On 12 December 2013 08:00, Michael Hudson-Doyle
<michael.hud...@linaro.org> wrote:
> Hi all,
>
> I have a bit of a strange one. I'm not after a full solution, just any
> hints that quickly come to mind :)
>
> After a few simple patches I have a build of mongodb for aarch64 (built
> with gcc-4.8). However, all of the test binaries that the build spits
> out immediately segfault. gdb-ing shows that they segfault inside this
> macro:
>
> TSP_DECLARE(OwnedOstreamVector, threadOstreamCache);
>
> This expands to:
>
> # define TSP_DECLARE(T,p) \
> extern __thread T* _ ## p; \
> template<> inline T* TSP<T>::get() const { return _ ## p; } \
> extern TSP<T> p;
>
> And indeed, it's mongo::TSP<mongo::OwnedPointerVector<...> >::get()
> const that we're segfaulting in. This is the disassembly of this
> function (at -O0) with the faulting instruction marked:
>
> 0x00000000004b4b6c <+0>: stp x29, x30, [sp,#-32]!
> 0x00000000004b4b70 <+4>: mov x29, sp
> 0x00000000004b4b74 <+8>: str x0, [x29,#16]
> 0x00000000004b4b78 <+12>: adrp x0, 0x64c000
> 0x00000000004b4b7c <+16>: ldr x0, [x0,#776]
> 0x00000000004b4b80 <+20>: nop
> 0x00000000004b4b84 <+24>: nop
> 0x00000000004b4b88 <+28>: mrs x1, tpidr_el0
> 0x00000000004b4b8c <+32>: add x0, x1, x0
> => 0x00000000004b4b90 <+36>: ldr x0, [x0]
> 0x00000000004b4b94 <+40>: ldp x29, x30, [sp],#32
> 0x00000000004b4b98 <+44>: ret
>
> And the registers:
>
> (gdb) info registers
> x0 0x7fb863fd70 548554407280
This value looks surprisingly large if it is an offset from TP (x1).
> x1 0x7fb7ff76f0 548547819248
Have you tried printing the memory at this address? It looks like it
is probably ok...
> x2 0x0 0
> x3 0x7fb7fc11b8 548547596728
> x4 0x1 1
> x5 0x0 0
> x6 0x50 80
> x7 0x0 0
> x8 0x0 0
> x9 0x6165727473676f4c 7018141438804717388
> x10 0x0 0
> x11 0x0 0
> x12 0x2 2
> x13 0x10 16
> x14 0x0 0
> x15 0x7fb7e5e590 548546143632
> x16 0x64b3d8 6599640
> x17 0x7fb7f667d0 548547225552
> x18 0x7fffffdab0 549755804336
> x19 0x7fffffed50 549755809104
> x20 0xb 11
> x21 0xb 11
> x22 0x6500b0 6619312
> x23 0x650070 6619248
> x24 0x7fffffff 2147483647
> x25 0x64db40 6609728
> x26 0x7fffffeda0 549755809184
> x27 0x653d00 6634752
> x28 0x7fffffe750 549755807568
> x29 0x7fffffe4d0 549755806928
> x30 0x4b4ed4 4935380
> sp 0x7fffffe4d0 0x7fffffe4d0
> pc 0x4b4b90 0x4b4b90
> <mongo::TSP<mongo::OwnedPointerVector<std::basic_ostringstream<char,
> std::char_traits<char>, std::allocator<char> > > >::get() const+36>
> cpsr 0x20000000 536870912
> fpsr 0x0 0
> fpcr 0x0 0
>
> If I recompile this object file without -fPIC, it works.
>
> I guess I see three things that could be wrong:
>
> 1) The operand to "adrp x0, 0x64c000"[1]
> 2) The operand to "ldr x0, [x0,#776]"
Is there a dynamic reloc for this GOT slot?
--
Will Newton
Toolchain Working Group, Linaro
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