JDK-8234930 : Use MAP_JIT when allocating pages for code cache on macOS
- Type: Enhancement
- Component: hotspot
- Sub-Component: compiler
- Affected Version: 11,14,17
- Priority: P4
- Status: Resolved
- Resolution: Fixed
- OS: os_x
- Submitted: 2019-11-27
- Updated: 2022-05-26
- Resolved: 2020-12-15
The Version table provides details related to the release that this issue/RFE will be addressed.
Unresolved : Release in which this issue/RFE will be addressed.
Resolved: Release in which this issue/RFE has been resolved.
Fixed : Release in which this issue/RFE has been fixed. The release containing this fix may be available for download as an Early Access Release or a General Availability Release.
To download the current JDK release, click here.
Unresolved : Release in which this issue/RFE will be addressed.
Resolved: Release in which this issue/RFE has been resolved.
Fixed : Release in which this issue/RFE has been fixed. The release containing this fix may be available for download as an Early Access Release or a General Availability Release.
To download the current JDK release, click here.
| JDK 11 | JDK 17 | JDK 8 |
|---|---|---|
| 11.0.15Fixed | 17 b02Fixed  |
8u351Fixed |
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Description
According to Apple documentation (e.g. https://developer.apple.com/documentation/bundleresources/entitlements/com_apple_security_cs_allow-jit ) the MAP_JIT flag should be used when mmap:ing memory for JIT compilers. We should investigate if that flag can and should be used for the code cache. On macOS MAP_JIT cannot be used in conjunction with MAP_FIXED when mapping a page for codecache. Therefore our traditional technique of doing commit and uncommit - replacing a mapping with another one at the same address range but swapped MAP_NORESERVE - does not work. The "exec" flag basically means "its code cache" and it should be used consistently for the same mapping (reserve-commit-uncommit etc) This affects pd_reserve_memory, pd_commit_memory, pd_uncommit_memory functions
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