RFR: 8369994: Mixed mode jhsdb jstack cannot resolve symbol with cold attribute [v2]

Yasumasa Suenaga ysuenaga at openjdk.org
Mon Oct 20 01:23:45 UTC 2025


> `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 at 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

Yasumasa Suenaga has updated the pull request incrementally with two additional commits since the last revision:

 - Add fallback code to process DWARF with RIP-1 in Linux AMD64
 - Revert "8369994: Mixed mode jhsdb jstack cannot resolve symbol with cold attribute"
   
   This reverts commit 570b65c6b56ba3378d4f532fa0874ff08ff18451.

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/27846/files
  - new: https://git.openjdk.org/jdk/pull/27846/files/570b65c6..3492a833

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27846&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27846&range=00-01

  Stats: 56 lines in 2 files changed: 26 ins; 15 del; 15 mod
  Patch: https://git.openjdk.org/jdk/pull/27846.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27846/head:pull/27846

PR: https://git.openjdk.org/jdk/pull/27846


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