RFR: 8328306: AArch64: MacOS lazy JIT "write xor execute" switching [v3]

[Andrew Haley]

On Tue, 19 Aug 2025 14:35:23 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> Yes, we should do that. As you say, we do this on Windows already. 
>> 
>> The only slight problem is that dladdr does not give me the end of the last mappings belonging to libjvm.so, only the base address. We also have multiple mappings. I only ever saw them being loaded adjacent to each other, but am not sure if that is guaranteed.
>
>> Yes, we should do that. As you say, we do this on Windows already.
> 
> Where is that Windows code?

> To make it safe to call from a signal handler, we could take a snapshot of the boundaries during startup, something like what os::get_loaded_modules_info() does.

Unfortunately there is no way to get the end address of a [dll](https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man3/dyld.3.html) The only way to do it, I think, would be to get all of the libraries at startup, and find the successor of libjvm.dll.

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PR Review Comment: https://git.openjdk.org/jdk/pull/26562#discussion_r2379720558