Lookup libraries in libjulia-* before jl_exe_handle
#50162
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We do not use `dlvsym` to separate the symbols between multiple copies
of libjulia, instead preferring to resolve symbols directly against the
appropriate internal library handle.
During bootstrapping, many internal symbols (e.g. `jl_fl_parse`) are
available in the global EXE namespace, so we need to adapt our search
order to resolve symbols in internal libraries first.
With this fix, no sysimage symbols are resolved to `jl_exe_handle`
(which is generally broken in Julia-in-Julia scenarios):
```
$ cat objdump_after.txt | grep libjulia_internal_handle | wc
1131 14703 145899
$ cat objdump_after.txt | grep jl_exe_handle | wc
0 0 0
```
versus before:
```
$ cat objdump_before.txt | grep libjulia_internal_handle | wc
577 7501 74433
$ cat objdump_before.txt | grep jl_exe_handle | wc
554 7202 63710
```
This flag is needed to ensure that `libclang_rt.asan-*.so` appears explicitly in the DT_NEEDED entries of libjulia-*. Without this entry, e.g. `dlsym(libjulia_internal_handle)` can end up finding symbols directly in libc.so.6, effectively bypassing the ASAN interceptors.
vtjnash
approved these changes
Jun 14, 2023
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In order for Due to #50170, I'm not able to test installation/relocatability with the new Makefile changes, but otherwise I think this is approximately the right approach. It works for me with |
staticfloat
approved these changes
Jun 20, 2023
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The reordering in |
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During bootstrapping, many internal symbols (e.g.
jl_fl_parse) are found in the global EXE namespace leading to an ambiguous lookup in Julia-in-Julia scenarios.With this search order change, no sysimage symbols are resolved to
jl_exe_handle:versus before: