+// See LICENSE for license details.
+
+#ifndef _RISCV_MMU_H
+#define _RISCV_MMU_H
+
#include "decode.h"
#include "trap.h"
-#include "icsim.h"
#include "common.h"
-#include <assert.h>
-
-class processor_t;
+#include "config.h"
+#include "processor.h"
+#include "memtracer.h"
+#include <vector>
+// virtual memory configuration
typedef reg_t pte_t;
-
-const reg_t LEVELS = 4;
+const reg_t LEVELS = sizeof(pte_t) == 8 ? 3 : 2;
const reg_t PGSHIFT = 12;
-const reg_t PGSIZE = 1 << PGSHIFT;
const reg_t PTIDXBITS = PGSHIFT - (sizeof(pte_t) == 8 ? 3 : 2);
-const reg_t PPN_BITS = 8*sizeof(reg_t) - PGSHIFT;
-
-#define PTE_T 0x001 // Entry is a page Table descriptor
-#define PTE_E 0x002 // Entry is a page table Entry
-#define PTE_R 0x004 // Referenced
-#define PTE_D 0x008 // Dirty
-#define PTE_UX 0x010 // User eXecute permission
-#define PTE_UW 0x020 // User Read permission
-#define PTE_UR 0x040 // User Write permission
-#define PTE_SX 0x080 // Supervisor eXecute permission
-#define PTE_SW 0x100 // Supervisor Read permission
-#define PTE_SR 0x200 // Supervisor Write permission
-#define PTE_PERM (PTE_SR | PTE_SW | PTE_SX | PTE_UR | PTE_UW | PTE_UX)
-#define PTE_PERM_SHIFT 4
-#define PTE_PPN_SHIFT 12
+const reg_t PGSIZE = 1 << PGSHIFT;
+const reg_t VPN_BITS = PTIDXBITS * LEVELS;
+const reg_t VA_BITS = VPN_BITS + PGSHIFT;
+
+struct insn_fetch_t
+{
+ insn_func_t func;
+ insn_t insn;
+};
+struct icache_entry_t {
+ reg_t tag;
+ reg_t pad;
+ insn_fetch_t data;
+};
+
+// this class implements a processor's port into the virtual memory system.
+// an MMU and instruction cache are maintained for simulator performance.
class mmu_t
{
public:
- mmu_t(char* _mem, size_t _memsz)
- : mem(_mem), memsz(_memsz), badvaddr(0),
- ptbr(0), supervisor(true), vm_enabled(false),
- icsim(NULL), dcsim(NULL), itlbsim(NULL), dtlbsim(NULL)
- {
- }
-
- #ifdef RISCV_ENABLE_ICSIM
- # define dcsim_tick(dcsim, dtlbsim, addr, size, st) \
- do { if(dcsim) (dcsim)->tick(addr, size, st); \
- if(dtlbsim) (dtlbsim)->tick(addr, sizeof(reg_t), false); } while(0)
- #else
- # define dcsim_tick(dcsim, dtlbsim, addr, size, st)
- #endif
+ mmu_t(char* _mem, size_t _memsz);
+ ~mmu_t();
+ // template for functions that load an aligned value from memory
#define load_func(type) \
- type##_t load_##type(reg_t addr) { \
- if(unlikely(addr % sizeof(type##_t))) \
- { \
- badvaddr = addr; \
- throw trap_load_address_misaligned; \
- } \
- addr = translate(addr, false, false); \
- dcsim_tick(dcsim, dtlbsim, addr, sizeof(type##_t), false); \
- return *(type##_t*)(mem+addr); \
+ type##_t load_##type(reg_t addr) __attribute__((always_inline)) { \
+ void* paddr = translate(addr, sizeof(type##_t), false, false); \
+ return *(type##_t*)paddr; \
}
- #define store_func(type) \
- void store_##type(reg_t addr, type##_t val) { \
- if(unlikely(addr % sizeof(type##_t))) \
- { \
- badvaddr = addr; \
- throw trap_store_address_misaligned; \
- } \
- addr = translate(addr, true, false); \
- dcsim_tick(dcsim, dtlbsim, addr, sizeof(type##_t), true); \
- *(type##_t*)(mem+addr) = val; \
- }
-
- insn_t __attribute__((always_inline)) load_insn(reg_t addr, bool rvc)
- {
- insn_t insn;
-
- reg_t idx = (addr/sizeof(insn_t)) % ICACHE_ENTRIES;
- bool hit = addr % 4 == 0 && icache_tag[idx] == (addr | 1);
- if(likely(hit))
- return icache_data[idx];
-
- #ifdef RISCV_ENABLE_RVC
- if(addr % 4 == 2 && rvc)
- {
- reg_t paddr_lo = translate(addr, false, true);
- insn.bits = *(uint16_t*)(mem+paddr_lo);
-
- if(!INSN_IS_RVC(insn.bits))
- {
- reg_t paddr_hi = translate(addr+2, false, true);
- insn.bits |= (uint32_t)*(uint16_t*)(mem+paddr_hi) << 16;
- }
- }
- else
- #endif
- {
- if(unlikely(addr % 4))
- {
- badvaddr = addr;
- throw trap_instruction_address_misaligned;
- }
- reg_t paddr = translate(addr, false, true);
- insn = *(insn_t*)(mem+paddr);
-
- icache_tag[idx] = addr | 1;
- icache_data[idx] = insn;
- }
-
- #ifdef RISCV_ENABLE_ICSIM
- if(icsim)
- icsim->tick(addr, insn_length(insn.bits), false);
- if(itlbsim)
- itlbsim->tick(addr, sizeof(reg_t), false);
- #endif
-
- return insn;
- }
-
+ // load value from memory at aligned address; zero extend to register width
load_func(uint8)
load_func(uint16)
load_func(uint32)
load_func(uint64)
+ // load value from memory at aligned address; sign extend to register width
load_func(int8)
load_func(int16)
load_func(int32)
load_func(int64)
+ // template for functions that store an aligned value to memory
+ #define store_func(type) \
+ void store_##type(reg_t addr, type##_t val) { \
+ void* paddr = translate(addr, sizeof(type##_t), true, false); \
+ *(type##_t*)paddr = val; \
+ }
+
+ // store value to memory at aligned address
store_func(uint8)
store_func(uint16)
store_func(uint32)
store_func(uint64)
- reg_t get_badvaddr() { return badvaddr; }
- reg_t get_ptbr() { return ptbr; }
+ static const reg_t ICACHE_ENTRIES = 1024;
- void set_supervisor(bool sup) { supervisor = sup; }
- void set_vm_enabled(bool en) { vm_enabled = en; }
- void set_ptbr(reg_t addr) { ptbr = addr & ~(PGSIZE-1); flush_tlb(); }
+ inline size_t icache_index(reg_t addr)
+ {
+ // for instruction sizes != 4, this hash still works but is suboptimal
+ return (addr / 4) % ICACHE_ENTRIES;
+ }
+
+ // load instruction from memory at aligned address.
+ icache_entry_t* access_icache(reg_t addr) __attribute__((always_inline))
+ {
+ reg_t idx = icache_index(addr);
+ icache_entry_t* entry = &icache[idx];
+ if (likely(entry->tag == addr))
+ return entry;
+
+ char* iaddr = (char*)translate(addr, 1, false, true);
+ insn_bits_t insn = *(uint16_t*)iaddr;
+
+ if (likely(insn_length(insn) == 4)) {
+ if (likely(addr % PGSIZE < PGSIZE-2))
+ insn |= (insn_bits_t)*(int16_t*)(iaddr + 2) << 16;
+ else
+ insn |= (insn_bits_t)*(int16_t*)translate(addr + 2, 1, false, true) << 16;
+ } else if (insn_length(insn) == 2) {
+ insn = (int16_t)insn;
+ } else if (insn_length(insn) == 6) {
+ insn |= (insn_bits_t)*(int16_t*)translate(addr + 4, 1, false, true) << 32;
+ insn |= (insn_bits_t)*(uint16_t*)translate(addr + 2, 1, false, true) << 16;
+ } else {
+ static_assert(sizeof(insn_bits_t) == 8, "insn_bits_t must be uint64_t");
+ insn |= (insn_bits_t)*(int16_t*)translate(addr + 6, 1, false, true) << 48;
+ insn |= (insn_bits_t)*(uint16_t*)translate(addr + 4, 1, false, true) << 32;
+ insn |= (insn_bits_t)*(uint16_t*)translate(addr + 2, 1, false, true) << 16;
+ }
- void set_icsim(icsim_t* _icsim) { icsim = _icsim; }
- void set_dcsim(icsim_t* _dcsim) { dcsim = _dcsim; }
- void set_itlbsim(icsim_t* _itlbsim) { itlbsim = _itlbsim; }
- void set_dtlbsim(icsim_t* _dtlbsim) { dtlbsim = _dtlbsim; }
+ insn_fetch_t fetch = {proc->decode_insn(insn), insn};
+ icache[idx].tag = addr;
+ icache[idx].data = fetch;
+
+ reg_t paddr = iaddr - mem;
+ if (!tracer.empty() && tracer.interested_in_range(paddr, paddr + 1, false, true))
+ {
+ icache[idx].tag = -1;
+ tracer.trace(paddr, 1, false, true);
+ }
+ return &icache[idx];
+ }
+
+ inline insn_fetch_t load_insn(reg_t addr)
+ {
+ return access_icache(addr)->data;
+ }
+
+ void set_processor(processor_t* p) { proc = p; flush_tlb(); }
void flush_tlb();
void flush_icache();
+ void register_memtracer(memtracer_t*);
+
private:
char* mem;
size_t memsz;
- reg_t badvaddr;
+ processor_t* proc;
+ memtracer_list_t tracer;
- reg_t ptbr;
- bool supervisor;
- bool vm_enabled;
+ // implement an instruction cache for simulator performance
+ icache_entry_t icache[ICACHE_ENTRIES];
+ // implement a TLB for simulator performance
static const reg_t TLB_ENTRIES = 256;
- pte_t tlb_data[TLB_ENTRIES];
- reg_t tlb_tag[TLB_ENTRIES];
+ char* tlb_data[TLB_ENTRIES];
+ reg_t tlb_insn_tag[TLB_ENTRIES];
+ reg_t tlb_load_tag[TLB_ENTRIES];
+ reg_t tlb_store_tag[TLB_ENTRIES];
- static const reg_t ICACHE_ENTRIES = 256;
- insn_t icache_data[ICACHE_ENTRIES];
- reg_t icache_tag[ICACHE_ENTRIES];
+ // finish translation on a TLB miss and upate the TLB
+ void* refill_tlb(reg_t addr, reg_t bytes, bool store, bool fetch);
- icsim_t* icsim;
- icsim_t* dcsim;
- icsim_t* itlbsim;
- icsim_t* dtlbsim;
+ // perform a page table walk for a given VA; set referenced/dirty bits
+ pte_t walk(reg_t addr, bool supervisor, bool store, bool fetch);
- reg_t translate(reg_t addr, bool store, bool fetch)
+ // translate a virtual address to a physical address
+ void* translate(reg_t addr, reg_t bytes, bool store, bool fetch)
+ __attribute__((always_inline))
{
reg_t idx = (addr >> PGSHIFT) % TLB_ENTRIES;
- pte_t pte = tlb_data[idx];
- reg_t tag = tlb_tag[idx];
+ reg_t expected_tag = addr >> PGSHIFT;
+ reg_t* tags = fetch ? tlb_insn_tag : store ? tlb_store_tag :tlb_load_tag;
+ reg_t tag = tags[idx];
+ void* data = tlb_data[idx] + addr;
- trap_t trap = store ? trap_store_access_fault
- : fetch ? trap_instruction_access_fault
- : trap_load_access_fault;
+ if (unlikely(addr & (bytes-1)))
+ store ? throw trap_store_address_misaligned(addr) :
+ fetch ? throw trap_instruction_address_misaligned(addr) :
+ throw trap_load_address_misaligned(addr);
- bool hit = (pte & PTE_E) && tag == (addr >> PGSHIFT);
- if(unlikely(!hit))
- {
- pte = walk(addr);
- if(!(pte & PTE_E))
- {
- badvaddr = addr;
- throw trap;
- }
-
- tlb_data[idx] = pte;
- tlb_tag[idx] = addr >> PGSHIFT;
- }
+ if (likely(tag == expected_tag))
+ return data;
- reg_t access_type = store ? PTE_UW : fetch ? PTE_UX : PTE_UR;
- if(supervisor)
- access_type <<= 3;
- if(unlikely(!(access_type & pte & PTE_PERM)))
- {
- badvaddr = addr;
- throw trap;
- }
-
- return (addr & (PGSIZE-1)) | ((pte >> PTE_PPN_SHIFT) << PGSHIFT);
- }
-
- pte_t walk(reg_t addr)
- {
- pte_t pte = 0;
-
- if(!vm_enabled)
- {
- if(addr < memsz)
- pte = PTE_E | PTE_PERM | ((addr >> PGSHIFT) << PTE_PPN_SHIFT);
- }
- 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;
-
- base = (ptd >> PTE_PPN_SHIFT) << PGSHIFT;
- }
- }
-
- return pte;
+ return refill_tlb(addr, bytes, store, fetch);
}
friend class processor_t;
};
+
+#endif
projects / riscv-isa-sim.git / blobdiff