Fixes#68987
Early on we load the interpreter (most commonly ld-linux) in
LoadInterpreterModule. Then later when we get the first DYLD rendezvous
we get a list of libraries that commonly includes ld-linux again.
Previously we would load this duplicate, see that it was a duplicate,
and unload it.
Problem was that this unloaded the section information of the first copy
of ld-linux. On platforms where you can place a breakpoint using only an
address, this wasn't an issue.
On ARM you have ARM and Thumb modes. We must know which one the section
we're breaking in is, otherwise we'll go there in the wrong mode and
SIGILL. This happened on ARM when lldb tried to call mmap during
expression evaluation.
To fix this, I am making the assumption that the base address we see in
the module prior to loading can be compared with what we know the
interpreter base address is. Then we don't have to load the module to
know we can ignore it.
This fixes the lldb test suite on Ubuntu versions where
https://bugs.launchpad.net/ubuntu/+source/gdb/+bug/1927192 has been
fixed. Which was recently done on Jammy.
This patch implements the thread local storage support for linux
(https://github.com/llvm/llvm-project/issues/28766).
TLS feature is originally only implemented for Mac. With my previous
patch to enable `fs_base` register for Linux
(https://reviews.llvm.org/D155256), now it is feasible to implement this
feature for Linux.
The major changes are:
* Track the main module's link address during launch
* Fetch thread pointer from `fs_base` register
* Create register alias for thread pointer
* Read pthread metadata from target memory instead of process so that it
works for coredump
With the patch the failing test is passing now. Note: I am only enabling
this test for Mac and Linux because I do not have machine to test for
FreeBSD/NetBSD.
---------
Co-authored-by: jeffreytan81 <jeffreytan@fb.com>
Fixes#65157
07c215e8a8af54d0084af7291ac29fef3672fcd8 added some extra logging
which compiles ok with clang but not msvc. Use LLVM_PRETTY_FUNCTION
to fix that.
Fix suggested by Carlos Alberto Enciso.
We ran into a case where shared libraries would fail to load in some processes on linux. The issue turned out to be if the main executable or a shared library defined a symbol named "_r_debug", then it would cause problems once the executable that contained it was loaded into the process. The "_r_debug" structure is currently found by looking through the .dynamic section in the main executable and finding the DT_DEBUG entry which points to this structure. The dynamic loader will update this structure as shared libraries are loaded and LLDB watches the contents of this structure as the dyld breakpoint is hit. Currently we expect the "state" in this structure to change as things happen. An issue comes up if someone defines another "_r_debug" struct in their program:
```
r_debug _r_debug;
```
If this code is included, a new "_r_debug" structure is created and it causes problems once the executable is loaded. This is because of the way symbol lookups happen in linux: they use the shared library list in the order it created and the dynamic loader is always last. So at some point the dynamic loader will start updating this other copy of "_r_debug", yet LLDB is only watching the copy inside of the dynamic loader.
Steps that show the problem are:
- lldb finds the "_r_debug" structure via the DT_DEBUG entry in the .dynamic section and this points to the "_r_debug" in ld.so
- ld.so modifies its copy of "_r_debug" with "state = eAdd" before it loads the shared libraries and calls the dyld function that LLDB has set a breakpoint on and we find this state and do nothing (we are waiting for a state of eConsistent to tell us the shared libraries have been fully loaded)
- ld.so loads the main executable and any dependent shared libraries and wants to update the "_r_debug" structure, but it now finds "_r_debug" in the a.out program and updates the state in this other copy
- lldb hits the notification breakpoint and checks the ld.so copy of "_r_debug" which still has a state of "eAdd". LLDB wants the new "eConsistent" state which will trigger the shared libraries to load, but it gets stale data and doesn't do anyhing and library load is missed. The "_r_debug" in a.out has the state set correctly, but we don't know which "_r_debug" is the right one.
The new fix detects the two "eAdd" states and loads shared libraries and will emit a log message in the "log enable lldb dyld" log channel which states there might be multiple "_r_debug" structs.
The correct solution is that no one should be adding a duplicate "_r_debug" symbol to their binaries, but we have programs that are doing this already and since it can be done, we should be able to work with this and keep debug sessions working as expected. If a user #includes the <link.h> file, they can just use the existing "_r_debug" structure as it is defined in this header file as "extern struct r_debug _r_debug;" and no local copies need to be made.
If your ld.so has debug info, you can easily see the duplicate "_r_debug" structs by doing:
```
(lldb) target variable _r_debug --raw
(r_debug) _r_debug = {
r_version = 1
r_map = 0x00007ffff7e30210
r_brk = 140737349972416
r_state = RT_CONSISTENT
r_ldbase = 0
}
(r_debug) _r_debug = {
r_version = 1
r_map = 0x00007ffff7e30210
r_brk = 140737349972416
r_state = RT_ADD
r_ldbase = 140737349943296
}
(lldb) target variable &_r_debug
(r_debug *) &_r_debug = 0x0000555555601040
(r_debug *) &_r_debug = 0x00007ffff7e301e0
```
And if you do a "image lookup --address <addr>" in the addresses, you can see one is in the a.out and one in the ld.so.
Adding more logging to print out the m_previous and m_current Rendezvous structures to make things more clear. Also added a log when we detect multiple eAdd states in a row to detect this problem in logs.
Differential Revision: https://reviews.llvm.org/D158583
Re-lands 04aa943be8ed5c03092e2a90112ac638360ec253 with modifications
to fix tests.
I originally reverted this because it caused a test to fail on Linux.
The problem was that I inverted a condition on accident.
There are many situations where we'll iterate over a SymbolContextList
with the pattern:
```
SymbolContextList sc_list;
// Fill in sc_list here
for (auto i = 0; i < sc_list.GetSize(); i++) {
SymbolContext sc;
sc_list.GetSymbolAtContext(i, sc);
// Do work with sc
}
```
Adding an iterator to iterate over the instances directly means we don't
have to do bounds checking or create a copy of every element of the
SymbolContextList.
Differential Revision: https://reviews.llvm.org/D149900
Prior to this fix, no shared libraries would be loaded for a core file, even if they exist on the current machine. The issue was the DYLDRendezvous would read a DYLDRendezvous::Rendezvous from memory of the process in DYLDRendezvous::Resolve() which would read some ld.so structures as they existed in the middle of a process' lifetime. In core files we see, the DYLDRendezvous::Rendezvous::state would be set to eAdd for running processes. When ProcessELFCore.cpp would load the core file, it would call DynamicLoaderPOSIXDYLD::DidAttach(), which would call the above Rendezvous functions. The issue came when during the DidAttach function it call DYLDRendezvous::GetAction() which would return eNoAction if the DYLDRendezvous::m_current.state was read from memory as eAdd. This caused no shared libraries to be loaded for any ELF core files. We now detect if we have a core file and after reading the DYLDRendezvous::m_current.state from memory we set it to eConsistent, which causes DYLDRendezvous::GetAction() to return the correct action of eTakeSnapshot and shared libraries get loaded.
We also improve the DynamicLoaderPOSIXDYLD class to not try and set any breakpoints to catch shared library loads/unloads when we have a core file, which saves a bit of time.
Differential Revision: https://reviews.llvm.org/D134842
I went over the output of the following mess of a command:
(ulimit -m 2000000; ulimit -v 2000000; git ls-files -z | parallel
--xargs -0 cat | aspell list --mode=none --ignore-case | grep -E
'^[A-Za-z][a-z]*$' | sort | uniq -c | sort -n | grep -vE '.{25}' |
aspell pipe -W3 | grep : | cut -d' ' -f2 | less)
and proceeded to spend a few days looking at it to find probable typos
and fixed a few hundred of them in all of the llvm project (note, the
ones I found are not anywhere near all of them, but it seems like a
good start).
Differential revision: https://reviews.llvm.org/D131122
Resubmission of https://reviews.llvm.org/D130309 with the 2 patches that fixed the linux buildbot, and new windows fixes.
The FileSpec APIs allow users to modify instance variables directly by getting a non const reference to the directory and filename instance variables. This makes it impossible to control all of the times the FileSpec object is modified so we can clear cached member variables like m_resolved and with an upcoming patch caching if the file is relative or absolute. This patch modifies the APIs of FileSpec so no one can modify the directory or filename instance variables directly by adding set accessors and by removing the get accessors that are non const.
Many clients were using FileSpec::GetCString(...) which returned a unique C string from a ConstString'ified version of the result of GetPath() which returned a std::string. This caused many locations to use this convenient function incorrectly and could cause many strings to be added to the constant string pool that didn't need to. Most clients were converted to using FileSpec::GetPath().c_str() when possible. Other clients were modified to use the newly renamed version of this function which returns an actualy ConstString:
ConstString FileSpec::GetPathAsConstString(bool denormalize = true) const;
This avoids the issue where people were getting an already uniqued "const char *" that came from a ConstString only to put the "const char *" back into a "ConstString" object. By returning the ConstString instead of a "const char *" clients can be more efficient with the result.
The patch:
- Removes the non const GetDirectory() and GetFilename() get accessors
- Adds set accessors to replace the above functions: SetDirectory() and SetFilename().
- Adds ClearDirectory() and ClearFilename() to replace usage of the FileSpec::GetDirectory().Clear()/FileSpec::GetFilename().Clear() call sites
- Fixed all incorrect usage of FileSpec::GetCString() to use FileSpec::GetPath().c_str() where appropriate, and updated other call sites that wanted a ConstString to use the newly returned ConstString appropriately and efficiently.
Differential Revision: https://reviews.llvm.org/D130549
This reverts commit 9429b67b8e300e638d7828bbcb95585f85c4df4d.
It broke the build on Windows, see comments on https://reviews.llvm.org/D130309
It also reverts these follow-ups:
Revert "Fix buildbot breakage after https://reviews.llvm.org/D130309."
This reverts commit f959d815f4637890ebbacca379f1c38ab47e4e14.
Revert "Fix buildbot breakage after https://reviews.llvm.org/D130309."
This reverts commit 0bbce7a4c2d2bff622bdadd4323f93f5d90e6d24.
Revert "Cache the value for absolute path in FileSpec."
This reverts commit dabe877248b85b34878e75d5510339325ee087d0.
The FileSpect APIs allow users to modify instance variables directly by getting a non const reference to the directory and filename instance variables. This makes it impossibly to control all of the times the FileSpec object is modified so we can clear the cache. This patch modifies the APIs of FileSpec so no one can modify the directory or filename directly by adding set accessors and by removing the get accessors that are non const.
Many clients were using FileSpec::GetCString(...) which returned a unique C string from a ConstString'ified version of the result of GetPath() which returned a std::string. This caused many locations to use this convenient function incorrectly and could cause many strings to be added to the constant string pool that didn't need to. Most clients were converted to using FileSpec::GetPath().c_str() when possible. Other clients were modified to use the newly renamed version of this function which returns an actualy ConstString:
ConstString FileSpec::GetPathAsConstString(bool denormalize = true) const;
This avoids the issue where people were getting an already uniqued "const char *" that came from a ConstString only to put the "const char *" back into a "ConstString" object. By returning the ConstString instead of a "const char *" clients can be more efficient with the result.
The patch:
- Removes the non const GetDirectory() and GetFilename() get accessors
- Adds set accessors to replace the above functions: SetDirectory() and SetFilename().
- Adds ClearDirectory() and ClearFilename() to replace usage of the FileSpec::GetDirectory().Clear()/FileSpec::GetFilename().Clear() call sites
- Fixed all incorrect usage of FileSpec::GetCString() to use FileSpec::GetPath().c_str() where appropriate, and updated other call sites that wanted a ConstString to use the newly returned ConstString appropriately and efficiently.
Differential Revision: https://reviews.llvm.org/D130309
New glibc versions (since 2.34 or including this
<ed3ce71f5c>
patch) trigger the rendezvous breakpoint after they have already added
some modules to the list. This did not play well with our dynamic
loader plugin which was doing a diff of the the reported modules in the
before (RT_ADD) and after (RT_CONSISTENT) states. Specifically, it
caused us to miss some of the modules.
While I think the old behavior makes more sense, I don't think that lldb
is doing the right thing either, as the documentation states that we
should not be expecting a consistent view in the RT_ADD (and RT_DELETE)
states.
Therefore, this patch changes the lldb algorithm to compare the module
list against the previous consistent snapshot. This fixes the previous
issue, and I believe it is more correct in general. It also reduces the
number of times we are fetching the module info, which should speed up
the debugging of processes with many shared libraries.
The change in RefreshModules ensures we don't broadcast the loaded
notification for the dynamic loader (ld.so) module more than once.
Differential Revision: https://reviews.llvm.org/D128264
The DynamicLoaderPOSIXDYLD::GetStepThroughTrampolinePlan() function was
doing the symbol lookup using the demangled name. This stopped working
with https://reviews.llvm.org/D118814. To get things working again, just
use the mangled name for the lookup instead.
Reviewed By: labath
Differential Revision: https://reviews.llvm.org/D127999
A previous commit enabled LLDB to be able to debug a program launched via ld: https://reviews.llvm.org/D108061.
This commit adds the ability to debug a program launched via ld when it happens during an exec into the dynamic loader. There was an issue where after the exec we would locate the rendezvous structure right away but it didn't contain any valid values and we would try to set the dyanamic loader breakpoint at address zero. This patch fixes that and adds a test.
Differential Revision: https://reviews.llvm.org/D125253
When opening core files (and also in some other situations) we could end
up with two vdso modules. This could happen because the vdso module is
very special, and over the years, we have accumulated various ways to
load it.
In D10800, we added one mechanism for loading it, which took the form of
a generic load-from-memory capability. Unfortunately loading an elf file
from memory is not possible (because the loader never loads the entire
file), and our attempts to do so were causing crashes. So, in D34352, we
partially reverted D10800 and implemented a custom mechanism specific to
the vdso.
Unfortunately, enough of D10800 remained such that, under the right
circumstances, it could end up loading a second (non-functional) copy of
the vdso module. This happened when the process plugin did not support
the extended MemoryRegionInfo query (added in D22219, to workaround a
different bug), which meant that the loader plugin was not able to
recognise that the linux-vdso.so.1 module (this is how the loader calls
it) is in fact the same as the [vdso] module (the name used in
/proc/$PID/maps) we loaded before. This typically happened in a core
file, as they don't store this kind of information.
This patch fixes the issue by completing the revert of D10800 -- the
memory loading code is removed completely. It also reduces the scope of
the hackaround introduced in D22219 -- it isn't completely sound and is
only relevant for fairly old (but still supported) versions of android.
I added the memory loading logic to the wasm dynamic loader, which has
since appeared and is relying on this feature (it even has a test). As
far as I can tell loading wasm modules from memory is possible and
reliable. MachO memory loading is not affected by this patch, as it uses
a completely different code path.
Since the scenarios/patches I described came without test cases, I have
created two new gdb-client tests cases for them. They're not
particularly readable, but right now, this is the best way we can
simulate the behavior (bugs) of a particular dynamic linker.
Differential Revision: https://reviews.llvm.org/D122660
The call is useless, as any modules loaded there will be removed in
ResolveExecutableModule. Modules will be reloaded again through the
GetLoadedModuleList call in DYLDRendezvous.cpp.
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.
There is no reason why this function should be returning a ConstString.
While modifying these files, I also fixed several instances where
GetPluginName and GetPluginNameStatic were returning different strings.
I am not changing the return type of GetPluginNameStatic in this patch, as that
would necessitate additional changes, and this patch is big enough as it is.
Differential Revision: https://reviews.llvm.org/D111877
When rebase_exec=true in DidAttach(), all modules are loaded
before the rendezvous breakpoint is set, which means the
LoadInterpreterModule() method is not called and m_interpreter_module
is not initialized.
This causes the very first rendezvous breakpoint hit with
m_initial_modules_added=false to accidentally unload the
module_sp that corresponds to the dynamic loader.
This bug (introduced in D92187) was causing the rendezvous
mechanism to not work in Android 28. The mechanism works
fine on older/newer versions of Android.
Test: Verified rendezvous on Android 28 and 29
Test: Added dlopen test
Reviewed By: labath
Differential Revision: https://reviews.llvm.org/D109797
In all these years, we haven't found a use for this function (it has
zero callers). Lets just remove the boilerplate.
Differential Revision: https://reviews.llvm.org/D109600
This converts a default constructor's member initializers into C++11
default member initializers. This patch was automatically generated with
clang-tidy and the modernize-use-default-member-init check.
$ run-clang-tidy.py -header-filter='lldb' -checks='-*,modernize-use-default-member-init' -fix
This is a mass-refactoring patch and this commit will be added to
.git-blame-ignore-revs.
Differential revision: https://reviews.llvm.org/D103483
This issue was introduced in https://reviews.llvm.org/D92187.
The guard I'm changing were is supposed to act when linux is loading the linker for the second time (due to differences in paths like symlinks).
This is done by checking `module_sp != m_interpreter_module.lock()` however this will be true when `m_interpreter_module` wasn't initialized, making linux unload the linker module (the most visible result here is that lldb will stop getting notified about new modules loaded by the process, because it can't set the rendezvous breakpoint again after the stepping over it once).
The `m_interpreter_module` is not getting initialize when it goes through this path: dbfdb139f7/lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DynamicLoaderPOSIXDYLD.cpp (L332), which happens when lldb was able to read the address from the dynamic section of the executable.
What I'm not sure about though, is if when we go through this path if we still load the linker twice on linux. If that's the case then it means we need to somehow set the m_interpreter_module instead of the fix I provide here. I've only tested this on Android.
Differential Revision: https://reviews.llvm.org/D96637
Fix the POSIX-DYLD plugin to update the cached executable path after
attaching. Previously, the path was cached in DYLDRendezvous
constructor and not updated afterwards. This meant that if LLDB was
attaching to a process (e.g. via connecting to lldb-server), the code
stored the empty path before DidAttach() resolved it. The fix updates
the cached path in DidAttach().
This fixes a new instance of https://llvm.org/pr17880
Differential Revision: https://reviews.llvm.org/D92264
Explicitly consider the libraries reported on the initial rendezvous
breakpoint hit added. This is necessary on FreeBSD since the dynamic
loader issues only a single 'consistent' state rendezvous breakpoint hit
for all the libraries present in DT_NEEDED. It is also helpful on Linux
where it ensures that ld-linux is considered loaded as well
as the shared system libraries reported afterwards.
Reenable memory maps on FreeBSD since this fixed the issue triggered
by them.
Differential Revision: https://reviews.llvm.org/D92187
This reverts commit 09b08833f301ea375137931d26b7193101f82ceb.
This code is wrong on Linux, and causes ld-linux and linux-vdso to be
reported twice. I need to work on it more.
Explicitly consider the libraries reported on the initial eTakeSnapshot
action added, through adding them to the added soentry list
in DYLDRendezvous::SaveSOEntriesFromRemote(). This is necessary
on FreeBSD since the dynamic loader issues only a single 'consistent'
state rendezvous breakpoint hit for all the libraries present
in DT_NEEDED (while Linux issues an added-consistent event pair).
Reenable memory maps on FreeBSD since this fixed the issue triggered
by them.
Differential Revision: https://reviews.llvm.org/D92187
LLDB has a few different styles of header guards and they're not very
consistent because things get moved around or copy/pasted. This patch
unifies the header guards across LLDB and converts everything to match
LLVM's style.
Differential revision: https://reviews.llvm.org/D74743
Use LLDB_PLUGIN_DEFINE_ADV to make the name of the generated initializer
match the name of the plugin. This is a step towards generating the
initializers with a def file. I'm landing this change in pieces so I can
narrow down what exactly breaks the Windows bot.
This patch changes the way we initialize and terminate the plugins in
the system initializer. It uses an approach similar to LLVM's
TARGETS_TO_BUILD with a def file that enumerates the plugins.
The previously landed patch got reverted because it was lacking:
(1) A plugin definition for the Objective-C language runtime,
(2) The dependency between the Static and WASM dynamic loader,
(3) Explicit initialization of ScriptInterpreterNone for lldb-test.
All issues have been addressed in this patch.
Differential revision: https://reviews.llvm.org/D73067
This patch changes the way we initialize and terminate the plugins in
the system initializer. It uses an approach similar to LLVM's
TARGETS_TO_BUILD with a def file that enumerates the plugins.
Differential revision: https://reviews.llvm.org/D73067
