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Refactor: Use thread-locked goroutine for ptrace ops

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Previously either the terminal client or the debugger service would
either lock main goroutine to a thread or provide a locked goroutine to
run _all_ DebuggedProcess functions in. This is unnecessary because only
ptrace functions need to be run from the same thread that originated the
PT_ATTACH request.

Here we use a specific thread-locked goroutine to service any ptrace
request. That goroutine is also responsible for the initial spawning /
attaching of the process, since it must be responsible for the PT_ATTACH
request.
This commit is contained in:
Derek Parker
2015-06-12 23:47:30 -05:00
parent fe23036035
commit e4fc5e32c2
15 changed files with 391 additions and 459 deletions
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19
proc/breakpoints_linux_amd64.go
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@ -21,7 +21,7 @@ import "fmt"
// debug register `reg` with the address of the instruction
// that we want to break at. There are only 4 debug registers
// DR0-DR3. Debug register 7 is the control register.
func setHardwareBreakpoint(reg, tid int, addr uint64) error {
func (dbp *DebuggedProcess) setHardwareBreakpoint(reg, tid int, addr uint64) error {
if reg < 0 || reg > 3 {
return fmt.Errorf("invalid debug register value")
}
@ -32,10 +32,12 @@ func setHardwareBreakpoint(reg, tid int, addr uint64) error {
drxmask = uintptr((((1 << C.DR_CONTROL_SIZE) - 1) << uintptr(reg*C.DR_CONTROL_SIZE)) | (((1 << C.DR_ENABLE_SIZE) - 1) << uintptr(reg*C.DR_ENABLE_SIZE)))
drxenable = uintptr(0x1) << uintptr(reg*C.DR_ENABLE_SIZE)
drxctl = uintptr(C.DR_RW_EXECUTE|C.DR_LEN_1) << uintptr(reg*C.DR_CONTROL_SIZE)
dr7 uintptr
)
// Get current state
dr7, err := PtracePeekUser(tid, dr7off)
var err error
dbp.execPtraceFunc(func() { dr7, err = PtracePeekUser(tid, dr7off) })
if err != nil {
return err
}
@ -43,12 +45,14 @@ func setHardwareBreakpoint(reg, tid int, addr uint64) error {
// If addr == 0 we are expected to disable the breakpoint
if addr == 0 {
dr7 &= ^drxmask
return PtracePokeUser(tid, dr7off, dr7)
dbp.execPtraceFunc(func() { err = PtracePokeUser(tid, dr7off, dr7) })
return err
}
// Set the debug register `reg` with the address of the
// instruction we want to trigger a debug exception.
if err := PtracePokeUser(tid, drxoff, uintptr(addr)); err != nil {
dbp.execPtraceFunc(func() { err = PtracePokeUser(tid, drxoff, uintptr(addr)) })
if err != nil {
return err
}
@ -61,12 +65,13 @@ func setHardwareBreakpoint(reg, tid int, addr uint64) error {
// instructs the cpu to raise a debug
// exception when hitting the address of
// an instruction stored in dr0-dr3.
return PtracePokeUser(tid, dr7off, dr7)
dbp.execPtraceFunc(func() { err = PtracePokeUser(tid, dr7off, dr7) })
return err
}
// Clears a hardware breakpoint. Essentially sets
// the debug reg to 0 and clears the control register
// flags for that reg.
func clearHardwareBreakpoint(reg, tid int) error {
return setHardwareBreakpoint(reg, tid, 0)
func (dbp *DebuggedProcess) clearHardwareBreakpoint(reg, tid int) error {
return dbp.setHardwareBreakpoint(reg, tid, 0)
}