On Thu, 16 Oct 2025 13:32:28 GMT, Yasumasa Suenaga <[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-) ------------- PR Comment: https://git.openjdk.org/jdk/pull/27846#issuecomment-3419917455
