riscv/rocket-chip
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dcache/dtlb overhaul

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This commit is contained in:
Rimas Avizienis 2011-11-11 18:18:47 -08:00
parent e4fa94aa27
commit a1ce908541
5 changed files with 242 additions and 173 deletions
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9
rocket/src/main/scala/cpu.scala
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@ -76,7 +76,7 @@ class rocketProc extends Component
dtlb.io.cpu.req_val := ctrl.io.dmem.req_val; dtlb.io.cpu.req_val := ctrl.io.dmem.req_val;
dtlb.io.cpu.req_cmd := ctrl.io.dmem.req_cmd; dtlb.io.cpu.req_cmd := ctrl.io.dmem.req_cmd;
dtlb.io.cpu.req_asid := Bits(0,ASID_BITS); // FIXME: connect to PCR dtlb.io.cpu.req_asid := Bits(0,ASID_BITS); // FIXME: connect to PCR
dtlb.io.cpu.req_addr := dpath.io.dmem.req_addr; dtlb.io.cpu.req_vpn := dpath.io.dmem.req_addr(VADDR_BITS-1,PGIDX_BITS);
ctrl.io.xcpt_dtlb_ld := dtlb.io.cpu.xcpt_ld; ctrl.io.xcpt_dtlb_ld := dtlb.io.cpu.xcpt_ld;
ctrl.io.xcpt_dtlb_st := dtlb.io.cpu.xcpt_st; ctrl.io.xcpt_dtlb_st := dtlb.io.cpu.xcpt_st;
ctrl.io.dtlb_miss := dtlb.io.cpu.resp_miss; ctrl.io.dtlb_miss := dtlb.io.cpu.resp_miss;
@ -90,10 +90,13 @@ class rocketProc extends Component
arb.io.mem ^^ io.dmem arb.io.mem ^^ io.dmem
// connect arbiter to ctrl+dpath+DTLB // connect arbiter to ctrl+dpath+DTLB
arb.io.cpu.req_val := dtlb.io.cpu.resp_val; // arb.io.cpu.req_val := dtlb.io.cpu.resp_val;
arb.io.cpu.req_val := ctrl.io.dmem.req_val;
arb.io.cpu.req_cmd := ctrl.io.dmem.req_cmd; arb.io.cpu.req_cmd := ctrl.io.dmem.req_cmd;
arb.io.cpu.req_type := ctrl.io.dmem.req_type; arb.io.cpu.req_type := ctrl.io.dmem.req_type;
arb.io.cpu.req_addr := dtlb.io.cpu.resp_addr; // arb.io.cpu.req_addr := dtlb.io.cpu.resp_addr;
arb.io.cpu.req_idx := dpath.io.dmem.req_addr(PGIDX_BITS-1,0);
arb.io.cpu.req_ppn := dtlb.io.cpu.resp_ppn;
arb.io.cpu.req_data := dpath.io.dmem.req_data; arb.io.cpu.req_data := dpath.io.dmem.req_data;
arb.io.cpu.req_tag := dpath.io.dmem.req_tag; arb.io.cpu.req_tag := dpath.io.dmem.req_tag;
ctrl.io.dmem.req_rdy := dtlb.io.cpu.req_rdy && arb.io.cpu.req_rdy; ctrl.io.dmem.req_rdy := dtlb.io.cpu.req_rdy && arb.io.cpu.req_rdy;

3
rocket/src/main/scala/ctrl.scala
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@ -326,7 +326,8 @@ class rocketCtrl extends Component
val jr_taken = (ex_reg_br_type === BR_JR); val jr_taken = (ex_reg_br_type === BR_JR);
val j_taken = (ex_reg_br_type === BR_J); val j_taken = (ex_reg_br_type === BR_J);
io.dmem.req_val := ex_reg_mem_val; // && ~io.dpath.killx; // io.dmem.req_val := ex_reg_mem_val;
io.dmem.req_val := ex_reg_mem_val && ~io.dpath.killx;
io.dmem.req_cmd := ex_reg_mem_cmd; io.dmem.req_cmd := ex_reg_mem_cmd;
io.dmem.req_type := ex_reg_mem_type; io.dmem.req_type := ex_reg_mem_type;

326
rocket/src/main/scala/dcache.scala
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@ -5,13 +5,15 @@ import Node._;
import Constants._; import Constants._;
import scala.math._; import scala.math._;
// interface between D$ and processor pipeline // interface between D$ and processor/DTLB
class ioDmem(view: List[String] = null) extends Bundle(view) { class ioDmem(view: List[String] = null) extends Bundle(view) {
val req_val = Bool('input); val req_val = Bool('input);
val req_rdy = Bool('output); val req_rdy = Bool('output);
val req_cmd = Bits(4, 'input); val req_cmd = Bits(4, 'input);
val req_type = Bits(3, 'input); val req_type = Bits(3, 'input);
val req_addr = UFix(PADDR_BITS, 'input); val req_idx = Bits(PGIDX_BITS, 'input);
val req_ppn = Bits(PPN_BITS, 'input);
// val req_addr = UFix(PADDR_BITS, 'input);
val req_data = Bits(64, 'input); val req_data = Bits(64, 'input);
val req_tag = Bits(5, 'input); val req_tag = Bits(5, 'input);
val resp_miss = Bool('output); val resp_miss = Bool('output);
@ -38,6 +40,70 @@ class ioDCacheDM extends Bundle() {
val mem = new ioDcache().flip(); val mem = new ioDcache().flip();
} }
class rocketDCacheStoreGen extends Component {
val io = new Bundle {
val req_type = Bits(3, 'input);
val req_addr_lsb = Bits(3, 'input);
val req_data = Bits(64, 'input);
val store_wmask = Bits(64, 'output);
val store_data = Bits(64, 'output);
}
// generate write mask and store data signals based on store type and address LSBs
val wmask_b =
Mux(io.req_addr_lsb === UFix(0, 3), Bits("b0000_0001", 8),
Mux(io.req_addr_lsb === UFix(1, 3), Bits("b0000_0010", 8),
Mux(io.req_addr_lsb === UFix(2, 3), Bits("b0000_0100", 8),
Mux(io.req_addr_lsb === UFix(3, 3), Bits("b0000_1000", 8),
Mux(io.req_addr_lsb === UFix(4, 3), Bits("b0001_0000", 8),
Mux(io.req_addr_lsb === UFix(5, 3), Bits("b0010_0000", 8),
Mux(io.req_addr_lsb === UFix(6, 3), Bits("b0100_0000", 8),
Mux(io.req_addr_lsb === UFix(7, 3), Bits("b1000_0000", 8),
UFix(0, 8)))))))));
val wmask_h =
Mux(io.req_addr_lsb(2,1) === UFix(0, 2), Bits("b0000_0011", 8),
Mux(io.req_addr_lsb(2,1) === UFix(1, 2), Bits("b0000_1100", 8),
Mux(io.req_addr_lsb(2,1) === UFix(2, 2), Bits("b0011_0000", 8),
Mux(io.req_addr_lsb(2,1) === UFix(3, 2), Bits("b1100_0000", 8),
UFix(0, 8)))));
val wmask_w =
Mux(io.req_addr_lsb(2) === UFix(0, 1), Bits("b0000_1111", 8),
Mux(io.req_addr_lsb(2) === UFix(1, 1), Bits("b1111_0000", 8),
UFix(0, 8)));
val wmask_d =
Bits("b1111_1111", 8);
val store_wmask_byte =
Mux(io.req_type === MT_B, wmask_b,
Mux(io.req_type === MT_H, wmask_h,
Mux(io.req_type === MT_W, wmask_w,
Mux(io.req_type === MT_D, wmask_d,
UFix(0, 8)))));
io.store_wmask :=
Cat(Fill(8, store_wmask_byte(7)),
Fill(8, store_wmask_byte(6)),
Fill(8, store_wmask_byte(5)),
Fill(8, store_wmask_byte(4)),
Fill(8, store_wmask_byte(3)),
Fill(8, store_wmask_byte(2)),
Fill(8, store_wmask_byte(1)),
Fill(8, store_wmask_byte(0)));
io.store_data :=
Mux(io.req_type === MT_B, Fill(8, io.req_data( 7,0)),
Mux(io.req_type === MT_H, Fill(4, io.req_data(15,0)),
Mux(io.req_type === MT_W, Fill(2, io.req_data(31,0)),
Mux(io.req_type === MT_D, io.req_data,
UFix(0, 64)))));
}
// state machine to flush (write back dirty lines, invalidate clean ones) the D$ // state machine to flush (write back dirty lines, invalidate clean ones) the D$
class rocketDCacheDM_flush(lines: Int) extends Component { class rocketDCacheDM_flush(lines: Int) extends Component {
val io = new ioDCacheDM(); val io = new ioDCacheDM();
@ -48,6 +114,7 @@ class rocketDCacheDM_flush(lines: Int) extends Component {
val offsetbits = 6; val offsetbits = 6;
val tagmsb = addrbits - 1; val tagmsb = addrbits - 1;
val taglsb = indexbits+offsetbits; val taglsb = indexbits+offsetbits;
val tagbits = tagmsb-taglsb+1;
val indexmsb = taglsb-1; val indexmsb = taglsb-1;
val indexlsb = offsetbits; val indexlsb = offsetbits;
val offsetmsb = indexlsb-1; val offsetmsb = indexlsb-1;
@ -82,7 +149,11 @@ class rocketDCacheDM_flush(lines: Int) extends Component {
dcache.io.cpu.req_val := (io.cpu.req_val && (io.cpu.req_cmd != M_FLA) && !flush_waiting) || flushing; dcache.io.cpu.req_val := (io.cpu.req_val && (io.cpu.req_cmd != M_FLA) && !flush_waiting) || flushing;
dcache.io.cpu.req_cmd := Mux(flushing, M_FLA, io.cpu.req_cmd); dcache.io.cpu.req_cmd := Mux(flushing, M_FLA, io.cpu.req_cmd);
dcache.io.cpu.req_addr := Mux(flushing, Cat(Bits(0,tagmsb-taglsb+1), flush_count, Bits(0,offsetbits)).toUFix, io.cpu.req_addr); dcache.io.cpu.req_idx := Mux(flushing, Cat(flush_count, Bits(0,offsetbits)), io.cpu.req_idx);
dcache.io.cpu.req_ppn := Mux(flushing, UFix(0,PPN_BITS), io.cpu.req_ppn);
// dcache.io.cpu.req_addr :=
// Mux(flushing, Cat(Bits(0,tagmsb-taglsb+1), flush_count, Bits(0,offsetbits)).toUFix,
// io.cpu.req_addr);
dcache.io.cpu.req_tag := Mux(flushing, r_cpu_req_tag, io.cpu.req_tag); dcache.io.cpu.req_tag := Mux(flushing, r_cpu_req_tag, io.cpu.req_tag);
dcache.io.cpu.req_type := io.cpu.req_type; dcache.io.cpu.req_type := io.cpu.req_type;
dcache.io.cpu.req_data ^^ io.cpu.req_data; dcache.io.cpu.req_data ^^ io.cpu.req_data;
@ -102,9 +173,10 @@ class rocketDCacheDM(lines: Int) extends Component {
val addrbits = PADDR_BITS; val addrbits = PADDR_BITS;
val indexbits = ceil(log10(lines)/log10(2)).toInt; val indexbits = ceil(log10(lines)/log10(2)).toInt;
val offsetbits = 6; val offsetbits = 6; // 64 byte cache lines = 2^6 bytes
val tagmsb = addrbits - 1; val tagmsb = PADDR_BITS-1;
val taglsb = indexbits+offsetbits; val taglsb = indexbits+offsetbits;
val tagbits = tagmsb-taglsb+1;
val indexmsb = taglsb-1; val indexmsb = taglsb-1;
val indexlsb = offsetbits; val indexlsb = offsetbits;
val offsetmsb = indexlsb-1; val offsetmsb = indexlsb-1;
@ -113,45 +185,48 @@ class rocketDCacheDM(lines: Int) extends Component {
val s_reset :: s_ready :: s_replay_load :: s_start_writeback :: s_writeback :: s_req_refill :: s_refill :: s_resolve_miss :: Nil = Enum(8) { UFix() }; val s_reset :: s_ready :: s_replay_load :: s_start_writeback :: s_writeback :: s_req_refill :: s_refill :: s_resolve_miss :: Nil = Enum(8) { UFix() };
val state = Reg(resetVal = s_reset); val state = Reg(resetVal = s_reset);
val r_cpu_req_addr = Reg(resetVal = Bits(0, addrbits)); // idx arrives one clock cycle prior to ppn b/c of DTLB
val r_cpu_req_idx = Reg(resetVal = Bits(0, PGIDX_BITS));
val r_cpu_req_ppn = Reg(resetVal = Bits(0, PPN_BITS));
val r_cpu_req_val = Reg(resetVal = Bool(false)); val r_cpu_req_val = Reg(resetVal = Bool(false));
val r_cpu_req_cmd = Reg(resetVal = Bits(0,4)); val r_cpu_req_cmd = Reg(resetVal = Bits(0,4));
val r_cpu_req_type = Reg(resetVal = Bits(0,3)); val r_cpu_req_type = Reg(resetVal = Bits(0,3));
val r_cpu_req_tag = Reg(resetVal = Bits(0,5)); val r_cpu_req_tag = Reg(resetVal = Bits(0,5));
val r_cpu_resp_val = Reg(resetVal = Bool(false));
val p_store_data = Reg(resetVal = Bits(0,64)); val p_store_data = Reg(resetVal = Bits(0,64));
val p_store_addr = Reg(resetVal = Bits(0,64)); val p_store_idx = Reg(resetVal = Bits(0,PGIDX_BITS));
val p_store_cmd = Reg(resetVal = Bits(0,4)); val p_store_type = Reg(resetVal = Bits(0,3));
val p_store_type = Reg(resetVal = Bits(0,3)); val p_store_valid = Reg(resetVal = Bool(false));
val p_store_valid = Reg(resetVal = Bool(false));
val req_load = (r_cpu_req_cmd === M_XRD) || (r_cpu_req_cmd === M_PRD); val req_store = (io.cpu.req_cmd === M_XWR);
val req_store = (r_cpu_req_cmd === M_XWR); val r_req_load = (r_cpu_req_cmd === M_XRD) || (r_cpu_req_cmd === M_PRD);
val req_flush = (r_cpu_req_cmd === M_FLA); val r_req_store = (r_cpu_req_cmd === M_XWR);
val req_ptw_load = (r_cpu_req_cmd === M_PRD); val r_req_flush = (r_cpu_req_cmd === M_FLA);
val r_req_ptw_load = (r_cpu_req_cmd === M_PRD);
when (io.cpu.req_val && io.cpu.req_rdy) { when (io.cpu.req_val && io.cpu.req_rdy) {
r_cpu_req_addr <== io.cpu.req_addr; r_cpu_req_idx <== io.cpu.req_idx;
r_cpu_req_cmd <== io.cpu.req_cmd; r_cpu_req_cmd <== io.cpu.req_cmd;
r_cpu_req_type <== io.cpu.req_type; r_cpu_req_type <== io.cpu.req_type;
r_cpu_req_tag <== io.cpu.req_tag; r_cpu_req_tag <== io.cpu.req_tag;
} }
when (io.cpu.req_val && io.cpu.req_rdy && (io.cpu.req_cmd === M_XWR)) { when (state === s_ready) {
p_store_data <== io.cpu.req_data; r_cpu_req_ppn <== io.cpu.req_ppn;
p_store_addr <== io.cpu.req_addr;
p_store_type <== io.cpu.req_type;
p_store_valid <== Bool(true);
} }
when (io.cpu.req_rdy) { when (io.cpu.req_rdy) {
r_cpu_req_val <== io.cpu.req_val; r_cpu_req_val <== io.cpu.req_val;
} }
when ((state === s_resolve_miss) && !req_load) { when (state === s_resolve_miss) {
r_cpu_req_val <== Bool(false); r_cpu_req_val <== Bool(false);
when (r_req_load) {
r_cpu_resp_val <== Bool(true);
}
} }
r_cpu_resp_val <== Bool(false);
// counter // refill counter
val rr_count = Reg(resetVal = UFix(0,2)); val rr_count = Reg(resetVal = UFix(0,2));
val rr_count_next = rr_count + UFix(1); val rr_count_next = rr_count + UFix(1);
when (((state === s_refill) && io.mem.resp_val) || ((state === s_writeback) && io.mem.req_rdy)) { when (((state === s_refill) && io.mem.resp_val) || ((state === s_writeback) && io.mem.req_rdy)) {
@ -159,146 +234,115 @@ class rocketDCacheDM(lines: Int) extends Component {
} }
// tag array // tag array
val tagbits = addrbits-(indexbits+offsetbits); val tag_addr =
Mux((state === s_ready), io.cpu.req_idx(PGIDX_BITS-1,offsetbits),
r_cpu_req_idx(PGIDX_BITS-1,offsetbits)).toUFix;
val tag_we = val tag_we =
((state === s_refill) && io.mem.req_rdy && (rr_count === UFix(3,2))) || ((state === s_refill) && io.mem.req_rdy && (rr_count === UFix(3,2))) ||
((state === s_resolve_miss) && req_flush); ((state === s_resolve_miss) && r_req_flush);
val tag_array = new rocketSRAMsp(lines, tagbits);
val tag_raddr = val tag_array = new rocketSRAMsp(lines, tagbits);
Mux((state === s_ready), io.cpu.req_addr(indexmsb, indexlsb).toUFix, tag_array.io.a := tag_addr;
r_cpu_req_addr(indexmsb, indexlsb).toUFix); tag_array.io.d := r_cpu_req_ppn;
tag_array.io.a := tag_raddr;
tag_array.io.d := r_cpu_req_addr(tagmsb, taglsb);
tag_array.io.we := tag_we; tag_array.io.we := tag_we;
tag_array.io.bweb := ~Bits(0,tagbits); tag_array.io.bweb := ~Bits(0,tagbits);
tag_array.io.ce := Bool(true); // FIXME tag_array.io.ce := Bool(true); // FIXME
val tag_rdata = tag_array.io.q; val tag_rdata = tag_array.io.q;
// valid bit array // valid bit array
val vb_array = Reg(resetVal = Bits(0, lines)); val vb_array = Reg(resetVal = Bits(0, lines));
val vb_rdata = Reg(vb_array(tag_raddr)); // val vb_rdata = Reg(vb_array(tag_raddr));
when (tag_we && !req_flush) { when (tag_we && !r_req_flush) {
vb_array <== vb_array.bitSet(r_cpu_req_addr(indexmsb, indexlsb).toUFix, UFix(1,1)); vb_array <== vb_array.bitSet(r_cpu_req_idx(PGIDX_BITS-1,offsetbits).toUFix, UFix(1,1));
} }
when (tag_we && req_flush) { when (tag_we && r_req_flush) {
vb_array <== vb_array.bitSet(r_cpu_req_addr(indexmsb, indexlsb).toUFix, UFix(0,1)); vb_array <== vb_array.bitSet(r_cpu_req_idx(PGIDX_BITS-1,offsetbits).toUFix, UFix(0,1));
} }
val tag_valid = vb_rdata.toBool; val tag_valid = Reg(vb_array(tag_addr)).toBool;
val tag_match = tag_valid && (tag_rdata === r_cpu_req_addr(tagmsb, taglsb)); val tag_match = (tag_rdata === io.cpu.req_ppn);
val addr_match = (r_cpu_req_idx(PGIDX_BITS-1,offsetbits) === p_store_idx(PGIDX_BITS-1,offsetbits));
val ldst_conflict = r_cpu_req_val && r_req_load && p_store_valid && addr_match;
// write the pending store data when the cache is idle, when the next command isn't a load
// or when there's a load to the same address (in which case there's a 2 cycle delay:
// once cycle to write the store data and another to read the data back)
val drain_store = p_store_valid && (!io.cpu.req_val || req_store || ldst_conflict);
// write pending store data from a store which missed
// after the cache line refill has completed
val resolve_store = (state === s_resolve_miss) && r_req_store;
// generate write mask and store data signals based on store type and address LSBs
val wmask_b =
Mux(p_store_addr(2,0) === UFix(0, 3), Bits("b0000_0001", 8),
Mux(p_store_addr(2,0) === UFix(1, 3), Bits("b0000_0010", 8),
Mux(p_store_addr(2,0) === UFix(2, 3), Bits("b0000_0100", 8),
Mux(p_store_addr(2,0) === UFix(3, 3), Bits("b0000_1000", 8),
Mux(p_store_addr(2,0) === UFix(4, 3), Bits("b0001_0000", 8),
Mux(p_store_addr(2,0) === UFix(5, 3), Bits("b0010_0000", 8),
Mux(p_store_addr(2,0) === UFix(6, 3), Bits("b0100_0000", 8),
Mux(p_store_addr(2,0) === UFix(7, 3), Bits("b1000_0000", 8),
UFix(0, 8)))))))));
val wmask_h =
Mux(p_store_addr(2,1) === UFix(0, 2), Bits("b0000_0011", 8),
Mux(p_store_addr(2,1) === UFix(1, 2), Bits("b0000_1100", 8),
Mux(p_store_addr(2,1) === UFix(2, 2), Bits("b0011_0000", 8),
Mux(p_store_addr(2,1) === UFix(3, 2), Bits("b1100_0000", 8),
UFix(0, 8)))));
val wmask_w =
Mux(p_store_addr(2) === UFix(0, 1), Bits("b0000_1111", 8),
Mux(p_store_addr(2) === UFix(1, 1), Bits("b1111_0000", 8),
UFix(0, 8)));
val wmask_d =
Bits("b1111_1111", 8);
val store_wmask =
Mux(p_store_type === MT_B, wmask_b,
Mux(p_store_type === MT_H, wmask_h,
Mux(p_store_type === MT_W, wmask_w,
Mux(p_store_type === MT_D, wmask_d,
UFix(0, 8)))));
val store_data =
Mux(p_store_type === MT_B, Fill(8, p_store_data( 7,0)),
Mux(p_store_type === MT_H, Fill(4, p_store_data(15,0)),
Mux(p_store_type === MT_W, Fill(2, p_store_data(31,0)),
Mux(p_store_type === MT_D, p_store_data,
UFix(0, 64)))));
val addr_match = (r_cpu_req_addr(tagmsb, offsetlsb) === p_store_addr(tagmsb, offsetlsb));
val ldst_conflict = r_cpu_req_val && req_load && p_store_valid && addr_match;
val drain_store =
(state === s_ready) && p_store_valid &&
(!(io.cpu.req_val && (io.cpu.req_cmd === M_XRD)) ||
r_cpu_req_val && req_load && p_store_valid && addr_match);
val resolve_store = (state === s_resolve_miss) && req_store;
val do_store = drain_store | resolve_store;
// dirty bit array // dirty bit array
val db_array = Reg(resetVal = Bits(0, lines)); val db_array = Reg(resetVal = Bits(0, lines));
val db_rdata = Reg(db_array(tag_raddr)); // val db_rdata = Reg(db_array(tag_raddr));
val tag_dirty = db_rdata.toBool; val tag_dirty = Reg(db_array(tag_addr)).toBool;
when (do_store) { when (io.cpu.req_val && io.cpu.req_rdy && req_store) {
p_store_idx <== io.cpu.req_idx;
p_store_data <== io.cpu.req_data;
p_store_type <== io.cpu.req_type;
p_store_valid <== Bool(true);
}
when (drain_store) {
p_store_valid <== Bool(false); p_store_valid <== Bool(false);
db_array <== db_array.bitSet(p_store_addr(indexmsb, indexlsb).toUFix, UFix(1,1)); db_array <== db_array.bitSet(p_store_idx(PGIDX_BITS-1,offsetbits).toUFix, UFix(1,1));
}
when (resolve_store) {
db_array <== db_array.bitSet(p_store_idx(PGIDX_BITS-1,offsetbits).toUFix, UFix(1,1));
} }
when (tag_we) { when (tag_we) {
db_array <== db_array.bitSet(r_cpu_req_addr(indexmsb, indexlsb).toUFix, UFix(0,1)); db_array <== db_array.bitSet(r_cpu_req_idx(PGIDX_BITS-1,offsetbits).toUFix, UFix(0,1));
} }
// generate write mask and data signals for stores
val storegen = new rocketDCacheStoreGen();
storegen.io.req_addr_lsb := p_store_idx(2,0);
storegen.io.req_data := p_store_data;
storegen.io.req_type := p_store_type
val store_data = Fill(2, storegen.io.store_data);
val store_wmask_d = storegen.io.store_wmask;
val store_idx_sel = p_store_idx(offsetlsb).toBool;
val store_wmask =
Mux(store_idx_sel,
Cat(store_wmask_d, Bits(0,64)),
Cat(Bits(0,64), store_wmask_d));
// data array // data array
val data_array = new rocketSRAMsp(lines*4, 128); val data_array = new rocketSRAMsp(lines*4, 128);
val store_wmask_expand =
Cat(Fill(8, store_wmask(7)),
Fill(8, store_wmask(6)),
Fill(8, store_wmask(5)),
Fill(8, store_wmask(4)),
Fill(8, store_wmask(3)),
Fill(8, store_wmask(2)),
Fill(8, store_wmask(1)),
Fill(8, store_wmask(0)));
val da_store_wmask =
Mux(p_store_addr(offsetlsb).toBool,
Cat(store_wmask_expand, Bits(0,64)),
Cat(Bits(0,64), store_wmask_expand));
data_array.io.a := data_array.io.a :=
Mux(do_store, p_store_addr(indexmsb, offsetmsb-1), Mux(drain_store || resolve_store, p_store_idx(PGIDX_BITS-1, offsetmsb-1),
Mux((state === s_writeback) && io.mem.req_rdy, Cat(r_cpu_req_addr(indexmsb, indexlsb), rr_count_next), Mux((state === s_writeback) && io.mem.req_rdy, Cat(r_cpu_req_idx(PGIDX_BITS-1, offsetbits), rr_count_next),
Mux((state === s_start_writeback) || (state === s_writeback) || (state === s_refill), Cat(r_cpu_req_addr(indexmsb, indexlsb), rr_count), Mux((state === s_start_writeback) || (state === s_writeback) || (state === s_refill), Cat(r_cpu_req_idx(PGIDX_BITS-1, offsetbits), rr_count),
Mux((state === s_resolve_miss) || (state === s_replay_load), r_cpu_req_addr(indexmsb, offsetmsb-1), Mux((state === s_resolve_miss) || (state === s_replay_load), r_cpu_req_idx(PGIDX_BITS-1, offsetmsb-1),
io.cpu.req_addr(indexmsb, offsetmsb-1))))).toUFix; io.cpu.req_idx(PGIDX_BITS-1, offsetmsb-1))))).toUFix;
data_array.io.d := data_array.io.d :=
Mux((state === s_refill), io.mem.resp_data, Mux((state === s_refill), io.mem.resp_data,
Cat(store_data, store_data)); Mux((state === s_resolve_miss), Fill(2, p_store_data),
store_data));
data_array.io.we := ((state === s_refill) && io.mem.resp_val) || do_store; data_array.io.we := ((state === s_refill) && io.mem.resp_val) || drain_store || resolve_store;
data_array.io.bweb := data_array.io.bweb := Mux((state === s_refill), ~Bits(0,128), store_wmask);
Mux((state === s_refill), ~Bits(0,128),
da_store_wmask);
data_array.io.ce := Bool(true); // FIXME data_array.io.ce := Bool(true); // FIXME
val data_array_rdata = data_array.io.q; val data_array_rdata = data_array.io.q;
val miss = (state === s_ready) && r_cpu_req_val && req_load && (!tag_match || (p_store_valid && addr_match)); // signal a load miss when the data isn't present in the cache and when it's in the pending store data register
// (causes the cache to block for 2 cycles and the load instruction is replayed)
val hit = tag_valid && tag_match;
val load_miss = (state === s_ready) && r_cpu_req_val && r_req_load && (!hit || (p_store_valid && addr_match));
// output signals // output signals
io.cpu.req_rdy := (state === s_ready) && !ldst_conflict && (!r_cpu_req_val || (tag_match && !req_flush)); // busy when there's a load to the same address as a pending store, or on a cache miss, or when executing a flush
io.cpu.req_rdy := (state === s_ready) && !ldst_conflict && (!r_cpu_req_val || (hit && !r_req_flush));
io.cpu.resp_val := ((state === s_ready) && r_cpu_req_val && tag_match && req_load && !(p_store_valid && addr_match)) || io.cpu.resp_val := ((state === s_ready) && r_cpu_req_val && r_req_load && hit && !(p_store_valid && addr_match)) ||
((state === s_resolve_miss) && req_flush); ((state === s_resolve_miss) && r_req_flush) ||
r_cpu_resp_val;
io.cpu.resp_miss := miss; io.cpu.resp_miss := load_miss;
// io.cpu.resp_tag := Cat(Bits(0,1), r_cpu_req_type, r_cpu_req_addr(2,0), r_cpu_req_tag); // tag MSB distinguishes between loads destined for the PTW and CPU
io.cpu.resp_tag := Cat(req_ptw_load, r_cpu_req_type, r_cpu_req_addr(2,0), r_cpu_req_tag); io.cpu.resp_tag := Cat(r_req_ptw_load, r_cpu_req_type, r_cpu_req_idx(2,0), r_cpu_req_tag);
io.cpu.resp_data := io.cpu.resp_data :=
Mux(r_cpu_req_addr(offsetlsb).toBool, data_array_rdata(127, 64), Mux(r_cpu_req_idx(offsetlsb).toBool, data_array_rdata(127, 64),
data_array_rdata(63,0)); data_array_rdata(63,0));
io.mem.req_val := (state === s_req_refill) || (state === s_writeback); io.mem.req_val := (state === s_req_refill) || (state === s_writeback);
@ -306,8 +350,8 @@ class rocketDCacheDM(lines: Int) extends Component {
io.mem.req_wdata := data_array_rdata; io.mem.req_wdata := data_array_rdata;
io.mem.req_tag := UFix(0); io.mem.req_tag := UFix(0);
io.mem.req_addr := io.mem.req_addr :=
Mux(state === s_writeback, Cat(tag_rdata, r_cpu_req_addr(indexmsb, indexlsb), rr_count).toUFix, Mux(state === s_writeback, Cat(tag_rdata, r_cpu_req_idx(PGIDX_BITS-1, offsetbits), rr_count),
Cat(r_cpu_req_addr(tagmsb, indexlsb), Bits(0,2)).toUFix); Cat(r_cpu_req_ppn, r_cpu_req_idx(PGIDX_BITS-1, offsetbits), Bits(0,2))).toUFix;
// control state machine // control state machine
switch (state) { switch (state) {
@ -318,13 +362,13 @@ class rocketDCacheDM(lines: Int) extends Component {
when (ldst_conflict) { when (ldst_conflict) {
state <== s_replay_load; state <== s_replay_load;
} }
when (!r_cpu_req_val || tag_match) { when (!r_cpu_req_val || (hit && !r_req_flush)) {
state <== s_ready; state <== s_ready;
} }
when (tag_valid & tag_dirty) { when (tag_valid & tag_dirty) {
state <== s_start_writeback; state <== s_start_writeback;
} }
when (req_flush) { when (r_req_flush) {
state <== s_resolve_miss; state <== s_resolve_miss;
} }
otherwise { otherwise {
@ -339,8 +383,12 @@ class rocketDCacheDM(lines: Int) extends Component {
} }
is (s_writeback) { is (s_writeback) {
when (io.mem.req_rdy && (rr_count === UFix(3,2))) { when (io.mem.req_rdy && (rr_count === UFix(3,2))) {
when (req_flush) { state <== s_resolve_miss; } when (r_req_flush) {
otherwise { state <== s_req_refill; } state <== s_resolve_miss;
}
otherwise {
state <== s_req_refill;
}
} }
} }
is (s_req_refill) is (s_req_refill)

66
rocket/src/main/scala/dtlb.scala
View File

@ -18,11 +18,11 @@ class ioDTLB_CPU(view: List[String] = null) extends Bundle(view)
val req_cmd = Bits(4, 'input); // load/store/amo val req_cmd = Bits(4, 'input); // load/store/amo
val req_rdy = Bool('output); val req_rdy = Bool('output);
val req_asid = Bits(ASID_BITS, 'input); val req_asid = Bits(ASID_BITS, 'input);
val req_addr = UFix(VADDR_BITS, 'input); val req_vpn = UFix(VPN_BITS, 'input);
// lookup responses // lookup responses
val resp_miss = Bool('output); val resp_miss = Bool('output);
val resp_val = Bool('output); // val resp_val = Bool('output);
val resp_addr = UFix(PADDR_BITS, 'output); val resp_ppn = UFix(PPN_BITS, 'output);
val xcpt_ld = Bool('output); val xcpt_ld = Bool('output);
val xcpt_st = Bool('output); val xcpt_st = Bool('output);
} }
@ -35,25 +35,40 @@ class ioDTLB extends Bundle
class rocketDTLB(entries: Int) extends Component class rocketDTLB(entries: Int) extends Component
{ {
val addr_bits = ceil(log10(entries)/log10(2)).toInt;
val io = new ioDTLB(); val io = new ioDTLB();
val addr_bits = ceil(log10(entries)/log10(2)).toInt;
val s_ready :: s_request :: s_wait :: Nil = Enum(3) { UFix() }; val s_ready :: s_request :: s_wait :: Nil = Enum(3) { UFix() };
val state = Reg(resetVal = s_ready); val state = Reg(resetVal = s_ready);
val tag_cam = new rocketCAM(entries, addr_bits, ASID_BITS+VPN_BITS);
val req_vpn = io.cpu.req_addr(VADDR_BITS-1,PGIDX_BITS); val r_cpu_req_vpn = Reg(resetVal = Bits(0, VPN_BITS));
val req_idx = io.cpu.req_addr(PGIDX_BITS-1,0); val r_cpu_req_val = Reg(resetVal = Bool(false));
val req_load = (io.cpu.req_cmd === M_XRD); val r_cpu_req_cmd = Reg(resetVal = Bits(0,4));
val req_store = (io.cpu.req_cmd === M_XWR); val r_cpu_req_asid = Reg(resetVal = Bits(0,ASID_BITS));
val r_refill_tag = Reg(resetVal = Bits(0,ASID_BITS+VPN_BITS));
val r_refill_waddr = Reg(resetVal = UFix(0,addr_bits));
val repl_count = Reg(resetVal = UFix(0,addr_bits));
when (io.cpu.req_val && io.cpu.req_rdy) {
r_cpu_req_vpn <== io.cpu.req_vpn;
r_cpu_req_cmd <== io.cpu.req_cmd;
r_cpu_req_asid <== io.cpu.req_asid;
}
when (io.cpu.req_rdy) {
r_cpu_req_val <== io.cpu.req_val;
}
// val req_vpn = r_cpu_req_addr(VADDR_BITS-1,PGIDX_BITS);
// val req_idx = io.cpu.req_addr(PGIDX_BITS-1,0);
val req_load = (r_cpu_req_cmd === M_XRD);
val req_store = (r_cpu_req_cmd === M_XWR);
// val req_amo = io.cpu.req_cmd(3).toBool; // val req_amo = io.cpu.req_cmd(3).toBool;
val lookup_tag = Cat(io.cpu.req_asid, req_vpn); val lookup_tag = Cat(r_cpu_req_asid, r_cpu_req_vpn);
val r_refill_tag = Reg(resetVal = Bits(0, ASID_BITS+VPN_BITS));
val r_refill_waddr = Reg(resetVal = UFix(0, addr_bits)); val tag_cam = new rocketCAM(entries, addr_bits, ASID_BITS+VPN_BITS);
val repl_count = Reg(resetVal = UFix(0, addr_bits));
val tag_ram = Mem(entries, io.ptw.resp_val, r_refill_waddr.toUFix, io.ptw.resp_ppn); val tag_ram = Mem(entries, io.ptw.resp_val, r_refill_waddr.toUFix, io.ptw.resp_ppn);
tag_cam.io.clear := io.cpu.invalidate; tag_cam.io.clear := io.cpu.invalidate;
@ -61,6 +76,7 @@ class rocketDTLB(entries: Int) extends Component
tag_cam.io.write := io.ptw.resp_val; tag_cam.io.write := io.ptw.resp_val;
tag_cam.io.write_tag := r_refill_tag; tag_cam.io.write_tag := r_refill_tag;
tag_cam.io.write_addr := r_refill_waddr; tag_cam.io.write_addr := r_refill_waddr;
val tag_hit = tag_cam.io.hit;
val tag_hit_addr = tag_cam.io.hit_addr; val tag_hit_addr = tag_cam.io.hit_addr;
// extract fields from status register // extract fields from status register
@ -75,10 +91,10 @@ class rocketDTLB(entries: Int) extends Component
val ptw_perm_sw = io.ptw.resp_perm(5); val ptw_perm_sw = io.ptw.resp_perm(5);
// permission bit arrays // permission bit arrays
val ur_array = Reg(resetVal = Bits(0, entries)); // user execute permission val ur_array = Reg(resetVal = Bits(0, entries)); // user read permission
val uw_array = Reg(resetVal = Bits(0, entries)); // user execute permission val uw_array = Reg(resetVal = Bits(0, entries)); // user write permission
val sr_array = Reg(resetVal = Bits(0, entries)); // supervisor execute permission val sr_array = Reg(resetVal = Bits(0, entries)); // supervisor read permission
val sw_array = Reg(resetVal = Bits(0, entries)); // supervisor execute permission val sw_array = Reg(resetVal = Bits(0, entries)); // supervisor write permission
when (io.ptw.resp_val) { when (io.ptw.resp_val) {
ur_array <== ur_array.bitSet(r_refill_waddr, ptw_perm_ur); ur_array <== ur_array.bitSet(r_refill_waddr, ptw_perm_ur);
uw_array <== uw_array.bitSet(r_refill_waddr, ptw_perm_uw); uw_array <== uw_array.bitSet(r_refill_waddr, ptw_perm_uw);
@ -103,12 +119,13 @@ class rocketDTLB(entries: Int) extends Component
val repl_waddr = Mux(invalid_entry, ie_addr, repl_count).toUFix; val repl_waddr = Mux(invalid_entry, ie_addr, repl_count).toUFix;
val lookup_hit = (state === s_ready) && io.cpu.req_val && tag_cam.io.hit; val lookup_hit = (state === s_ready) && r_cpu_req_val && tag_hit;
val lookup_miss = (state === s_ready) && io.cpu.req_val && !tag_cam.io.hit; val lookup_miss = (state === s_ready) && r_cpu_req_val && !tag_hit;
val tlb_hit = status_vm && lookup_hit; val tlb_hit = status_vm && lookup_hit;
val tlb_miss = status_vm && lookup_miss; val tlb_miss = status_vm && lookup_miss;
// currently replace TLB entries in LIFO order
// TODO: implement LRU replacement policy
when (tlb_miss) { when (tlb_miss) {
r_refill_tag <== lookup_tag; r_refill_tag <== lookup_tag;
r_refill_waddr <== repl_waddr; r_refill_waddr <== repl_waddr;
@ -130,10 +147,7 @@ class rocketDTLB(entries: Int) extends Component
io.cpu.req_rdy := (state === s_ready); io.cpu.req_rdy := (state === s_ready);
io.cpu.resp_miss := tlb_miss; io.cpu.resp_miss := tlb_miss;
io.cpu.resp_val := Mux(status_vm, lookup_hit, io.cpu.req_val); io.cpu.resp_ppn := Mux(status_vm, tag_ram(tag_hit_addr), r_cpu_req_vpn(PPN_BITS-1,0)).toUFix;
io.cpu.resp_addr :=
Mux(status_vm, Cat(tag_ram(tag_hit_addr), req_idx),
io.cpu.req_addr(PADDR_BITS-1,0)).toUFix;
io.ptw.req_val := (state === s_request); io.ptw.req_val := (state === s_request);
io.ptw.req_vpn := r_refill_tag(VPN_BITS-1,0); io.ptw.req_vpn := r_refill_tag(VPN_BITS-1,0);

11
rocket/src/main/scala/ptw.scala
View File

@ -7,7 +7,7 @@ import scala.math._;
class ioDmemArbiter extends Bundle class ioDmemArbiter extends Bundle
{ {
val ptw = new ioDmem(List("req_val", "req_rdy", "req_cmd", "req_type", "req_addr", "resp_data", "resp_val")); val ptw = new ioDmem(List("req_val", "req_rdy", "req_cmd", "req_type", "req_idx", "req_ppn", "resp_data", "resp_val"));
val cpu = new ioDmem(); val cpu = new ioDmem();
val mem = new ioDmem().flip(); val mem = new ioDmem().flip();
} }
@ -19,7 +19,8 @@ class rocketDmemArbiter extends Component
io.mem.req_val := io.ptw.req_val || io.cpu.req_val; io.mem.req_val := io.ptw.req_val || io.cpu.req_val;
io.mem.req_cmd := Mux(io.ptw.req_val, io.ptw.req_cmd, io.cpu.req_cmd); io.mem.req_cmd := Mux(io.ptw.req_val, io.ptw.req_cmd, io.cpu.req_cmd);
io.mem.req_type := Mux(io.ptw.req_val, io.ptw.req_type, io.cpu.req_type); io.mem.req_type := Mux(io.ptw.req_val, io.ptw.req_type, io.cpu.req_type);
io.mem.req_addr := Mux(io.ptw.req_val, io.ptw.req_addr, io.cpu.req_addr); io.mem.req_idx := Mux(io.ptw.req_val, io.ptw.req_idx, io.cpu.req_idx);
io.mem.req_ppn := Mux(io.ptw.req_val, io.ptw.req_ppn, io.cpu.req_ppn);
io.mem.req_data := io.cpu.req_data; io.mem.req_data := io.cpu.req_data;
io.mem.req_tag := Mux(io.ptw.req_val, Bits(0,5), io.cpu.req_tag); io.mem.req_tag := Mux(io.ptw.req_val, Bits(0,5), io.cpu.req_tag);
@ -40,7 +41,7 @@ class ioPTW extends Bundle
{ {
val itlb = new ioTLB_PTW().flip(); val itlb = new ioTLB_PTW().flip();
val dtlb = new ioTLB_PTW().flip(); val dtlb = new ioTLB_PTW().flip();
val dmem = new ioDmem(List("req_val", "req_rdy", "req_cmd", "req_type", "req_addr", "resp_data", "resp_val")).flip(); val dmem = new ioDmem(List("req_val", "req_rdy", "req_cmd", "req_type", "req_ppn", "req_idx", "resp_data", "resp_val")).flip();
val ptbr = UFix(PADDR_BITS, 'input); val ptbr = UFix(PADDR_BITS, 'input);
} }
@ -90,7 +91,9 @@ class rocketPTW extends Component
io.dmem.req_cmd := M_PRD; io.dmem.req_cmd := M_PRD;
io.dmem.req_type := MT_D; io.dmem.req_type := MT_D;
io.dmem.req_addr := req_addr; // io.dmem.req_addr := req_addr;
io.dmem.req_idx := req_addr(PGIDX_BITS-1,0);
io.dmem.req_ppn := req_addr(PADDR_BITS-1,PGIDX_BITS);
val resp_val = (state === s_done) || (state === s_l1_fake) || (state === s_l2_fake); val resp_val = (state === s_done) || (state === s_l1_fake) || (state === s_l2_fake);
val resp_err = (state === s_error); val resp_err = (state === s_error);