Add exception handler to edger8r.

[kongoshuu]

Add a exception_handler to the edger8r. If any function in .edl file is marked
as "exception_handler", it should be set the "is_exception" field in the ecall
table. This is used for users to set their own exception, like signal
handler.

[ghost]

What is the motivation to high light the exception function in the edl file?

[kongoshuu]

This is used when a user what to register their own exception handler. They can design their own exception handling that enters an enclave by highlighting the ecall as "exception_handler". Another PR has the changed code that deals with this flag (#223 ).

[ghost]

The alternative solution is, when the application get the SIGCHLD, SIGUSR1, SIGRTMIN + n, etc, the application can use another free thread to handle this exception.

[bot-cc1s-branch-sync]

Important

🔀 The Intel® SGX SDK codebase has moved

Thank you for your contribution!
The code this pull request modifies now resides in a new repository,¹ so, unfortunately, it can no longer be merged here as-is. If your change is still relevant, please re-open it against the SDK repository, where this code is now maintained.

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Footnotes

1. The affected sources were migrated from confidential-computing.sgx to the dedicated confidential-computing.sgx.sdk repo. The migration covered the SDK sources (sdk/), shared headers (common/), samples (SampleCode/), and the runtime libraries (psw/urts, psw/enclave_common). ↩