src/arch/riscv/virtual_memory.c

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Early initialization code for riscv virtual memory
   4  */
   5
   6 #include <arch/cpu.h>
   7 #include <arch/encoding.h>
   8 #include <vm.h>
   9
  10 /* Delegate controls which traps are delegated to the payload. If you
  11  * wish to temporarily disable some or all delegation you can, in a
  12  * debugger, set it to a different value (e.g. 0 to have all traps go
  13  * to M-mode). In practice, this variable has been a lifesaver.  It is
  14  * still not quite determined which delegation might by unallowed by
  15  * the spec so for now we enumerate and set them all. */
  16 static int delegate = 0
  17         | (1 << CAUSE_MISALIGNED_FETCH)
  18         | (1 << CAUSE_FETCH_ACCESS)
  19         | (1 << CAUSE_ILLEGAL_INSTRUCTION)
  20         | (1 << CAUSE_BREAKPOINT)
  21         | (1 << CAUSE_LOAD_ACCESS)
  22         | (1 << CAUSE_STORE_ACCESS)
  23         | (1 << CAUSE_USER_ECALL)
  24         | (1 << CAUSE_FETCH_PAGE_FAULT)
  25         | (1 << CAUSE_LOAD_PAGE_FAULT)
  26         | (1 << CAUSE_STORE_PAGE_FAULT)
  27         ;
  28
  29 void mstatus_init(void)
  30 {
  31         // clear any pending timer interrupts.
  32         clear_csr(mip,  MIP_STIP | MIP_SSIP);
  33
  34         // enable machine and supervisor timer and
  35         // all other supervisor interrupts.
  36         set_csr(mie, MIP_MTIP | MIP_STIP | MIP_SSIP);
  37
  38         // Delegate supervisor timer and other interrupts to supervisor mode,
  39         // if supervisor mode is supported.
  40         if (supports_extension('S')) {
  41                 set_csr(mideleg, MIP_STIP | MIP_SSIP);
  42                 set_csr(medeleg, delegate);
  43         }
  44
  45         // Enable all user/supervisor-mode counters
  46         write_csr(mcounteren, 7);
  47 }