On Sun, 19 Oct 2025 20:02:32 GMT, Kevin Walls <[email protected]> wrote:
>> `jhsdb jstack --mixed` with coredump cannot resolve function symbol which >> has `.cold` attribute. >> >> >> ----------------- 120485 ----------------- >> "Thread-0" #24 prio=5 tid=0x00007f50dc1aa7c0 nid=120485 waiting on condition >> [0x00007f50c0d1a000] >> java.lang.Thread.State: TIMED_WAITING (sleeping) >> JavaThread state: _thread_blocked >> 0x00007f50e4710735 __GI_abort + 0x8b >> 0x00007f50e1e01f33 ???????? >> >> >> 0x7f50e1e01f33 was `os::abort(bool, void const*, void const*) [clone .cold]` >> and I could see it in GDB. However it has `.cold` suffix, it means the code >> has been relocated as ["cold" >> function](https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-cold-function-attribute). >> In GDB, we can see the code in another area from function body as following: >> >> >> (gdb) disas 0x7f50e1e01f2e, 0x7f50e1e01f34 >> Dump of assembler code from 0x7f50e1e01f2e to 0x7f50e1e01f34: >> 0x00007f50e1e01f2e <_ZN2os5abortEbPKvS1_.cold+0>: call 0x7f50e1e01010 >> <abort@plt> >> => 0x00007f50e1e01f33: nop >> End of assembler dump. >> >> >> libsaproc.so checks address range to resolve symbol whether the address is >> in between `start` and `start + size - 1`. As you can see in assembler dump, >> the code in `.cold` section is `call` instruction, thus IP points next >> `nop`, thus we should allow address range between `start` and `start + size`. >> >> After this PR, you can see the right symbol as following: >> >> >> ----------------- 120485 ----------------- >> "Thread-0" #24 prio=5 tid=0x00007f50dc1aa7c0 nid=120485 waiting on condition >> [0x00007f50c0d1a000] >> java.lang.Thread.State: TIMED_WAITING (sleeping) >> JavaThread state: _thread_blocked >> 0x00007f50e4710735 __GI_abort + 0x8b >> 0x00007f50e1e01f33 os::abort(bool, void const*, void const*) [clone >> .cold] + 0x5 > > Are you thinking of doing a second pass: if symbol not found, look again > using RIP-1. That should work for this case. > (Or on the second pass, use the one byte longer object/function length.) > > It won't be perfect but I'm not sure what will be without getting quite > context sensitive. Even recognising that we are looking one byte past the > end of a function, and that the instruction immediately lower in memory was > a call, would need checking whether the called frame is that call, or if we > just jumped to a function that starts in memory immediately after a funtion > that ends in a call. > > I think we should be OK with something that works for most cases, and works > better than today, and maybe the second pass does that. 8-) @kevinjwalls Thanks a lot for your comment! I added second pass with `RIP-1` if DWARF would not be processed with given `RIP`. All of hotspot_serviceability tests have been passed. ------------- PR Comment: https://git.openjdk.org/jdk/pull/27846#issuecomment-3420191937
