Try to run PMP protection on QEMU

earth/cpu_mmu.c

@@ -148,15 +148,16 @@ void mmu_init() {
 
  char buf[2];
  for (buf[0] = 0; buf[0] != '0' && buf[0] != '1'; earth->tty_read(buf, 2));
- INFO("%s translation is chosen", (buf[0] == '0')? "Page table" : "Software");
+ earth->translation = (buf[0] == '0') ? PAGE_TABLE : SOFT_TLB;
+ INFO("%s translation is chosen", earth->translation == PAGE_TABLE ? "Page table" : "Software");
 
  /* Check whether the hardware platform supports supervisor mode */
  earth->platform = QEMU;
  earth->excp_register(platform_detect);
  /* This memory access triggers an exception on Arty, but not QEMU */
  *(int*)(0x1000) = 1;
  earth->excp_register(NULL);
- if (earth->platform == ARTY && buf[0] == '0')
+ if (earth->platform == ARTY && earth->translation == PAGE_TABLE)
  FATAL("Arty board doesn't support page tables (supervisor mode).");
 
  /* Initialize MMU interface functions */
@@ -165,7 +166,7 @@ void mmu_init() {
  earth->mmu_map = soft_mmu_map;
  earth->mmu_switch = soft_mmu_switch;
 
- if (buf[0] == '0') {
+ if (earth->translation == PAGE_TABLE) {
  pagetable_identity_mapping(0);
  earth->mmu_map = pagetable_mmu_map;
  earth->mmu_switch = pagetable_mmu_switch;

earth/earth.c

@@ -51,7 +51,7 @@ int main() {
  earth_init();
  elf_load(0, grass_read, 0, 0);
 
- if (earth->platform == ARTY){
+ if (earth->translation == SOFT_TLB){
  /* Arty board does not support supervisor mode */
  void (*grass_entry)() = (void*)GRASS_ENTRY;
  grass_entry();

grass/grass.c

@@ -42,7 +42,7 @@ int main() {
 
  timer_reset();
  /* For QEMU, interrupt has been enabled in machine-mode earth layer */
- if (earth->platform == ARTY) earth->intr_enable();
+ if (earth->translation == SOFT_TLB) earth->intr_enable();
 
  void (*sys_proc_entry)() = (void*)APPS_ENTRY;
  asm("mv a0, %0" ::"r"(APPS_ARG));

library/egos.h

@@ -27,6 +27,7 @@ struct earth {
 
  /* QEMU or Arty, detected in mmu_init() */
  enum { QEMU, ARTY } platform;
+ enum { PAGE_TABLE, SOFT_TLB } translation;
 };
 
 #define MAX_NPROCESS 16