lldb-server had limited support for single-stepping through the lr/sc
atomic sequence. This patch enhances that support for all possible
atomic sequences.
The previous version contained an incorrect regex pattern in the test,
causing the riscv-specific test to run on other platforms. This reland
fixes the regex (see lldb/test/API/riscv/step/TestSoftwareStep.py)
lldb-server had limited support for single-stepping through the lr/sc
atomic sequence. This patch enhances that support for all possible
atomic sequences.
lldb-server built with NativeProcessLinux.cpp and
NativeProcessFreeBSD.cpp can use breakpoints to implement instruction
stepping on cores where there is no native instruction-step primitive.
Currently these set a breakpoint, continue, and if we hit the breakpoint
with the original thread, set the stop reason to be "trace".
I am wrapping up a change to lldb's breakpoint algorithm where I change
its current behavior of
"if a thread stops at a breakpoint site, we set
the thread's stop reason to breakpoint-hit, even if the breakpoint
hasn't been executed" +
"when resuming any thread at a breakpoint site, instruction-step past
the breakpoint before resuming"
to a behavior of
"when a thread executes a breakpoint, set the stop reason to
breakpoint-hit" +
"when a thread has hit a breakpoint, when the thread resumes, we
silently step past the breakpoint and then resume the thread".
For these lldb-server targets doing breakpoint stepping, this means that
if we are sitting on a breakpoint that has not yet executed, and
instruction-step the thread, we will execute the breakpoint instruction
at $pc (instead of $next-pc where it meant to go), and stop again -- at
the same pc value. Then we will rewrite the stop reason to 'trace'. The
higher level logic will see that we haven't hit the breakpoint
instruction again, so it will try to instruction step again, hitting the
breakpoint again forever.
To fix this, I'm checking that the thread matches the one we are
instruction-stepping-by-breakpoint AND that we've stopped at the
breakpoint address we are stepping to. Only in that case will the stop
reason be rewritten to "trace" hiding the implementation detail that the
step was done by breakpoints.
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.
535da10842c7309e9eeaf9828cf6bb034fecaf16 introduced a check, when execve fails,
to see if we are allowed to trace programs at all.
Unfortunately because we like to call Status vars "error" and "status"
in various combinations, one got misnamed. This lead to lldb-server trying
to make an error value out of a success value when you did the following:
```
$ ./bin/lldb-server gdbserver 127.0.0.1:1234 -- is_not_a_file
Assertion failed: (Err && "Cannot create Expected<T> from Error success value."), function Expected...
```
This happened because the execve fails, but the check whether we can
trace says yes we can trace, but then we use the Status from the check
to create the return value. That Status is in fact a success value not
the failed Status we got from the execve attempt.
With the name corrected you now get:
```
$ ./bin/lldb-server gdbserver 127.0.0.1:1234 -- is_not_a_file
error: failed to launch 'is_not_a_file': execve failed: No such file or directory
```
Which is what we expect to see. This also fixes the test `TestGDBRemoteLaunch.py`
when asserts are enabled.
This is a follow-up to D116372, which had a rather unfortunate side
effect of making the processing of a single SIGCHLD quadratic in the
number of threads -- which does not matter for simple applications, but
can get really bad for applications with thousands of threads.
This patch fixes the problem by implementing the other possibility
mentioned in the first patch -- doing waitpid(-1) centrally and then
routing the events to the correct process instance. The "uncollected"
threads are held in the process factory class -- which I've renamed to
Manager for this purpose, as it now does more than creating processes.
Differential Revision: https://reviews.llvm.org/D146977
Do not send SIGSTOP when requested to halt a process that's already
stopped. This results in the signal being queued for delivery once
the process is resumed, and unexpectedly stopping it again.
This is necessary for non-stop protocol patches to land.
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.llvm.org/D126770
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
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
PT_COREDUMP is a relatively recent addition. Use an #ifdef to skip it
if the underlying system does not support it.
Differential Revision: https://reviews.llvm.org/D111214
Remove hardcoded platform list for QPassSignals, qXfer:auxv:read
and qXfer:libraries-svr4:read and instead query the process plugin
via the GetSupportedExtensions() API.
Differential Revision: https://reviews.llvm.org/D101241
The original commit was reverted because of the problems it introduced
on Linux. However, FreeBSD should not be affected, so restore that part
and we will address Linux separately.
While at it, remove the dbreg hack as the underlying issue has been
fixed in the FreeBSD kernel and the problem is unlikely to happen
in real life use anyway.
Differential Revision: https://reviews.llvm.org/D98822
This commit has caused the following tests to be flaky:
TestThreadSpecificBpPlusCondition.py
TestExitDuringExpression.py
The exact cause is not known yet, but since both tests deal with
threads, my guess is it has something to do with the tracking of
creation of new threads (which the commit touches upon).
This reverts the following commits:
d01bff8cbdc98fb8751f7bf10af19b47ae5c445d,
ba62ebc48e8c424ce3a78ba01acda679d536dd47,
e761b6b4c58d4f7ae1073d925d7cb321d68ee93a,
a345419ee03095c8cdfbe1c2728467c4da8fa0a4.
In all this time, we've never used more than one delegate. The logic to
support multiple delegates is therefore untested, and becomes
particularly unwieldy once we need to support multiple processes.
Just remove it.
Watch for fork(2)/vfork(2) (also fork/vfork-style clone(2) on Linux)
notifications and explicitly detach the forked child process, and add
initial tests for these cases. The code covers FreeBSD, Linux
and NetBSD process plugins. There is no new user-visible functionality
provided -- this change lays foundations over subsequent work on fork
support.
Differential Revision: https://reviews.llvm.org/D98822
Split out the common base of Linux hardware breakpoint/watchpoint
support for AArch64 into a Utility class, and use it to implement
the matching support on FreeBSD.
Differential Revision: https://reviews.llvm.org/D96548
Ensure that the llvm::Error instances are always considered handled
by replacing LLDB_LOG with LLDB_LOG_ERROR.
Differential Revision: https://reviews.llvm.org/D96558
