forked from go-delve/delve
-
Notifications
You must be signed in to change notification settings - Fork 0
/
threads.go
315 lines (281 loc) · 8.24 KB
/
threads.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
package proc
import (
"debug/gosym"
"encoding/binary"
"fmt"
"path/filepath"
sys "golang.org/x/sys/unix"
"github.com/derekparker/delve/dwarf/frame"
)
// Thread represents a single thread in the traced process
// Id represents the thread id or port, Process holds a reference to the
// Process struct that contains info on the process as
// a whole, and Status represents the last result of a `wait` call
// on this thread.
type Thread struct {
Id int // Thread ID or mach port
Status *sys.WaitStatus // Status returned from last wait call
CurrentBreakpoint *Breakpoint // Breakpoint thread is currently stopped at
dbp *Process
singleStepping bool
running bool
os *OSSpecificDetails
}
// Represents the location of a thread.
// Holds information on the current instruction
// address, the source file:line, and the function.
type Location struct {
PC uint64
File string
Line int
Fn *gosym.Func
}
// Continue the execution of this thread.
//
// If we are currently at a breakpoint, we'll clear it
// first and then resume execution. Thread will continue until
// it hits a breakpoint or is signaled.
func (thread *Thread) Continue() error {
pc, err := thread.PC()
if err != nil {
return err
}
// Check whether we are stopped at a breakpoint, and
// if so, single step over it before continuing.
if _, ok := thread.dbp.FindBreakpoint(pc); ok {
if err := thread.Step(); err != nil {
return err
}
}
return thread.resume()
}
// Step a single instruction.
//
// Executes exactly one instruction and then returns.
// If the thread is at a breakpoint, we first clear it,
// execute the instruction, and then replace the breakpoint.
// Otherwise we simply execute the next instruction.
func (thread *Thread) Step() (err error) {
thread.running = true
thread.singleStepping = true
defer func() {
thread.singleStepping = false
thread.running = false
}()
pc, err := thread.PC()
if err != nil {
return err
}
bp, ok := thread.dbp.FindBreakpoint(pc)
if ok {
// Clear the breakpoint so that we can continue execution.
_, err = bp.Clear(thread)
if err != nil {
return err
}
// Restore breakpoint now that we have passed it.
defer func() {
err = thread.dbp.writeSoftwareBreakpoint(thread, bp.Addr)
}()
}
err = thread.singleStep()
if err != nil {
return fmt.Errorf("step failed: %s", err.Error())
}
return nil
}
// Returns the threads location, including the file:line
// of the corresponding source code, the function we're in
// and the current instruction address.
func (thread *Thread) Location() (*Location, error) {
pc, err := thread.PC()
if err != nil {
return nil, err
}
f, l, fn := thread.dbp.PCToLine(pc)
return &Location{PC: pc, File: f, Line: l, Fn: fn}, nil
}
type ThreadBlockedError struct{}
func (tbe ThreadBlockedError) Error() string {
return ""
}
// Set breakpoints for potential next lines.
func (thread *Thread) setNextBreakpoints() (err error) {
if thread.blocked() {
return ThreadBlockedError{}
}
curpc, err := thread.PC()
if err != nil {
return err
}
// Grab info on our current stack frame. Used to determine
// whether we may be stepping outside of the current function.
fde, err := thread.dbp.frameEntries.FDEForPC(curpc)
if err != nil {
return err
}
// Get current file/line.
loc, err := thread.Location()
if err != nil {
return err
}
if filepath.Ext(loc.File) == ".go" {
err = thread.next(curpc, fde, loc.File, loc.Line)
} else {
err = thread.cnext(curpc, fde, loc.File)
}
return err
}
// Go routine is exiting.
type GoroutineExitingError struct {
goid int
}
func (ge GoroutineExitingError) Error() string {
return fmt.Sprintf("goroutine %d is exiting", ge.goid)
}
// Set breakpoints at every line, and the return address. Also look for
// a deferred function and set a breakpoint there too.
func (thread *Thread) next(curpc uint64, fde *frame.FrameDescriptionEntry, file string, line int) error {
pcs := thread.dbp.lineInfo.AllPCsBetween(fde.Begin(), fde.End(), file)
g, err := thread.GetG()
if err != nil {
return err
}
if g.DeferPC != 0 {
f, lineno, _ := thread.dbp.goSymTable.PCToLine(g.DeferPC)
for {
lineno++
dpc, _, err := thread.dbp.goSymTable.LineToPC(f, lineno)
if err == nil {
// We want to avoid setting an actual breakpoint on the
// entry point of the deferred function so instead create
// a fake breakpoint which will be cleaned up later.
thread.dbp.Breakpoints[g.DeferPC] = new(Breakpoint)
defer func() { delete(thread.dbp.Breakpoints, g.DeferPC) }()
if _, err = thread.dbp.SetTempBreakpoint(dpc); err != nil {
return err
}
break
}
}
}
ret, err := thread.ReturnAddress()
if err != nil {
return err
}
var covered bool
for i := range pcs {
if fde.Cover(pcs[i]) {
covered = true
break
}
}
if !covered {
fn := thread.dbp.goSymTable.PCToFunc(ret)
if fn != nil && fn.Name == "runtime.goexit" {
g, err := thread.GetG()
if err != nil {
return err
}
return GoroutineExitingError{goid: g.Id}
}
}
pcs = append(pcs, ret)
return thread.setNextTempBreakpoints(curpc, pcs)
}
// Set a breakpoint at every reachable location, as well as the return address. Without
// the benefit of an AST we can't be sure we're not at a branching statement and thus
// cannot accurately predict where we may end up.
func (thread *Thread) cnext(curpc uint64, fde *frame.FrameDescriptionEntry, file string) error {
pcs := thread.dbp.lineInfo.AllPCsBetween(fde.Begin(), fde.End(), file)
ret, err := thread.ReturnAddress()
if err != nil {
return err
}
pcs = append(pcs, ret)
return thread.setNextTempBreakpoints(curpc, pcs)
}
func (thread *Thread) setNextTempBreakpoints(curpc uint64, pcs []uint64) error {
for i := range pcs {
if pcs[i] == curpc || pcs[i] == curpc-1 {
continue
}
if _, err := thread.dbp.SetTempBreakpoint(pcs[i]); err != nil {
if _, ok := err.(BreakpointExistsError); !ok {
return err
}
}
}
return nil
}
// Sets the PC for this thread.
func (thread *Thread) SetPC(pc uint64) error {
regs, err := thread.Registers()
if err != nil {
return err
}
return regs.SetPC(thread, pc)
}
// Returns information on the G (goroutine) that is executing on this thread.
//
// The G structure for a thread is stored in thread local storage. Here we simply
// calculate the address and read and parse the G struct.
//
// We cannot simply use the allg linked list in order to find the M that represents
// the given OS thread and follow its G pointer because on Darwin mach ports are not
// universal, so our port for this thread would not map to the `id` attribute of the M
// structure. Also, when linked against libc, Go prefers the libc version of clone as
// opposed to the runtime version. This has the consequence of not setting M.id for
// any thread, regardless of OS.
//
// In order to get around all this craziness, we read the address of the G structure for
// the current thread from the thread local storage area.
func (thread *Thread) GetG() (g *G, err error) {
regs, err := thread.Registers()
if err != nil {
return nil, err
}
if thread.dbp.arch.GStructOffset() == 0 {
// GetG was called through SwitchThread / updateThreadList during initialization
// thread.dbp.arch isn't setup yet (it needs a CurrentThread to read global variables from)
return nil, fmt.Errorf("g struct offset not initialized")
}
gaddrbs, err := thread.readMemory(uintptr(regs.TLS()+thread.dbp.arch.GStructOffset()), thread.dbp.arch.PtrSize())
if err != nil {
return nil, err
}
gaddr := binary.LittleEndian.Uint64(gaddrbs)
g, err = parseG(thread, gaddr, false)
if err == nil {
g.thread = thread
}
return
}
// Returns whether the thread is stopped at
// the operating system level. Actual implementation
// is OS dependant, look in OS thread file.
func (thread *Thread) Stopped() bool {
return thread.stopped()
}
// Stops this thread from executing. Actual
// implementation is OS dependant. Look in OS
// thread file.
func (thread *Thread) Halt() (err error) {
defer func() {
if err == nil {
thread.running = false
}
}()
if thread.Stopped() {
return
}
err = thread.halt()
return
}
func (thread *Thread) Scope() (*EvalScope, error) {
locations, err := thread.Stacktrace(0)
if err != nil {
return nil, err
}
return locations[0].Scope(thread), nil
}