Re: Missing backtrace information on aarch64

[Stephen Hemminger]

On Thu, 19 Mar 2020 08:34:35 +0800
Phil Reid <address@hidden> wrote:

> On 19/03/2020 01:45, Stephen Hemminger wrote:
> > Trying to use libunwind on Arm64 and discovered that it is not working
> > as expected. Only one function is printed.
> > 
> > On x86 Debian 10 (1.2.1-9)
> > $ ./bt
> > ^\Signal Quit recevied
> > #0 0x5640deb47308 (sigquit+0x29)
> > #1 0x7f4337b8587f (killpg+0x40)
> > #2 0x7f4337c146f4 (nanosleep+0x14)
> > #3 0x7f4337c1462a (sleep+0x3a)
> > #4 0x5640deb4732c (main+0x1f)
> > #5 0x7f4337b7209b (__libc_start_main+0xeb)
> > #6 0x564
> > 
> > 
> > On Arm64
> > 
> > # /tmp/bt
> > ^\Signal Quit recevied
> > #0 0xab9f2f927bf0 (sigquit+0x34)
> > Aborted (core dumped)
> >   
> 
> I patched gcc libs with the following for an 32bit arm system to get more 
> complete backtraces.
> 
> 
> diff -Naur a/libsupc++/eh_terminate.cc b/libsupc++/eh_terminate.cc
> --- a/libstdc++-v3/libsupc++/eh_terminate.cc  2019-02-28 14:31:50.951261183 
> +0800
> +++ b/libstdc++-v3/libsupc++/eh_terminate.cc  2019-02-28 14:32:42.040396849 
> +0800
> @@ -40,7 +40,7 @@
>   using namespace __cxxabiv1;
> 
>   void
> -__cxxabiv1::__terminate (std::terminate_handler handler) throw ()
> +__cxxabiv1::__terminate (std::terminate_handler handler)
>   {
>     __try
>       {
> diff -Naur a/libsupc++/unwind-cxx.h b/libsupc++/unwind-cxx.h
> --- a/libstdc++-v3/libsupc++/unwind-cxx.h     2019-02-28 14:31:50.949253953 
> +0800
> +++ b/libstdc++-v3/libsupc++/unwind-cxx.h     2019-02-28 14:32:53.073426806 
> +0800
> @@ -189,8 +189,7 @@
> 
>   // Invokes given handler, dying appropriately if the user handler was
>   // so inconsiderate as to return.
> -extern void __terminate(std::terminate_handler) throw ()
> -  __attribute__((__noreturn__));
> +extern void __terminate(std::terminate_handler);
>   extern void __unexpected(std::unexpected_handler)
>     __attribute__((__noreturn__));

But gcc backtrace already works on this platform, I am confused.