Internal breakpoints do not need IDs and assigning them from a counter
separate from the user ID counter can be a cause of confusion.
If a user breakpoint is overlayed on top of a pre-existing internal
breakpoint the temporary ID will be surfaced as if it was a user ID,
possibly conflicting with another user ID.
If a temporary breakpoint is overlayed on top of a pre-existing user
breakpoint and the user breakpoint is first deleted and then
re-created, the user ID will be resurrected along with the breakpoint,
instead of allocating a fresh one.
This change removes internal breakpoint IDs entirely, only user
breakpoints receive an ID.
This patch enables the eBPF tracer backend to parse the ID of the
Goroutine which hit the uprobe. This implementation is specific to AMD64
and will have to be generalized further in order to be used on other
architectures.
Adds a script that check automatically that the the assumptions that
pkg/proc makes about runtime are met by the actual runtime, using a
combination of parsing and magic comments.
Also emits a file describing all the struct fields, constants and
variables of the runtime that we use in pkg/proc.
In order for DAP to support halting the program (either manually or on a breakpoint) performing some action and then resuming execution, there needs to be a way to stop the program without clearing the internal breakpoints. This is necessary for log points and stopping the program to set breakpoints.
The debugging UI makes it seem like a user should be able to set or clear a breakpoint at any time. Adding this ability to complete synchronous requests while the program is running is thus important to create a seamless user experience.
This change just adds a configuration to determine whether the target should clear the stepping breakpoints, and changes the server to use this new mode. Using the new mode means that the DAP server must determine when it expect the next to be canceled and do this manually.
* proc: move breakpoint condition evaluation out of backends
Moves breakpoint condition evaluation from the point where breakpoints
are set, inside ContinueOnce, to (*Target).Continue.
This accomplishes three things:
1. the breakpoint evaluation method needs not be exported anymore
2. breakpoint condition evaluation can be done with a full scope,
containing a Target object, something that wasn't possible before
because ContinueOnce doesn't have access to the Target object.
3. moves breakpoint condition evaluation out of the critical section
where some of the threads of the target process might be still
running.
* proc/native: handle process death during stop() on Windows
It is possible that the thread dies while we are inside the stop()
function. This results in an Access is denied error being returned by
SuspendThread being called on threads that no longer exist.
Delay the reporting the error from SuspendThread until the end of
stop() and only report it if the thread still exists at that point.
Fixes flakyness with TestIssue1101 that was exacerbated by moving
breakpoint condition evaluation outside of the backends.
* pkg/proc: Prefer throw instead of fatalthrow
Currently there is a breakpoint set at runtime.fatalthrow to catch any
situation where the runtime crashes (e.g. deadlock).
When we do this, we go up a frame in order to parse the crash reason.
The problem is that there is no guarentee the "s" variable we attempt to
parse will still be considered "live".
Since runtime.fatalthrow is never called directly, set a breakpoint on
runtime.throw instead and prevent having
to search up a stack frame in order to
get the throw reason.
Fixes#2602
* service/dap: Fix TestFatalThrowBreakpoint
* Reenable TestFatalThrow DAP test
* service/dap: Don't skip test on < 1.17
* service/dap: Update test constraint for 1.16
* pkg/proc: Reinstate runtime.fatalthrow as switchstack exception
* proc: support new Go 1.17 panic/defer mechanism
Go 1.17 will create wrappers for deferred calls that take arguments.
Change defer reading code so that wrappers are automatically unwrapped.
Also the deferred function is called directly by runtime.gopanic, without going through runtime.callN which means that sometimes when a panic happens the stack is either:
0. deferred function call
1. deferred call wrapper
2. runtime.gopanic
or:
0. deferred function call
1. runtime.gopanic
instead of always being:
0. deferred function call
1. runtime.callN
2. runtime.gopanic
the isPanicCall check is changed accordingly.
* test: miscellaneous minor test fixes for Go 1.17
* proc: resolve inlined calls when stepping out of runtime.breakpoint
Calls to runtime.Breakpoint are inlined in Go 1.17 when inlining is
enabled, resolve inlined calls in stepInstructionOut.
* proc: add support for debugCallV2 with regabi
This change adds support for the new debug call protocol which had to
change for the new register ABI introduced in Go 1.17.
Summary of changes:
- Abstracts over the debug call version depending on the Go version
found in the binary.
- Uses R12 instead of RAX as the debug protocol register when the binary
is from Go 1.17 or later.
- Creates a variable directly from the DWARF entry for function
arguments to support passing arguments however the ABI expects.
- Computes a very conservative stack frame size for the call when
injecting a call into a Go process whose version is >=1.17.
Co-authored-by: Michael Anthony Knyszek <mknyszek@google.com>
Co-authored-by: Alessandro Arzilli <alessandro.arzilli@gmail.com>
* TeamCity: enable tests on go-tip
* goversion: version compatibility bump
* TeamCity: fix go-tip builds on macOS/arm64
Co-authored-by: Michael Anthony Knyszek <mknyszek@google.com>
We told clients that further loading of variables can be done by
specifying a type cast using the address of a variable that we
returned.
This does not work for registerized variables (or, in general,
variables that have a complex location expression) because we don't
give them unique addresses and we throw away the compositeMemory object
we made to read them.
This commit changes proc so that:
1. variables with location expression divided in pieces do get a unique
memory address
2. the compositeMemory object is saved somewhere
3. when an integer is cast back into a pointer type we look through our
saved compositeMemory objects to see if there is one that covers the
specified address and use it.
The unique memory addresses we generate have the MSB set to 1, as
specified by the Intel 86x64 manual addresses in this form are reserved
for kernel memory (which we can not read anyway) so we are guaranteed
to never generate a fake memory address that overlaps a real memory
address of the application.
The unfortunate side effect of this is that it will break clients that
do not deserialize the address to a 64bit integer. This practice is
contrary to how we defined our types and contrary to the specification
of the JSON format, as of json.org, however it is also fairly common,
due to javascript itself having only 53bit integers.
We could come up with a new mechanism but then even more old clients
would have to be changed.
Ensure that any command executed after the process we are trying to
debug prints a correct and consistent exit status.
Previously the exit code was being lost after the first time we printed
that a process has exited. Additionally, certain commands would print
the PID of the process and other would not. This change makes everything
more correct and consistent.
Adds the low-level support for watchpoints (aka data breakpoints) to
the native linux/amd64 backend.
Does not add user interface or functioning support for watchpoints
on stack variables.
Updates #279
When restarting we must take care of setting breakpoint IDs correctly
so that enabled breakpoints do not end up having the same ID as a
disabled breakpoint, also we must make sure that breakpoints created
after restart will not get an ID already used by a disabled breakpoint.
* Adds toggle command
Also adds two rpc2 tests for testing the new functionality
* Removes Debuggers' ToggleBreakpoint method
rpc2's ToggleBreakpoint now calls AmendBreakpoint
Refactors the ClearBreakpoint to avoid a lock.
This adds a workaround for the bug described at:
https://github.com/golang/go/issues/25841
Because dsymutil running on PIE does not adjust the address of
debug_frame entries (but adjusts debug_info entries) we try to do the
adjustment ourselves.
Updates #2346
When cgo is used the address of the g struct is saved on the special
register TPIDR_EL0. Because executing C code could overwrite the
contents of R28 that normally contains the address of g we should read
it from TPIDR_EL0 instead when runtime.iscgo is set.
* proc/core: off-by-one error reading ELF core files
core.(*splicedMemory).ReadMemory checked the entry interval
erroneously when dealing with contiguous entries.
* terminal,service,proc/*: adds dump command (gcore equivalent)
Adds the `dump` command that creates a core file from the target process.
Backends will need to implement a new, optional, method `MemoryMap` that
returns a list of mapped memory regions.
Additionally the method `DumpProcessNotes` can be implemented to write out
to the core file notes describing the target process and its threads. If
DumpProcessNotes is not implemented `proc.Dump` will write a description of
the process and its threads in a OS/arch-independent format (that only Delve
understands).
Currently only linux/amd64 implements `DumpProcessNotes`.
Core files are only written in ELF, there is no minidump or macho-o writers.
# Conflicts:
# pkg/proc/proc_test.go
On linux we can not read memory if the thread we use to do it is
occupied doing certain system calls. The exact conditions when this
happens have never been clear.
This problem was worked around by using the Blocked method which
recognized the most common circumstances where this would happen.
However this is a hack: Blocked returning true doesn't mean that the
problem will manifest and Blocked returning false doesn't necessarily
mean the problem will not manifest. A side effect of this is issue
#2151 where sometimes we can't read the memory of a thread and find its
associated goroutine.
This commit fixes this problem by always reading memory using a thread
we know to be good for this, specifically the one returned by
ContinueOnce. In particular the changes are as follows:
1. Remove (ProcessInternal).CurrentThread and
(ProcessInternal).SetCurrentThread, the "current thread" becomes a
field of Target, CurrentThread becomes a (*Target) method and
(*Target).SwitchThread basically just sets a field Target.
2. The backends keep track of their own internal idea of what the
current thread is, to use it to read memory, this is the thread they
return from ContinueOnce as trapthread
3. The current thread in the backend and the current thread in Target
only ever get synchronized in two places: when the backend creates a
Target object the currentThread field of Target is initialized with the
backend's current thread and when (*Target).Restart gets called (when a
recording is rewound the currentThread used by Target might not exist
anymore).
4. We remove the MemoryReadWriter interface embedded in Thread and
instead add a Memory method to Process that returns a MemoryReadWriter.
The backends will return something here that will read memory using
the current thread saved by the backend.
5. The Thread.Blocked method is removed
One possible problem with this change is processes that have threads
with different memory maps. As far as I can determine this could happen
on old versions of linux but this option was removed in linux 2.5.
Fixes#2151
* proc,proc/*: move SelectedGoroutine to proc.Target, remove PostInitializationSetup
moves SelectedGoroutine, SwitchThread and SwitchGoroutine to
proc.Target, merges PostInitializationSetup with NewTarget.
* proc,proc/*: add StopReason field to Target
Adds a StopReason field to the Target object describing why the target
process is currently stopped. This will be useful for the DAP server
(which needs to report this reason in one of its requests) as well as
making pull request #1785 (reverse step) conformant to the new
architecture.
* proc: collect NewTarget arguments into a struct
* tests: misc test fixes for go1.14
- math.go is now ambiguous due to changes to the go runtime so specify
that we mean our own math.go in _fixtures
- go list -m requires vendor-mode to be disabled so pass '-mod=' to it
in case user has GOFLAGS=-mod=vendor
- update version of go/packages, required to work with go 1.14 (and
executed go mod vendor)
- Increased goroutine migration in one development version of Go 1.14
revealed a problem with TestCheckpoints in command_test.go and
rr_test.go. The tests were always wrong because Restart(checkpoint)
doesn't change the current thread but we can't assume that when the
checkpoint was taken the current goroutine was running on the same
thread.
* goversion: update maximum supported version
* Makefile: disable testing lldb-server backend on linux with Go 1.14
There seems to be some incompatibility with lldb-server version 6.0.0
on linux and Go 1.14.
* proc/gdbserial: better handling of signals
- if multiple signals are received simultaneously propagate all of them to the
target threads instead of only one.
- debugserver will drop an interrupt request if a target thread simultaneously
receives a signal, handle this situation.
* dwarf/line: normalize backslashes for windows executables
Starting with Go 1.14 the compiler sometimes emits backslashes as well
as forward slashes in debug_line, normalize everything to / for
conformity with the behavior of previous versions.
* proc/native: partial support for Windows async preempt mechanism
See https://github.com/golang/go/issues/36494 for a description of why
full support for 1.14 under windows is problematic.
* proc/native: disable Go 1.14 async preemption on Windows
See https://github.com/golang/go/issues/36494
* pkg/proc: Introduce Target
* pkg/proc: Remove Common.fncallEnabled
Realistically we only block it on recorded backends.
* pkg/proc: Move fncallForG to Target
* pkg/proc: Remove CommonProcess
Remove final bit of functionality stored in CommonProcess and move it to
*Target.
* pkg/proc: Add SupportsFunctionCall to Target
