program: trace multi-threaded programs.
LGTM=r
R=r
https://golang.org/cl/86370043
diff --git a/program/client/client.go b/program/client/client.go
index bc585b1..57ce552 100644
--- a/program/client/client.go
+++ b/program/client/client.go
@@ -162,10 +162,8 @@
panic("unimplemented")
}
-func (p *Program) Run(start bool) (program.Status, error) {
- req := proxyrpc.RunRequest{
- Start: start,
- }
+func (p *Program) Run() (program.Status, error) {
+ req := proxyrpc.RunRequest{}
var resp proxyrpc.RunResponse
err := p.client.Call("Server.Run", &req, &resp)
if err != nil {
diff --git a/program/program.go b/program/program.go
index bc71091..2bed9dd 100644
--- a/program/program.go
+++ b/program/program.go
@@ -34,11 +34,9 @@
// and execs a new instance of the target binary file
// (which may have changed underfoot).
// Breakpoints and open files are re-established.
- // The flag specifies whether to run the program (true)
- // or stop it before it executes any instructions (false).
// The call hangs until the program stops executing,
// at which point it returns the program status.
- Run(start bool) (Status, error)
+ Run() (Status, error)
// Stop stops execution of the current process but
// does not kill it.
diff --git a/program/proxyrpc/proxyrpc.go b/program/proxyrpc/proxyrpc.go
index eeef340..e201f1f 100644
--- a/program/proxyrpc/proxyrpc.go
+++ b/program/proxyrpc/proxyrpc.go
@@ -52,7 +52,6 @@
}
type RunRequest struct {
- Start bool
}
type RunResponse struct {
diff --git a/program/server/ptrace.go b/program/server/ptrace.go
index 0072e7f..0f25e80 100644
--- a/program/server/ptrace.go
+++ b/program/server/ptrace.go
@@ -4,9 +4,6 @@
package server
-// TODO: syscall.PTRACE_O_TRACECLONE shenanigans to trace multi-threaded
-// programs.
-
import (
"fmt"
"os"
@@ -50,13 +47,6 @@
return <-s.ec
}
-func (s *Server) ptraceSetRegs(pid int, regs *syscall.PtraceRegs) (err error) {
- s.fc <- func() error {
- return syscall.PtraceSetRegs(pid, regs)
- }
- return <-s.ec
-}
-
func (s *Server) ptracePeek(pid int, addr uintptr, out []byte) (err error) {
s.fc <- func() error {
n, err := syscall.PtracePeekText(pid, addr, out)
@@ -85,6 +75,20 @@
return <-s.ec
}
+func (s *Server) ptraceSetOptions(pid int, options int) (err error) {
+ s.fc <- func() error {
+ return syscall.PtraceSetOptions(pid, options)
+ }
+ return <-s.ec
+}
+
+func (s *Server) ptraceSetRegs(pid int, regs *syscall.PtraceRegs) (err error) {
+ s.fc <- func() error {
+ return syscall.PtraceSetRegs(pid, regs)
+ }
+ return <-s.ec
+}
+
func (s *Server) ptraceSingleStep(pid int) (err error) {
s.fc <- func() error {
return syscall.PtraceSingleStep(pid)
@@ -92,12 +96,11 @@
return <-s.ec
}
-func (s *Server) wait() (err error) {
- var status syscall.WaitStatus
+func (s *Server) wait(pid int) (wpid int, status syscall.WaitStatus, err error) {
s.fc <- func() error {
- _, err1 := syscall.Wait4(-1, &status, 0, nil)
+ var err1 error
+ wpid, err1 = syscall.Wait4(pid, &status, syscall.WALL, nil)
return err1
}
- // TODO: do something with status.
- return <-s.ec
+ return wpid, status, <-s.ec
}
diff --git a/program/server/server.go b/program/server/server.go
index fb6a503..c9a425c 100644
--- a/program/server/server.go
+++ b/program/server/server.go
@@ -40,6 +40,9 @@
ec chan error
proc *os.Process
+ procIsUp bool
+ stoppedPid int
+ stoppedRegs syscall.PtraceRegs
breakpoints map[uint64]breakpoint
files []*file // Index == file descriptor.
}
@@ -183,6 +186,9 @@
if s.proc != nil {
s.proc.Kill()
s.proc = nil
+ s.procIsUp = false
+ s.stoppedPid = 0
+ s.stoppedRegs = syscall.PtraceRegs{}
}
p, err := s.startProcess(s.executable, nil, &os.ProcAttr{
Files: []*os.File{
@@ -191,17 +197,15 @@
os.Stderr,
},
Sys: &syscall.SysProcAttr{
- Ptrace: !req.Start,
+ Pdeathsig: syscall.SIGKILL,
+ Ptrace: true,
},
})
if err != nil {
return err
}
s.proc = p
-
- if !req.Start {
- // TODO: wait until /proc/{s.proc.Pid}/status says "State: t (tracing stop)".
- }
+ s.stoppedPid = p.Pid
return nil
}
@@ -209,29 +213,41 @@
s.mu.Lock()
defer s.mu.Unlock()
- regs := syscall.PtraceRegs{}
- err := s.ptraceGetRegs(s.proc.Pid, ®s)
- if err != nil {
- return err
+ if s.proc == nil {
+ return fmt.Errorf("Resume: Run did not successfully start a process")
}
- if _, ok := s.breakpoints[regs.Rip]; ok {
- err = s.ptraceSingleStep(s.proc.Pid)
+
+ if !s.procIsUp {
+ s.procIsUp = true
+ _, err := s.waitForTrap(s.stoppedPid)
+ if err != nil {
+ return err
+ }
+ err = s.ptraceSetOptions(s.stoppedPid, syscall.PTRACE_O_TRACECLONE)
+ if err != nil {
+ return fmt.Errorf("ptraceSetOptions: %v", err)
+ }
+ } else if _, ok := s.breakpoints[s.stoppedRegs.Rip]; ok {
+ err := s.ptraceSingleStep(s.stoppedPid)
if err != nil {
return fmt.Errorf("ptraceSingleStep: %v", err)
}
+ _, err = s.waitForTrap(s.stoppedPid)
+ if err != nil {
+ return err
+ }
}
- err = s.setBreakpoints()
+ err := s.setBreakpoints()
if err != nil {
return err
}
-
- err = s.ptraceCont(s.proc.Pid, 0)
+ err = s.ptraceCont(s.stoppedPid, 0)
if err != nil {
- return err
+ return fmt.Errorf("ptraceCont: %v", err)
}
- err = s.wait()
+ s.stoppedPid, err = s.waitForTrap(-1)
if err != nil {
return err
}
@@ -241,22 +257,39 @@
return err
}
- err = s.ptraceGetRegs(s.proc.Pid, ®s)
+ err = s.ptraceGetRegs(s.stoppedPid, &s.stoppedRegs)
if err != nil {
- return err
+ return fmt.Errorf("ptraceGetRegs: %v", err)
}
- regs.Rip -= uint64(s.arch.BreakpointSize)
- err = s.ptraceSetRegs(s.proc.Pid, ®s)
+ s.stoppedRegs.Rip -= uint64(s.arch.BreakpointSize)
+
+ err = s.ptraceSetRegs(s.stoppedPid, &s.stoppedRegs)
if err != nil {
return fmt.Errorf("ptraceSetRegs: %v", err)
}
- resp.Status.PC = regs.Rip
- resp.Status.SP = regs.Rsp
+ resp.Status.PC = s.stoppedRegs.Rip
+ resp.Status.SP = s.stoppedRegs.Rsp
return nil
}
+func (s *Server) waitForTrap(pid int) (wpid int, err error) {
+ for {
+ wpid, status, err := s.wait(pid)
+ if err != nil {
+ return 0, fmt.Errorf("wait: %v", err)
+ }
+ if status.StopSignal() == syscall.SIGTRAP && status.TrapCause() != syscall.PTRACE_EVENT_CLONE {
+ return wpid, nil
+ }
+ err = s.ptraceCont(wpid, 0) // TODO: non-zero when wait catches other signals?
+ if err != nil {
+ return 0, fmt.Errorf("ptraceCont: %v", err)
+ }
+ }
+}
+
func (s *Server) Breakpoint(req *proxyrpc.BreakpointRequest, resp *proxyrpc.BreakpointResponse) (err error) {
s.mu.Lock()
defer s.mu.Unlock()
@@ -275,7 +308,7 @@
return fmt.Errorf("breakpoint already set at %#x (TODO)", pc)
}
- err = s.ptracePeek(s.proc.Pid, uintptr(pc), bp.origInstr[:s.arch.BreakpointSize])
+ err = s.ptracePeek(s.stoppedPid, uintptr(pc), bp.origInstr[:s.arch.BreakpointSize])
if err != nil {
return fmt.Errorf("ptracePeek: %v", err)
}
@@ -288,7 +321,7 @@
func (s *Server) setBreakpoints() error {
for pc := range s.breakpoints {
- err := s.ptracePoke(s.proc.Pid, uintptr(pc), s.arch.BreakpointInstr[:s.arch.BreakpointSize])
+ err := s.ptracePoke(s.stoppedPid, uintptr(pc), s.arch.BreakpointInstr[:s.arch.BreakpointSize])
if err != nil {
return fmt.Errorf("setBreakpoints: %v", err)
}
@@ -298,7 +331,7 @@
func (s *Server) liftBreakpoints() error {
for pc, breakpoint := range s.breakpoints {
- err := s.ptracePoke(s.proc.Pid, uintptr(pc), breakpoint.origInstr[:s.arch.BreakpointSize])
+ err := s.ptracePoke(s.stoppedPid, uintptr(pc), breakpoint.origInstr[:s.arch.BreakpointSize])
if err != nil {
return fmt.Errorf("liftBreakpoints: %v", err)
}
@@ -381,7 +414,7 @@
// TODO: we're assuming we're at a function's entry point (LowPC).
regs := syscall.PtraceRegs{}
- err := s.ptraceGetRegs(s.proc.Pid, ®s)
+ err := s.ptraceGetRegs(s.stoppedPid, ®s)
if err != nil {
return err
}
@@ -432,7 +465,7 @@
if location == 0 {
return fmt.Errorf("no location for FormalParameter")
}
- err = s.ptracePeek(s.proc.Pid, location, buf[:s.arch.IntSize])
+ err = s.ptracePeek(s.stoppedPid, location, buf[:s.arch.IntSize])
if err != nil {
return err
}
