1 // See LICENSE for license details.
7 mmu_t::mmu_t(sim_t
* sim
, processor_t
* proc
)
17 void mmu_t::flush_icache()
19 for (size_t i
= 0; i
< ICACHE_ENTRIES
; i
++)
23 void mmu_t::flush_tlb()
25 memset(tlb_insn_tag
, -1, sizeof(tlb_insn_tag
));
26 memset(tlb_load_tag
, -1, sizeof(tlb_load_tag
));
27 memset(tlb_store_tag
, -1, sizeof(tlb_store_tag
));
32 reg_t
mmu_t::translate(reg_t addr
, access_type type
)
37 reg_t mode
= proc
->state
.prv
;
40 if (!proc
->state
.dcsr
.cause
&& get_field(proc
->state
.mstatus
, MSTATUS_MPRV
))
41 mode
= get_field(proc
->state
.mstatus
, MSTATUS_MPP
);
42 pum
= (mode
== PRV_S
&& get_field(proc
->state
.mstatus
, MSTATUS_PUM
));
44 if (get_field(proc
->state
.mstatus
, MSTATUS_VM
) == VM_MBARE
)
48 reg_t msb_mask
= (reg_t(2) << (proc
->xlen
-1))-1; // zero-extend from xlen
49 return addr
& msb_mask
;
51 return walk(addr
, type
, mode
> PRV_U
, pum
) | (addr
& (PGSIZE
-1));
54 const uint16_t* mmu_t::fetch_slow_path(reg_t vaddr
)
56 reg_t paddr
= translate(vaddr
, FETCH
);
58 // mmu_t::walk() returns -1 if it can't find a match. Of course -1 could also
59 // be a valid address.
60 if (paddr
== ~(reg_t
) 0 && vaddr
!= ~(reg_t
) 0) {
61 throw trap_instruction_access_fault(vaddr
);
64 if (sim
->addr_is_mem(paddr
)) {
65 refill_tlb(vaddr
, paddr
, FETCH
);
66 return (const uint16_t*)sim
->addr_to_mem(paddr
);
68 if (!sim
->mmio_load(paddr
, sizeof fetch_temp
, (uint8_t*)&fetch_temp
))
69 throw trap_instruction_access_fault(vaddr
);
74 void mmu_t::load_slow_path(reg_t addr
, reg_t len
, uint8_t* bytes
)
76 reg_t paddr
= translate(addr
, LOAD
);
77 if (sim
->addr_is_mem(paddr
)) {
78 memcpy(bytes
, sim
->addr_to_mem(paddr
), len
);
79 if (tracer
.interested_in_range(paddr
, paddr
+ PGSIZE
, LOAD
))
80 tracer
.trace(paddr
, len
, LOAD
);
82 refill_tlb(addr
, paddr
, LOAD
);
83 } else if (!sim
->mmio_load(paddr
, len
, bytes
)) {
84 throw trap_load_access_fault(addr
);
88 void mmu_t::store_slow_path(reg_t addr
, reg_t len
, const uint8_t* bytes
)
90 reg_t paddr
= translate(addr
, STORE
);
91 if (sim
->addr_is_mem(paddr
)) {
92 memcpy(sim
->addr_to_mem(paddr
), bytes
, len
);
93 if (tracer
.interested_in_range(paddr
, paddr
+ PGSIZE
, STORE
))
94 tracer
.trace(paddr
, len
, STORE
);
96 refill_tlb(addr
, paddr
, STORE
);
97 } else if (!sim
->mmio_store(paddr
, len
, bytes
)) {
98 throw trap_store_access_fault(addr
);
102 void mmu_t::refill_tlb(reg_t vaddr
, reg_t paddr
, access_type type
)
104 reg_t idx
= (vaddr
>> PGSHIFT
) % TLB_ENTRIES
;
105 reg_t expected_tag
= vaddr
>> PGSHIFT
;
107 if (tlb_load_tag
[idx
] != expected_tag
) tlb_load_tag
[idx
] = -1;
108 if (tlb_store_tag
[idx
] != expected_tag
) tlb_store_tag
[idx
] = -1;
109 if (tlb_insn_tag
[idx
] != expected_tag
) tlb_insn_tag
[idx
] = -1;
111 if (type
== FETCH
) tlb_insn_tag
[idx
] = expected_tag
;
112 else if (type
== STORE
) tlb_store_tag
[idx
] = expected_tag
;
113 else tlb_load_tag
[idx
] = expected_tag
;
115 tlb_data
[idx
] = sim
->addr_to_mem(paddr
) - vaddr
;
118 reg_t
mmu_t::walk(reg_t addr
, access_type type
, bool supervisor
, bool pum
)
120 int levels
, ptidxbits
, ptesize
;
121 switch (get_field(proc
->get_state()->mstatus
, MSTATUS_VM
))
123 case VM_SV32
: levels
= 2; ptidxbits
= 10; ptesize
= 4; break;
124 case VM_SV39
: levels
= 3; ptidxbits
= 9; ptesize
= 8; break;
125 case VM_SV48
: levels
= 4; ptidxbits
= 9; ptesize
= 8; break;
129 // verify bits xlen-1:va_bits-1 are all equal
130 int va_bits
= PGSHIFT
+ levels
* ptidxbits
;
131 reg_t mask
= (reg_t(1) << (proc
->xlen
- (va_bits
-1))) - 1;
132 reg_t masked_msbs
= (addr
>> (va_bits
-1)) & mask
;
133 if (masked_msbs
!= 0 && masked_msbs
!= mask
)
136 reg_t base
= proc
->get_state()->sptbr
<< PGSHIFT
;
137 int ptshift
= (levels
- 1) * ptidxbits
;
138 for (int i
= 0; i
< levels
; i
++, ptshift
-= ptidxbits
) {
139 reg_t idx
= (addr
>> (PGSHIFT
+ ptshift
)) & ((1 << ptidxbits
) - 1);
141 // check that physical address of PTE is legal
142 reg_t pte_addr
= base
+ idx
* ptesize
;
143 if (!sim
->addr_is_mem(pte_addr
))
146 void* ppte
= sim
->addr_to_mem(pte_addr
);
147 reg_t pte
= ptesize
== 4 ? *(uint32_t*)ppte
: *(uint64_t*)ppte
;
148 reg_t ppn
= pte
>> PTE_PPN_SHIFT
;
150 if (PTE_TABLE(pte
)) { // next level of page table
151 base
= ppn
<< PGSHIFT
;
152 } else if (pum
&& PTE_CHECK_PERM(pte
, 0, type
== STORE
, type
== FETCH
)) {
154 } else if (!PTE_CHECK_PERM(pte
, supervisor
, type
== STORE
, type
== FETCH
)) {
157 // set referenced and possibly dirty bits.
158 *(uint32_t*)ppte
|= PTE_R
| ((type
== STORE
) * PTE_D
);
159 // for superpage mappings, make a fake leaf PTE for the TLB's benefit.
160 reg_t vpn
= addr
>> PGSHIFT
;
161 reg_t value
= (ppn
| (vpn
& ((reg_t(1) << ptshift
) - 1))) << PGSHIFT
;
169 void mmu_t::register_memtracer(memtracer_t
* t
)