On Sun, 25 Jan 2026 03:55:13 GMT, Yasumasa Suenaga <[email protected]> wrote:
> Some functions / signal trampoline would be provided by vDSO in Linux.
> However SA cannot find symbols in it because it is not a regular ELF, it is
> on the memory only.
> For example, mixed jstack could not decode the symbol in the coredump crashed
> in gettimeofday(2) as following:
>
>
> 0x00007faae3dd0818 VMError::report_and_die(Thread*, unsigned int,
> unsigned char*, void const*, void const*) + 0x58
> 0x00007faae3aff1ba JVM_handle_linux_signal + 0x42a
> 0x00007faae4ad9290 <signal handler called>
> 0x00007faae4cd8e69 ????????
> 0x00007faaca78ffa1 <nep_invoker_blob>
> 0x00007faaca73fd48 *
> java.lang.invoke.LambdaForm$MH+0x0000000028156c00.invoke(java.lang.Object,
> long, long, long) bci:12 (Interpreted frame)
>
>
> It should be:
>
>
> 0x00007fb5841d0818 VMError::report_and_die(Thread*, unsigned int,
> unsigned char*, void const*, void const*) + 0x58
> 0x00007fb583eff1ba JVM_handle_linux_signal + 0x42a
> 0x00007fb584fd9290 <signal handler called>
> 0x00007fb5851d8e69 __cvdso_gettimeofday_data.constprop.0 + 0x99
> 0x00007fb56a78f321 <nep_invoker_blob>
> 0x00007fb56a73fd48 *
> java.lang.invoke.LambdaForm$MH+0x000000000e156c00.invoke(java.lang.Object,
> long, long, long) bci:12 (Interpreted frame)
>
>
> Some platforms (Ubuntu 24.04 and Fedora 43 at least) provide vDSO binary in
> `/lib/modules/<kernel version>/vdso`. This patch attempts to load it if we
> can refer it because we want to use debuginfo of vDSO if possible. Otherwise
> load vDSO memory.
src/jdk.hotspot.agent/linux/native/libsaproc/ps_core.c line 702:
> 700: if (strcmp("linux-vdso.so.1", lib_name) == 0 ||
> 701: strcmp("linux-vdso64.so.1", lib_name) == 0) {
> 702: struct utsname uts;
It might be more readable if all the new code below this point was in a new
function, but I'll leave it up to you to decide if it is worth doing.
src/jdk.hotspot.agent/linux/native/libsaproc/ps_core.c line 709:
> 707: = "vdso64.so";
> 708: #else
> 709: = "vdso32.so";
Do we need 32 bit support? I though it was already dropped.
src/jdk.hotspot.agent/linux/native/libsaproc/ps_core.c line 712:
> 710: #endif
> 711:
> 712: // Check vDSO binary at first (for referring debuginfo if
> possible).
Suggestion:
// Check vDSO binary first (for referring debuginfo if possible).
src/jdk.hotspot.agent/linux/native/libsaproc/ps_core.c line 720:
> 718: lib_fd = pathmap_open(lib_name);
> 719: } else {
> 720: // Copy vDSO memory segment to temporal memory from core
Suggestion:
// Copy vDSO memory segment from core to temporal memory
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/29400#discussion_r2738464103
PR Review Comment: https://git.openjdk.org/jdk/pull/29400#discussion_r2738450779
PR Review Comment: https://git.openjdk.org/jdk/pull/29400#discussion_r2738471726
PR Review Comment: https://git.openjdk.org/jdk/pull/29400#discussion_r2738469538
