >> > triple fault and reboot. >> > >> > I had to rely on qemu tracing and gdb. >> >> Can you ask GDB or objtool to disassemble around those addresses? Can >> you also attach the big dump that QEMU throws out that shows register >> state? In particular, CR2, CR3, and CR4 could be useful. > > The last three execptions: > > check_exception old: 0xffffffff new 0xe, cr2: 0xffffffff7ffffff8, rip: 0xffffffff84bb3036 > RAX=00000000ffffffff RBX=ffffffff800000d8 RCX=ffffffff84be4021 RDX=dffffc0000000000 > RSI=0000000000000006 RDI=ffffffff84c57000 RBP=ffffffff800000c8 RSP=ffffffff80000000 So RSP was 0xffffffff80000000, a push happened, and we tried to write to 0xffffffff7ffffff8, which failed. > check_exception old: 0xe new 0xe, cr2: 0xffffffff7ffffff8, rip: 0xffffffff84bb3141 > RAX=00000000ffffffff RBX=ffffffff800000d8 RCX=ffffffff84be4021 RDX=dffffc0000000000 > RSI=0000000000000006 RDI=ffffffff84c57000 RBP=ffffffff800000c8 RSP=ffffffff80000000 And #PF doesn't use IST, so it double-faulted. Either the stack isn't mapped in the page tables, RSP is corrupt, or there's a genuine stack overflow here.
