3075 Commits

Author SHA1 Message Date
Jakob Johnson
22077627ae Minor refactor and renaming:
- Rename IntelPTManager class and files to IntelPTCollector
  - Change GetTimestampCounter API to general trace counter API,
    GetCounter

Differential Revision: https://reviews.llvm.org/D121711
2022-03-16 15:35:36 -07:00
Jonas Devlieghere
2fc38b2b7b
[lldb] Report debugger diagnostics as events
Report warnings and errors through events instead of printing directly
the to the debugger's error stream. By using events, IDEs such as Xcode
can report these issues in the UI instead of having them show up in the
debugger console.

The new diagnostic events are handled by the default event loop. If a
diagnostic is reported while nobody is listening for the new event
types, it is printed directly to the debugger's error stream.

Differential revision: https://reviews.llvm.org/D121511
2022-03-16 08:33:01 -07:00
Jonas Devlieghere
a6eeffa106
[lldb] Include lldb/Host/HostInfo.h in ProcessWindows.cpp 2022-03-11 12:34:41 -08:00
Jonas Devlieghere
530bc61901
[lldb] Fix typo in ProcessWindows.h 2022-03-11 11:33:16 -08:00
Jonas Devlieghere
68099b1d5c
[lldb] Add a getter for the process' system architecture
This patch adds a getter for the process' system architecture. I went
with Process::GetSystemArchitecture to match
Platform::GetSystemArchitecture.

Differential revision: https://reviews.llvm.org/D121443
2022-03-11 10:58:04 -08:00
Jonas Devlieghere
4ef07e5ffe
[lldb] Don't overwrite the host arch with the process arch
Don't overwrite the host architecture (obtained from qHostInfo) with the
process info (obtained from qProcessInfo).

Differential revision: https://reviews.llvm.org/D121442
2022-03-11 09:23:01 -08:00
Pavel Labath
ed1a83befe [lldb/gdb-remote] Remove ancient debugserver workaround
This workaround is the source of an awkwared Process->Platform
dependency. While this could be solved in various ways (the only thing
we really use is the plugin name), it may be better to just remove it --
the workaround was added 10 years ago (43c555dfc), and the affected
debugservers were "old" even then, so hopefully they are not in use
anymore.

Differential Revision: https://reviews.llvm.org/D121305
2022-03-10 20:26:54 +01:00
Med Ismail Bennani
680ca7f21a [lldb/Plugins] Add ability to load modules to Scripted Processes
This patch introduces a new way to load modules programatically with
Scripted Processes. To do so, the scripted process blueprint holds a
list of dictionary describing the modules to load, which their path or
uuid, load address and eventually a slide offset.

LLDB will fetch that list after launching the ScriptedProcess, and
iterate over each entry to create the module that will be loaded in the
Scripted Process' target.

The patch also refactors the StackCoreScriptedProcess test to stop
inside the `libbaz` module and make sure it's loaded correctly and that
we can fetch some variables from it.

rdar://74520238

Differential Revision: https://reviews.llvm.org/D120969

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>
2022-03-04 13:35:28 -08:00
Med Ismail Bennani
6eddd987c9 [lldb/Plugin] Use static ScriptedInterface::ErrorWithMessage function (NFC)
This patch replaces the calls to ErrorWithMessage using the GetInterface
message by a call to the static method directly.

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>
2022-03-04 13:35:19 -08:00
Pavel Labath
d2edca6276 [lldb/Platform] Prepare decouple instance and plugin names
This patch changes the return value of Platform::GetName() to a
StringRef, and uses the opportunity (compile errors) to change some
callsites to use GetPluginName() instead. The two methods still remain
hardwired to return the same thing, but this will change once the ideas
in
<https://discourse.llvm.org/t/multiple-platforms-with-the-same-name/59594>
are implemented.

Differential Revision: https://reviews.llvm.org/D119146
2022-03-02 14:57:01 +01:00
Pavel Labath
12c9c4a885 [lldb/host] Remove monitor_signals argument from process monitoring functions
All current callers set the argument to false. monitor_signals=true used
to be used in the Process plugins (which needed to know when the
debugged process gets a signal), but this implementation has several
serious issues, which means that individual process plugins now
orchestrate the monitoring of debugged processes themselves.

This allows us to simplify the implementation (no need to play with
process groups), and the interface (we only catch fatal events, so the
callback is always called just once).

Differential Revision: https://reviews.llvm.org/D120425
2022-02-24 11:12:59 +01:00
Pavel Labath
d0810779b1 [lldb] Modernize ThreadLauncher
Accept a function object instead of a raw pointer. This avoids a bunch
of boilerplate typically needed to pass arguments to the thread
functions.

Differential Revision: https://reviews.llvm.org/D120321
2022-02-23 14:25:59 +01:00
Shafik Yaghmour
14101f48d2 [LLDB] Remove recursive include of GDBRemoteCommunicationServerCommon.h
GDBRemoteCommunicationServerCommon.h includes itself, removing this include.

Differential Revision: https://reviews.llvm.org/D120105
2022-02-21 18:46:12 -08:00
Med Ismail Bennani
7c54ffdc6c [lldb/crashlog] Add CrashLogScriptedProcess & remove interactive mode
This patch introduces a new type of ScriptedProcess: CrashLogScriptedProcess.
It takes advantage of lldb's crashlog parsers and Scripted Processes to
reconstruct a static debugging session with symbolicated stackframes, instead
of just dumping out everything in the user's terminal.

The crashlog command also has an interactive mode that only provide a
very limited experience. This is why this patch removes all the logic
for this interactive mode and creates CrashLogScriptedProcess instead.

This will fetch and load all the libraries that were used by the crashed
thread and re-create all the frames artificially.

rdar://88721117

Differential Revision: https://reviews.llvm.org/D119501

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>
2022-02-16 11:44:07 -08:00
Med Ismail Bennani
7066584491 [lldb/Plugin] Add artificial stackframe loading in ScriptedThread
This patch adds the ability for ScriptedThread to load artificial stack
frames. To do so, the interpreter instance can create a list that will
contain the frame index and its pc address.

Then, when the Scripted Process plugin stops, it will refresh its
Scripted Threads state by invalidating their register context and load
to list from the interpreter object and reconstruct each frame.

This patch also removes all of the default implementation for
`get_stackframes` from the derived ScriptedThread classes, and add the
interface code for the Scripted Thread Interface.

rdar://88721095

Differential Revision: https://reviews.llvm.org/D119388

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>
2022-02-16 11:44:07 -08:00
David Spickett
2937b28218 Reland "[lldb] Remove non address bits when looking up memory regions"
This reverts commit 0df522969a7a0128052bd79182c8d58e00556e2f.

Additional checks are added to fix the detection of the last memory region
in GetMemoryRegions or repeating the "memory region" command when the
target has non-address bits.

Normally you keep reading from address 0, looking up each region's end
address until you get LLDB_INVALID_ADDR as the region end address.
(0xffffffffffffffff)

This is what the remote will return once you go beyond the last mapped region:
[0x0000fffffffdf000-0x0001000000000000) rw- [stack]
[0x0001000000000000-0xffffffffffffffff) ---

Problem is that when we "fix" the lookup address, we remove some bits
from it. On an AArch64 system we have 48 bit virtual addresses, so when
we fix the end address of the [stack] region the result is 0.
So we loop back to the start.

[0x0000fffffffdf000-0x0001000000000000) rw- [stack]
[0x0000000000000000-0x0000000000400000) ---

To fix this I added an additional check for the last range.
If the end address of the region is different once you apply
FixDataAddress, we are at the last region.

Since the end of the last region will be the last valid mappable
address, plus 1. That 1 will be removed by the ABI plugin.

The only side effect is that on systems with non-address bits, you
won't get that last catch all unmapped region from the max virtual
address up to 0xf...f.

[0x0000fffff8000000-0x0000fffffffdf000) ---
[0x0000fffffffdf000-0x0001000000000000) rw- [stack]
<ends here>

Though in some way this is more correct because that region is not
just unmapped, it's not mappable at all.

No extra testing is needed because this is already covered by
TestMemoryRegion.py, I simply forgot to run it on system that had
both top byte ignore and pointer authentication.

This change has been tested on a qemu VM with top byte ignore,
memory tagging and pointer authentication enabled.

Reviewed By: omjavaid

Differential Revision: https://reviews.llvm.org/D115508
2022-02-10 10:42:49 +00:00
Mariusz Ceier
385f5c4d33 [lldb][CMake] Fix linking of gdb-remote when LLVM_ENABLE_ZLIB is ON
When LLVM_ENABLE_ZLIB is ON gdb-remote should link against ZLIB::ZLIB.

This fixes
```
/mnt/b/yoe/master/build/tmp/hosttools/ld: lib/liblldbPluginProcessGDBRemote.a(GDBRemoteCommunication.cpp.o): in function `lldb_private::process_gdb_remote::GDBRemoteCommunication::DecompressPacket() [clone .localalias]':
GDBRemoteCommunication.cpp:(.text._ZN12lldb_private18process_gdb_remote22GDBRemoteCommunication16DecompressPacketEv+0x59a): undefined reference to `inflateInit2_'
/mnt/b/yoe/master/build/tmp/hosttools/ld: GDBRemoteCommunication.cpp:(.text._ZN12lldb_private18process_gdb_remote22GDBRemoteCommunication16DecompressPacketEv+0x5af): undefined reference to `inflate'
```

Reviewed By: JDevlieghere, MaskRay

Differential Revision: https://reviews.llvm.org/D119186
2022-02-07 23:26:22 -08:00
Zequan Wu
ac73e12ee0 [LLDB] remove an extra register enum on windows x64 2022-02-03 14:12:24 -08:00
Pavel Labath
359a2deb6f [lldb] Fix windows&mac builds for c34698a811b13 2022-02-03 18:06:55 +01:00
Pavel Labath
c34698a811 [lldb] Rename Logging.h to LLDBLog.h and clean up includes
Most of our code was including Log.h even though that is not where the
"lldb" log channel is defined (Log.h defines the generic logging
infrastructure). This worked because Log.h included Logging.h, even
though it should.

After the recent refactor, it became impossible the two files include
each other in this direction (the opposite inclusion is needed), so this
patch removes the workaround that was put in place and cleans up all
files to include the right thing. It also renames the file to LLDBLog to
better reflect its purpose.
2022-02-03 14:47:01 +01:00
Zequan Wu
f3e1ba1d03 [LLDB] add sub regigter enums on x64 Windows
Differential Revision: https://reviews.llvm.org/D118750
2022-02-02 14:21:08 -08:00
Pavel Labath
a007a6d844 [lldb] Convert "LLDB" log channel to the new API 2022-02-02 14:13:08 +01:00
Pavel Labath
b1127753b9 [lldb] Convert ProcessGDBRemoteLog to the new API 2022-02-01 14:36:29 +01:00
Pavel Labath
c8fbf8037d [lldb] Convert Process KDP Log to the new API 2022-01-31 08:59:41 +01:00
Michał Górny
ac666d1799 [lldb] [gdb-remote] Support getting siginfo via API
Add Thread::GetSiginfo() and SBThread::GetSiginfo() methods to retrieve
the siginfo value from server.

Differential Revision: https://reviews.llvm.org/D118055
2022-01-28 17:47:47 +01:00
Michał Górny
59a3f65f5e Revert "[lldb] [gdb-remote] Support getting siginfo via API"
This reverts commit 1a8f60f5f5b8638a3e8e7fb31ba7ae9e17a7ff2d.
The API requires further work.
2022-01-28 10:15:52 +01:00
Michał Górny
1a8f60f5f5 [lldb] [gdb-remote] Support getting siginfo via API
Add Thread::GetSiginfo() and SBThread::GetSiginfo() methods to retrieve
the siginfo value from server.

Differential Revision: https://reviews.llvm.org/D118055
2022-01-27 13:33:47 +01:00
Pavel Labath
6730df4779 [lldb] Convert ProcessWindowsLog to the new API 2022-01-27 10:05:05 +01:00
Benjamin Kramer
f15014ff54 Revert "Rename llvm::array_lengthof into llvm::size to match std::size from C++17"
This reverts commit ef8206320769ad31422a803a0d6de6077fd231d2.

- It conflicts with the existing llvm::size in STLExtras, which will now
  never be called.
- Calling it without llvm:: breaks C++17 compat
2022-01-26 16:55:53 +01:00
serge-sans-paille
ef82063207 Rename llvm::array_lengthof into llvm::size to match std::size from C++17
As a conquence move llvm::array_lengthof from STLExtras.h to
STLForwardCompat.h (which is included by STLExtras.h so no build
breakage expected).
2022-01-26 16:17:45 +01:00
Pavel Labath
4fa1ad0521 [lldb] Convert POSIXLog to use the new API 2022-01-26 13:10:10 +01:00
David Spickett
ee0c3820f8 [lldb][AArch64] Add MakeTaggedRanges to MemoryTagManager
This is to be used when you want to know what subranges
of a larger range have memory tagging. Like MakeTaggedRange
but memory without tags is skipped and you get a list of ranges back.

Will be used later by DumpDataExtractor to show memory tags.

MakeTaggedRanges assumes that the memory regions it is
given are sorted in ascending order and do not overlap.
For the current use case where you get regions from
GetMemoryRegions and are on some Linux like OS, this is
reasonable to assume.

I've used asserts to check those conditions. In future
any API binding will check them up front to prevent a crash.

Reviewed By: omjavaid

Differential Revision: https://reviews.llvm.org/D112824
2022-01-26 11:30:10 +00:00
Pavel Labath
2a1b7aa016 [lldb] Fix ProcessKDPLog for the logging refactor 2022-01-25 20:51:19 +01:00
Pavel Labath
6b67e89b45 [lldb] Fix windows build for D117490
I forgot to update ProcessWindowsLog to the new API.
2022-01-25 13:51:53 +01:00
Pavel Labath
0f08db66db [lldb] Make logging machinery type-safe
This patch makes use of c++ type checking and scoped enums to make
logging statements shorter and harder to misuse.

Defines like LIBLLDB_LOG_PROCESS are replaces with LLDBLog::Process.
Because it now carries type information we do not need to worry about
matching a specific enum value with the right getter function -- the
compiler will now do that for us.

The main entry point for the logging machinery becomes the GetLog
(template) function, which will obtain the correct Log object based on
the enum type. It achieves this through another template function
(LogChannelFor<T>), which must be specialized for each type, and should
return the appropriate channel object.

This patch also removes the ability to log a message if multiple
categories are enabled simultaneously as it was unused and confusing.

This patch does not actually remove any of the existing interfaces. The
defines and log retrieval functions are left around as wrappers around
the new interfaces. They will be removed in follow-up patch.

Differential Revision: https://reviews.llvm.org/D117490
2022-01-25 12:13:49 +01:00
Med Ismail Bennani
91bb116190 [lldb/Interpreter] Make ScriptedInterface::ErrorWithMessage static (NFC)
This patch changes the `ScriptedInterface::ErrorWithMessage` method to
make it `static` which makes it easier to call.

The patch also updates its various call sites to reflect this change.

Differential Revision: https://reviews.llvm.org/D117374

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>
2022-01-24 20:25:54 +01:00
Med Ismail Bennani
45148bfe8a [lldb/Plugins] Fix ScriptedThread IndexID reporting
When listing all the Scripted Threads of a ScriptedProcess, we can see that all
have the thread index set to 1. This is caused by the lldb_private::Thread
constructor, which sets the m_index_id member using the provided thread id `tid`.

Because the call to the super constructor is done before instantiating
the `ScriptedThreadInterface`, lldb can't fetch the thread id from the
script instance, so it uses `LLDB_INVALID_THREAD_ID` instead.

To mitigate this, this patch takes advantage of the `ScriptedThread::Create`
fallible constructor idiom to defer calling the `ScriptedThread` constructor
(and the `Thread` super constructor with it), until we can fetch a valid
thread id `tid` from the `ScriptedThreadInterface`.

rdar://87432065

Differential Revision: https://reviews.llvm.org/D117076

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>
2022-01-24 20:25:54 +01:00
Med Ismail Bennani
cfa55bfe78 [lldb/Plugins] Enrich ScriptedThreads Stop Reasons with Exceptions
This patch adds Exceptions to the list of supported stop reasons for
Scripted Threads.

The main motivation for this is that breakpoints are triggered as a
special exception class on ARM platforms, so adding it as a stop reason
allows the ScriptedProcess to selected the ScriptedThread that stopped at
a breakpoint (or crashed :p).

rdar://87430376

Differential Revision: https://reviews.llvm.org/D117074

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>
2022-01-24 20:25:54 +01:00
Med Ismail Bennani
d3e0f7e150 [lldb/Plugins] Add support of multiple ScriptedThreads in a ScriptedProcess
This patch adds support of multiple Scripted Threads in a ScriptedProcess.

This is done by fetching the Scripted Threads info dictionary at every
ScriptedProcess::DoUpdateThreadList and iterate over each element to
create a new ScriptedThread using the object instance, if it was not
already available.

This patch also adds the ability to pass a pointer of a script interpreter
object instance to initialize a ScriptedInterface instead of having to call
the script object initializer in the ScriptedInterface constructor.

This is used to instantiate the ScriptedThreadInterface from the
ScriptedThread constructor, to be able to perform call on that script
interpreter object instance.

Finally, the patch also updates the scripted process test to check for
multiple threads.

rdar://84507704

Differential Revision: https://reviews.llvm.org/D117071

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>
2022-01-24 20:25:53 +01:00
Med Ismail Bennani
1b86344fa8 [lldb/Plugins] Move ScriptedThreadInterface to ScriptedThread
Since we can have multiple Scripted Threads per Scripted Process, having
only a single ScriptedThreadInterface (with a single object instance)
will cause the method calls to be done on the wrong object.

Instead, this patch creates a separate ScriptedThreadInterface for each
new lldb_private::ScriptedThread to make sure we interact with the right
instance.

rdar://87427911

Differential Revision: https://reviews.llvm.org/D117070

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>
2022-01-24 20:25:53 +01:00
David Spickett
585abe3ba5 [lldb] Rename MemoryTagManager RemoveNonAddressBits to RemoveTagBits
This better describes the intent of the method. Which for AArch64
is removing the top byte which includes the memory tags.

It does not include pointer signatures, for those we need to use
the ABI plugin. The rename makes this a little more clear.

It's a bit awkward that the memory tag manager is removing the whole
top byte not just the memory tags but it's an improvement for now.

Reviewed By: omjavaid

Differential Revision: https://reviews.llvm.org/D117671
2022-01-20 10:47:05 +00:00
Pavel Labath
8bfa7a6dcc [lldb] Fix NativeThreadLinux to build with older compilers 2022-01-19 12:49:47 +01:00
Michał Górny
e69a3d18f4 [lldb] [gdb-remote] Support client fallback for servers without reg defs
Provide minimal register definition defaults for working with servers
that implement neither target.xml nor qRegisterInfo packets.  This is
useful e.g. when interacting with FreeBSD's kernel minimal gdbserver
that does not send target.xml but uses the same layout for its supported
register subset as GDB.

The prerequisite for this is the ability to determine the correct
architecture, e.g. from the target executable.

Differential Revision: https://reviews.llvm.org/D116896
2022-01-17 22:31:49 +01:00
Michał Górny
1e74e5e9e3 [lldb] [llgs] Implement qXfer:siginfo:read
Implement the qXfer:siginfo:read that is used to read the siginfo_t
(extended signal information) for the current thread.  This is currently
implemented on FreeBSD and Linux.

Differential Revision: https://reviews.llvm.org/D117113
2022-01-13 11:24:36 +01:00
Michał Górny
9a1ce35d7e [lldb] [Process/FreeBSD] Set current thread ID on events
Set the current thread ID to the thread where an event happened.
As a result, e.g. when a signal is delivered to a thread other than
the first one, the respective T packet refers to the signaled thread
rather than the first thread (with no stop reason).  While this doesn't
strictly make a difference to the LLDB client, it is the expected
behavior.

Differential Revision: https://reviews.llvm.org/D117103
2022-01-12 15:40:13 +01:00
Lirong Yuan
1267506ea5 [lldb] fix memory leak in "GetGDBServerRegisterInfoXMLAndProcess"
While running heap checker on a test that uses LLDB API, the following memory leak is found:

RAW: HeapChecker started...
RAW: Leak check _main_ detected leaks of 34 bytes in 4 objects
RAW: The 2 largest leaks:
RAW: Leak of 17 bytes in 2 objects allocated from:
@ 0x7fb93bd20166 NewHook()
@ 0x7fb929372a73 absl::base_internal::MallocHook::InvokeNewHookSlow()
@ 0x5600d1046093 libc_malloc
@ 0x7fb974529c03 xmlStrdup
@ 0x7fb9744c2a0b xmlGetProp
@ 0x7fb9749d9ed6 lldb_private::XMLNode::GetAttributeValue()
@ 0x7fb979043001 std::u::function::policy_invoker<>::__call_impl<>()
@ 0x7fb9749da06d lldb_private::XMLNode::ForEachChildElement()
@ 0x7fb97903c54d lldb_private::process_gdb_remote::ProcessGDBRemote::GetGDBServerRegisterInfoXMLAndProcess()
@ 0x7fb97902cfe4 lldb_private::process_gdb_remote::ProcessGDBRemote::GetGDBServerRegisterInfo()
@ 0x7fb97902c1d0 lldb_private::process_gdb_remote::ProcessGDBRemote::BuildDynamicRegisterInfo()
@ 0x7fb97902e92a lldb_private::process_gdb_remote::ProcessGDBRemote::SetThreadStopInfo()
@ 0x7fb97902db18 lldb_private::process_gdb_remote::ProcessGDBRemote::DoConnectRemote()
@ 0x7fb97584965e lldb_private::Process::ConnectRemote()
@ 0x7fb975839fa6 lldb_private::Platform::DoConnectProcess()
@ 0x7fb97583a39e lldb_private::Platform::ConnectProcessSynchronous()
@ 0x7fb97545b28b CommandObjectProcessConnect::DoExecute()
@ 0x7fb9755a70c9 lldb_private::CommandObjectParsed::Execute()
@ 0x7fb97559c0e9 lldb_private::CommandInterpreter::HandleCommand()
@ 0x7fb975460145 lldb_private::CommandObjectRegexCommand::DoExecute()
@ 0x7fb9755a72d2 lldb_private::CommandObjectRaw::Execute()
@ 0x7fb97559c0e9 lldb_private::CommandInterpreter::HandleCommand()
@ 0x7fb997a5f22e lldb::SBCommandInterpreter::HandleCommand()
@ 0x7fb997a5ef9b lldb::SBCommandInterpreter::HandleCommand()

This change fixes the memory leaks by freeing memory after it is no
longer in use. Tested with "ninja check-lldb".

Differential revision: https://reviews.llvm.org/D116707
2022-01-10 14:33:09 -08:00
Michał Górny
9b1d27b2fa [lldb] [Process/FreeBSDKernel] Support finding all processes
Include the complete list of threads of all running processes
in the FreeBSDKernel plugin.  This makes it possible to inspect
the states (including partial register dumps from PCB) of all kernel
and userspace threads at the time of crash, or at the time of reading
/dev/mem first.

Differential Revision: https://reviews.llvm.org/D116255
2022-01-06 21:53:28 +01:00
Pavel Labath
df4ad3625f [lldb/linux] Fix a race in handling of simultaneous thread exits
D116372, while fixing one kind of a race, ended up creating a new one.
The new issue could occur when one inferior thread exits while another
thread initiates termination of the entire process (exit_group(2)).

With some bad luck, we could start processing the exit notification
(PTRACE_EVENT_EXIT) only to have the become unresponsive (ESRCH) in the
middle of the MonitorCallback function. This function would then delete
the thread from our list even though it wasn't completely dead (it stays
zombified until we read the WIFEXITED event). The linux kernel will not
deliver the exited event for the entire process until we process
individual thread exits.

In a pre-D116372 world, this wouldn't be a problem because we would read
this event (even though we would not know what to do with it) with
waitpid(-1). Now, when we issue invididual waitpids, this event will
never be picked up, and we end up hanging.

The fix for this is actually quite simple -- don't delete the thread in
this situation. The thread will be deleted when the WIFEXITED event
comes.

This situation was kind of already tested by
TestCreateDuringInstructionStep (which is how I found this problem), but
it was mostly accidental, so I am also creating a dedicated test which
reproduces this situation.
2022-01-05 13:21:35 +01:00
Pavel Labath
a8ae6828a9 [lldb] Delete GDBRemoteCommunicationReplayServer
This survived the reproducer deletion.
2022-01-03 16:13:57 +01:00
Pavel Labath
ca271f4ef5 [lldb-server/linux] Fix waitpid for multithreaded forks
The lldb-server code is currently set up in a way that each
NativeProcess instance does its own waitpid handling. This works fine
for BSDs, where the code can do a waitpid(process_id), and get
information for all threads in that process.

The situation is trickier on linux, because waitpid(pid) will only
return information for the main thread of the process (one whose tid ==
pid). For this reason the linux code does a waitpid(-1), to get
information for all threads. This was fine while we were supporting just
a single process, but becomes a problem when we have multiple processes
as they end up stealing each others events.

There are two possible solutions to this problem:
- call waitpid(-1) centrally, and then dispatch the events to the
  appropriate process
- have each process call waitpid(tid) for all the threads it manages

This patch implements the second approach. Besides fitting better into
the existing design, it also has the added benefit of ensuring
predictable ordering for thread/process creation events (which come in
pairs -- one for the parent and one for the child). The first approach
OTOH, would make this ordering even more complicated since we would
have to keep the half-threads hanging in mid-air until we find the
process we should attach them to.

The downside to this approach is an increased number of syscalls (one
waitpid for each thread), but I think we're pretty far from optimizing
things like this, and so the cleanliness of the design is worth it.

The included test reproduces the circumstances which should demonstrate
the bug (which manifests as a hung test), but I have not been able to
get it to fail. The only place I've seen this failure modes are very
rare hangs in the thread sanitizer tests (tsan forks an addr2line
process to produce its error messages).

Differential Revision: https://reviews.llvm.org/D116372
2022-01-03 14:27:52 +01:00