signal handler is called within "kernel" #10326
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wenyongh
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Sep 20, 2023
Send a signal whose handler is no-op to a blocking thread to wake up the blocking syscall with either EINTR equivalent or partial success. Unlike the approach taken in the `dev/interrupt_block_insn` branch (that is, signal + longjmp similarly to `OS_ENABLE_HW_BOUND_CHECK`), this PR does not use longjmp because: * longjmp from signal handler doesn't work on nuttx refer to apache/nuttx#10326 * the singal+longjmp approach may be too difficult for average programmers who might implement host functions to deal with See also #1910
victoryang00
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May 27, 2024
Send a signal whose handler is no-op to a blocking thread to wake up the blocking syscall with either EINTR equivalent or partial success. Unlike the approach taken in the `dev/interrupt_block_insn` branch (that is, signal + longjmp similarly to `OS_ENABLE_HW_BOUND_CHECK`), this PR does not use longjmp because: * longjmp from signal handler doesn't work on nuttx refer to apache/nuttx#10326 * the singal+longjmp approach may be too difficult for average programmers who might implement host functions to deal with See also bytecodealliance#1910
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nuttx, at least w/o CONFIG_LIB_SYSCALL, calls user-specified signal hander within the "kernel" part of the code directly.
it isn't safe because user handler can call system calls.
in the extreme case, the user handler escapes with a
longjmp. it likely crashes the kernel later.unfortunately it's somehow common for apps for posix environment to use longjmp within a signal handler.
while CONFIG_LIB_SYSCALL seems to defer signal delivery as expected (i haven't tested this. just glancing the code)
it isn't always desirable because:
i guess a lighter-weight fix is nicer to have. eg. making every syscall-type functions call, say,
enter_kernel/leave_kernel.The text was updated successfully, but these errors were encountered: