ia32/exceptions: fix FPU exceptions #624
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Unit Test Results7 958 tests 7 416 ✅ 40m 32s ⏱️ Results for commit 887e356. ♻️ This comment has been updated with latest results. |
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jnz .exception_pushRegisters should have flags from andl not subl instruction. JIRA: RTOS-954
savesp saved in exception_pushContext pointed to savesp instead of edi. JIRA: RTOS-954
Checking for FPU exception in preambule of exception handling causes infinite recursion of FPU exceptions if one is found. JIRA: RTOS-954
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cr0Bits were overwriteen by eax in the context during restoration. This resulted in a crash on second context restoration. JIRA: RTOS-954
As we use interirupt gate for exceptions the interrupts are already disabled. JIRA: RTOS-954
Apply same optimizations as to exceptions_pushContext JIRA: RTOS-954
JIRA: RTOS-954
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agkaminski
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Nov 28, 2024
mateusz-bloch
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Description
This PR aims to resolve situation with exceptions caused by FPU on Intel.
First commit resolves issue where recently instead of a triple fault on FPU error exception 16 got presented on the screen, due to wrong instruction setting flag.
Second, commit fixes saving context in exceptions.
Third commit changes
fsavein context saving procedure tofnsaveto prevent infinite recursion on FPU exception causing a triple fault. Due to this change exception 16 is reported correctly as exception 16 not as tripple fault. Thus, exception 16 is excepted to appear not Triple fault.Fourth, commit fixes the root cause of the intermittent error. The
cr0Bitswere overwritten by eax during context restoration. We may restore twice from the same context in case of a signal pushed during_threads_schedule. Then we restore once from the context to go to the signal handler, after the signal is handled the context is modified to have originaleipandespand we longjump to it resulting in second restoration from the context with overwrittencr0Bits. This resulted inTSflag being removed without proper FPU initialization on next restore.The following commits are optimizations.
Fixes: phoenix-rtos/phoenix-rtos-project#1012
Motivation and Context
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