On Tue, 11 Feb 2025 21:47:31 GMT, Volodymyr Paprotski <vpaprot...@openjdk.org> wrote:
>> (Also see `8319429: Resetting MXCSR flags degrades ecore`) >> >> This PR fixes two issues: >> - the original issue is a crash caused by `__ warn` corrupting the stack on >> Windows only >> - This issue also uncovered that -Xcheck:jni test cases were getting 65k >> lines of warning on HelloWorld (on both Linux _and_ windows): >> >> OpenJDK 64-Bit Server VM warning: MXCSR changed by native JNI code, use >> -XX:+RestoreMXCSROnJNICall >> >> >> First, the crash. Caused when FXRSTOR is attempting to write reserved bits >> into MXCSR. If those bits happen to be set, crash. (Hence the crash isn't >> deterministic. But frequent enough if `__ warn` is used). It is caused by >> the binding not reserving stack space for register parameters () >>  >> Prolog of the warn function then proceeds to store the for arg registers >> onto the stack, overriding the fxstore save area. (See >> https://learn.microsoft.com/en-us/cpp/build/x64-calling-convention?view=msvc-170#calling-convention-defaults) >> >> Fix uses `frame::arg_reg_save_area_bytes` to bump the stack pointer. >> >> --- >> >> I also kept the fix to `verify_mxcsr` since without it, `-Xcheck:jni` is >> practically unusable when `-XX:+EnableX86ECoreOpts` are set (65k+ lines of >> warnings) > > Volodymyr Paprotski has updated the pull request incrementally with one > additional commit since the last revision: > > comments from Sandhya Looks good otherwise src/hotspot/cpu/x86/macroAssembler_x86.cpp line 783: > 781: > 782: #ifdef _WIN64 > 783: // Windows always allocates space for it's register args Suggestion: // Windows always allocates space for its register args src/hotspot/os/windows/os_windows.cpp line 2757: > 2755: > 2756: #if defined(_M_AMD64) > 2757: extern bool handle_FLT_exception(struct _EXCEPTION_POINTERS* > exceptionInfo); This seems strange to declare inside another method like this, not a showstopper but it might be better to declare it where handle_FLT_exception used to be defined in this file ------------- Marked as reviewed by jwaters (Committer). PR Review: https://git.openjdk.org/jdk/pull/22673#pullrequestreview-2612367075 PR Review Comment: https://git.openjdk.org/jdk/pull/22673#discussion_r1952906388 PR Review Comment: https://git.openjdk.org/jdk/pull/22673#discussion_r1952902264
