RFR: 8374482: SA does not handle signal handler frame in mixed jstack [v5]

[Yasumasa Suenaga]

On Fri, 23 Jan 2026 09:23:02 GMT, Kevin Walls <kevinw at openjdk.org> wrote:

> Yes, the bytes were Linux x64 specific. I was thinking that the check would be in a file that is platform/arch specific, and would check for the specific signal return method for that architecture.

However the bytes might be different - where does signal trampoline comes from (libc, vDSO), how is it implemented (whether `mov $0xf, %rax` is always come first)

> If we do this with symbol names, or by looking at the bytes, it looks odd to have a generic method in the symtab file or LinuxCDebugger/LinuxDebuggerLocal that recognises a signal return method from any platform.

AFAICS name of signal trampoline is `__restore_rt`, `__kernel_sigreturn`, or `__kernel_rt_sigreturn` on AMD64 / AArch64. They do not have architecture-dependent string. Thus I defined it in LinuxDebugger.java, and I will use it in other CFrame implementation like LinuxAArch64CFrame. I think it is not so complex because we just add a new name to `LinuxDebugger.SIGHANDLER_NAMES`, and tweak how can we get register values in each CFrame implementation like LinuxAMD64CFrame if we want to support new architecture.

I want to support DWARF on both AMD64 and AArch64. Thus I make change carefully we can separate DWARF parser easily in near future.
(I will start it after few patches - add support for frameless function and vDSO)

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

PR Comment: https://git.openjdk.org/jdk/pull/29023#issuecomment-3789774825