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riscv: add a variable to control trap management 

This variable can be set in a debugger (e.g. Spike)
to finely control which traps go to coreboot and
which go to the supervisor.

Change-Id: I292264c15f002c41cf8d278354d8f4c0efbd0895
Signed-off-by: Ronald G. Minnich <rminnich@gmail.com>
Reviewed-on: https://review.coreboot.org/17404
Tested-by: build bot (Jenkins)
Reviewed-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
This commit is contained in:
Ronald G. Minnich 2016-11-12 07:31:16 -08:00
parent 42c1e43cb1
commit 3d302b03f4
1 changed files with 16 additions and 10 deletions
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26
src/arch/riscv/virtual_memory.c
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@ -23,6 +23,21 @@
#include <vm.h> #include <vm.h>
#include <symbols.h> #include <symbols.h>
/* Delegate controls which traps are delegated to the payload. If you
* wish to temporarily disable some or all delegation you can, in a
* debugger, set it to a different value (e.g. 0 to have all traps go
* to M-mode). In practice, this variable has been a lifesaver. It is
* still not quite determined which delegation might by unallowed by
* the spec so for now we enumerate and set them all. */
static int delegate = 0
| (1 << CAUSE_MISALIGNED_FETCH)
| (1 << CAUSE_FAULT_FETCH)
| (1 << CAUSE_ILLEGAL_INSTRUCTION)
| (1 << CAUSE_BREAKPOINT)
| (1 << CAUSE_FAULT_LOAD)
| (1 << CAUSE_FAULT_STORE)
| (1 << CAUSE_USER_ECALL)
;
pte_t* root_page_table; pte_t* root_page_table;
/* Indent the following text by 2*level spaces */ /* Indent the following text by 2*level spaces */
@ -223,16 +238,7 @@ void mstatus_init(void)
clear_csr(mip, MIP_MSIP); clear_csr(mip, MIP_MSIP);
set_csr(mie, MIP_MSIP); set_csr(mie, MIP_MSIP);
/* Configure which exception causes are delegated to supervisor mode */ set_csr(medeleg, delegate);
set_csr(medeleg, (1 << CAUSE_MISALIGNED_FETCH)
| (1 << CAUSE_FAULT_FETCH)
| (1 << CAUSE_ILLEGAL_INSTRUCTION)
| (1 << CAUSE_BREAKPOINT)
| (1 << CAUSE_FAULT_LOAD)
| (1 << CAUSE_FAULT_STORE)
| (1 << CAUSE_USER_ECALL)
);
/* Enable all user/supervisor-mode counters */ /* Enable all user/supervisor-mode counters */
/* We'll turn these on once lowrisc gets their bitstream up to /* We'll turn these on once lowrisc gets their bitstream up to