On Wed, 14 Oct 2026 09:14:01 GMT, Long Yang <[email protected]> wrote:
> Hi, could I have a review of this patch. > > This patch fixes [JDK-8391637](https://bugs.openjdk.org/browse/JDK-8391637). > > On `risc-v`, > [LinuxRISCV64CFrame.sender()](https://github.com/openjdk/jdk/blob/c368bac40e185398fbc40dc4d75a457f7a36f954/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/debugger/linux/riscv64/LinuxRISCV64CFrame.java#L70) > validates only FP alignment, then dereferences FP for SP, link, and return > address. An aligned arbitrary FP (such as 0x90) can therefore cause > UnmappedAddressException, and lead to incomplete stack for the target thread. > > `aarch64` and `amdf64`already use `dwarf` to unwind native frames, see > https://github.com/openjdk/jdk/blob/c368bac40e185398fbc40dc4d75a457f7a36f954/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/debugger/linux/amd64/LinuxAMD64CFrame.java#L36 > https://github.com/openjdk/jdk/blob/c368bac40e185398fbc40dc4d75a457f7a36f954/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/debugger/linux/aarch64/LinuxAARCH64CFrame.java#L38 > > This patch makes `risc-v` to unwind with `dwarf` too. > > The `risc-v` version basically has the same design as the `aarch64` version. > There are also several differences , primarily due to differences in calling > conventions. Almost every difference is accompanied by an explanatory > comment. > > I have ran tests in `test/hotspot/jtreg/serviceability/sa` on `risc-v` and > `amd64`, all passed. > > --------- > - [x] I confirm that I make this contribution in accordance with the [OpenJDK > Interim AI Policy](https://openjdk.org/legal/ai). ### 🔵 Needs a closer look Architecture-specific unwinding, signal-frame offsets, and shared DWARF parser changes require final validation on RISC-V hardware. **0 open findings** <details> <summary><strong>What changed in this PR</strong></summary> Adds DWARF-based native stack unwinding for Linux RISC-V to prevent incomplete SA stack traces caused by invalid frame pointers. **Changes:** - Implements RISC-V DWARF register and frame unwinding support. - Handles RISC-V signal trampolines and continuation frames. - Extends mixed-stack tests to RISC-V and strengthens failure detection. | File | Description | | ---- | ----------- | | `make/​modules/​jdk.hotspot.agent/​Lib.gmk` | Enables DWARF sources on RISC-V. | | `src/​jdk.hotspot.agent/​linux/​native/​libsaproc/​dwarf.cpp` | Corrects CFI processing at PC boundaries. | | `src/​jdk.hotspot.agent/​linux/​native/​libsaproc/​dwarf.hpp` | Selects RISC-V register definitions. | | `src/​jdk.hotspot.agent/​linux/​native/​libsaproc/​dwarf_regs_riscv64.h` | Defines RISC-V DWARF register mappings. | | `src/​jdk.hotspot.agent/​share/​classes/​sun/​jvm/​hotspot/​debugger/​linux/​LinuxCDebugger.java` | Uses the new RISC-V top-frame builder. | | `src/​jdk.hotspot.agent/​share/​classes/​sun/​jvm/​hotspot/​debugger/​linux/​LinuxDebugger.java` | Recognizes the RISC-V signal trampoline. | | `src/​jdk.hotspot.agent/​share/​classes/​sun/​jvm/​hotspot/​debugger/​linux/​riscv64/​LinuxRISCV64CFrame.java` | Implements DWARF-based RISC-V unwinding. | | `src/​jdk.hotspot.agent/​share/​classes/​sun/​jvm/​hotspot/​debugger/​linux/​riscv64/​LinuxRISCV64ThreadContext.java` | Restores registers from signal contexts. | | `src/​jdk.hotspot.agent/​share/​classes/​sun/​jvm/​hotspot/​runtime/​riscv64/​RISCV64ContinuationEntry.java` | Corrects continuation entry FP calculation. | | `test/​hotspot/​jtreg/​serviceability/​sa/​TestJhsdbJstackMixed.java` | Associates the test with the fixed issue. | | `test/​hotspot/​jtreg/​serviceability/​sa/​TestJhsdbJstackMixedCore.java` | Adds RISC-V coverage and stronger assertions. | </details> 🧠**Review effort:** Balanced --- 💡 <a href="/openjdk/jdk/new/master?filename=.github/skills/code-review/SKILL.md" class="Link--inTextBlock" target="_blank" rel="noopener noreferrer">Add a `code-review` agent skill</a> or configure MCP servers for context-aware, tailored reviews. <a href="https://docs.github.com/copilot/how-tos/use-copilot-agents/request-a-code-review/use-code-review?tool=webui#mcp-servers-and-agent-skills"; class="Link--inTextBlock" target="_blank" rel="noopener noreferrer">Learn more in the docs.</a> ------------- PR Review: https://git.openjdk.org/jdk/pull/33358#pullrequestreview-5515719021
