Fix infinite loop due to integer overflow in PMP check

riscv/mmu.cc

@@ -491,15 +491,15 @@ bool mmu_t::pmp_ok(reg_t addr, reg_t len, access_type type, reg_t mode, bool hlv
     return true;
 
   reg_t gran = reg_t(1) << proc->lg_pmp_granularity;
-  auto first_addr_aligned = addr & -gran;
-  auto last_addr_aligned = (addr + len - 1) & -gran;
+  reg_t addr_aligned = addr & -gran;
+  reg_t len_aligned = ((addr + len + gran - 1) & -gran) - addr_aligned;
 
   for (size_t i = 0; i < proc->n_pmp; i++) {
     // Check each PMP-granularity sector of the access
     bool any_match = false;
     bool all_match = true;
-    for (reg_t cur_addr = first_addr_aligned; cur_addr <= last_addr_aligned; cur_addr += gran) {
-      bool match = proc->state.pmpaddr[i]->match4(cur_addr);
+    for (reg_t offset = 0; offset < len_aligned; offset += gran) {
+      bool match = proc->state.pmpaddr[i]->match4(addr_aligned + offset);
       any_match |= match;
       all_match &= match;
     }