Implementation of user-level fault handler

WenyuanShao commented 6 years ago

Summary of this Pull Request (PR)

This PR is the implementation of user_level fault handlers. When a fault happens, it will make a sinv call to the user_level fault handler to handle the fault.

Modified the invstk and set a bit into the captbl of the component on the top of the stack to indicate whether this is a sinv call to fault handlers or not. Add some additional comments to make this design easier to understand.
Created a new type for sinv cap to the fault handlers, so we can get rid of a branch in the fast path.
Expanded the thd_introspect to get the register information in user_level and print these register information when fault happens.
Create an interface for fault handlers so different components can implement fault handlers differently.

Intent for your PR

Choose one (Mandatory):

[x] This PR is for a code-review and is intended to get feedback, but not to be pulled yet.
[x] This PR is mature, and ready to be integrated into the repo.

Reviewers (Mandatory):

@gparmer @hungry-foolish @phanikishoreg

Code Quality

As part of this pull request, I've considered the following:

Style:

[x] Comments adhere to the Style Guide (SG)
[x] Spacing adhere's to the SG
[x] Naming adhere's to the SG
[x] All other aspects of the SG are adhered to, or exceptions are justified in this pull request
[ ] I have run the auto formatter on my code before submitting this PR (see doc/auto_formatter.md for instructions)

Code Craftsmanship:

[x] I've made an attempt to remove all redundant code
[x] I've considered ways in which my changes might impact existing code, and cleaned it up
[x] I've formatted the code in an effort to make it easier to read (proper error handling, function use, etc...)
[ ] I've commented appropriately where code is tricky
[ ] I agree that there is no "throw-away" code, and that code in this PR is of high quality

Testing

I've tested the code using the following test programs (provide list here):

-llbooter_test.sh, llbooter_pong.sh, microboot.sh

phanikishoreg commented 6 years ago

Oh well.. Didn't notice, you need to pull the latest and fix the conflicts..

phanikishoreg commented 6 years ago

Just curious, why haven't you checked:

[ ] I've commented appropriately where code is tricky
[ ] I agree that there is no "throw-away" code, and that code in this PR is of high quality

If you don't, I think you should mention somewhere in the PR why! Helps reviewers.. ;)

And another nitpick:

[ ] This PR is for a code-review and is intended to get feedback, but not to be pulled yet.
[ ] This PR is mature, and ready to be integrated into the repo.

You should check one of these boxes only only.. Should really be treated as a radio-button.. :P

gwsystems / composite