On Wed, 3 Feb 2021 20:01:15 GMT, Anton Kozlov <akoz...@openjdk.org> wrote:
>> Please review the implementation of JEP 391: macOS/AArch64 Port. >> >> It's heavily based on existing ports to linux/aarch64, macos/x86_64, and >> windows/aarch64. >> >> Major changes are in: >> * src/hotspot/cpu/aarch64: support of the new calling convention (subtasks >> JDK-8253817, JDK-8253818) >> * src/hotspot/os_cpu/bsd_aarch64: copy of os_cpu/linux_aarch64 with >> necessary adjustments (JDK-8253819) >> * src/hotspot/share, test/hotspot/gtest: support of write-xor-execute (W^X), >> required on macOS/AArch64 platform. It's implemented with >> pthread_jit_write_protect_np provided by Apple. The W^X mode is local to a >> thread, so W^X mode change relates to the java thread state change (for java >> threads). In most cases, JVM executes in write-only mode, except when >> calling a generated stub like SafeFetch, which requires a temporary switch >> to execute-only mode. The same execute-only mode is enabled when a java >> thread executes in java or native states. This approach of managing W^X mode >> turned out to be simple and efficient enough. >> * src/jdk.hotspot.agent: serviceability agent implementation (JDK-8254941) > > Anton Kozlov has updated the pull request incrementally with six additional > commits since the last revision: > > - Merge remote-tracking branch 'origin/jdk/jdk-macos' into jdk-macos > - Add comments to WX transitions > > + minor change of placements > - Use macro conditionals instead of empty functions > - Add W^X to tests > - Do not require known W^X state > - Revert w^x in gtests I reviewed bsd_aarch64.cpp digging bit deeper and left some comments. ------------- Changes requested by gziemski (Committer). PR: https://git.openjdk.java.net/jdk/pull/2200
