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.
The existing algorithm was performing the following comparisons for an
`aaa,bbb,ccc,ddd`:
aaa\0bbb,ccc,ddd == "stack"
aaa\0bbb\0ccc,ddd == "stack"
aaa\0bbb\0ccc\0ddd == "stack"
Which wouldn't work. This commit just dispatches to a known algorithm
implementation.
This PR is in reference to porting LLDB on AIX.
Link to discussions on llvm discourse and github:
1. https://discourse.llvm.org/t/port-lldb-to-ibm-aix/80640
2. #101657
The complete changes for porting are present in this draft PR:
https://github.com/llvm/llvm-project/pull/102601
The changes on this PR are intended to avoid namespace collision for
certain typedefs between lldb and other platforms:
1. tid_t --> lldb::tid_t
2. offset_t --> lldb::offset_t
This fixes https://github.com/llvm/llvm-project/issues/56125 and
https://github.com/vadimcn/codelldb/issues/666, as well as the
downstream issue in our binary ninja debugger:
https://github.com/Vector35/debugger/issues/535
Basically, lldb does not claim to support the `swbreak` packet so the
gdbserver would not use it. As a result, the gdbserver always sends the
unmodified program counter value which, on systems like x86, causes the
program counter to be off-by-one (or otherwise wrong). For reference,
the lldb-server always sends the modified program counter value so it
works perfectly with lldb.
https://sourceware.org/gdb/current/onlinedocs/gdb.html/Stop-Reply-Packets.html#swbreak-stop-reason
No new code is added to add support `swbreak`, since the way lldb works
already expects the remote to have adjusted the program counter. The
change just lets the gdbserver know that lldb supports it, so that it
will send the adjusted program counter.
To test this PR, you can use lldb to connect to a gdbserver running on
e.g., Ubuntu 22.04, and see the program counter is off-by-one without
the patch. With the patch, things work as expected
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>
MAX_PATH is definitely larger than 6 bytes we are expecting for this
message, and could be rather large depending on the target OS (4K for
some Linux OSs).
Since the buffer gets allocated on the stack we better be conservative
and allocate what we actually need.
This reverts commit 05f0e86cc895181b3d2210458c78938f83353002.
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
TestPlatformLaunchGDBServer.py runs `ldb-server` w/o parameters
`--min-gdbserver-port`, `--max-gdbserver-port` or `--gdbserver-port`. So
`gdbserver_portmap` is empty and
`gdbserver_portmap.GetNextAvailablePort()` will return 0. Do not call
`portmap_for_child.AllowPort(0)` in this case. Otherwise
`portmap_for_child.GetNextAvailablePort()` will allocate and never free
the port 0 and next call `portmap_for_child.GetNextAvailablePort()` will
fail.
Added few asserts in `GDBRemoteCommunicationServerPlatform::PortMap` to
avoid such issue in the future.
This patch fixes a bug added in #88845. The behaviour is very close to
#97537 w/o parameters `--min-gdbserver-port`, `--max-gdbserver-port` and
`--gdbserver-port`.
This enables XML output for enums and adds enums for 2 fields on AArch64
Linux:
* mte_ctrl.tcf, which controls how tag faults are delivered.
* fpcr.rmode, which sets the rounding mode for floating point
operations.
The other one we could do is cpsr.btype, but it is not clear what would
be useful here so I'm not including it in this change.
This reverts commit d9e659c538516036e40330b6a98160cbda4ff100.
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.
Fixes#92541
When e69a3d18f48bc0d81b5dd12e735a2ec898ce64d added fallback register
layouts, it assumed that the choices were target XML with registers, or
no target XML at all.
In the linked issue, a user has a debug stub that does have target XML,
but it's missing register information.
This caused us to finalize the register information using an empty set
of registers got from target XML, then fail an assert when we attempted
to add the fallback set. Since we think we've already completed the
register information.
This change adds a check to prevent that first call and expands the
existing tests to check each architecture without target XML and with
target XML missing register information.
This teaches lldb to parse the enum XML elements sent by lldb-server,
and make use of the information in `register read` and `register info`.
The format is described in
https://sourceware.org/gdb/current/onlinedocs/gdb.html/Enum-Target-Types.html.
The target XML parser will drop any invalid enum or evalue. If we find
multiple evalue for the same value, we will use the last one we find.
The order of evalues from the XML is preserved as there may be good
reason they are not in numerical order.
The `else if` condition for checking `m_compression_type` is redundant
as it matches with a previous `if` condition, making the expression
always false. Reported by cppcheck as a possible cut-and-paste error.
Caught by cppcheck -
lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp:543:35:
style: Expression is always false because 'else if' condition matches
previous condition at line 535. [multiCondition]
Fix#91222
Currently, GDBRemoteCommunicationServerLLGS::Handle_qfThreadInfo asserts
if the number of processes under debug isn’t 1 and the multiprocess
feature isn’t supported. This is so that we don't string IDs of threads
belonging to different processes together without including the IDs of
the processes themselves in the response when there are multiple
processes under debug. However, it’s conceivable that we have no process
under debug and the multiprocess feature isn’t supported. So, have
GDBRemoteCommunicationServerLLGS::Handle_qfThreadInfo assert if the
number of processes under debug is greater than 1 and the multiprocess
feature isn’t supported.
This PR adds a check within `PutFile` to exit early when both local and
destination files have matching MD5 hashes. If they differ, or there is
trouble getting the hashes, the regular code path to put the file is
run.
As I needed this to talk to an `lldb-server` which runs the gdb-remote
protocol, I enabled `CalculateMD5` within `Platform/gdb-server` and also
found and fixed a parsing bug within it as well. Before this PR, the
client is incorrectly parsing the response packet containing the
checksum; after this PR, hopefully this is fixed. There is a test for
the parsing behavior included in this PR.
---------
Co-authored-by: Anthony Ha <antha@microsoft.com>
AddressableBits is in the Utility module of LLDB. It currently directly
refers to Process, which is from the Target LLDB module. This is a
layering violation which concretely means that it is impossible to link
anything that uses Utility without it also using Target as well. This is
generally not an issue for LLDB (since everything is built together) but
it may make it difficult to write unit tests for AddressableBits later
on.
We got user reporting lldb crash while the debuggee is calling vfork()
concurrently from multiple threads.
The crash happens because the current implementation can only handle
single vfork, vforkdone protocol transaction.
This diff fixes the crash by lldb-server storing forked debuggee's <pid,
tid> pair in jstopinfo which will be decoded by lldb client to create
StopInfoVFork for follow parent/child policy. Each StopInfoVFork will
later have a corresponding vforkdone packet. So the patch also changes
the `m_vfork_in_progress` to be reference counting based.
Two new test cases are added which crash/assert without the changes in
this patch.
---------
Co-authored-by: jeffreytan81 <jeffreytan@fb.com>
Partly, there's just a lot of unnecessary boiler plate. It's also
possible to define combinations of arguments that make no sense (e.g.
eArgRepeatPlus followed by eArgRepeatPlain...) but these are never
checked since we just push_back directly into the argument definitions.
This commit is step 1 of this cleanup - do the obvious stuff. In it, all
the simple homogenous argument lists and the breakpoint/watchpoint
ID/Range types, are set with common functions. This is an NFC change, it
just centralizes boiler plate. There's no checking yet because you can't
get a single argument wrong.
The end goal is that all argument definition goes through functions and
m_arguments is hidden so that you can't define inconsistent argument
sets.
This is next in my series of "fix the racey tests that fail on
greendragon" addressing the failure of TestConcurrentManyBreakpoints.py
where we set a breakpoint in a function that 100 threads execute, and we
check that we hit the breakpoint 100 times. But sometimes it is only hit
99 times, and the test fails.
When we hit a software breakpoint, the pc value for the thread is the
address of the breakpoint instruction - as if it had not been hit yet.
And because a user might ADD a breakpoint for the current pc from the
commandline, when we go to resume execution, any thread that is sitting
at a breakpoint site will be silently advanced past the breakpoint
instruction (disable bp, instruction step that thread, re-enable bp)
before resuming -- whether that thread has hit its breakpoint or not.
What this test is exposing is that there is another corner case, a
thread that is sitting at a breakpoint site but has not yet executed the
breakpoint instruction. The thread will have no stop reason, no mach
exception, so it will not be recorded as having hit the breakpoint
(because it hasn't yet). But when we resume execution, because it is
sitting at a breakpoint site, we advance past it and miss the breakpoint
hit.
In 2016 Abhishek Aggarwal handled a similar issue with a patch in
`ProcessGDBRemote::SetThreadStopInfo()`, adding a breakpoint StopInfo
for a thread sitting at a breakpoint site that has no stop reason.
debugserver's `jThreadsInfo` would not correctly execute Abhishek's code
though because it would respond with `"reason":"none"` for a thread with
no stop reason, and `SetThreadStopInfo()` expected an empty reason here.
The first part of my patch is to clear the `reason` if it is `"none"` so
we flow through the code correctly.
On Darwin, though, our stop reply packet (Txx...) includes the
`threads`, `thread-pcs`, and `jstopinfo` keys, which give us the tids
for all current threads, the pc values for those threads, and
`jstopinfo` has a JSON dictionary with the mach exceptions for all
threads that have a mach exception. In
`ProcessGDBRemote::CalculateThreadStopInfo()` we set the StopInfo for
each thread for a private stop and if we have `jstopinfo` it is the
source of all the StopInfos. I have to add the same logic here, to give
the thread a breakpoint StopInfo even though it hasn't executed the
breakpoint yet. In this case we are very early in thread construction
and I only have the information in the Txx stop reply packet -- tids,
pcs, and jstopinfo, so I can't use the normal general mechanisms of
going through the RegisterContext to get the pc, it's a bit different.
If I hack debugserver to not issue `jstopinfo`,
`CalculateThreadStopInfo` will fall back to sending `qThreadStopInfo`
for each thread and going through
`ProcessGDBRemote::SetThreadStopInfo()` to set the stop infos (and with
the `reason:none` fix, use Abhishek's code).
rdar://110549165
debugserver on arm64 devices can manage both Byte Address Select
watchpoints (1-8 bytes) and MASK watchpoints (8 bytes-2 gigabytes). This
adds a SupportedWatchpointTypes key to the QSupported response from
debugserver with a list of these, so lldb can take full advantage of
them when creating larger regions with a single hardware watchpoint.
Also add documentation for this, and two other lldb extensions, to the
lldb-gdb-remote.txt documentation.
Re-enable TestLargeWatchpoint.py on Darwin systems when testing with the
in-tree built debugserver. I can remove the "in-tree built debugserver"
in the future when this new key is handled by an Xcode debugserver.
This patch is the next piece of work in my Large Watchpoint proposal,
https://discourse.llvm.org/t/rfc-large-watchpoint-support-in-lldb/72116
This patch breaks a user's watchpoint into one or more
WatchpointResources which reflect what the hardware registers can cover.
This means we can watch objects larger than 8 bytes, and we can watched
unaligned address ranges. On a typical 64-bit target with 4 watchpoint
registers you can watch 32 bytes of memory if the start address is
doubleword aligned.
Additionally, if the remote stub implements AArch64 MASK style
watchpoints (e.g. debugserver on Darwin), we can watch any power-of-2
size region of memory up to 2GB, aligned to that same size.
I updated the Watchpoint constructor and CommandObjectWatchpoint to
create a CompilerType of Array<UInt8> when the size of the watched
region is greater than pointer-size and we don't have a variable type to
use. For pointer-size and smaller, we can display the watched granule as
an integer value; for larger-than-pointer-size we will display as an
array of bytes.
I have `watchpoint list` now print the WatchpointResources used to
implement the watchpoint.
I added a WatchpointAlgorithm class which has a top-level static method
that takes an enum flag mask WatchpointHardwareFeature and a user
address and size, and returns a vector of WatchpointResources covering
the request. It does not take into account the number of watchpoint
registers the target has, or the number still available for use. Right
now there is only one algorithm, which monitors power-of-2 regions of
memory. For up to pointer-size, this is what Intel hardware supports.
AArch64 Byte Address Select watchpoints can watch any number of
contiguous bytes in a pointer-size memory granule, that is not currently
supported so if you ask to watch bytes 3-5, the algorithm will watch the
entire doubleword (8 bytes). The newly default "modify" style means we
will silently ignore modifications to bytes outside the watched range.
I've temporarily skipped TestLargeWatchpoint.py for all targets. It was
only run on Darwin when using the in-tree debugserver, which was a proxy
for "debugserver supports MASK watchpoints". I'll be adding the
aforementioned feature flag from the stub and enabling full mask
watchpoints when a debugserver with that feature is enabled, and
re-enable this test.
I added a new TestUnalignedLargeWatchpoint.py which only has one test
but it's a great one, watching a 22-byte range that is unaligned and
requires four 8-byte watchpoints to cover.
I also added a unit test, WatchpointAlgorithmsTests, which has a number
of simple tests against WatchpointAlgorithms::PowerOf2Watchpoints. I
think there's interesting possible different approaches to how we cover
these; I note in the unit test that a user requesting a watch on address
0x12e0 of 120 bytes will be covered by two watchpoints today, a
128-bytes at 0x1280 and at 0x1300. But it could be done with a 16-byte
watchpoint at 0x12e0 and a 128-byte at 0x1300, which would have fewer
false positives/private stops. As we try refining this one, it's helpful
to have a collection of tests to make sure things don't regress.
I tested this on arm64 macOS, (genuine) x86_64 macOS, and AArch64
Ubuntu. I have not modifed the Windows process plugins yet, I might try
that as a standalone patch, I'd be making the change blind, but the
necessary changes (see ProcessGDBRemote::EnableWatchpoint) are pretty
small so it might be obvious enough that I can change it and see what
the Windows CI thinks.
There isn't yet a packet (or a qSupported feature query) for the gdb
remote serial protocol stub to communicate its watchpoint capabilities
to lldb. I'll be doing that in a patch right after this is landed,
having debugserver advertise its capability of AArch64 MASK watchpoints,
and have ProcessGDBRemote add eWatchpointHardwareArmMASK to
WatchpointAlgorithms so we can watch larger than 32-byte requests on
Darwin.
I haven't yet tackled WatchpointResource *sharing* by multiple
Watchpoints. This is all part of the goal, especially when we may be
watching a larger memory range than the user requested, if they then add
another watchpoint next to their first request, it may be covered by the
same WatchpointResource (hardware watchpoint register). Also one "read"
watchpoint and one "write" watchpoint on the same memory granule need to
be handled, making the WatchpointResource cover all requests.
As WatchpointResources aren't shared among multiple Watchpoints yet,
there's no handling of running the conditions/commands/etc on multiple
Watchpoints when their shared WatchpointResource is hit. The goal beyond
"large watchpoint" is to unify (much more) the Watchpoint and Breakpoint
behavior and commands. I have a feeling I may be slowly chipping away at
this for a while.
Re-landing this patch after fixing two undefined behaviors in
WatchpointAlgorithms found by UBSan and by failures on different
CI bots.
rdar://108234227
This patch is the next piece of work in my Large Watchpoint proposal,
https://discourse.llvm.org/t/rfc-large-watchpoint-support-in-lldb/72116
This patch breaks a user's watchpoint into one or more
WatchpointResources which reflect what the hardware registers can cover.
This means we can watch objects larger than 8 bytes, and we can watched
unaligned address ranges. On a typical 64-bit target with 4 watchpoint
registers you can watch 32 bytes of memory if the start address is
doubleword aligned.
Additionally, if the remote stub implements AArch64 MASK style
watchpoints (e.g. debugserver on Darwin), we can watch any power-of-2
size region of memory up to 2GB, aligned to that same size.
I updated the Watchpoint constructor and CommandObjectWatchpoint to
create a CompilerType of Array<UInt8> when the size of the watched
region is greater than pointer-size and we don't have a variable type to
use. For pointer-size and smaller, we can display the watched granule as
an integer value; for larger-than-pointer-size we will display as an
array of bytes.
I have `watchpoint list` now print the WatchpointResources used to
implement the watchpoint.
I added a WatchpointAlgorithm class which has a top-level static method
that takes an enum flag mask WatchpointHardwareFeature and a user
address and size, and returns a vector of WatchpointResources covering
the request. It does not take into account the number of watchpoint
registers the target has, or the number still available for use. Right
now there is only one algorithm, which monitors power-of-2 regions of
memory. For up to pointer-size, this is what Intel hardware supports.
AArch64 Byte Address Select watchpoints can watch any number of
contiguous bytes in a pointer-size memory granule, that is not currently
supported so if you ask to watch bytes 3-5, the algorithm will watch the
entire doubleword (8 bytes). The newly default "modify" style means we
will silently ignore modifications to bytes outside the watched range.
I've temporarily skipped TestLargeWatchpoint.py for all targets. It was
only run on Darwin when using the in-tree debugserver, which was a proxy
for "debugserver supports MASK watchpoints". I'll be adding the
aforementioned feature flag from the stub and enabling full mask
watchpoints when a debugserver with that feature is enabled, and
re-enable this test.
I added a new TestUnalignedLargeWatchpoint.py which only has one test
but it's a great one, watching a 22-byte range that is unaligned and
requires four 8-byte watchpoints to cover.
I also added a unit test, WatchpointAlgorithmsTests, which has a number
of simple tests against WatchpointAlgorithms::PowerOf2Watchpoints. I
think there's interesting possible different approaches to how we cover
these; I note in the unit test that a user requesting a watch on address
0x12e0 of 120 bytes will be covered by two watchpoints today, a
128-bytes at 0x1280 and at 0x1300. But it could be done with a 16-byte
watchpoint at 0x12e0 and a 128-byte at 0x1300, which would have fewer
false positives/private stops. As we try refining this one, it's helpful
to have a collection of tests to make sure things don't regress.
I tested this on arm64 macOS, (genuine) x86_64 macOS, and AArch64
Ubuntu. I have not modifed the Windows process plugins yet, I might try
that as a standalone patch, I'd be making the change blind, but the
necessary changes (see ProcessGDBRemote::EnableWatchpoint) are pretty
small so it might be obvious enough that I can change it and see what
the Windows CI thinks.
There isn't yet a packet (or a qSupported feature query) for the gdb
remote serial protocol stub to communicate its watchpoint capabilities
to lldb. I'll be doing that in a patch right after this is landed,
having debugserver advertise its capability of AArch64 MASK watchpoints,
and have ProcessGDBRemote add eWatchpointHardwareArmMASK to
WatchpointAlgorithms so we can watch larger than 32-byte requests on
Darwin.
I haven't yet tackled WatchpointResource *sharing* by multiple
Watchpoints. This is all part of the goal, especially when we may be
watching a larger memory range than the user requested, if they then add
another watchpoint next to their first request, it may be covered by the
same WatchpointResource (hardware watchpoint register). Also one "read"
watchpoint and one "write" watchpoint on the same memory granule need to
be handled, making the WatchpointResource cover all requests.
As WatchpointResources aren't shared among multiple Watchpoints yet,
there's no handling of running the conditions/commands/etc on multiple
Watchpoints when their shared WatchpointResource is hit. The goal beyond
"large watchpoint" is to unify (much more) the Watchpoint and Breakpoint
behavior and commands. I have a feeling I may be slowly chipping away at
this for a while.
rdar://108234227
There are 3 ways to create an EventDataBytes object: (const char *),
(llvm::StringRef), and (const void *, size_t len). All of these cases
can be handled under `llvm::StringRef`. Additionally, this allows us to
remove the otherwise unused `SetBytes`, `SwapBytes`, and
`SetBytesFromCString` methods.
BroadcastEvent currently takes its EventData* param and shoves it into
an Event object, which takes ownership of the pointer and places it into
a shared_ptr to manage the lifetime.
Instead of relying on `new` and passing raw pointers around, I think it
would make more sense to create the shared_ptr up front.
This patch replaces uses of StringRef::{starts,ends}with with
StringRef::{starts,ends}_with for consistency with
std::{string,string_view}::{starts,ends}_with in C++20.
I'm planning to deprecate and eventually remove
StringRef::{starts,ends}with.
We need to generate events when finalizing, or we won't know that we
succeeded in stopping the process to detach/kill. Instead, we stall and
then after our 20 interrupt timeout, we kill the process (even if we
were supposed to detach) and exit.
OTOH, we have to not generate events when the Process is being
destructed because shared_from_this has already been torn down, and
using it will cause crashes.
This patch is rearranging code a bit to add WatchpointResources to
Process. A WatchpointResource is meant to represent a hardware
watchpoint register in the inferior process. It has an address, a size,
a type, and a list of Watchpoints that are using this
WatchpointResource.
This current patch doesn't add any of the features of
WatchpointResources that make them interesting -- a user asking to watch
a 24 byte object could watch this with three 8 byte WatchpointResources.
Or a Watchpoint on 1 byte at 0x1002 and a second watchpoint on 1 byte at
0x1003, these must both be served by a single WatchpointResource on that
doubleword at 0x1000 on a 64-bit target, if two hardware watchpoint
registers were used to track these separately, one of them may not be
hit. Or if you have one Watchpoint on a variable with a condition set,
and another Watchpoint on that same variable with a command defined or
different condition, or ignorecount, both of those Watchpoints need to
evaluate their criteria/commands when their WatchpointResource has been
hit.
There's a bit of code movement to rearrange things in the direction I'll
need for implementing this feature, so I want to start with reviewing &
landing this mostly NFC patch and we can focus on the algorithmic
choices about how WatchpointResources are shared and handled as they're
triggeed, separately.
This patch also stops printing "Watchpoint <n> hit: old value: <x>, new
vlaue: <y>" for Read watchpoints. I could make an argument for print
"Watchpoint <n> hit: current value <x>" but the current output doesn't
make any sense, and the user can print the value if they are
particularly interested. Read watchpoints are used primarily to
understand what code is reading a variable.
This patch adds more fallbacks for how to print the objects being
watched if we have types, instead of assuming they are all integral
values, so a struct will print its elements. As large watchpoints are
added, we'll be doing a lot more of those.
To track the WatchpointSP in the WatchpointResources, I changed the
internal API which took a WatchpointSP and devolved it to a Watchpoint*,
which meant touching several different Process files. I removed the
watchpoint code in ProcessKDP which only reported that watchpoints
aren't supported, the base class does that already.
I haven't yet changed how we receive a watchpoint to identify the
WatchpointResource responsible for the trigger, and identify all
Watchpoints that are using this Resource to evaluate their conditions
etc. This is the same work that a BreakpointSite needs to do when it has
been tiggered, where multiple Breakpoints may be at the same address.
There is not yet any printing of the Resources that a Watchpoint is
implemented in terms of ("watchpoint list", or
SBWatchpoint::GetDescription).
"watchpoint set var" and "watchpoint set expression" take a size
argument which was previously 1, 2, 4, or 8 (an enum). I've changed this
to an unsigned int. Most hardware implementations can only watch 1, 2,
4, 8 byte ranges, but with Resources we'll allow a user to ask for
different sized watchpoints and set them in hardware-expressble terms
soon.
I've annotated areas where I know there is work still needed with
LWP_TODO that I'll be working on once this is landed.
I've tested this on aarch64 macOS, aarch64 Linux, and Intel macOS.
https://discourse.llvm.org/t/rfc-large-watchpoint-support-in-lldb/72116
(cherry picked from commit fc6b72523f3d73b921690a713e97a433c96066c6)
Currently when you interrupt a:
(lldb) process attach -w -n some_process
lldb just closes the connection to the stub and kills the
lldb_private::Process it made for the attach. The stub at the other end
notices the connection go down and exits because of that. But when
communication to a device is handled through some kind of proxy server
which isn't as well behaved as one would wish, that signal might not be
reliable, causing debugserver to persist on the machine, waiting to
steal the next instance of that process.
We can work around those failures by sending an explicit interrupt
before closing down the connection. The stub will also have to be
waiting for the interrupt for this to make any difference. I changed
debugserver to do that.
I didn't make the equivalent change in lldb-server. So long as you
aren't faced with a flakey connection, this should not be necessary.
...and follow ups.
As it has caused test failures on Linux Arm and AArch64:
https://lab.llvm.org/buildbot/#/builders/96/builds/49126https://lab.llvm.org/buildbot/#/builders/17/builds/45824
```
lldb-shell :: Subprocess/clone-follow-child-wp.test
lldb-shell :: Subprocess/fork-follow-child-wp.test
lldb-shell :: Subprocess/vfork-follow-child-wp.test
```
This reverts commit a6c62bf1a4717accc852463b664cd1012237d334,
commit a0a1ff3ab40e347589b4e27d8fd350c600526735 and commit
fc6b72523f3d73b921690a713e97a433c96066c6.
This patch is rearranging code a bit to add WatchpointResources to
Process. A WatchpointResource is meant to represent a hardware
watchpoint register in the inferior process. It has an address, a size,
a type, and a list of Watchpoints that are using this
WatchpointResource.
This current patch doesn't add any of the features of
WatchpointResources that make them interesting -- a user asking to watch
a 24 byte object could watch this with three 8 byte WatchpointResources.
Or a Watchpoint on 1 byte at 0x1002 and a second watchpoint on 1 byte at
0x1003, these must both be served by a single WatchpointResource on that
doubleword at 0x1000 on a 64-bit target, if two hardware watchpoint
registers were used to track these separately, one of them may not be
hit. Or if you have one Watchpoint on a variable with a condition set,
and another Watchpoint on that same variable with a command defined or
different condition, or ignorecount, both of those Watchpoints need to
evaluate their criteria/commands when their WatchpointResource has been
hit.
There's a bit of code movement to rearrange things in the direction I'll
need for implementing this feature, so I want to start with reviewing &
landing this mostly NFC patch and we can focus on the algorithmic
choices about how WatchpointResources are shared and handled as they're
triggeed, separately.
This patch also stops printing "Watchpoint <n> hit: old value: <x>, new
vlaue: <y>" for Read watchpoints. I could make an argument for print
"Watchpoint <n> hit: current value <x>" but the current output doesn't
make any sense, and the user can print the value if they are
particularly interested. Read watchpoints are used primarily to
understand what code is reading a variable.
This patch adds more fallbacks for how to print the objects being
watched if we have types, instead of assuming they are all integral
values, so a struct will print its elements. As large watchpoints are
added, we'll be doing a lot more of those.
To track the WatchpointSP in the WatchpointResources, I changed the
internal API which took a WatchpointSP and devolved it to a Watchpoint*,
which meant touching several different Process files. I removed the
watchpoint code in ProcessKDP which only reported that watchpoints
aren't supported, the base class does that already.
I haven't yet changed how we receive a watchpoint to identify the
WatchpointResource responsible for the trigger, and identify all
Watchpoints that are using this Resource to evaluate their conditions
etc. This is the same work that a BreakpointSite needs to do when it has
been tiggered, where multiple Breakpoints may be at the same address.
There is not yet any printing of the Resources that a Watchpoint is
implemented in terms of ("watchpoint list", or
SBWatchpoint::GetDescription).
"watchpoint set var" and "watchpoint set expression" take a size
argument which was previously 1, 2, 4, or 8 (an enum). I've changed this
to an unsigned int. Most hardware implementations can only watch 1, 2,
4, 8 byte ranges, but with Resources we'll allow a user to ask for
different sized watchpoints and set them in hardware-expressble terms
soon.
I've annotated areas where I know there is work still needed with
LWP_TODO that I'll be working on once this is landed.
I've tested this on aarch64 macOS, aarch64 Linux, and Intel macOS.
https://discourse.llvm.org/t/rfc-large-watchpoint-support-in-lldb/72116
The Watchpoint and Breakpoint objects try to track the hardware index
that was used for them, if they are hardware wp/bp's. The majority of
our debugging goes over the gdb remote serial protocol, and when we set
the watchpoint/breakpoint, there is no (standard) way for the remote
stub to communicate to lldb which hardware index was used. We have an
lldb-extension packet to query the total number of watchpoint registers.
When a watchpoint is hit, there is an lldb extension to the stop reply
packet (documented in lldb-gdb-remote.txt) to describe the watchpoint
including its actual hardware index,
<addr within wp range> <wp hw index> <actual accessed address>
(the third field is specifically needed for MIPS). At this point, if the
stub reported these three fields (the stub is only required to provide
the first), we can know the actual hardware index for this watchpoint.
Breakpoints are worse; there's never any way for us to be notified about
which hardware index was used. Breakpoints got this as a side effect of
inherting from StoppointSite with Watchpoints.
We expose the watchpoint hardware index through "watchpoint list -v" and
through SBWatchpoint::GetHardwareIndex.
With my large watchpoint support, there is no *single* hardware index
that may be used for a watchpoint, it may need multiple resources. Also
I don't see what a user is supposed to do with this information, or an
IDE. Knowing the total number of watchpoint registers on the target, and
knowing how many Watchpoint Resources are currently in use, is helpful.
Knowing how many Watchpoint Resources
a single user-specified watchpoint needed to be implemented is useful.
But knowing which registers were used is an implementation detail and
not available until we hit the watchpoint when using gdb remote serial
protocol.
So given all that, I'm removing watchpoint hardware index numbers. I'm
changing the SB API to always return -1.
Similar to my previous patch (#71613) where I changed
`GetItemAtIndexAsString`, this patch makes the same change to
`GetItemAtIndexAsDictionary`.
`GetItemAtIndexAsDictionary` now returns a std::optional that is either
`std::nullopt` or is a valid pointer. Therefore, if the optional is
populated, we consider the pointer to always be valid (i.e. no need to
check pointer validity).
This removes AArch64 specific code from the GDB* classes.
To do this I've added 2 new methods to Architecture:
* RegisterWriteCausesReconfigure to check if what you are about to do
will trash the register info.
* ReconfigureRegisterInfo to do the reconfiguring. This tells you if
anything changed so that we only invalidate registers when needed.
So that ProcessGDBRemote can call ReconfigureRegisterInfo in
SetThreadStopInfo,
I've added forwarding calls to GDBRemoteRegisterContext and the base
class
RegisterContext.
(which removes a slightly sketchy static cast as well)
RegisterContext defaults to doing nothing for both the methods
so anything other than GDBRemoteRegisterContext will do nothing.
This completes the conversion of LocateSymbolFile into a SymbolLocator
plugin. The only remaining function is DownloadSymbolFileAsync which
doesn't really fit into the plugin model, and therefore moves into the
SymbolLocator class, while still relying on the plugins to do the
underlying work.
