Hi Andrew, I checked with GDB, readelf and libsaproc debug message. I found that we should calculate .dynamic address from entry point in ELF.
I uploaded webrev. This patch works fine on JDK 9 and JDK 10. http://cr.openjdk.java.net/~ysuenaga/JDK-8173941/webrev.00/ Thanks, Yasumasa On 2017/02/08 23:21, Yasumasa Suenaga wrote:
Hi Andrew, I could reproduce it in my environment. * libsaproc debug ``` libsaproc DEBUG: address of _DYNAMIC is 0x563bc6dd8d28 ``` * Address of .dynamic in GDB ``` 0x0000563bc6dd7d28 - 0x0000563bc6dd7f68 is .dynamic ``` It differs 1 page (0x1000). In this case, according to GDB, `java` was loaded 0x563bc6dd7000. According to readelf of `java`, offset of dynamic section is 0x1d28. So I want to investigate why we found 1 memory page difference. (Is it caused by ASLR? Do you have any idea?) Thanks, Yasumasa On 2017/02/08 20:46, Andrew Haley wrote:Okay, thanks. The patch will have to be submitted to JDK 9 first and then back- ported to earlier releases. Unfortunately it doesn't work on JDK 9. I don't know why: I spent some time looking at it, but I couldn't figure out what was wrong. Is there any way you could have a look? This is using hg.openjdk.java.net/jdk9/hs on F25. Thanks, Andrew. [aph@localhost hs-8173941]$ LIBSAPROC_DEBUG=1 ./build/linux-x86_64-normal-server-fastdebug/images/jdk/bin/jhsdb jstack --core core.63600 --exe build/linux-x86_64-normal-server-fastdebug/images/jdk/bin/java Attaching to core core.63600 from executable build/linux-x86_64-normal-server-fastdebug/images/jdk/bin/java, please wait... libsaproc DEBUG: Note header with n_type = 3 and n_descsz = 136 libsaproc DEBUG: Note header with n_type = 1 and n_descsz = 336 libsaproc DEBUG: got integer regset for lwp 63600 libsaproc DEBUG: integer regset ... libsaproc DEBUG: Note address of NT_FILE is 0x564be32e5000 libsaproc DEBUG: ELF interpreter /lib64/ld-linux-x86-64.so.2 libsaproc DEBUG: address of _DYNAMIC p_vaddr is 0x201d28 libsaproc DEBUG: address of _DYNAMIC is 0x564be32e6d28 libsaproc DEBUG: ---- sorted virtual address map ---- ... libsaproc DEBUG: base = 0x7fe62227c000 size = 4096 libsaproc DEBUG: base = 0x7ffeabb33000 size = 135168 libsaproc DEBUG: base = 0x7ffeabbc0000 size = 8192 libsaproc DEBUG: base = 0xffffffffff600000 size = 4096 libsaproc DEBUG: can't locate map_info at 0x564be32e7000 libsaproc DEBUG: core read failed for 16 byte(s) @ 0x564be32e7000 (8 more bytes) libsaproc DEBUG: 1: can't read debug info from _DYNAMIC Error attaching to core file: Can't attach to the core file sun.jvm.hotspot.debugger.DebuggerException: Can't attach to the core file at jdk.hotspot.agent/sun.jvm.hotspot.debugger.linux.LinuxDebuggerLocal.attach0(Native Method) at jdk.hotspot.agent/sun.jvm.hotspot.debugger.linux.LinuxDebuggerLocal.attach(LinuxDebuggerLocal.java:286) at jdk.hotspot.agent/sun.jvm.hotspot.HotSpotAgent.attachDebugger(HotSpotAgent.java:679) at jdk.hotspot.agent/sun.jvm.hotspot.HotSpotAgent.setupDebuggerLinux(HotSpotAgent.java:617)
