https://sourceware.org/bugzilla/show_bug.cgi?id=28875
--- Comment #2 from Thiago Macieira <thiago at kde dot org> ---
(In reply to H.J. Lu from comment #1)
> Created attachment 13964 [details]
> A patch
>
> Try this.
Confirmed for copy relocations:
$ cat main.cpp
extern __attribute__((visibility("default"))) long internal_i;
extern __attribute__((visibility("default"))) long internal_f();
int main()
{
internal_i = (long) &internal_f;
return (long) &internal_f;
}
$ gcc main.cpp libb.so
/home/tjmaciei/dev/gcc/lib/gcc/x86_64-pc-linux-gnu/12.0.1/../../../../x86_64-pc-linux-gnu/bin/ld:
/tmp/ccwnIS4o.o: copy relocation against non-copyable protected symbol
`internal_i' in libb.so
collect2: error: ld returned 1 exit status
But not for PLT entries:
$ cat main2.cpp
extern __attribute__((visibility("default"))) long internal_f();
int main()
{
return (long) &internal_f;
}
$ gcc main2.cpp libb.so
[no error]
$ objdump --no-show -Cdr a.out| sed -n '/<main>:/,/^$/p'
0000000000401126 <main>:
401126: push %rbp
401127: mov %rsp,%rbp
40112a: mov $0x401030,%eax
40112f: pop %rbp
401130: ret
glibc 2.35 does not complain about this binary by default:
$ LD_LIBRARY_PATH=. ./a.out; printf %x\\n $?
30
Only if the PLT is processed:
$ LD_BIND_NOW=1 LD_LIBRARY_PATH=. ./a.out
./a.out: _Z10internal_fv: ./libb.so: non-canonical reference to canonical
protected function
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