d0d2d47885
This change adds `ProcessVmRead` and `ProcessVmWrite` wrappers around the syscalls `process_vm_readv` and `process_vm_writev`, available since Linux 3.2. These follow the same permission model as `ptrace`, but they don't actually require being attached, which means they can be called directly from any thread in the debugger. They also use `iovec` to write entire blocks at once, rather than having to peek/poke each `uintptr`. These wrappers are used in `Thread.ReadMemory` and `WriteMemory`, still falling back to `ptrace` if that fails for any reason. Notably, `process_vm_writev` respects memory protection, so it can't modify read-only memory like `ptrace`. This frequently occurs when writing breakpoints in read-only `.text`, so to avoid a lot of wasted `EFAULT` calls, we only try `process_vm_writev` for larger writes.
117 lines
2.6 KiB
Go
117 lines
2.6 KiB
Go
package native
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import (
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"fmt"
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sys "golang.org/x/sys/unix"
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"github.com/go-delve/delve/pkg/proc"
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)
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type WaitStatus sys.WaitStatus
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// OSSpecificDetails hold Linux specific
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// process details.
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type OSSpecificDetails struct {
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delayedSignal int
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registers sys.PtraceRegs
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running bool
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}
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func (t *Thread) stop() (err error) {
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err = sys.Tgkill(t.dbp.pid, t.ID, sys.SIGSTOP)
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if err != nil {
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err = fmt.Errorf("stop err %s on thread %d", err, t.ID)
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return
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}
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return
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}
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// Stopped returns whether the thread is stopped at
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// the operating system level.
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func (t *Thread) Stopped() bool {
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state := status(t.ID, t.dbp.os.comm)
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return state == StatusTraceStop || state == StatusTraceStopT
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}
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func (t *Thread) resume() error {
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sig := t.os.delayedSignal
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t.os.delayedSignal = 0
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return t.resumeWithSig(sig)
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}
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func (t *Thread) resumeWithSig(sig int) (err error) {
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t.os.running = true
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t.dbp.execPtraceFunc(func() { err = PtraceCont(t.ID, sig) })
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return
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}
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func (t *Thread) singleStep() (err error) {
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for {
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t.dbp.execPtraceFunc(func() { err = sys.PtraceSingleStep(t.ID) })
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if err != nil {
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return err
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}
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wpid, status, err := t.dbp.waitFast(t.ID)
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if err != nil {
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return err
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}
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if (status == nil || status.Exited()) && wpid == t.dbp.pid {
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t.dbp.postExit()
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rs := 0
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if status != nil {
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rs = status.ExitStatus()
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}
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return proc.ErrProcessExited{Pid: t.dbp.pid, Status: rs}
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}
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if wpid == t.ID && status.StopSignal() == sys.SIGTRAP {
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return nil
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}
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}
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}
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func (t *Thread) Blocked() bool {
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regs, err := t.Registers(false)
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if err != nil {
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return false
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}
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pc := regs.PC()
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fn := t.BinInfo().PCToFunc(pc)
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if fn != nil && ((fn.Name == "runtime.futex") || (fn.Name == "runtime.usleep") || (fn.Name == "runtime.clone")) {
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return true
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}
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return false
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}
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func (t *Thread) WriteMemory(addr uintptr, data []byte) (written int, err error) {
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if t.dbp.exited {
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return 0, proc.ErrProcessExited{Pid: t.dbp.pid}
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}
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if len(data) == 0 {
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return
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}
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// ProcessVmWrite can't poke read-only memory like ptrace, so don't
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// even bother for small writes -- likely breakpoints and such.
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if len(data) > sys.SizeofPtr {
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written, _ = ProcessVmWrite(t.ID, addr, data)
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}
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if written == 0 {
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t.dbp.execPtraceFunc(func() { written, err = sys.PtracePokeData(t.ID, addr, data) })
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}
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return
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}
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func (t *Thread) ReadMemory(data []byte, addr uintptr) (n int, err error) {
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if t.dbp.exited {
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return 0, proc.ErrProcessExited{Pid: t.dbp.pid}
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}
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if len(data) == 0 {
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return
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}
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n, _ = ProcessVmRead(t.ID, addr, data)
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if n == 0 {
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t.dbp.execPtraceFunc(func() { n, err = sys.PtracePeekData(t.ID, addr, data) })
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}
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return
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}
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