+// See LICENSE for license details.
+
#include "mmu.h"
-#include "sim.h"
+#include "simif.h"
#include "processor.h"
-mmu_t::mmu_t(char* _mem, size_t _memsz)
- : mem(_mem), memsz(_memsz), badvaddr(0),
- ptbr(0), supervisor(true), vm_enabled(false)
+mmu_t::mmu_t(simif_t* sim, processor_t* proc)
+ : sim(sim), proc(proc),
+ check_triggers_fetch(false),
+ check_triggers_load(false),
+ check_triggers_store(false),
+ matched_trigger(NULL)
{
flush_tlb();
}
void mmu_t::flush_icache()
{
- memset(icache_tag, -1, sizeof(icache_tag));
+ for (size_t i = 0; i < ICACHE_ENTRIES; i++)
+ icache[i].tag = -1;
}
void mmu_t::flush_tlb()
flush_icache();
}
-void* mmu_t::refill_tlb(reg_t addr, reg_t bytes, bool store, bool fetch)
+reg_t mmu_t::translate(reg_t addr, access_type type)
{
- reg_t idx = (addr >> PGSHIFT) % TLB_ENTRIES;
- reg_t expected_tag = addr & ~(PGSIZE-1);
+ if (!proc)
+ return addr;
- reg_t pte = walk(addr);
+ reg_t mode = proc->state.prv;
+ if (type != FETCH) {
+ if (!proc->state.dcsr.cause && get_field(proc->state.mstatus, MSTATUS_MPRV))
+ mode = get_field(proc->state.mstatus, MSTATUS_MPP);
+ }
- reg_t pte_perm = pte & PTE_PERM;
- if(supervisor) // shift supervisor permission bits into user perm bits
- pte_perm = (pte_perm/(PTE_SX/PTE_UX)) & PTE_PERM;
- pte_perm |= pte & PTE_E;
+ return walk(addr, type, mode) | (addr & (PGSIZE-1));
+}
- reg_t perm = (fetch ? PTE_UX : store ? PTE_UW : PTE_UR) | PTE_E;
- if(unlikely((pte_perm & perm) != perm))
- {
- if (fetch)
- throw trap_instruction_access_fault;
+tlb_entry_t mmu_t::fetch_slow_path(reg_t vaddr)
+{
+ reg_t paddr = translate(vaddr, FETCH);
+
+ if (auto host_addr = sim->addr_to_mem(paddr)) {
+ return refill_tlb(vaddr, paddr, host_addr, FETCH);
+ } else {
+ if (!sim->mmio_load(paddr, sizeof fetch_temp, (uint8_t*)&fetch_temp))
+ throw trap_instruction_access_fault(vaddr);
+ tlb_entry_t entry = {(char*)&fetch_temp - vaddr, paddr - vaddr};
+ return entry;
+ }
+}
- badvaddr = addr;
- throw store ? trap_store_access_fault : trap_load_access_fault;
+reg_t reg_from_bytes(size_t len, const uint8_t* bytes)
+{
+ switch (len) {
+ case 1:
+ return bytes[0];
+ case 2:
+ return bytes[0] |
+ (((reg_t) bytes[1]) << 8);
+ case 4:
+ return bytes[0] |
+ (((reg_t) bytes[1]) << 8) |
+ (((reg_t) bytes[2]) << 16) |
+ (((reg_t) bytes[3]) << 24);
+ case 8:
+ return bytes[0] |
+ (((reg_t) bytes[1]) << 8) |
+ (((reg_t) bytes[2]) << 16) |
+ (((reg_t) bytes[3]) << 24) |
+ (((reg_t) bytes[4]) << 32) |
+ (((reg_t) bytes[5]) << 40) |
+ (((reg_t) bytes[6]) << 48) |
+ (((reg_t) bytes[7]) << 56);
}
+ abort();
+}
- reg_t pgoff = addr & (PGSIZE-1);
- reg_t pgbase = pte >> PTE_PPN_SHIFT << PGSHIFT;
- reg_t paddr = pgbase + pgoff;
-
- if (unlikely(tracer.interested_in_range(pgbase, pgbase + PGSIZE, store, fetch)))
- tracer.trace(paddr, bytes, store, 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_insn_tag[idx] = (pte_perm & PTE_UX) ? expected_tag : -1;
- tlb_data[idx] = (char*)mem + pgbase;
+void mmu_t::load_slow_path(reg_t addr, reg_t len, uint8_t* bytes)
+{
+ reg_t paddr = translate(addr, LOAD);
+
+ if (auto host_addr = sim->addr_to_mem(paddr)) {
+ memcpy(bytes, host_addr, len);
+ if (tracer.interested_in_range(paddr, paddr + PGSIZE, LOAD))
+ tracer.trace(paddr, len, LOAD);
+ else
+ refill_tlb(addr, paddr, host_addr, LOAD);
+ } else if (!sim->mmio_load(paddr, len, bytes)) {
+ throw trap_load_access_fault(addr);
}
- return (char*)mem + paddr;
+ if (!matched_trigger) {
+ reg_t data = reg_from_bytes(len, bytes);
+ matched_trigger = trigger_exception(OPERATION_LOAD, addr, data);
+ if (matched_trigger)
+ throw *matched_trigger;
+ }
}
-pte_t mmu_t::walk(reg_t addr)
+void mmu_t::store_slow_path(reg_t addr, reg_t len, const uint8_t* bytes)
{
- pte_t pte = 0;
-
- // the address must be a canonical sign-extended VA_BITS-bit number
- int shift = 8*sizeof(reg_t) - VA_BITS;
- if (((sreg_t)addr << shift >> shift) != (sreg_t)addr)
- ;
- else if(!vm_enabled)
- {
- if(addr < memsz)
- pte = PTE_E | PTE_PERM | ((addr >> PGSHIFT) << PTE_PPN_SHIFT);
+ reg_t paddr = translate(addr, STORE);
+
+ if (!matched_trigger) {
+ reg_t data = reg_from_bytes(len, bytes);
+ matched_trigger = trigger_exception(OPERATION_STORE, addr, data);
+ if (matched_trigger)
+ throw *matched_trigger;
}
- else
- {
- reg_t base = ptbr;
- reg_t ptd;
-
- int ptshift = (LEVELS-1)*PTIDXBITS;
- for(reg_t i = 0; i < LEVELS; i++, ptshift -= PTIDXBITS)
- {
- reg_t idx = (addr >> (PGSHIFT+ptshift)) & ((1<<PTIDXBITS)-1);
-
- reg_t pte_addr = base + idx*sizeof(pte_t);
- if(pte_addr >= memsz)
- break;
- ptd = *(pte_t*)(mem+pte_addr);
- if(ptd & PTE_E)
- {
- // if this PTE is from a larger PT, fake a leaf
- // PTE so the TLB will work right
- reg_t vpn = addr >> PGSHIFT;
- ptd |= (vpn & ((1<<(ptshift))-1)) << PTE_PPN_SHIFT;
-
- // fault if physical addr is invalid
- reg_t ppn = ptd >> PTE_PPN_SHIFT;
- if((ppn << PGSHIFT) + (addr & (PGSIZE-1)) < memsz)
- pte = ptd;
- break;
- }
- else if(!(ptd & PTE_T))
- break;
+ if (auto host_addr = sim->addr_to_mem(paddr)) {
+ memcpy(host_addr, bytes, len);
+ if (tracer.interested_in_range(paddr, paddr + PGSIZE, STORE))
+ tracer.trace(paddr, len, STORE);
+ else
+ refill_tlb(addr, paddr, host_addr, STORE);
+ } else if (!sim->mmio_store(paddr, len, bytes)) {
+ throw trap_store_access_fault(addr);
+ }
+}
+
+tlb_entry_t mmu_t::refill_tlb(reg_t vaddr, reg_t paddr, char* host_addr, access_type type)
+{
+ reg_t idx = (vaddr >> PGSHIFT) % TLB_ENTRIES;
+ reg_t expected_tag = vaddr >> PGSHIFT;
+
+ if ((tlb_load_tag[idx] & ~TLB_CHECK_TRIGGERS) != expected_tag)
+ tlb_load_tag[idx] = -1;
+ if ((tlb_store_tag[idx] & ~TLB_CHECK_TRIGGERS) != expected_tag)
+ tlb_store_tag[idx] = -1;
+ if ((tlb_insn_tag[idx] & ~TLB_CHECK_TRIGGERS) != expected_tag)
+ tlb_insn_tag[idx] = -1;
+
+ if ((check_triggers_fetch && type == FETCH) ||
+ (check_triggers_load && type == LOAD) ||
+ (check_triggers_store && type == STORE))
+ expected_tag |= TLB_CHECK_TRIGGERS;
+
+ if (type == FETCH) tlb_insn_tag[idx] = expected_tag;
+ else if (type == STORE) tlb_store_tag[idx] = expected_tag;
+ else tlb_load_tag[idx] = expected_tag;
+
+ tlb_entry_t entry = {host_addr - vaddr, paddr - vaddr};
+ tlb_data[idx] = entry;
+ return entry;
+}
- base = (ptd >> PTE_PPN_SHIFT) << PGSHIFT;
+reg_t mmu_t::walk(reg_t addr, access_type type, reg_t mode)
+{
+ vm_info vm = decode_vm_info(proc->max_xlen, mode, proc->get_state()->satp);
+ if (vm.levels == 0)
+ return addr & ((reg_t(2) << (proc->xlen-1))-1); // zero-extend from xlen
+
+ bool s_mode = mode == PRV_S;
+ bool sum = get_field(proc->state.mstatus, MSTATUS_SUM);
+ bool mxr = get_field(proc->state.mstatus, MSTATUS_MXR);
+
+ // verify bits xlen-1:va_bits-1 are all equal
+ int va_bits = PGSHIFT + vm.levels * vm.idxbits;
+ reg_t mask = (reg_t(1) << (proc->xlen - (va_bits-1))) - 1;
+ reg_t masked_msbs = (addr >> (va_bits-1)) & mask;
+ if (masked_msbs != 0 && masked_msbs != mask)
+ vm.levels = 0;
+
+ reg_t base = vm.ptbase;
+ for (int i = vm.levels - 1; i >= 0; i--) {
+ int ptshift = i * vm.idxbits;
+ reg_t idx = (addr >> (PGSHIFT + ptshift)) & ((1 << vm.idxbits) - 1);
+
+ // check that physical address of PTE is legal
+ auto ppte = sim->addr_to_mem(base + idx * vm.ptesize);
+ if (!ppte)
+ goto fail_access;
+
+ reg_t pte = vm.ptesize == 4 ? *(uint32_t*)ppte : *(uint64_t*)ppte;
+ reg_t ppn = pte >> PTE_PPN_SHIFT;
+
+ if (PTE_TABLE(pte)) { // next level of page table
+ base = ppn << PGSHIFT;
+ } else if ((pte & PTE_U) ? s_mode && (type == FETCH || !sum) : !s_mode) {
+ break;
+ } else if (!(pte & PTE_V) || (!(pte & PTE_R) && (pte & PTE_W))) {
+ break;
+ } else if (type == FETCH ? !(pte & PTE_X) :
+ type == LOAD ? !(pte & PTE_R) && !(mxr && (pte & PTE_X)) :
+ !((pte & PTE_R) && (pte & PTE_W))) {
+ break;
+ } else if ((ppn & ((reg_t(1) << ptshift) - 1)) != 0) {
+ break;
+ } else {
+ reg_t ad = PTE_A | ((type == STORE) * PTE_D);
+#ifdef RISCV_ENABLE_DIRTY
+ // set accessed and possibly dirty bits.
+ *(uint32_t*)ppte |= ad;
+#else
+ // take exception if access or possibly dirty bit is not set.
+ if ((pte & ad) != ad)
+ break;
+#endif
+ // for superpage mappings, make a fake leaf PTE for the TLB's benefit.
+ reg_t vpn = addr >> PGSHIFT;
+ reg_t value = (ppn | (vpn & ((reg_t(1) << ptshift) - 1))) << PGSHIFT;
+ return value;
}
}
- return pte;
+fail:
+ switch (type) {
+ case FETCH: throw trap_instruction_page_fault(addr);
+ case LOAD: throw trap_load_page_fault(addr);
+ case STORE: throw trap_store_page_fault(addr);
+ default: abort();
+ }
+
+fail_access:
+ switch (type) {
+ case FETCH: throw trap_instruction_access_fault(addr);
+ case LOAD: throw trap_load_access_fault(addr);
+ case STORE: throw trap_store_access_fault(addr);
+ default: abort();
+ }
}
void mmu_t::register_memtracer(memtracer_t* t)
projects / riscv-isa-sim.git / blobdiff