Fixed a case where multiple threads can be asking to send a packet to the GDB server and one of three things will happen:
1 - everything works
2 - one thread will fail to send the packet due to not being able to get the sequence mutex
3 - one thread will try and interrupt the other packet sending and fail and not send the packet
Now the flow is a bit different. Prior to this fix we did:
if (try_get_sequence_mutex()) {
send_packet()
return success;
} else {
if (async_ok) {
interrupt()
send_packet()
resume()
return success;
}
}
return fail
The issue is that the call to "try_get_sequence_mutex()" could fail if another thread was sending a packet and could cause us to just not send the packet and an error would be returned.
What we really want is to try and get the sequence mutex, and if this succeeds, send the packet. Else check if we are running and if we are, do what we used to do. The big difference is when we aren't running, we wait for the sequence mutex so we don't drop packets. Pseudo code is:
if (try_get_sequence_mutex()) {
// Safe to send the packet right away
send_packet()
return success;
} else {
if (running) {
// We are running, interrupt and send async packet if ok to do so,
// else it is ok to fail
if (async_ok) {
interrupt()
send_packet()
resume()
return success;
}
}
else {
// Not running, wait for the sequence mutex so we don't drop packets
get_sequence_mutex()
send_packet()
return success;
}
}
return fail
llvm-svn: 157751
Sending async packets can deadlock a program on darwin. We currently allow breakpoint packets and memory read/write packets (for software breakpoints) to be sent while a program is running. In the GDB remote plug-in, we will interrupt the run, send the async packet and resume (currently with the continue packet that caused the program to resume). If the GDB server supports the "vCont" packet, we might have initially continued with each thread stating it should continue. If new threads show up while we are stopped, which happend when running GCD, we can end up with new threads that we aren't mentioning in the continue list. So we start with a thread list of 1,2,3 and continue:
continue thread 1, continue thread 2, continue thread 3
Now we interrupt and set a breakpoint and we actually have threads 1,2,3,4 now when we are about to resume, yet we send:
continue thread 1, continue thread 2, continue thread 3
Any thread that isn't mentioned is currently going to stay suspended. This causes the deadlock.
llvm-svn: 157439
Add default Process::GetWatchpointSupportInfo() impl which returns an error of "not supported".
Add "qWatchpointSupportInfo" packet to the gdb communication layer to support this, and modify TestWatchpointCommands.py to test it.
llvm-svn: 157345
the value_regs field, which is useful for future expansion purposes. As of now, we have:
calculated_offset_of_eax = offset_of_rax + (offset_of_eax_from_the_descriptor which is 0)
llvm-svn: 157275
Add convenience registers eax, ebx, ecx, edx, edi, esi, ebp, esp to the 'register read' command for x86_64.
Add a GDBRemoteRegisterContext::Addx86_64ConvenienceRegisters() method called from ProcessGDBRemote::BuildDynamicRegisterInfo().
Servicing of eax, for example, is accomplished by delegating to rax with an adjusted offset into the register context.
llvm-svn: 157230
that dynamically discovers remote register context information.
o GDBRemoteRegisterContext.h:
Change the prototype of HardcodeARMRegisters() to take a boolean flag, which now becomes
void
HardcodeARMRegisters(bool from_scratch);
o GDBRemoteRegisterContext.cpp:
HardcodeARMRegisters() now checks the from_scratch flag and decides whether to add composite registers to the already
existing primordial registers based on a table called g_composites which describes the composite registers.
o ProcessGDBRemote.cpp:
Modify the logic of ProcessGDBRemote::BuildDynamicRegisterInfo() to call m_register_info.HardcodeARMRegisters()
with the newly introduced 'bool from_scrach' flag.
rdar://problem/10652076
llvm-svn: 156773
Switch over to the "*-apple-macosx" for desktop and "*-apple-ios" for iOS triples.
Also make the selection process for auto selecting platforms based off of an arch much better.
llvm-svn: 156354
No one was using it and Locker(pthread_mutex_t *) immediately asserts for
pthread_mutex_t's that don't come from a Mutex anyway. Rather than try to make
that work, we should maintain the Mutex abstraction and not pass around the
platform implementation...
Make Mutex::Locker::Lock take a Mutex & or a Mutex *, and remove the constructor
taking a pthread_mutex_t *. You no longer need to call Mutex::GetMutex to pass
your mutex to a Locker (you can't in fact, since I made it private.)
llvm-svn: 156221
us of its architecture, use that to set the Target's arch if it
doesn't already have one set.
In Process::CompleteAttach(), if the Target has a valid arch make
sure that the Platform we pick up is compatible with that arch; if
not, find a Platform that is compatible. Don't let the the default
platform override the Target's arch.
<rdar://problem/11185420>
llvm-svn: 156116
Hello everyone,
please find the attached patch for TOT and lldb-platform-work branch, which provides the following changes:
- fixed a crash in the ProcessPOSIX constructor when an executable module object is not yet created.
- added support for the multi instanciated FreeBSD platform objects (the local host and remote as example).
- enabled the remote gdb plugin on FreeBSD.
llvm-svn: 154724
Enable logging the packet history when registers fail to read due to not getting the sequence mutex if "--verbose" is enabled on the log channel for the "gdb-remote" log category.
This will help us track down some issues.
llvm-svn: 154704
The less locks there are, the better. I removed the thread ID mutex and now just shared the m_thread_list's mutex to make sure we don't deadlock due to lock inversion.
llvm-svn: 154652
for packet confirmation.
Also added a bit more logging.
Also, unlock the writer end of the run lock in Process.cpp on our way out of the private state
thread so that the Process can shut down cleanly.
<rdar://problem/11228538>
llvm-svn: 154601
Cleaned up the Mutex::Locker and the ReadWriteLock classes a bit.
Also cleaned up the GDBRemoteCommunication class to not have so many packet functions. Used the "NoLock" versions of send/receive packet functions when possible for a bit of performance.
llvm-svn: 154458
QListThreadsInStopReply
This GDB remote query command can enable added a "threads" key/value pair to all stop reply packets so that we always get a list of all threads in each stop reply packet. It increases performance if enabled (the reply to the "QListThreadsInStopReply" is "OK") by saving us from sending to command/reply pairs (the "qfThreadInfo" and "qsThreadInfo" packets), and also helps us keep the current process state up to date.
llvm-svn: 154380
The next step is to have our stop reply packets send the thread list in the actual stop reply packet to avoid a 2 packet overhead of sending the qfThreadInfo + response and qfThreadInfo + response.
llvm-svn: 154376
The current ProcessGDBRemote function that updates the threads could end up with an empty list if any other thread had the sequence mutex. We now don't clear the thread list when we can't access it, and we also have changed how lldb_private::Process handles the return code from the:
virtual bool
Process::UpdateThreadList (lldb_private::ThreadList &old_thread_list,
lldb_private::ThreadList &new_thread_list) = 0;
A bool is now returned to indicate if the list was actually updated or not and the lldb_private::Process class will only update the stop ID of the validity of the thread list if "true" is returned.
The ProcessGDBRemote also got an extra assertion that will hopefully assert when running debug builds so we can find the source of this issue.
llvm-svn: 154365
spin up a temporary "private state thread" that will respond to events from the lower level process plugins. This check-in should work to do
that, but it is still buggy. However, if you don't call functions on the private state thread, these changes make no difference.
This patch also moves the code in the AppleObjCRuntime step-through-trampoline handler that might call functions (in the case where the debug
server doesn't support the memory allocate/deallocate packet) out to a safe place to do that call.
llvm-svn: 154230
<rdar://problem/11051056>
Found a race condition when sending async packets in the ProcessGDBRemote.
A little background: GDB remote clients can only send one packet at a time. You must send a packet and wait for a response. So when we continue, we obviously can't hold up the calling thread waiting for the process to stop again, so we have an async thread in the ProcessGDBRemote whose only job is to run packets that control the inferior process. When you send a continue packet, the only packet you can send is an interrupt packet (which consists of sending a CTRL+C (or a '\x03' byte)). This then stops the inferior and we can send the async packet, and then resume the target. There was a race condition that often happened during stepping where we are doing a source level single step which consists of many instruction steps and a few runs here and there when we step into a function. So the flow looks like:
inst single step
inst single step
inst single step
inst single step
inst single step
step BP and run
inst single step
inst single step
inst single step
Now if we got an async packet while the program is running we get something like:
send --> continue
send --> interrupt
recv <-- interrupt stop reply packet
send --> async packet
recv <-- async response
send --> continue again and wait for actual stop
Problems arise when this was happening when single stepping a thread where we would get:
send --> step thread 123
send --> interrupt
send --> stop reply for thread 123 (from the step)
Now we _might_ have an extra stop reply packet from the "interrupt" which we weren't checking for and we could end up with:
send --> async packet (like memory read!)
recv <-- async response (which is the interrupt stop reply packet)
Now we have the read memroy reply sitting in our buffer and waiting to be used as the reply for the next packet...
To further complicate things, the single step should have exited the async thread since the run control is finished, but now it will continue if it was interrupted.
The fixes I checked in to two major things:
- watch for the extra stop reply if we need to
- make sure we exit from the async thread run loop when the previous run control (like the instruction level single step) is finished.
Needless to say this makes very fast stepping in Xcode much more reliable.
llvm-svn: 153629
This fix really needed to happen as a previous fix I had submitted for
calculating symbol sizes made many symbols appear to have zero size since
the function that was calculating the symbol size was calling another function
that would cause the calculation to happen again. This resulted in some symbols
having zero size when they shouldn't. This could then cause infinite stack
traces and many other side affects.
llvm-svn: 152244
Fixed STDERR to not be opened as readable. Also cleaned up some of the code that implemented the file actions as some of the code was using the wrong variables, they now use the right ones (in for stdin, out for stdout, err for stderr).
llvm-svn: 152102
which require a valid CFA address to create a stack frame. On connecting
to just-starting-up hardware we may have a stack pointer/frame pointer of 0
but we should still create a stack frame so other code in lldb can retrieve
register values via a stackframe.
llvm-svn: 151796
Incremental check in to calculate the offsets of registers correctly. Registers can be primordial or composite,
for example, r0-r12 are primordial, s0-s31 are primordial, while q0 is composite consisting of (s0, s1, s2, s3).
Modify q0-q8 to be composed of the primordial s0-s31 registers.
llvm-svn: 151757
an unwind because RegisterContextLLDB::InitializeZerothFrame() would
create a minimal stack frame to fetch the pc value of the current
instruction. This proved fragile when another section of code was
trying to create the first stack frame and UnwindLLDB called
RegisterContextLLDB which tried to create its minimal stack frame.
Instead, get the live RegisterContext, retrieve the pc value from
the registers, and create an Address object from that.
llvm-svn: 151714
