#include "config.h"
#include "sim.h"
#include "mmu.h"
-#include "htif.h"
#include "disasm.h"
-#include "gdbserver.h"
#include <cinttypes>
#include <cmath>
#include <cstdlib>
processor_t::processor_t(const char* isa, sim_t* sim, uint32_t id,
bool halt_on_reset)
- : debug(false), sim(sim), ext(NULL), disassembler(new disassembler_t),
- id(id), run(false), halt_on_reset(halt_on_reset)
+ : debug(false), halt_request(false), sim(sim), ext(NULL), id(id),
+ halt_on_reset(halt_on_reset)
{
parse_isa_string(isa);
+ register_base_instructions();
mmu = new mmu_t(sim, this);
+ disassembler = new disassembler_t(max_xlen);
- reset(true);
-
- register_base_instructions();
+ reset();
}
processor_t::~processor_t()
isa_string = "rv" + std::to_string(max_xlen) + p;
isa |= 1L << ('s' - 'a'); // advertise support for supervisor mode
+ isa |= 1L << ('u' - 'a'); // advertise support for user mode
while (*p) {
isa |= 1L << (*p - 'a');
// advertise support for supervisor and user modes
isa |= 1L << ('s' - 'a');
isa |= 1L << ('u' - 'a');
+
+ max_isa = isa;
}
void state_t::reset()
memset(this, 0, sizeof(*this));
prv = PRV_M;
pc = DEFAULT_RSTVEC;
- mtvec = DEFAULT_MTVEC;
load_reservation = -1;
+ tselect = 0;
+ for (unsigned int i = 0; i < num_triggers; i++)
+ mcontrol[i].type = 2;
}
void processor_t::set_debug(bool value)
#endif
}
-void processor_t::reset(bool value)
+void processor_t::reset()
{
- if (run == !value)
- return;
- run = !value;
-
state.reset();
state.dcsr.halt = halt_on_reset;
halt_on_reset = false;
ext->reset(); // reset the extension
}
-void processor_t::raise_interrupt(reg_t which)
-{
- throw trap_t(((reg_t)1 << (max_xlen-1)) | which);
-}
-
+// Count number of contiguous 0 bits starting from the LSB.
static int ctz(reg_t val)
{
int res = 0;
return res;
}
-void processor_t::take_interrupt()
+void processor_t::take_interrupt(reg_t pending_interrupts)
{
- reg_t pending_interrupts = state.mip & state.mie;
-
reg_t mie = get_field(state.mstatus, MSTATUS_MIE);
reg_t m_enabled = state.prv < PRV_M || (state.prv == PRV_M && mie);
reg_t enabled_interrupts = pending_interrupts & ~state.mideleg & -m_enabled;
reg_t sie = get_field(state.mstatus, MSTATUS_SIE);
reg_t s_enabled = state.prv < PRV_S || (state.prv == PRV_S && sie);
- enabled_interrupts |= pending_interrupts & state.mideleg & -s_enabled;
+ if (enabled_interrupts == 0)
+ enabled_interrupts = pending_interrupts & state.mideleg & -s_enabled;
if (enabled_interrupts)
- raise_interrupt(ctz(enabled_interrupts));
+ throw trap_t(((reg_t)1 << (max_xlen-1)) | ctz(enabled_interrupts));
}
-static bool validate_priv(reg_t priv)
+static int xlen_to_uxl(int xlen)
{
- return priv == PRV_U || priv == PRV_S || priv == PRV_M;
+ if (xlen == 32)
+ return 1;
+ if (xlen == 64)
+ return 2;
+ abort();
}
void processor_t::set_privilege(reg_t prv)
{
- assert(validate_priv(prv));
+ assert(prv <= PRV_M);
+ if (prv == PRV_H)
+ prv = PRV_U;
mmu->flush_tlb();
state.prv = prv;
}
void processor_t::enter_debug_mode(uint8_t cause)
{
- fprintf(stderr, "enter_debug_mode(%d), mstatus=0x%lx, prv=0x%lx\n", cause, state.mstatus, state.prv);
state.dcsr.cause = cause;
state.dcsr.prv = state.prv;
set_privilege(PRV_M);
state.dpc = state.pc;
- state.pc = DEBUG_ROM_START;
- //debug = true; // TODO
+ state.pc = DEBUG_ROM_ENTRY;
}
void processor_t::take_trap(trap_t& t, reg_t epc)
t.get_badaddr());
}
+ if (state.dcsr.cause) {
+ if (t.cause() == CAUSE_BREAKPOINT) {
+ state.pc = DEBUG_ROM_ENTRY;
+ } else {
+ state.pc = DEBUG_ROM_TVEC;
+ }
+ return;
+ }
+
if (t.cause() == CAUSE_BREAKPOINT && (
(state.prv == PRV_M && state.dcsr.ebreakm) ||
(state.prv == PRV_H && state.dcsr.ebreakh) ||
return;
}
- if (state.dcsr.cause) {
- state.pc = DEBUG_ROM_EXCEPTION;
- return;
- }
-
// by default, trap to M-mode, unless delegated to S-mode
reg_t bit = t.cause();
reg_t deleg = state.medeleg;
- if (bit & ((reg_t)1 << (max_xlen-1)))
+ bool interrupt = (bit & ((reg_t)1 << (max_xlen-1))) != 0;
+ if (interrupt)
deleg = state.mideleg, bit &= ~((reg_t)1 << (max_xlen-1));
if (state.prv <= PRV_S && bit < max_xlen && ((deleg >> bit) & 1)) {
// handle the trap in S-mode
state.sbadaddr = t.get_badaddr();
reg_t s = state.mstatus;
- s = set_field(s, MSTATUS_SPIE, get_field(s, MSTATUS_UIE << state.prv));
+ s = set_field(s, MSTATUS_SPIE, get_field(s, MSTATUS_SIE));
s = set_field(s, MSTATUS_SPP, state.prv);
s = set_field(s, MSTATUS_SIE, 0);
set_csr(CSR_MSTATUS, s);
set_privilege(PRV_S);
} else {
- state.pc = state.mtvec;
+ reg_t vector = (state.mtvec & 1) && interrupt ? 4*bit : 0;
+ state.pc = (state.mtvec & ~(reg_t)1) + vector;
state.mepc = epc;
state.mcause = t.cause();
if (t.has_badaddr())
state.mbadaddr = t.get_badaddr();
reg_t s = state.mstatus;
- s = set_field(s, MSTATUS_MPIE, get_field(s, MSTATUS_UIE << state.prv));
+ s = set_field(s, MSTATUS_MPIE, get_field(s, MSTATUS_MIE));
s = set_field(s, MSTATUS_MPP, state.prv);
s = set_field(s, MSTATUS_MIE, 0);
set_csr(CSR_MSTATUS, s);
void processor_t::disasm(insn_t insn)
{
+ static uint64_t last_pc = 1, last_bits;
+ static uint64_t executions = 1;
+
uint64_t bits = insn.bits() & ((1ULL << (8 * insn_length(insn.bits()))) - 1);
- fprintf(stderr, "core %3d: 0x%016" PRIx64 " (0x%08" PRIx64 ") %s\n",
- id, state.pc, bits, disassembler->disassemble(insn).c_str());
+ if (last_pc != state.pc || last_bits != bits) {
+ if (executions != 1) {
+ fprintf(stderr, "core %3d: Executed %" PRIx64 " times\n", id, executions);
+ }
+
+ fprintf(stderr, "core %3d: 0x%016" PRIx64 " (0x%08" PRIx64 ") %s\n",
+ id, state.pc, bits, disassembler->disassemble(insn).c_str());
+ last_pc = state.pc;
+ last_bits = bits;
+ executions = 1;
+ } else {
+ executions++;
+ }
}
-static bool validate_vm(int max_xlen, reg_t vm)
+int processor_t::paddr_bits()
{
- if (max_xlen == 64 && (vm == VM_SV39 || vm == VM_SV48))
- return true;
- if (max_xlen == 32 && vm == VM_SV32)
- return true;
- return vm == VM_MBARE;
+ assert(xlen == max_xlen);
+ return max_xlen == 64 ? 50 : 34;
}
void processor_t::set_csr(int which, reg_t val)
break;
case CSR_MSTATUS: {
if ((val ^ state.mstatus) &
- (MSTATUS_VM | MSTATUS_MPP | MSTATUS_MPRV | MSTATUS_PUM))
+ (MSTATUS_MPP | MSTATUS_MPRV | MSTATUS_SUM | MSTATUS_MXR))
mmu->flush_tlb();
reg_t mask = MSTATUS_SIE | MSTATUS_SPIE | MSTATUS_MIE | MSTATUS_MPIE
- | MSTATUS_SPP | MSTATUS_FS | MSTATUS_MPRV | MSTATUS_PUM
- | (ext ? MSTATUS_XS : 0);
-
- if (validate_vm(max_xlen, get_field(val, MSTATUS_VM)))
- mask |= MSTATUS_VM;
- if (validate_priv(get_field(val, MSTATUS_MPP)))
- mask |= MSTATUS_MPP;
+ | MSTATUS_SPP | MSTATUS_FS | MSTATUS_MPRV | MSTATUS_SUM
+ | MSTATUS_MPP | MSTATUS_MXR | MSTATUS_TW | MSTATUS_TVM
+ | MSTATUS_TSR | MSTATUS_UXL | MSTATUS_SXL |
+ (ext ? MSTATUS_XS : 0);
state.mstatus = (state.mstatus & ~mask) | (val & mask);
else
state.mstatus = set_field(state.mstatus, MSTATUS64_SD, dirty);
- // spike supports the notion of xlen < max_xlen, but current priv spec
- // doesn't provide a mechanism to run RV32 software on an RV64 machine
+ state.mstatus = set_field(state.mstatus, MSTATUS_UXL, xlen_to_uxl(max_xlen));
+ state.mstatus = set_field(state.mstatus, MSTATUS_SXL, xlen_to_uxl(max_xlen));
+ // U-XLEN == S-XLEN == M-XLEN
xlen = max_xlen;
break;
}
state.medeleg = (state.medeleg & ~mask) | (val & mask);
break;
}
- case CSR_MUCOUNTEREN:
- state.mucounteren = val & 7;
+ case CSR_MINSTRET:
+ case CSR_MCYCLE:
+ if (xlen == 32)
+ state.minstret = (state.minstret >> 32 << 32) | (val & 0xffffffffU);
+ else
+ state.minstret = val;
+ break;
+ case CSR_MINSTRETH:
+ case CSR_MCYCLEH:
+ state.minstret = (val << 32) | (state.minstret << 32 >> 32);
break;
- case CSR_MSCOUNTEREN:
- state.mscounteren = val & 7;
+ case CSR_SCOUNTEREN:
+ state.scounteren = val;
+ break;
+ case CSR_MCOUNTEREN:
+ state.mcounteren = val;
break;
case CSR_SSTATUS: {
reg_t mask = SSTATUS_SIE | SSTATUS_SPIE | SSTATUS_SPP | SSTATUS_FS
- | SSTATUS_XS | SSTATUS_PUM;
+ | SSTATUS_XS | SSTATUS_SUM | SSTATUS_MXR;
return set_csr(CSR_MSTATUS, (state.mstatus & ~mask) | (val & mask));
}
- case CSR_SIP:
- return set_csr(CSR_MIP,
- (state.mip & ~state.mideleg) | (val & state.mideleg));
+ case CSR_SIP: {
+ reg_t mask = MIP_SSIP & state.mideleg;
+ return set_csr(CSR_MIP, (state.mip & ~mask) | (val & mask));
+ }
case CSR_SIE:
return set_csr(CSR_MIE,
(state.mie & ~state.mideleg) | (val & state.mideleg));
+ case CSR_SPTBR: {
+ mmu->flush_tlb();
+ if (max_xlen == 32)
+ state.sptbr = val & (SPTBR32_PPN | SPTBR32_MODE);
+ if (max_xlen == 64 && (get_field(val, SPTBR64_MODE) == SPTBR_MODE_OFF ||
+ get_field(val, SPTBR64_MODE) == SPTBR_MODE_SV39 ||
+ get_field(val, SPTBR64_MODE) == SPTBR_MODE_SV48))
+ state.sptbr = val & (SPTBR64_PPN | SPTBR64_MODE);
+ break;
+ }
case CSR_SEPC: state.sepc = val; break;
case CSR_STVEC: state.stvec = val >> 2 << 2; break;
- case CSR_SPTBR: state.sptbr = val; break;
case CSR_SSCRATCH: state.sscratch = val; break;
case CSR_SCAUSE: state.scause = val; break;
case CSR_SBADADDR: state.sbadaddr = val; break;
case CSR_MEPC: state.mepc = val; break;
- case CSR_MTVEC: state.mtvec = val >> 2 << 2; break;
+ case CSR_MTVEC: state.mtvec = val & ~(reg_t)2; break;
case CSR_MSCRATCH: state.mscratch = val; break;
case CSR_MCAUSE: state.mcause = val; break;
case CSR_MBADADDR: state.mbadaddr = val; break;
+ case CSR_MISA: {
+ if (!(val & (1L << ('F' - 'A'))))
+ val &= ~(1L << ('D' - 'A'));
+
+ // allow MAFDC bits in MISA to be modified
+ reg_t mask = 0;
+ mask |= 1L << ('M' - 'A');
+ mask |= 1L << ('A' - 'A');
+ mask |= 1L << ('F' - 'A');
+ mask |= 1L << ('D' - 'A');
+ mask |= 1L << ('C' - 'A');
+ mask &= max_isa;
+
+ isa = (val & mask) | (isa & ~mask);
+ break;
+ }
+ case CSR_TSELECT:
+ if (val < state.num_triggers) {
+ state.tselect = val;
+ }
+ break;
+ case CSR_TDATA1:
+ {
+ mcontrol_t *mc = &state.mcontrol[state.tselect];
+ if (mc->dmode && !state.dcsr.cause) {
+ break;
+ }
+ mc->dmode = get_field(val, MCONTROL_DMODE(xlen));
+ mc->select = get_field(val, MCONTROL_SELECT);
+ mc->timing = get_field(val, MCONTROL_TIMING);
+ mc->action = (mcontrol_action_t) get_field(val, MCONTROL_ACTION);
+ mc->chain = get_field(val, MCONTROL_CHAIN);
+ mc->match = (mcontrol_match_t) get_field(val, MCONTROL_MATCH);
+ mc->m = get_field(val, MCONTROL_M);
+ mc->h = get_field(val, MCONTROL_H);
+ mc->s = get_field(val, MCONTROL_S);
+ mc->u = get_field(val, MCONTROL_U);
+ mc->execute = get_field(val, MCONTROL_EXECUTE);
+ mc->store = get_field(val, MCONTROL_STORE);
+ mc->load = get_field(val, MCONTROL_LOAD);
+ // Assume we're here because of csrw.
+ if (mc->execute)
+ mc->timing = 0;
+ trigger_updated();
+ }
+ break;
+ case CSR_TDATA2:
+ if (state.mcontrol[state.tselect].dmode && !state.dcsr.cause) {
+ break;
+ }
+ if (state.tselect < state.num_triggers) {
+ state.tdata2[state.tselect] = val;
+ }
+ break;
case CSR_DCSR:
state.dcsr.prv = get_field(val, DCSR_PRV);
state.dcsr.step = get_field(val, DCSR_STEP);
reg_t processor_t::get_csr(int which)
{
+ uint32_t ctr_en = -1;
+ if (state.prv < PRV_M)
+ ctr_en &= state.mcounteren;
+ if (state.prv < PRV_S)
+ ctr_en &= state.scounteren;
+ bool ctr_ok = (ctr_en >> (which & 31)) & 1;
+
+ if (ctr_ok) {
+ if (which >= CSR_HPMCOUNTER3 && which <= CSR_HPMCOUNTER31)
+ return 0;
+ if (xlen == 32 && which >= CSR_HPMCOUNTER3H && which <= CSR_HPMCOUNTER31H)
+ return 0;
+ }
+ if (which >= CSR_MHPMCOUNTER3 && which <= CSR_MHPMCOUNTER31)
+ return 0;
+ if (xlen == 32 && which >= CSR_MHPMCOUNTER3H && which <= CSR_MHPMCOUNTER31H)
+ return 0;
+ if (which >= CSR_MHPMEVENT3 && which <= CSR_MHPMEVENT31)
+ return 0;
+
switch (which)
{
case CSR_FFLAGS:
if (!supports_extension('F'))
break;
return (state.fflags << FSR_AEXC_SHIFT) | (state.frm << FSR_RD_SHIFT);
- case CSR_TIME:
case CSR_INSTRET:
case CSR_CYCLE:
- if ((state.mucounteren >> (which & (xlen-1))) & 1)
- return get_csr(which + (CSR_MCYCLE - CSR_CYCLE));
+ if (ctr_ok)
+ return state.minstret;
break;
- case CSR_STIME:
- case CSR_SINSTRET:
- case CSR_SCYCLE:
- if ((state.mscounteren >> (which & (xlen-1))) & 1)
- return get_csr(which + (CSR_MCYCLE - CSR_SCYCLE));
+ case CSR_MINSTRET:
+ case CSR_MCYCLE:
+ return state.minstret;
+ case CSR_MINSTRETH:
+ case CSR_MCYCLEH:
+ if (xlen == 32)
+ return state.minstret >> 32;
break;
- case CSR_MUCOUNTEREN: return state.mucounteren;
- case CSR_MSCOUNTEREN: return state.mscounteren;
- case CSR_MUCYCLE_DELTA: return 0;
- case CSR_MUTIME_DELTA: return 0;
- case CSR_MUINSTRET_DELTA: return 0;
- case CSR_MSCYCLE_DELTA: return 0;
- case CSR_MSTIME_DELTA: return 0;
- case CSR_MSINSTRET_DELTA: return 0;
- case CSR_MUCYCLE_DELTAH: if (xlen > 32) break; else return 0;
- case CSR_MUTIME_DELTAH: if (xlen > 32) break; else return 0;
- case CSR_MUINSTRET_DELTAH: if (xlen > 32) break; else return 0;
- case CSR_MSCYCLE_DELTAH: if (xlen > 32) break; else return 0;
- case CSR_MSTIME_DELTAH: if (xlen > 32) break; else return 0;
- case CSR_MSINSTRET_DELTAH: if (xlen > 32) break; else return 0;
- case CSR_MCYCLE: return state.minstret;
- case CSR_MINSTRET: return state.minstret;
- case CSR_MCYCLEH: if (xlen > 32) break; else return state.minstret >> 32;
- case CSR_MINSTRETH: if (xlen > 32) break; else return state.minstret >> 32;
+ case CSR_SCOUNTEREN: return state.scounteren;
+ case CSR_MCOUNTEREN: return state.mcounteren;
case CSR_SSTATUS: {
reg_t mask = SSTATUS_SIE | SSTATUS_SPIE | SSTATUS_SPP | SSTATUS_FS
- | SSTATUS_XS | SSTATUS_PUM;
+ | SSTATUS_XS | SSTATUS_SUM | SSTATUS_UXL;
reg_t sstatus = state.mstatus & mask;
if ((sstatus & SSTATUS_FS) == SSTATUS_FS ||
(sstatus & SSTATUS_XS) == SSTATUS_XS)
if (max_xlen > xlen)
return state.scause | ((state.scause >> (max_xlen-1)) << (xlen-1));
return state.scause;
- case CSR_SPTBR: return state.sptbr;
- case CSR_SASID: return 0;
+ case CSR_SPTBR:
+ if (get_field(state.mstatus, MSTATUS_TVM))
+ require_privilege(PRV_M);
+ return state.sptbr;
case CSR_SSCRATCH: return state.sscratch;
case CSR_MSTATUS: return state.mstatus;
case CSR_MIP: return state.mip;
case CSR_MTVEC: return state.mtvec;
case CSR_MEDELEG: return state.medeleg;
case CSR_MIDELEG: return state.mideleg;
+ case CSR_TSELECT: return state.tselect;
+ case CSR_TDATA1:
+ if (state.tselect < state.num_triggers) {
+ reg_t v = 0;
+ mcontrol_t *mc = &state.mcontrol[state.tselect];
+ v = set_field(v, MCONTROL_TYPE(xlen), mc->type);
+ v = set_field(v, MCONTROL_DMODE(xlen), mc->dmode);
+ v = set_field(v, MCONTROL_MASKMAX(xlen), mc->maskmax);
+ v = set_field(v, MCONTROL_SELECT, mc->select);
+ v = set_field(v, MCONTROL_TIMING, mc->timing);
+ v = set_field(v, MCONTROL_ACTION, mc->action);
+ v = set_field(v, MCONTROL_CHAIN, mc->chain);
+ v = set_field(v, MCONTROL_MATCH, mc->match);
+ v = set_field(v, MCONTROL_M, mc->m);
+ v = set_field(v, MCONTROL_H, mc->h);
+ v = set_field(v, MCONTROL_S, mc->s);
+ v = set_field(v, MCONTROL_U, mc->u);
+ v = set_field(v, MCONTROL_EXECUTE, mc->execute);
+ v = set_field(v, MCONTROL_STORE, mc->store);
+ v = set_field(v, MCONTROL_LOAD, mc->load);
+ return v;
+ } else {
+ return 0;
+ }
+ break;
+ case CSR_TDATA2:
+ if (state.tselect < state.num_triggers) {
+ return state.tdata2[state.tselect];
+ } else {
+ return 0;
+ }
+ break;
+ case CSR_TDATA3: return 0;
case CSR_DCSR:
{
uint32_t v = 0;
v = set_field(v, DCSR_XDEBUGVER, 1);
- v = set_field(v, DCSR_HWBPCOUNT, 0);
- v = set_field(v, DCSR_NDRESET, 0);
- v = set_field(v, DCSR_FULLRESET, 0);
- v = set_field(v, DCSR_PRV, state.dcsr.prv);
- v = set_field(v, DCSR_STEP, state.dcsr.step);
- v = set_field(v, DCSR_DEBUGINT, sim->debug_module.get_interrupt(id));
- v = set_field(v, DCSR_STOPCYCLE, 0);
- v = set_field(v, DCSR_STOPTIME, 0);
v = set_field(v, DCSR_EBREAKM, state.dcsr.ebreakm);
v = set_field(v, DCSR_EBREAKH, state.dcsr.ebreakh);
v = set_field(v, DCSR_EBREAKS, state.dcsr.ebreaks);
v = set_field(v, DCSR_EBREAKU, state.dcsr.ebreaku);
- v = set_field(v, DCSR_HALT, state.dcsr.halt);
+ v = set_field(v, DCSR_STOPCYCLE, 0);
+ v = set_field(v, DCSR_STOPTIME, 0);
v = set_field(v, DCSR_CAUSE, state.dcsr.cause);
+ v = set_field(v, DCSR_STEP, state.dcsr.step);
+ v = set_field(v, DCSR_PRV, state.dcsr.prv);
return v;
}
case CSR_DPC:
case CSR_DSCRATCH:
return state.dscratch;
}
- throw trap_illegal_instruction();
+ throw trap_illegal_instruction(0);
}
reg_t illegal_instruction(processor_t* p, insn_t insn, reg_t pc)
{
- throw trap_illegal_instruction();
+ throw trap_illegal_instruction(0);
}
insn_func_t processor_t::decode_insn(insn_t insn)
std::sort(instructions.begin(), instructions.end(), cmp());
for (size_t i = 0; i < OPCODE_CACHE_SIZE; i++)
- opcode_cache[i] = {1, 0, &illegal_instruction, &illegal_instruction};
+ opcode_cache[i] = {0, 0, &illegal_instruction, &illegal_instruction};
}
void processor_t::register_extension(extension_t* x)
bool processor_t::load(reg_t addr, size_t len, uint8_t* bytes)
{
+ switch (addr)
+ {
+ case 0:
+ if (len <= 4) {
+ memset(bytes, 0, len);
+ bytes[0] = get_field(state.mip, MIP_MSIP);
+ return true;
+ }
+ break;
+ }
+
return false;
}
switch (addr)
{
case 0:
- state.mip &= ~MIP_MSIP;
- if (bytes[0] & 1)
- state.mip |= MIP_MSIP;
- return true;
+ if (len <= 4) {
+ state.mip = set_field(state.mip, MIP_MSIP, bytes[0]);
+ return true;
+ }
+ break;
+ }
+
+ return false;
+}
+
+void processor_t::trigger_updated()
+{
+ mmu->flush_tlb();
+ mmu->check_triggers_fetch = false;
+ mmu->check_triggers_load = false;
+ mmu->check_triggers_store = false;
- default:
- return false;
+ for (unsigned i = 0; i < state.num_triggers; i++) {
+ if (state.mcontrol[i].execute) {
+ mmu->check_triggers_fetch = true;
+ }
+ if (state.mcontrol[i].load) {
+ mmu->check_triggers_load = true;
+ }
+ if (state.mcontrol[i].store) {
+ mmu->check_triggers_store = true;
+ }
}
}
projects / riscv-isa-sim.git / blobdiff