SIGILL in jdk.jfr.internal.PlatformRecorder.rotateDisk()

We are seeing intermittent crashes at customer site when JFR is rotating chunks.

{noformat}
A fatal error has been detected by the Java Runtime Environment:
SIGILL (0x4) at pc=0x00007fa665cd4e5e, pid=1, tid=376
JRE version: OpenJDK Runtime Environment Zulu11.41+23-CA (11.0.8+10) (build 11.0.8+10-LTS)
Java VM: OpenJDK 64-Bit Server VM Zulu11.41+23-CA (11.0.8+10-LTS, mixed mode, tiered, compressed oops, g1 gc, linux-amd64)
Problematic frame:
V [libjvm.so+0x8c9e5e]
Core dump will be written. Default location: //core
An error report file with more information is saved as:
/tmp/hs_err_pid1.log
{noformat}

Thanks to @evergizova the culprit was identified to be an erroneous memcpy in JfrStorage::flush_regular() or JfrStorage::flush_large() in combination with musl libc which inserts special traps for cases when memcpy src and dst regions overlap (https://git.2f30.org/fortify-headers/file/include/string.h.html#l39).

The problem boils down to the fact that for a non-empty buffer the JfrStorage::flush_regular_buffer() will
reset cur.pos() to the start offset while cur_pos will stay at the
start offset + N.
Then memcpy(cur.pos(), cur_pos, used) will have the
src and dest regions overlapping (given that used > N) and on Alpine
linux (musl libc) SIGILL will be raised.