As specified in the docs,
1) raw_string_ostream is always unbuffered and
2) the underlying buffer may be used directly
( 65b13610a5 for further reference )
* Don't call raw_string_ostream::flush(), which is essentially a no-op.
* Avoid unneeded calls to raw_string_ostream::str(), to avoid excess
indirection.
Recently in #107731 this change was revereted due to excess memory size
in `TestSkinnyCore`. This was due to a bug where a range's end was being
passed as size. Creating massive memory ranges.
Additionally, and requiring additional review, I added more unit tests
and more verbose logic to the merging of save core memory regions.
@jasonmolenda as an FYI.
This PR adds a statistics provider cache, which allows an individual
target to keep a rolling tally of it's total time and number of
invocations for a given summary provider. This information is then
available in statistics dump to help slow summary providers, and gleam
more into insight into LLDB's time use.
Reapplies #106293, testing identified issue in the merging code. I used
this opportunity to strip CoreFileMemoryRanges to it's own file and then
add unit tests on it's behavior.
This patch fixes an issue where the `memory find` command would
effectively stop searching after encountering a memory read error (which
could happen due to unreadable memory), without giving any indication
that it has done so (it would just print it could not find the pattern).
To make matters worse, it would not terminate after encountering this
error, but rather proceed to slowly increment the address pointer, which
meant that searching a large region could take a very long time (and
give the appearance that lldb is actually searching for the thing).
The patch fixes this first problem by detecting read errors and
skipping over (using GetMemoryRegionInfo) the unreadable parts of memory
and resuming the search after them. It also reads the memory in bulk
(`max(sizeof(pattern))`), which speeds up the search significantly (up
to 6x for live processes, 18x for core files).
`memory read` will return an error if you try to read more than 1k bytes
in a single command, instructing you to set
`target.max-memory-read-size` or use `--force` if you intended to read
more than that. This is a safeguard for a command where people are being
explicit about how much memory they would like lldb to read (either to
display, or save to a file) and is an annoyance every time you need to
read more than a small amount. If someone confuses the --count argument
with the start address, lldb may begin dumping gigabytes of data but I'd
rather that behavior than requiring everyone to special-case their way
around a common use case.
I don't want to remove the setting because many people have added (much
larger) default max read sizes to their ~/.lldbinit files after hitting
this behavior. Another option would be to stop reading/using the value
in Target.cpp, but I see no harm in leaving the setting if someone
really does prefer to have a small cap on their memory read size.
This PR fixes another race condition in
https://github.com/llvm/llvm-project/pull/90930. The failure was found
by @labath with this log: https://paste.debian.net/hidden/30235a5c/:
```
dotest_wrapper. < 15> send packet: $z0,224505,1#65
...
b-remote.async> < 22> send packet: $vCont;s:p1dcf.1dcf#4c
intern-state GDBRemoteClientBase::Lock::Lock sent packet: \x03
b-remote.async> < 818> read packet: $T13thread:p1dcf.1dcf;name:a.out;threads:1dcf,1dd2;jstopinfo:5b7b226e616d65223a22612e6f7574222c22726561736f6e223a227369676e616c222c227369676e616c223a31392c22746964223a373633317d2c7b226e616d65223a22612e6f7574222c22746964223a373633347d5d;thread-pcs:0000000000224505,00007f4e4302119a;00:0000000000000000;01:0000000000000000;02:0100000000000000;03:0000000000000000;04:9084997dfc7f0000;05:a8742a0000000000;06:b084997dfc7f0000;07:6084997dfc7f0000;08:0000000000000000;09:00d7e5424e7f0000;0a:d0d9e5424e7f0000;0b:0202000000000000;0c:80cc290000000000;0d:d8cc1c434e7f0000;0e:2886997dfc7f0000;0f:0100000000000000;10:0545220000000000;11:0602000000000000;12:3300000000000000;13:0000000000000000;14:0000000000000000;15:2b00000000000000;16:80fbe5424e7f0000;17:0000000000000000;18:0000000000000000;19:0000000000000000;reason:signal;#b9
```
It shows an async interrupt "\x03" was sent immediately after `vCont;s`
single step over breakpoint at address `0x224505` (which was disabled
before vCont). And the later stop was still at the original PC
(0x224505) not moving forward.
The investigation shows the failure happens when timeout is short and
async interrupt is sent to lldb-server immediately after vCont so
ptrace() resumes and then async interrupts debuggee immediately so
debuggee does not get a chance to execute and move PC. So it enters stop
mode immediately at original PC. `ThreadPlanStepOverBreakpoint` does not
expect PC not moving and reports stop at the original place.
To fix this, the PR prevents `ThreadPlanSingleThreadTimeout` from being
created during `ThreadPlanStepOverBreakpoint` by introduces a new
`SupportsResumeOthers()` method and `ThreadPlanStepOverBreakpoint`
returns false for it. This makes sense because we should never resume
threads during step over breakpoint anyway otherwise it might cause
other threads to miss breakpoint.
---------
Co-authored-by: jeffreytan81 <jeffreytan@fb.com>
This patch removes all of the Set.* methods from Status.
This cleanup is part of a series of patches that make it harder use the
anti-pattern of keeping a long-lives Status object around and updating
it while dropping any errors it contains on the floor.
This patch is largely NFC, the more interesting next steps this enables
is to:
1. remove Status.Clear()
2. assert that Status::operator=() never overwrites an error
3. remove Status::operator=()
Note that step (2) will bring 90% of the benefits for users, and step
(3) will dramatically clean up the error handling code in various
places. In the end my goal is to convert all APIs that are of the form
` ResultTy DoFoo(Status& error)
`
to
` llvm::Expected<ResultTy> DoFoo()
`
How to read this patch?
The interesting changes are in Status.h and Status.cpp, all other
changes are mostly
` perl -pi -e 's/\.SetErrorString/ = Status::FromErrorString/g' $(git
grep -l SetErrorString lldb/source)
`
plus the occasional manual cleanup.
With this commit, we also hide the implementation details of
`std::invoke`. To do so, the `LibCXXFrameRecognizer` got a couple more
regular expressions.
The regular expression passed into `AddRecognizer` became problematic,
as it was evaluated on the demangled name. Those names also included
result types for C++ symbols. For `std::__invoke` the return type is a
huge `decltype(...)`, making the regular expresison really hard to
write.
Instead, I added support to `AddRecognizer` for matching on the
demangled names without result type and argument types.
By hiding the implementation details of `invoke`, also the back traces
for `std::function` become even nicer, because `std::function` is using
`__invoke` internally.
Co-authored-by: Adrian Prantl <aprantl@apple.com>
This patch adds the option to specify specific memory ranges to be
included in a given core file. The current implementation lets user
specified ranges either be in addition to a certain save style, or
independent of them via the newly added custom enum.
To achieve being inclusive of save style, I've moved from a std::vector
of ranges to a RangeDataVector, and to join overlapping ranges to
prevent duplication of memory ranges in the core file.
As a non function bonus, when SBSavecore was initially created, the
header was included in the lldb-private interfaces, and I've fixed that
and moved it the forward declare as an oversight. CC @bulbazord in case
we need to include that into swift.
TargetProperties.td had a few settings listed as signed integral values,
but the Target.cpp methods reading those values were reading them as
unsigned. e.g. target.max-memory-read-size, some accesses of
target.max-children-count, still today, previously
target.max-string-summary-length.
After Jonas' change to use templates to read these values in
https://reviews.llvm.org/D149774, when the code tried to fetch these
values, we'd eventually end up calling OptionValue::GetAsUInt64 which
checks that the value is actually a UInt64 before returning it; finding
that it was an SInt64, it would drop the user setting and return the
default value. This manifested as a bug that target.max-memory-read-size
is never used for memory read.
target.max-children-count is less straightforward, where one read of
that setting was fetching it as an int64_t, the other as a uint64_t.
I suspect all of these settings were originally marked as SInt64 so a
user could do -1 for "infinite", getting it static_cast to a UINT64_MAX
value along the way. I can't find any documentation for this behavior,
but it seems like something Greg would have done. We've partially lost
that behavior already via
https://github.com/llvm/llvm-project/pull/72233 for
target.max-string-summary-length, and this further removes it.
We're still fetching UInt64's and returning them as uint32_t's but I'm
not overly pressed about someone setting a count/size limit over 4GB.
I added a simple API test for the memory read setting limit.
Compilers and language runtimes often use helper functions that are
fundamentally uninteresting when debugging anything but the
compiler/runtime itself. This patch introduces a user-extensible
mechanism that allows for these frames to be hidden from backtraces and
automatically skipped over when navigating the stack with `up` and
`down`.
This does not affect the numbering of frames, so `f <N>` will still
provide access to the hidden frames. The `bt` output will also print a
hint that frames have been hidden.
My primary motivation for this feature is to hide thunks in the Swift
programming language, but I'm including an example recognizer for
`std::function::operator()` that I wished for myself many times while
debugging LLDB.
rdar://126629381
Example output. (Yes, my proof-of-concept recognizer could hide even
more frames if we had a method that returned the function name without
the return type or I used something that isn't based off regex, but it's
really only meant as an example).
before:
```
(lldb) thread backtrace --filtered=false
* thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
* frame #0: 0x0000000100001f04 a.out`foo(x=1, y=1) at main.cpp:4:10
frame #1: 0x0000000100003a00 a.out`decltype(std::declval<int (*&)(int, int)>()(std::declval<int>(), std::declval<int>())) std::__1::__invoke[abi:se200000]<int (*&)(int, int), int, int>(__f=0x000000016fdff280, __args=0x000000016fdff224, __args=0x000000016fdff220) at invoke.h:149:25
frame #2: 0x000000010000399c a.out`int std::__1::__invoke_void_return_wrapper<int, false>::__call[abi:se200000]<int (*&)(int, int), int, int>(__args=0x000000016fdff280, __args=0x000000016fdff224, __args=0x000000016fdff220) at invoke.h:216:12
frame #3: 0x0000000100003968 a.out`std::__1::__function::__alloc_func<int (*)(int, int), std::__1::allocator<int (*)(int, int)>, int (int, int)>::operator()[abi:se200000](this=0x000000016fdff280, __arg=0x000000016fdff224, __arg=0x000000016fdff220) at function.h:171:12
frame #4: 0x00000001000026bc a.out`std::__1::__function::__func<int (*)(int, int), std::__1::allocator<int (*)(int, int)>, int (int, int)>::operator()(this=0x000000016fdff278, __arg=0x000000016fdff224, __arg=0x000000016fdff220) at function.h:313:10
frame #5: 0x0000000100003c38 a.out`std::__1::__function::__value_func<int (int, int)>::operator()[abi:se200000](this=0x000000016fdff278, __args=0x000000016fdff224, __args=0x000000016fdff220) const at function.h:430:12
frame #6: 0x0000000100002038 a.out`std::__1::function<int (int, int)>::operator()(this= Function = foo(int, int) , __arg=1, __arg=1) const at function.h:989:10
frame #7: 0x0000000100001f64 a.out`main(argc=1, argv=0x000000016fdff4f8) at main.cpp:9:10
frame #8: 0x0000000183cdf154 dyld`start + 2476
(lldb)
```
after
```
(lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
* frame #0: 0x0000000100001f04 a.out`foo(x=1, y=1) at main.cpp:4:10
frame #1: 0x0000000100003a00 a.out`decltype(std::declval<int (*&)(int, int)>()(std::declval<int>(), std::declval<int>())) std::__1::__invoke[abi:se200000]<int (*&)(int, int), int, int>(__f=0x000000016fdff280, __args=0x000000016fdff224, __args=0x000000016fdff220) at invoke.h:149:25
frame #2: 0x000000010000399c a.out`int std::__1::__invoke_void_return_wrapper<int, false>::__call[abi:se200000]<int (*&)(int, int), int, int>(__args=0x000000016fdff280, __args=0x000000016fdff224, __args=0x000000016fdff220) at invoke.h:216:12
frame #6: 0x0000000100002038 a.out`std::__1::function<int (int, int)>::operator()(this= Function = foo(int, int) , __arg=1, __arg=1) const at function.h:989:10
frame #7: 0x0000000100001f64 a.out`main(argc=1, argv=0x000000016fdff4f8) at main.cpp:9:10
frame #8: 0x0000000183cdf154 dyld`start + 2476
Note: Some frames were hidden by frame recognizers
```
Reapply #100443 and #101770. These were originally reverted due to a
test failure and an MSAN failure. I changed the test attribute to
restrict to x86 (following the other existing tests). I could not
reproduce the test or the MSAN failure and no repo steps were provided.
This PR fixes a potential race condition in
https://github.com/llvm/llvm-project/pull/90930.
This race can happen because the original code set `m_info->m_isAlive =
true` **after** the timer thread is created. So if there is a context
switch happens and timer thread checks `m_info->m_isAlive` before main
thread got a chance to run `m_info->m_isAlive = true`, the timer thread
may treat `ThreadPlanSingleThreadTimeout` as not alive and simply exit
resulting in async interrupt never being sent to resume all threads
(deadlock).
The PR fixes the race by initializing all states **before** worker timer
thread creates.
Co-authored-by: jeffreytan81 <jeffreytan@fb.com>
This fixes:
```
[6831/7617] Building CXX object
tools\lldb\source\Target\CMakeFiles\lldbTarget.dir\ThreadPlanSingleThreadTimeout.cpp.obj
C:\src\git\llvm-project\lldb\source\Target\ThreadPlanSingleThreadTimeout.cpp(66)
: warning C4715:
'lldb_private::ThreadPlanSingleThreadTimeout::StateToString': not all
control paths return a value
```
This PR fixes the ASAN failure in
https://github.com/llvm/llvm-project/pull/90930.
The original PR made the assumption that parent
`ThreadPlanStepOverRange`'s lifetime will always be longer than
`ThreadPlanSingleThreadTimeout` leaf plan so it passes the
`m_timeout_info` as reference to it.
From the ASAN failure, it seems that this assumption may not be true
(likely the thread stack is holding a strong reference to the leaf
plan).
This PR fixes this lifetime issue by using shared pointer instead of
passing by reference.
---------
Co-authored-by: jeffreytan81 <jeffreytan@fb.com>
This PR introduces a new `ThreadPlanSingleThreadTimeout` that will be
used to address potential deadlock during single-thread stepping.
While debugging a target with a non-trivial number of threads (around
5000 threads in one example target), we noticed that a simple step over
can take as long as 10 seconds. Enabling single-thread stepping mode
significantly reduces the stepping time to around 3 seconds. However,
this can introduce deadlock if we try to step over a method that depends
on other threads to release a lock.
To address this issue, we introduce a new
`ThreadPlanSingleThreadTimeout` that can be controlled by the
`target.process.thread.single-thread-plan-timeout` setting during
single-thread stepping mode. The concept involves counting the elapsed
time since the last internal stop to detect overall stepping progress.
Once a timeout occurs, we assume the target is not making progress due
to a potential deadlock, as mentioned above. We then send a new async
interrupt, resume all threads, and `ThreadPlanSingleThreadTimeout`
completes its task.
To support this design, the major changes made in this PR are:
1. `ThreadPlanSingleThreadTimeout` is popped during every internal stop
and reset (re-pushed) to the top of the stack (as a leaf node) during
resume. This is achieved by always returning `true` from
`ThreadPlanSingleThreadTimeout::DoPlanExplainsStop()` and
`ThreadPlanSingleThreadTimeout::MischiefManaged()`.
2. A new thread-specific async interrupt stop is introduced, which can
be detected/consumed by `ThreadPlanSingleThreadTimeout`.
3. The clearing of branch breakpoints in the range thread plan has been
moved from `DoPlanExplainsStop()` to `ShouldStop()`, as it is not
guaranteed that it will be called.
The detailed design is discussed in the RFC below:
[https://discourse.llvm.org/t/improve-single-thread-stepping/74599](https://discourse.llvm.org/t/improve-single-thread-stepping/74599)
---------
Co-authored-by: jeffreytan81 <jeffreytan@fb.com>
Following 9a9ec228cd, since the ThreadPlanPython class started making
use of the Scripted Interface instead of calling directly into the
python methods, this class can work with other scripting languages (as
long as someone add the interfact for that language ;p).
So it doesn't make sense anymore for it to keep this name and also we
should avoid having language specific related classes outside the plugin
directory.
This patch renames the internal class from `ThreadPlanPython` to
`ScriptedThreadPlan` as its advertised externally, and also updates the
various log messages.
This should hopefully make the codebase more coherent.
Signed-off-by: Med Ismail Bennani <ismail@bennani.ma>
In #98403 I enabled the SBSaveCoreOptions object, which allows users via
the scripting API to define what they want saved into their core file.
As the first option I've added a threadlist, so users can scan and
identify which threads and corresponding stacks they want to save.
In order to support this, I had to add a new method to `Process.h` on
how we identify which threads are to be saved, and I had to change the
book keeping in minidump to ensure we don't double save the stacks.
Important to @jasonmolenda I also changed the MachO coredump to accept
these new APIs.
This is used by various system routines (the capabilities checker and
dyld to name a few) to add extra color to an abort. This patch adds a
frame recognizer so people can easily see the details, and also adds the
information to the ExtendedCrashInformation dictionary.
I also had to rework how the dictionary is held; previously it was
created on demand, but that was inconvenient since it meant all the
entries had to be produced at that same time. That didn't work for the
recognizer.
This introduces a `target.object-map` which allows us to remap module
locations, much in the same way as source mapping works today. This is
useful, for instance, when debugging coredumps, so we can replace some
of the locations where LLDB attempts to load shared libraries and
executables from, without having to setup an entire sysroot.
This is useful for language runtimes that compute register values by
inspecting the state of the currently running process. Currently, there
are no mechanisms enabling these runtimes to set register values to
arbitrary values.
The alternative considered would involve creating a dwarf expression
that produces an arbitrary integer (e.g. using OP_constu). However, the
current data structure for Rows is such that they do not own any memory
associated with dwarf expressions, which implies any such expression
would need to have static storage and therefore could not contain a
runtime value.
Adding a new rule for constants leads to a simpler implementation. It's
also worth noting that this does not make the "Location" union any
bigger, since it already contains a pointer+size pair.
This reverts commit 05f0e86cc8.
The debuginfo dexter tests are failing, probably because the way
stepping over breakpoints has changed with my patches. And there
are two API tests fails on the ubuntu-arm (32-bit) bot. I'll need
to investigate both of these, neither has an obvious failure reason.
lldb today has two rules: When a thread stops at a BreakpointSite, we
set the thread's StopReason to be "breakpoint hit" (regardless if we've
actually hit the breakpoint, or if we've merely stopped *at* the
breakpoint instruction/point and haven't tripped it yet). And second,
when resuming a process, any thread sitting at a BreakpointSite is
silently stepped over the BreakpointSite -- because we've already
flagged the breakpoint hit when we stopped there originally.
In this patch, I change lldb to only set a thread's stop reason to
breakpoint-hit when we've actually executed the instruction/triggered
the breakpoint. When we resume, we only silently step past a
BreakpointSite that we've registered as hit. We preserve this state
across inferior function calls that the user may do while stopped, etc.
Also, when a user adds a new breakpoint at $pc while stopped, or changes
$pc to be the address of a BreakpointSite, we will silently step past
that breakpoint when the process resumes. This is purely a UX call, I
don't think there's any person who wants to set a breakpoint at $pc and
then hit it immediately on resuming.
One non-intuitive UX from this change, but I'm convinced it is
necessary: If you're stopped at a BreakpointSite that has not yet
executed, you `stepi`, you will hit the breakpoint and the pc will not
yet advance. This thread has not completed its stepi, and the thread
plan is still on the stack. If you then `continue` the thread, lldb will
now stop and say, "instruction step completed", one instruction past the
BreakpointSite. You can continue a second time to resume execution. I
discussed this with Jim, and trying to paper over this behavior will
lead to more complicated scenarios behaving non-intuitively. And mostly
it's the testsuite that was trying to instruction step past a breakpoint
and getting thrown off -- and I changed those tests to expect the new
behavior.
The bugs driving this change are all from lldb dropping the real stop
reason for a thread and setting it to breakpoint-hit when that was not
the case. Jim hit one where we have an aarch64 watchpoint that triggers
one instruction before a BreakpointSite. On this arch we are notified of
the watchpoint hit after the instruction has been unrolled -- we disable
the watchpoint, instruction step, re-enable the watchpoint and collect
the new value. But now we're on a BreakpointSite so the watchpoint-hit
stop reason is lost.
Another was reported by ZequanWu in
https://discourse.llvm.org/t/lldb-unable-to-break-at-start/78282 we
attach to/launch a process with the pc at a BreakpointSite and
misbehave. Caroline Tice mentioned it is also a problem they've had with
putting a breakpoint on _dl_debug_state.
The change to each Process plugin that does execution control is that
1. If we've stopped at a BreakpointSite that has not been executed yet,
we will call Thread::SetThreadStoppedAtUnexecutedBP(pc) to record
that. When the thread resumes, if the pc is still at the same site, we
will continue, hit the breakpoint, and stop again.
2. When we've actually hit a breakpoint (enabled for this thread or not),
the Process plugin should call Thread::SetThreadHitBreakpointSite().
When we go to resume the thread, we will push a step-over-breakpoint
ThreadPlan before resuming.
The biggest set of changes is to StopInfoMachException where we
translate a Mach Exception into a stop reason. The Mach exception codes
differ in a few places depending on the target (unambiguously), and I
didn't want to duplicate the new code for each target so I've tested
what mach exceptions we get for each action on each target, and
reorganized StopInfoMachException::CreateStopReasonWithMachException to
document these possible values, and handle them without specializing
based on the target arch.
rdar://123942164
When doing firmware/kernel debugging, it is frequent that binaries and
debug info need to be retrieved / downloaded, and the lack of progress
reports made for a poor experience, with lldb seemingly hung while
downloading things over the network. This PR adds progress reports to
the critical sites for these use cases.
This patch adds a frame recognizer for Clang's
`__builtin_verbose_trap`, which behaves like a
`__builtin_trap`, but emits a failure-reason string into debug-info in
order for debuggers to display
it to a user.
The frame recognizer triggers when we encounter
a frame with a function name that begins with
`__clang_trap_msg`, which is the magic prefix
Clang emits into debug-info for verbose traps.
Once such frame is encountered we display the
frame function name as the `Stop Reason` and display that frame to the
user.
Example output:
```
(lldb) run
warning: a.out was compiled with optimization - stepping may behave oddly; variables may not be available.
Process 35942 launched: 'a.out' (arm64)
Process 35942 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = Misc.: Function is not implemented
frame #1: 0x0000000100003fa4 a.out`main [inlined] Dummy::func(this=<unavailable>) at verbose_trap.cpp:3:5 [opt]
1 struct Dummy {
2 void func() {
-> 3 __builtin_verbose_trap("Misc.", "Function is not implemented");
4 }
5 };
6
7 int main() {
(lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = Misc.: Function is not implemented
frame #0: 0x0000000100003fa4 a.out`main [inlined] __clang_trap_msg$Misc.$Function is not implemented$ at verbose_trap.cpp:0 [opt]
* frame #1: 0x0000000100003fa4 a.out`main [inlined] Dummy::func(this=<unavailable>) at verbose_trap.cpp:3:5 [opt]
frame #2: 0x0000000100003fa4 a.out`main at verbose_trap.cpp:8:13 [opt]
frame #3: 0x0000000189d518b4 dyld`start + 1988
```
This patch hoists the `SymbolLocation` struct from the
`AssertFrameRecognizer` source file, since it's pretty generic and could
be reused for other purposes.
Signed-off-by: Med Ismail Bennani <ismail@bennani.ma>
This fixes a bug where Process events were being delivered to secondary
listeners when the Private state thread listener was processing the
event. That meant the secondary listener could get an event before the
Primary listener did. That in turn meant the state when the secondary
listener got the event wasn't right yet. Plus it meant that the
secondary listener saw more events than the primary (not all events get
forwarded from the private to the public Process listener.)
This bug became much more evident when we had a stop hook that did some
work, since that delays the Primary listener event delivery. So I also
added a stop-hook to the test, and put a little delay in as well.
Seemingly, #96256 removed the only call to
Platform::GetCachedExecutable, which broke the resolution of executable
modules in the remote debugging mode
(https://github.com/llvm/llvm-project/issues/97410).
This commit fixes that.
In RegisterContextUnwind::SavedLocationForRegister we have special logic
for retrieving the Return Address register when it has the caller's
return address in it. An example would be the lr register on AArch64.
This register is never retrieved from a newer stack frame because it is
necessarly overwritten by a normal ABI function call. We allow frame 0
to provide its lr value to get the caller's return address, if it has
not been overwritten/saved to stack yet.
When a function is interrupted asynchronously by a POSIX signal
(sigtramp), or a fault handler more generally, the sigtramp/fault
handler has the entire register context available. In this situation, if
the fault handler is frame 0, the function that was async interrupted is
frame 1 and frame 2's return address may still be stored in lr. We need
to get the lr value for frame 1 from the fault handler in frame 0, to
get the return address for frame 2.
Without this fix, a frameless function that faults in a firmware
environment (that's where we've seen this issue most commonly) hasn't
spilled lr to stack, so we need to retrieve it from the fault handler's
full-register-context to find the caller of the frameless function that
faulted.
It's an unsurprising fix, all of the work was finding exactly where in
RegisterContextUnwind we were only allowing RA register use for frame 0,
when it should have been frame 0 or above a fault handler function.
rdar://127518945
ThreadList uses the Process mutex to guard its state. This means its not
possible to safely modify its process member, as the member is required
to lock the mutex.
Fortunately for us, we never actually need to change the process member
(we always just juggle different kinds of thread lists belonging to the
same process).
This patch replaces the process member assignment (which is technically
a race even when it assigns the same value) with an assertion.
Since all this means that the class can never change its process member
value (and it also must be non-null at all times), I've also changed the
member type to a reference.
While looking at a TSAN report (patch coming soon) in the ThreadList
class, I noticed that this code would be simpler if it did not use the
ThreadList class.
Currently, LLDB prints out a rather unhelpful error message when passed
a file that it doesn't recognize as an executable.
> error: '/path/to/file' doesn't contain any 'host' platform
> architectures: arm64, armv7, armv7f, armv7k, armv7s, armv7m, armv7em,
> armv6m, armv6, armv5, armv4, arm, thumbv7, thumbv7k, thumbv7s,
> thumbv7f, thumbv7m, thumbv7em, thumbv6m, thumbv6, thumbv5, thumbv4t,
> thumb, x86_64, x86_64, arm64, arm64e
I did a quick search internally and found at least 24 instances of users
being confused by this. This patch improves the error message when it
doesn't recognize the file as an executable, but keeps the existing
error message otherwise, i.e. when it's an object file we understand,
but the current platform doesn't support.
This is an improved attempt to improve the semantics of SupportFile
equivalence, taking into account the feedback from #95606.
Pavel's comment about the lack of a concise name because the concept
isn't trivial made me realize that I don't want to abstract this concept
away behind a helper function. Instead, I opted for a rather verbose
enum that forces the caller to consider exactly what kind of comparison
is appropriate for every call.
This reverts commit d9e659c538.
I could not reproduce the Mac OS ASAN failure locally but I narrowed it
down to the test `test_many_fields_same_enum`. This test shares an enum
between x0, which is 64 bit, and cpsr, which is 32 bit.
My theory is that when it does `register read x0`, an enum type is
created where the undlerying enumerators are 64 bit, matching the
register size.
Then it does `register read cpsr` which used the cached enum type, but
this register is 32 bit. This caused lldb to try to read an 8 byte value
out of a 4 byte allocation:
READ of size 8 at 0x60200014b874 thread T0
<...>
=>0x60200014b800: fa fa fd fa fa fa fd fa fa fa fd fa fa fa[04]fa
To fix this I've added the register's size in bytes to the constructed
enum type's name. This means that x0 uses:
__lldb_register_fields_enum_some_enum_8
And cpsr uses:
__lldb_register_fields_enum_some_enum_4
If any other registers use this enum and are read, they will use the
cached type as long as their size matches, otherwise we make a new type.
