diff options
Diffstat (limited to 'riscv/mmu.cc')
| -rw-r--r-- | riscv/mmu.cc | 24 |
1 files changed, 12 insertions, 12 deletions
diff --git a/riscv/mmu.cc b/riscv/mmu.cc index 779383d..9bbb4e4 100644 --- a/riscv/mmu.cc +++ b/riscv/mmu.cc @@ -52,7 +52,7 @@ void* mmu_t::refill_tlb(reg_t addr, reg_t bytes, bool store, bool fetch) pte |= PTE_UR | PTE_SR | PTE_UW | PTE_SW; } } else { - pte = walk(addr); + pte = walk(addr, store); } reg_t pte_perm = pte & PTE_PERM; @@ -79,7 +79,7 @@ void* mmu_t::refill_tlb(reg_t addr, reg_t bytes, bool store, bool fetch) else { tlb_load_tag[idx] = (pte_perm & PTE_UR) ? expected_tag : -1; - tlb_store_tag[idx] = (pte_perm & PTE_UW) ? expected_tag : -1; + tlb_store_tag[idx] = (pte_perm & PTE_UW) && store ? expected_tag : -1; tlb_insn_tag[idx] = (pte_perm & PTE_UX) ? expected_tag : -1; tlb_data[idx] = mem + pgbase - (addr & ~(PGSIZE-1)); } @@ -87,14 +87,13 @@ void* mmu_t::refill_tlb(reg_t addr, reg_t bytes, bool store, bool fetch) return mem + paddr; } -pte_t mmu_t::walk(reg_t addr) +pte_t mmu_t::walk(reg_t addr, bool store) { reg_t msb_mask = -(reg_t(1) << (VA_BITS-1)); if ((addr & msb_mask) != 0 && (addr & msb_mask) != msb_mask) return 0; // address isn't properly sign-extended reg_t base = proc->get_state()->sptbr; - reg_t ptd; int ptshift = (LEVELS-1)*PTIDXBITS; for (reg_t i = 0; i < LEVELS; i++, ptshift -= PTIDXBITS) { @@ -105,23 +104,24 @@ pte_t mmu_t::walk(reg_t addr) if (pte_addr >= memsz) return 0; - ptd = *(pte_t*)(mem+pte_addr); + pte_t* ppte = (pte_t*)(mem+pte_addr); - if (!(ptd & PTE_V)) { // invalid mapping + if (!(*ppte & PTE_V)) { // invalid mapping return 0; - } else if (ptd & PTE_T) { // next level of page table - base = (ptd >> PGSHIFT) << PGSHIFT; + } else if (*ppte & PTE_T) { // next level of page table + base = (*ppte >> PGSHIFT) << PGSHIFT; } else { - // we've found the PTE. + // we've found the PTE. set referenced and possibly dirty bits. + *ppte |= PTE_R | (store ? PTE_D : 0); // for superpage mappings, make a fake leaf PTE for the TLB's benefit. reg_t vpn = addr >> PGSHIFT; - ptd |= (vpn & ((1<<(ptshift))-1)) << PGSHIFT; + reg_t pte = *ppte | ((vpn & ((1<<(ptshift))-1)) << PGSHIFT); // check that physical address is legal - if (((ptd >> PGSHIFT) << PGSHIFT) >= memsz) + if (((pte >> PGSHIFT) << PGSHIFT) >= memsz) return 0; - return ptd; + return pte; } } return 0; |