/
diff.go
168 lines (157 loc) · 4.57 KB
/
diff.go
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// Copyright 2019 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package main
import (
"debug/elf"
"errors"
"fmt"
"strings"
)
// diffWithSpike runs program under the VM and Spike, one instruction at a time,
// until they exit or their state differs. This mode is used for testing our
// riscv implementation. VM's initial state (e.g. memory) is set to Spike's
// state.
func diffWithSpike(prog string, argv, env []string, spikePath string) error {
f, err := elf.Open(prog)
if err != nil {
return errorf(nil, nil, "can't read the program: %v", err)
}
defer f.Close()
// Setup spike
spike, err := NewSpike(&Cmd{
SpikePath: spikePath,
Argv: append([]string{prog}, argv...),
Env: env,
Path: prog,
Start: f.Entry,
})
if err != nil {
return errorf(nil, spike, "can't create spike instance: %v", err)
}
const dbg = DebugRegs | DebugInstr
spike.Debug = dbg
defer spike.Close()
// Setup VM
sp, stack, err := spike.Stack()
if err != nil {
return errorf(nil, spike, "can't read stack from the Spike simulator: %v")
}
vm := NewVM(&Prog{
Argv: append([]string{prog}, argv...),
Env: env,
Start: f.Entry,
MemSize: sp + uint64(len(stack)),
})
vm.Debug = dbg
for _, s := range f.Sections {
if s.Flags&elf.SHF_ALLOC == 0 {
continue
}
if _, err := s.ReadAt(vm.Mem[s.Addr:s.Addr+s.Size], 0); err != nil {
return errorf(vm, spike, "Can't load section %s (addr %d): %v", s.Name, s.Addr, err)
}
}
vm.Reg[SP] = sp
copy(vm.Mem[sp:], stack)
// Execute until VM and spike produce different state.
for i := 0; i < *maxSteps; i++ {
serr := spike.Run(1)
vmerr := vm.Run(1)
if IsExit(serr) || IsExit(vmerr) {
if serr != vmerr {
return errorf(vm, spike, "VM and Spike didn't exit at the same time")
}
break
}
if serr != nil {
return errorf(vm, spike, "can't execute spike instruction: %v", err)
}
if vmerr != nil {
return errorf(vm, spike, "can't execute vm instruction: %v", err)
}
d := diffRegs(spike.Reg, vm.Reg)
if len(d) != 0 || spike.PC != vm.LastPC {
fmt.Println("\n================================================================================")
fmt.Printf(" FOUND DIFF AFTER %d STEPS:\n\n", i+1)
fmt.Println(spike)
fmt.Println(vm)
fmt.Println("Instruction:")
fmt.Printf("\tSpike: %s\n", spike.Instr)
fmt.Printf("\tVM : %s\n", vm.LastInstr)
fmt.Printf("\nRegisters diff:\n")
for _, j := range d {
fmt.Printf("\t%s %d(%#x):\n", RegNames[j], j, j)
fmt.Printf("\t\tSpike: %#x (%d)\n", spike.Reg[j], spike.Reg[j])
fmt.Printf("\t\tVM : %#x (%d)\n", vm.Reg[j], vm.Reg[j])
}
if spike.PC != vm.LastPC {
fmt.Printf("PC diff:\n\tspike: %#x\n\tvm: %#x\n", spike.PC, vm.LastPC)
}
return nil
}
}
fmt.Println("\n================================================================================")
fmt.Printf(" EXITTED AFTER %d STEPS:\n\n", vm.Steps)
fmt.Println(spike)
fmt.Println(vm)
fmt.Println("Instruction:")
fmt.Printf("\tSpike: %s\n", spike.Instr)
fmt.Printf("\tVM : %s\n", vm.LastInstr)
return nil
}
func diffRegs(a, b [32]uint64) []int {
var d []int
for r, v := range a {
if b[r] != v {
d = append(d, r)
}
}
return d
}
func printStack(start uint64, s []byte) {
if len(s)%8 != 0 {
panic(fmt.Sprintf("stack size must be a multiple of 8: got %d bytes", len(s)))
}
for sp := 7; sp < len(s); sp += 8 {
var buf strings.Builder
for i := 7; i >= 0; i-- {
if b := s[sp-i]; b >= 0x20 && b <= 0x7e {
fmt.Fprint(&buf, string(b))
} else {
fmt.Fprint(&buf, ".")
}
}
v := uint64(s[sp-7])<<0 |
uint64(s[sp-6])<<8 |
uint64(s[sp-5])<<16 |
uint64(s[sp-4])<<24 |
uint64(s[sp-3])<<32 |
uint64(s[sp-2])<<40 |
uint64(s[sp-1])<<48 |
uint64(s[sp-0])<<56
fmt.Printf("%#08x %#016x %s\n", uint64(sp)-7+start, v, buf.String())
}
}
func errorf(vm *VM, spike *Spike, format string, args ...interface{}) error {
b := new(strings.Builder)
if vm != nil {
fmt.Fprintln(b, vm)
}
if spike != nil {
fmt.Fprintln(b, spike)
}
fmt.Fprintf(b, format, args...)
fmt.Fprintln(b, "")
return errors.New(b.String())
}