The runtime calls into g0 in many places, not necessarily using
runtime.systemstack or runtime.asmcgocall.
One example of this is the call to runtime.newstack inside
runtime.morestack.
If we stop the process while one goroutine is executing
runtime.newstack we would be unable to fully scan its stack because we
don't know that we have to switch back to the goroutine stack after
runtime.newstack.
Instead of tracking down every possible way that the runtime switches
to g0 we switch to the goroutine stack immediately after the top of the
stack, unless cgo is being executed on the systemstack.
Fixes#1066
On macOS, externally linked programs will have an abbrev for
DW_TAG_subprogram without the haschildren flag set. We should handle
this case instead of expecting all DW_TAG_subprogram entries to have
list of children.
Fixes#1034
When creating a stack trace we should switch between the goroutine
stack and the system stack (where cgo code is executed) as appropriate
to reconstruct the logical stacktrace.
Goroutines that are currently executing on the system stack will have
the SystemStack flag set, frames of the goroutine stack will have a
negative FrameOffset (like always) and frames of the system stack will
have a positive FrameOffset (which is actually just the CFA value for
the frame).
Updates #935
Conditional breakpoints with unmet conditions would cause next and step
to skip the line.
This breakpoint changes the Kind field of proc.Breakpoint from a single
value to a bit field, each breakpoint object can represent
simultaneously a user breakpoint and one internal breakpoint (of which
we have several different kinds).
The breakpoint condition for internal breakpoints is stored in the new
internalCond field of proc.Breakpoint so that it will not conflict with
user specified conditions.
The breakpoint setting code is changed to allow overlapping one
internal breakpoint on a user breakpoint, or a user breakpoint on an
existing internal breakpoint. All other combinations are rejected. The
breakpoint clearing code is changed to clear the UserBreakpoint bit and
only remove the phisical breakpoint if no other bits are set in the
Kind field. ClearInternalBreakpoints does the same thing but clearing
all bits that aren't the UserBreakpoint bit.
Fixes#844
Move some duplicate code, related to breakpoints, that was in both
backends into a single place.
This is in preparation to solve issue #844 (conditional breakpoints
make step and next fail) which will make this common breakpoint code
more complicated.
Instead of only tracking a few cherrypicked registers in stack.go track
all DWARF registers.
This is needed for cgo code and for the locationlists emitted by go in
1.10:
* The debug_frame sections emitted by C compilers can not be used
without tracking all registers
* the loclists emitted by go1.10 need all registers of a frame to be
interpreted.
Make 'next' skip deferred functions unless they are called via a panic.
Call to a deferred function through 'return' are predictable, if the
user wants to step into them 'step' can be used but without this change
there is no way to avoid stepping into them.
Implements #956
On macOS we can also stop when we receive a signal,
propagate this reason upwards to the client.
Also clear internal breakpoints after an unrecovered-panic since they
can not be reached anymore.
Fixes#872
Before go1.9 embedded struct fields had name == "" in runtime and ==
type name in DWARF. After go1.9 both runtime and DWARF use a simplified
version of the type as name.
Embedded structs are distinguished from normal fields by setting a flag
in the runtime.structfield, for runtime, and by adding a custom
attribute in DWARF.
* Fix various issues detected by megacheck
I've ran honnef.co/go/tools/cmd/megacheck and fixed a few of the
things that came up there.
* Cleanup using Gogland
Implementing proc.Process.Running in a thread safe way is complicated
and nothing actually uses it besides tests, so we are better off
rewriting the tests without Running and removing it.
In particular:
* The call to d.target.Running() in service/debugger/debugger.go
(Restart) can never return true because that line executes while
holding processMutex and all continue operations are also executed
while holding processMutex.
* The call to dbp.Running() pkg/proc/native/proc.go (Detach) can never
return true, because it's only called from
debugger.(*Debugger).detach() which is also always called while
holding processMutex.
Since some tests are hard to write correctly without Process.Running a
simpler interface, Process.NotifyResumed, is introduced.
Fixes#830
Before this commit our temp breakpoints only checked that we would stay
on the same goroutine.
However this isn't enough for recursive functions we must check that we
stay on the same goroutine AND on the same stack frame (or, in the case
of the StepOut breakpoint, the previous stack frame).
This commit:
1. adds a new synthetic variable runtime.frameoff that returns the
offset of the current frame from the base of the call stack.
This is similar to runtime.curg
2. Changes the condition used for breakpoints on the lines of the
current function to check that runtime.frameoff hasn't changed.
3. Changes the condition used for breakpoints on the return address to
check that runtime.frameoff corresponds to the previous frame in the
stack.
4. All other temporary breakpoints (the step-into breakpoints and defer
breakpoints) remain unchanged.
Fixes#828
Debugserver does not work as documented, "--" needs to be specified to
pass arguments to the target process (but only if it's an argument that
starts with a dash).
Fixes#839
While implementing the gdbserial backend everything was changed to call
Detach to "close" a process so that gdbserial could do its clean up in
a single place. However the native implementation of Detach does not
actually kill processes we launched.
Fixes#821
- moved target.Interface into proc as proc.Process
- rename proc.IThread to proc.Thread
- replaced interfaces DisassembleInfo, Continuable and
EvalScopeConvertible with Process.
- removed superfluous Gdbserver prefix from types in the gdbserial
backend.
- removed superfluous Core prefix from types in the core backend.
* proc: Refactor stackIterator to use memoryReadWriter and BinaryInfo
* proc: refactor EvalScope to use memoryReadWriter and BinaryInfo
* proc: refactor Disassemble to use memoryReadWriter and BinaryInfo
* proc: refactor BinaryInfo part of proc.Process to own type
The data structures and associated code used by proc.Process
to implement target.BinaryInfo will also be useful to support a
backend for examining core dumps, split this part of proc.Process
to a different type.
* proc: compile support for all executable formats unconditionally
So far we only compiled in support for loading the executable format
supported by the host operating system.
Once support for core files is introduced it is however useful to
support loading in all executable formats, there is no reason why it
shouldn't be possible to examine a linux coredump on windows, or
viceversa.
* proc: bugfix: do not resume threads on detach if killing
* Replace BinaryInfo interface with BinInfo() method returning proc.BinaryInfo
Detach did not work for processes we attach to via PID.
Linux: we were only detaching from the main thread, all threads are
detached independently
Windows: we must resume all threads before detaching.
macOS: still broken.
Updates #772
Stack barriers were removed in Go 1.9, and thus code that
expected various stack-barrier-related symbols to exist
does not find them. Check for their absence and do not
crash when they are missing. Disable stack-barrier-handling
test for 1.9 and beyond.
Fixes#754.
The rest of the code uses Detach to "close" a proc.Process, the tests
should do the same.
Any cleanup that proc.Process needs to do can then be put inside Detach
and the tests will run it.
It was possible for TestStepParked to pick a runtime goroutine and
attempt to step it. Nothing guarantees that a goroutine other than the
ones we are using to run the code would actually ever resume before the
end of the program.
This makes the test more discerning in its choice of goroutines.
On Windows we can sometimes encounter threads stopped in locations for
which we do not have entries in debug_frame.
These cases seem to be due to calls to Windows API in the go runtime,
we can still produce a (partial) stack trace in this circumstance by
following frame pointers (starting with BP).
We still prefer debug_frame entries when available since go functions
do not have frame pointers before go1.8.
Sometimes windows will send us events about breakpoints we have
already removed from the code despite the fact that we go to great
lengths to avoid this already.
Change waitForDebugEvent to check that when we receive a breakpoint
event the corresponding memory actually contains an INT 3
instruction, if it doesn't ignore the event and restart the thread.
Changes to the GC in 1.8 make this test fail because the GC isn't
inserting stack barriers into our test program anymore. This isn't the
same thing as being unable to print stacktraces in presence of stack
barriers so the test shouldn't fail.
