Segfault when using c++11 thread

Segfault when using c++11 thread

[Dirk Vanden Boer]

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Hi,

I compiled a native x86_64-linux-musl toolchain on my arch linux box using
the musl-cross scripts (no modifications).

When running code that uses c++11 threading functionality I get segfaults:

Minimal reproduction file:
#include <thread>
#include <iostream>

int main()
{
    std::cout << "Thread id: " << std::this_thread::get_id() << std::endl;
}

compile with:
./cross/x86_64-linux-musl/bin/x86_64-linux-musl-g++ -pthread -std=c++11
-static -g main.cpp -o test

file test
test: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), statically
linked, not stripped

Running test crashes, gdb backtrace:

Program received signal SIGSEGV, Segmentation fault.
0x0000000000000000 in ?? ()
(gdb) bt
#0  0x0000000000000000 in ?? ()
#1  0x00000000004006ac in __gthread_self () at
/home/dirk/cross/x86_64-linux-musl/x86_64-linux-musl/include/c++/5.2.0/x86_64-linux-musl/bits/gthr-default.h:686
#2  0x00000000004007ad in std::this_thread::get_id () at
/home/dirk/cross/x86_64-linux-musl/x86_64-linux-musl/include/c++/5.2.0/thread:263
#3  0x00000000004006bc in main () at main.cpp:6

Am I doing something wrong?

Regards,
Dirk

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Re: Segfault when using c++11 thread

[Szabolcs Nagy]

* Dirk Vanden Boer <dirk.vdb@gmail.com> [2015-08-22 20:03:28 +0200]:
> I compiled a native x86_64-linux-musl toolchain on my arch linux box using
> the musl-cross scripts (no modifications).
> 
> When running code that uses c++11 threading functionality I get segfaults:
> 
> Minimal reproduction file:
> #include <thread>
> #include <iostream>
> 
> int main()
> {
>     std::cout << "Thread id: " << std::this_thread::get_id() << std::endl;
> }
> 
> compile with:
> ./cross/x86_64-linux-musl/bin/x86_64-linux-musl-g++ -pthread -std=c++11
> -static -g main.cpp -o test
> 

-static is broken if you don't patch gcc properly
maybe the musl-cross gcc patch is missing the gthr weak ref fix.

(fwiw static linking works for me with the backported
musl patches from gcc-trunk
http://port70.net/~nsz/musl/gcc-5.2.0/gcc-5.2.0-combined.diff
but this link might get broken in the future)

> file test
> test: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), statically
> linked, not stripped
> 
> Running test crashes, gdb backtrace:
> 
> Program received signal SIGSEGV, Segmentation fault.
> 0x0000000000000000 in ?? ()
> (gdb) bt
> #0  0x0000000000000000 in ?? ()
> #1  0x00000000004006ac in __gthread_self () at
> /home/dirk/cross/x86_64-linux-musl/x86_64-linux-musl/include/c++/5.2.0/x86_64-linux-musl/bits/gthr-default.h:686
> #2  0x00000000004007ad in std::this_thread::get_id () at
> /home/dirk/cross/x86_64-linux-musl/x86_64-linux-musl/include/c++/5.2.0/thread:263
> #3  0x00000000004006bc in main () at main.cpp:6
> 
> Am I doing something wrong?
> 
> Regards,
> Dirk

Re: Segfault when using c++11 thread

[Dirk Vanden Boer]

On Sun, Aug 23, 2015 at 8:35 PM, Szabolcs Nagy <nsz@port70.net> wrote:
>
> * Dirk Vanden Boer <dirk.vdb@gmail.com> [2015-08-22 20:03:28 +0200]:
> > I compiled a native x86_64-linux-musl toolchain on my arch linux box using
> > the musl-cross scripts (no modifications).
> >
> > When running code that uses c++11 threading functionality I get segfaults:
> >
> > Minimal reproduction file:
> > #include <thread>
> > #include <iostream>
> >
> > int main()
> > {
> >     std::cout << "Thread id: " << std::this_thread::get_id() << std::endl;
> > }
> >
> > compile with:
> > ./cross/x86_64-linux-musl/bin/x86_64-linux-musl-g++ -pthread -std=c++11
> > -static -g main.cpp -o test
> >
>
> -static is broken if you don't patch gcc properly
> maybe the musl-cross gcc patch is missing the gthr weak ref fix.
>
> (fwiw static linking works for me with the backported
> musl patches from gcc-trunk
> http://port70.net/~nsz/musl/gcc-5.2.0/gcc-5.2.0-combined.diff
> but this link might get broken in the future)
>

Thanks, using that patch everything works fine.