On Wed, 28 Oct 2026 19:36:48 GMT, Ashay Rane <[email protected]> wrote:
>> This patch enables PAC and AUT instructions for pointer signing and >> authentication in JIT code on Windows/ARM64 when "UseBranchProtection" >> flag is set and when the processor supports the feature. >> >> Specifically, JVM detects hardware support by reading ID_AA64ISAR1_EL1 >> and ID_AA64ISAR2_EL1 registers via CP4031 and CP4032 keys in the Windows >> registry. Then, if the "UseBranchProtection" flag is set, then HotSpot >> emits the signing and authenticating instructions. Windows uses >> AArch64's "B" key, so this patch selects between "paciaz" and "pacibz" >> instructions (and similarly, between "autiaz" and "autibz" instructions) >> depending on whether HotSpot is being compiled for Linux versus Windows. >> Both the MacroAssembler and the Windows' PAC helpers need to stay in >> sync, so this patch needs changes to both macroAssembler_aarch64.cpp as >> well as pauth_windows_aarch64.inline.hpp. >> >> Since Linux supports both "A" as well as "B" keys, it's possible to use >> "B" keys for both Linux and Windows, although I fear doing so may >> introduce more churn in the code. >> >> This patch also introduces a cross-platform (Linux and Windows) test >> that compiles and runs a method under both C1 and C2 before checking >> whether the generated instructions include the "paci[ab]z" and the >> "auti[ab]z" instructions. >> >> Since CI doesn't test with branch protection enabled, I manually changed >> the default value of "UseBranchProtection" in globals_aarch64.cpp to be >> "pac-ret" before running tier 1 through tier 3 tests in the HotSpot, >> JDK, and LangTools test groups to ensure that this patch does not >> introduce any new failures. I also validated this patch by running the >> same tests with the default value for "UseBranchProtection". >> >> --------- >> - [x] I confirm that I make this contribution in accordance with the >> [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai). > > Ashay Rane has updated the pull request incrementally with one additional > commit since the last revision: > > Documentation updates > > - Include section numbers from ARM ISA document > - Mark branch protection on Windows/ARM64 as supported > Since CI doesn't test with branch protection enabled We could fix that. I wouldn't be against, say, building and testing just the Windows/AArch64 build with it enabled. This would mean that ROP-breaking changes would be detected in CI. ------------- PR Comment: https://git.openjdk.org/jdk/pull/33595#issuecomment-6493859896
