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fix(debug): hardware watchpoints, signal stops and breakpoint restore

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Assisted-by: GLM 5.3
This commit is contained in:
petrbalvin
2026-09-19 23:49:19 +02:00
parent 375182ef1f
commit a8bfd54ed2
26 changed files with 1408 additions and 535 deletions
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debug/repl.go
+74 -18
View File
@@ -7,9 +7,10 @@ package debug
import (
"bufio"
"cmp"
"fmt"
"io"
"sort"
"slices"
"strconv"
"strings"
)
@@ -93,7 +94,7 @@ func REPL(s *Session, bm *Breakpoints, codeBase uint64, funcOffset, funcSize, ar
regs, _ := s.GetRegs()
pc := regs.GetPC()
text, instLen, _ := s.Disassemble(pc)
if strings.HasPrefix(strings.ToLower(text), "call") || strings.HasPrefix(strings.ToLower(text), "bl") {
if isCallInsn(text) {
afterAddr := pc + uint64(instLen)
_, err := bm.Set(afterAddr, "(next)")
if err != nil {
@@ -108,6 +109,21 @@ func REPL(s *Session, bm *Breakpoints, codeBase uint64, funcOffset, funcSize, ar
bm.Clear(afterAddr)
continue
}
if s.Exited() {
bm.Clear(afterAddr)
fmt.Println("debuggee exited")
continue
}
if sig := s.LastSignal(); sig != 0 {
bm.Clear(afterAddr)
regs, _ := s.GetRegs()
fmt.Printf("stopped on signal %v at %#x\n", sig, regs.GetPC())
continue
}
// Fetch the registers after the stop: the trap must be
// evaluated against the real PC, not the pre-Continue
// snapshot, and a stale SetRegs would clobber live state.
regs, _ = s.GetRegs()
bm.HandleTrap(&regs)
bm.Clear(afterAddr)
} else {
@@ -143,9 +159,21 @@ func REPL(s *Session, bm *Breakpoints, codeBase uint64, funcOffset, funcSize, ar
bm.Clear(retAddr)
continue
}
if !s.Exited() {
bm.HandleTrap(&regs)
if s.Exited() {
bm.Clear(retAddr)
fmt.Println("debuggee exited")
continue
}
if sig := s.LastSignal(); sig != 0 {
bm.Clear(retAddr)
regs, _ := s.GetRegs()
fmt.Printf("stopped on signal %v at %#x\n", sig, regs.GetPC())
continue
}
// Fetch the registers after the stop, as the continue case
// does: HandleTrap must see the PC the trap left behind.
regs, _ = s.GetRegs()
bm.HandleTrap(&regs)
bm.Clear(retAddr)
if s.Exited() {
fmt.Println("debuggee exited")
@@ -171,6 +199,15 @@ func REPL(s *Session, bm *Breakpoints, codeBase uint64, funcOffset, funcSize, ar
fmt.Println("debuggee exited")
break
}
if sig := s.LastSignal(); sig != 0 {
// A genuine signal-delivery-stop (a fault): report it
// and return to the prompt. Continuing would restart
// the faulting instruction and fault forever.
regs, _ := s.GetRegs()
fmt.Printf("stopped on signal %v at %#x (func+%#x)\n",
sig, regs.GetPC(), regs.GetPC()-codeBase-uint64(funcOffset))
break
}
reason, wpAddr := s.StopInfo()
if reason == StopWatchpoint {
fmt.Printf("watchpoint hit at %#x\n", wpAddr)
@@ -221,13 +258,27 @@ func REPL(s *Session, bm *Breakpoints, codeBase uint64, funcOffset, funcSize, ar
reg := strings.ToLower(parts[3])
op := parts[4]
operand := parts[5]
if val, err := strconv.ParseUint(operand, 0, 64); err == nil {
cond = &Condition{Reg: reg, Op: op, Value: val}
} else {
cond = &Condition{Reg: reg, Op: op, Reg2: strings.ToLower(operand)}
switch {
case strings.HasPrefix(operand, "*"):
// Memory operand: compare against the 8-byte word at
// the address, resolved in the debuggee when the
// breakpoint is evaluated.
addr, err := strconv.ParseUint(strings.TrimPrefix(operand, "*"), 0, 64)
if err != nil {
fmt.Printf("invalid memory operand: %s\n", operand)
continue
}
cond = &Condition{Reg: reg, Op: op, MemAddr: addr}
default:
val, err := strconv.ParseUint(operand, 0, 64)
if err == nil {
cond = &Condition{Reg: reg, Op: op, Value: val}
} else {
cond = &Condition{Reg: reg, Op: op, Reg2: strings.ToLower(operand)}
}
}
} else if len(parts) >= 4 && parts[2] == "if" {
fmt.Println("usage: break <label|addr> if <reg> <op> <value|reg>")
fmt.Println("usage: break <label|addr> if <reg> <op> <value|reg|*addr>")
continue
}
bp, err := bm.SetWithCond(addr, label, cond)
@@ -237,7 +288,7 @@ func REPL(s *Session, bm *Breakpoints, codeBase uint64, funcOffset, funcSize, ar
}
condStr := ""
if cond != nil {
condStr = fmt.Sprintf(" if %s %s %#x", cond.Reg, cond.Op, cond.Value)
condStr = " if " + cond.String()
}
fmt.Printf("breakpoint set: %s at %#x (func+%#x)%s\n", bp.Label, bp.Addr, bp.Addr-codeBase-uint64(funcOffset), condStr)
@@ -277,7 +328,11 @@ func REPL(s *Session, bm *Breakpoints, codeBase uint64, funcOffset, funcSize, ar
addr, _ = resolveAddr(parts[1], codeBase, uint64(funcOffset), labels)
}
if len(parts) > 2 {
length, _ = strconv.Atoi(parts[2])
// A malformed or non-positive length would panic
// ReadMemory's make; fall back to the default instead.
if n, err := strconv.Atoi(parts[2]); err == nil && n > 0 {
length = n
}
}
mem, err := s.ReadMemory(addr, length)
if err != nil {
@@ -336,10 +391,8 @@ func REPL(s *Session, bm *Breakpoints, codeBase uint64, funcOffset, funcSize, ar
}
case "labels", "l":
sorted := make([]Label, len(labels))
copy(sorted, labels)
sort.Slice(sorted, func(i, j int) bool { return sorted[i].Offset < sorted[j].Offset })
for _, l := range sorted {
slices.SortFunc(labels, func(a, b Label) int { return cmp.Compare(a.Offset, b.Offset) })
for _, l := range labels {
fmt.Printf(" func+%#04x %s\n", l.Offset, l.Name)
}
@@ -369,7 +422,10 @@ func REPL(s *Session, bm *Breakpoints, codeBase uint64, funcOffset, funcSize, ar
fmt.Println()
case "help", "h", "?":
fmt.Printf(` break <label|addr> [if <reg> <op> <val>] set a breakpoint
fmt.Printf(` break <label|addr> [if <reg> <op> <val|reg|*addr>]
set a breakpoint, optionally conditional on a
register compared to a constant, a register, or the
8-byte word at *addr
delete <label|addr> remove a breakpoint
info break list all breakpoints
watch <addr> [r|w] [size] set a hardware watchpoint (write by default)
@@ -463,8 +519,8 @@ func REPL(s *Session, bm *Breakpoints, codeBase uint64, funcOffset, funcSize, ar
case "unwatch":
if len(parts) >= 2 {
slot, err := strconv.Atoi(parts[1])
if err != nil || slot < 0 || slot > 3 {
fmt.Println("usage: unwatch [<slot>]")
if err != nil || slot < 0 || slot >= maxWatchpoints() {
fmt.Printf("usage: unwatch [<slot 0-%d>]\n", maxWatchpoints()-1)
continue
}
if err := s.ClearWatchpoint(slot); err != nil {