bin/56031: binary compiled with -pg (profiling) segfaults if linked against shared library

[silas_netbsd_gnats%nocafe.net@localhost]

>Number:         56031
>Category:       bin
>Synopsis:       binary compiled with -pg (profiling) segfaults if linked against shared library
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Mar 03 01:40:00 +0000 2021
>Originator:     silas_netbsd_gnats%nocafe.net@localhost
>Release:        NetBSD 9.0
>Organization:
>Environment:
System: NetBSD xyz 9.0 NetBSD 9.0 (GENERIC) #0: Fri Feb 14 00:06:28 UTC 2020 mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC amd64
Architecture: x86_64
Machine: amd64
>Description:
When compiling a binary file with gcc's -pg flag and a shared library, the
binary segfaults.

See this simple example:

$ cat test.c
#include <stdio.h>
int main(int argc, char *argv[]) {
	printf("hello world\n");
	return 0;
}

$ cc -pg -o test test.c
./test
hello world

$ cc -pg -lcurses -o test test.c
ld: /usr/lib/libc.so.12: warning: warning: __findenv is an internal obsolete function.

$ ./test
[1]   Segmentation fault (core dumped) ./test

Later, I decided to add the -g flag to get debug symbols and see if I'd get something useful from gdb:

$ cc -g -pg -lcurses -o test test.c
ld: /usr/lib/libc.so.12: warning: warning: __findenv is an internal obsolete function.

$ ./test
[1]   Segmentation fault (core dumped) ./test

$ gdb -c test.core -ex bt -ex q test
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Reading symbols from test...
[New process 1]
Core was generated by `test'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x0000000000433e10 in dl_iterate_phdr ()
#0  0x0000000000433e10 in dl_iterate_phdr ()
#1  0x0000000000409e05 in __libc_static_tls_setup ()
#2  0x0000000000494487 in _libc_init ()
#3  0x00006fb919441d14 in ?? () from /usr/lib/libc.so.12
#4  0x00006fb91a0e0200 in ?? ()
#5  0x00006fb91943cdf9 in _init () from /usr/lib/libc.so.12
#6  0x0000000000000000 in ?? ()

Curious fact: I can profile (generate binary, run the program and use gprof) the
same program normally in NetBSD 8.0 armv7hf (Raspberry Pi 2).

For reference, I started a thread about this in netbsd-users@: http://mail-index.netbsd.org/netbsd-users/2021/02/28/msg026655.html
>How-To-Repeat:
$ cat test.c
#include <stdio.h>
int main(int argc, char *argv[]) {
	printf("hello world\n");
	return 0;
}

$ cc -pg -lcurses -o test test.c
ld: /usr/lib/libc.so.12: warning: warning: __findenv is an internal obsolete function.

$ ./test
[1]   Segmentation fault (core dumped) ./test
>Fix: