Add support for Zicfilp and the hart ELP state #855
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| @@ -67,7 +67,7 @@ \section{Execution Based} \label{execution_based} | |||
| not executing from the Program Buffer. | |||
| Its recommended encoding is 0x7b200073. | |||
| When {\tt dret} is executed, \Rpc is restored from \RcsrDpc and normal execution resumes at the | |||
| privilege set by \FcsrDcsrPrv and \FcsrDcsrV. | |||
| privilege set by \FcsrDcsrPrv and \FcsrDcsrV and the ELP state set by \FcsrDcsrElp. | |||
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| privilege set by \FcsrDcsrPrv and \FcsrDcsrV and the ELP state set by \FcsrDcsrElp. | |
| privilege set by \FcsrDcsrPrv and \FcsrDcsrV, and the ELP state set by \FcsrDcsrElp. |
| \begin{table} | ||
| \centering | ||
| \caption{Expected Landing Pad Encoding} | ||
| \label{tab:elpmode} | ||
| \begin{tabular}{|c|l|} | ||
| \hline | ||
| elp & Name \\ | ||
| \hline | ||
| 0 & {\tt NO\_LP\_EXPECTED} \\ | ||
| \hline | ||
| 1 & {\tt LP\_EXPECTED} \\ | ||
| \hline | ||
| \end{tabular} | ||
| \end{table} |
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I think I prefer these values inlined in dcsr and priv using the XML value tags. v is a bit different since a single table contains v, prv, and what they mean depending on whether H is supported.
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Could also just reference Zicfilp for the syntax and semantics of ELP
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Should this be a different virtual register instead of being part of the priv virtual register?
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If it's literally just a gdb user interface thing then we might as well split out $elp from $priv but I wasn't sure how much of the stack splitting the two would touch and whether the new register might cause problems with debug middleware that doesn't otherwise need changes.
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Addressing just OpenOCD/gdb, either change would require modifications to OpenOCD but not to gdb. The changes required to OpenOCD are pretty minimal for either option.
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@rtwfroody - this PR can be closed without merge as the #1071 that integrates the Zicfilp extension is merged. |
Zicfilp adds a new ELP state to each hart, which is handled like the privilege mode: it affects all instructions, is not visible in any CSR, but is saved into CSR fields by traps and restored by trap returns.
Add it to the debug spec in the same fashion as the privilege mode, and specify that it does not affect execution in Debug Mode.
(Draft because Zicfilp is not frozen.)