* 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.
* pkg/proc: implement support for hit count breakpoints
* update comment
* udpate hitcount comment
* update HitCond description
* add test for hit condition error
* respond to review
* service/dap: add support for hit count breakpoints
* use amendbps to preserve hit counts
* update test health doc
* fix failing test
* simplify hit conditions
* REmove RequestString, use name instead
* update backend_test_health.md
* document hit count cond
* fix tests
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
* 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.
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
An internal breakpoint condition shouldn't ever error:
* use a ThreadContext to evaluate conditions if a goroutine isn't
available
* evaluate runtime.curg to a fake g variable containing only
`goid == 0` when there is no current goroutine
Fixes#2113
* proc: move defer breakpoint code into a function
Moves the code that sets a breakpoint on the first deferred function,
used by both next and StepOut, to its function.
* proc: implement reverse step/next/stepout
When the direction of execution is reversed (on a recording) Step, Next and
StepOut will behave similarly to their forward version. However there are
some subtle interactions between their behavior, prologue skipping, deferred
calls and normal calls. Specifically:
- when stepping backwards we need to set a breakpoint on the first
instruction after each CALL instruction, once this breakpoint is reached we
need to execute a single StepInstruction operation to reverse step into the
CALL.
- to insure that the prologue is skipped reverse next needs to check if it
is on the first instruction after the prologue, and if it is behave like
reverse stepout.
- there is no reason to set breakpoints on deferred calls when reverse
nexting or reverse stepping out, they will never be hit.
- reverse step out should generally place its breakpoint on the CALL
instruction that created the current stack frame (which will be the CALL
instruction immediately preceding the instruction at the return address).
- reverse step out needs to treat panic calls and deferreturn calls
specially.
* service,terminal: implement reverse step, next, stepout
Modifies FindFileLocation, FindFunctionLocation and LineToPC as well as
service/debugger to support inlining and introduces the concept of
logical breakpoints.
For inlined functions FindFileLocation, FindFunctionLocation and
LineToPC will now return one PC address for each inlining and one PC
for the concrete implementation of the function (if present).
A proc.Breakpoint will continue to represent a physical breakpoint, at
a single memory location.
Breakpoints returned by service/debugger, however, will represent
logical breakpoints and may be associated with multiple memory
locations and, therefore, multiple proc.Breakpoints.
The necessary logic is introduced in service/debugger so that a change
to a logical breakpoint will be mirrored to all its physical
breakpoints and physical breakpoints are aggregated into a single
logical breakpoint when returned.
If proc.Step encounters a CALL instruction that points to an address
that isn't associated with any function it should still follow the
CALL.
The circumstances creating this problem do not normally occur, it was
encountered in the process of fixing a bug created by Go1.12.
It was never true that return variables were in the inverse order.
Instead in Go1.11 return variables are saved in debug_info in an
arbitrary order and inverting them just happened to work for this
specific example.
This bug was fixed in Go 1.12, regardless we should attempt to
rearrange return variables anyway.
This patch is a slight refactor to share more code used for genericprocess initialization. There will always be OS/backend specificinitialization, but as much as can be shared should be to preventduplicating of any logic (setting internal breakpoints, loading bininfo,etc).
This patch allows the `trace` CLI subcommand to display return values of
a function. Additionally, it will also display information on where the
function exited, which could also be helpful in determining the path
taken during function execution.
Fixes#388
Implements the function call injection protocol introduced in go 1.11
by https://go-review.googlesource.com/c/go/+/109699.
This is only the basic support, see TODO comments in pkg/proc/fncall.go
for a list of missing features.
Updates #119
Displays the return values of the current function when we step out of
it after executing a step, next or stepout command.
Implementation of this feature is tricky: when the function has
returned the return variables are not in scope anymore. Implementing
this feature requires evaluating variables that are out of scope, using
a stack frame that doesn't exist anymore.
We can't calculate the address of these variables when the
next/step/stepout command is initiated either, because between that
point and the time where the stepout breakpoint is actually hit the
goroutine stack could grow and be moved to a different memory address.
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.
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
- 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
