Fixes c5840cc609a3674cf7453a45946f7e4a2a73590b.
On platforms where UL is 32 bit, like Windows or 32 bit Linux,
this shift was not correct, so we assumed GCS was not present.
Use ULL instead, to match the other HWCAP constants.
The features and locked registers hold the same bits, the latter
is a lock for the former. Tested with core files and live processes.
I thought about setting a non-zero lock register in the core file,
however:
* We can be pretty sure it's reading correctly because its between
the 2 other GCS registers in the same core file note.
* I can't make the test case modify lock bits because userspace
can't clear them (without using ptrace) and we don't know what the libc
has locked
(probably all feature bits).
This allows you to read the same registers as you would for a live
process.
As the content of proc/pid/smaps is not included in the core file, we
don't get the "ss" marker that tell us that it is shadow stack. The GCS
region is still in the list though.
As part of the "RemoveDIs" work to eliminate debug intrinsics, we're
replacing methods that use Instruction*'s as positions with iterators. A
number of these (such as getFirstNonPHIOrDbg) are sufficiently
infrequently used that we can just replace the pointer-returning version
with an iterator-returning version, hopefully without much/any
disruption.
Thus this patch has getFirstNonPHIOrDbg and
getFirstNonPHIOrDbgOrLifetime return an iterator, and updates all
call-sites. There are no concerns about the iterators returned being
converted to Instruction*'s and losing the debug-info bit: because the
methods skip debug intrinsics, the iterator head bit is always false
anyway.
This was causing Ubuntu buildbot failures:
```
/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp: In member function ‘llvm::SmallVector<clang::ParmVarDecl*> lldb_private::TypeSystemClang::CreateParameterDeclarations(clang::FunctionDecl*, const clang::FunctionProtoType&, const llvm::SmallVector<llvm::StringRef>&)’:
/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp:7728:10: error: could not convert ‘params’ from ‘SmallVector<[...],12>’ to ‘SmallVector<[...],6>’
7728 | return params;
| ^~~~~~
| |
| SmallVector<[...],12>
```
It's unclear why 12 was chosen here. Given we don't set the
size in other places where we parse parameters, this patch
just removes the constant.
While sifting through this part of the code I noticed that when we parse
C++ methods, `DWARFASTParserClang` creates two sets of `ParmVarDecls`,
one in `ParseChildParameters` and once in `AddMethodToCXXRecordType`.
The former is unused when we're dealing with methods. Moreover, the
`ParmVarDecls` we created in `ParseChildParameters` were created with an
incorrect `clang::DeclContext` (namely the DeclContext of the function,
and not the function itself). In Clang, there's
`ParmVarDecl::setOwningFunction` to adjust the DeclContext of a
parameter if the parameter was created before the FunctionDecl. But we
never used it.
This patch removes the `ParmVarDecl` creation from
`ParseChildParameters` and instead creates a
`TypeSystemClang::CreateParameterDeclarations` that ensures we set the
DeclContext correctly.
Note there is one differences in how `ParmVarDecl`s would be created
now: we won't set a ClangASTMetadata entry for any of the parameters. I
don't think this was ever actually useful for parameter DIEs anyway.
This wasn't causing any concrete issues (that I know of), but was quite
surprising. And this way of setting the parameters seems easier to
reason about (in my opinion).
When the Guarded Control Stack (GCS) is enabled, returns cause the
processor to validate that the address at the location pointed to by
gcspr_el0 matches the one in the link register.
```
ret (lr=A) << pc
| GCS |
+=====+
| A |
| B | << gcspr_el0
Fault: tried to return to A when you should have returned to B.
```
Therefore when an expression wrapper function tries to return to the
expression return address (usually `_start` if there is a libc), it
would fault.
```
ret (lr=_start) << pc
| GCS |
+============+
| user_func1 |
| user_func2 | << gcspr_el0
Fault: tried to return to _start when you should have returned to user_func2.
```
To fix this we must push that return address to the GCS in
PrepareTrivialCall. This value is then consumed by the final return and
the expression completes as expected.
If for some reason that fails, we will manually restore the value of
gcspr_el0, because it turns out that PrepareTrivialCall
does not restore registers if it fails at all. So for now I am handling
gcspr_el0 specifically, but I have filed
https://github.com/llvm/llvm-project/issues/124269 to address the
general problem.
(the other things PrepareTrivialCall does are exceedingly likely to not
fail, so we have never noticed this)
```
ret (lr=_start) << pc
| GCS |
+============+
| user_func1 |
| user_func2 |
| _start | << gcspr_el0
No fault, we return to _start as normal.
```
The gcspr_el0 register will be restored after expression evaluation so
that the program can continue correctly.
However, due to restrictions in the Linux GCS ABI, we will not restore
the enable bit of gcs_features_enabled. Re-enabling GCS via ptrace is
not supported because it requires memory to be allocated by the kernel.
We could disable GCS if the expression enabled GCS, however this would
use up that state transition that the program might later rely on. And
generally it is cleaner to ignore the enable bit, rather than one state
transition of it.
We will also not restore the GCS entry that was overwritten with the
expression's return address. On the grounds that:
* This entry will never be used by the program. If the program branches,
the entry will be overwritten. If the program returns, gcspr_el0 will
point to the entry before the expression return address and that entry
will instead be validated.
* Any expression that calls functions will overwrite even more entries,
so the user needs to be aware of that anyway if they want to preserve
the contents of the GCS for inspection.
* An expression could leave the program in a state where restoring the
value makes the situation worse. Especially if we ever support this in
bare metal debugging.
I will later document all this on
https://lldb.llvm.org/use/aarch64-linux.html.
Tests have been added for:
* A function call that does not interact with GCS.
* A call that does, and disables it (we do not re-enable it).
* A call that does, and enables it (we do not disable it again).
* Failure to push an entry to the GCS stack.
The Guarded Control Stack extension implements a shadow stack and the
Linux kernel provides access to 3 registers for it via ptrace.
struct user_gcs {
__u64 features_enabled;
__u64 features_locked;
__u64 gcspr_el0;
};
This commit adds support for reading those from a live process.
The first 2 are pseudo registers based on the real control register and
the 3rd is a real register. This is the stack pointer for the guarded
stack.
I have added a "gcs_" prefix to the "features" registers so that they
have a clear name when shown individually. Also this means they will tab
complete from "gcs", and be next to gcspr_el0 in any sorted lists of
registers.
Guarded Control Stack Registers:
gcs_features_enabled = 0x0000000000000000
gcs_features_locked = 0x0000000000000000
gcspr_el0 = 0x0000000000000000
Testing is more of the usual, where possible I'm writing a register then
doing something in the program to confirm the value was actually sent to
ptrace.
This is the behavior expected by DWARF. It also requires some fixups to
algorithms which were storing the addresses of some objects (Blocks and
Variables) relative to the beginning of the function.
There are plenty of things that still don't work in this setups, but
this change is sufficient for the expression evaluator to correctly
recognize the entry point of a function in this case.
.. by changing the signal stop reason format 🤦
The reason this did not work is because the code in
`StopInfo::GetCrashingDereference` was looking for the string "address="
to extract the address of the crash. Macos stop reason strings have the
form
```
EXC_BAD_ACCESS (code=1, address=0xdead)
```
while on linux they look like:
```
signal SIGSEGV: address not mapped to object (fault address: 0xdead)
```
Extracting the address from a string sounds like a bad idea, but I
suppose there's some value in using a consistent format across
platforms, so this patch changes the signal format to use the equals
sign as well. All of the diagnose tests pass except one, which appears
to fail due to something similar #115453 (disassembler reports
unrelocated call targets).
I've left the tests disabled on windows, as the stop reason reporting
code works very differently there, and I suspect it won't work out of
the box. If I'm wrong -- the XFAIL will let us know.
This reverts commit a8020930a8174d84da04fa91b6fef244207f42f5.
Relands original commit but fixing the unit-test to consume the
`llvm::Expected` error object.
Reverts llvm/llvm-project#124096
Broke linux CI:
```
Note: This is test shard 7 of 42.
[==========] Running 1 test from 1 test suite.
[----------] Global test environment set-up.
[----------] 1 test from DWARFASTParserClangTests
[ RUN ] DWARFASTParserClangTests.TestParseSubroutine_ExplicitObjectParameter
Expected<T> must be checked before access or destruction.
Expected<T> value was in success state. (Note: Expected<T> values in success mode must still be checked prior to being destroyed).
Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the environment var `LLVM_SYMBOLIZER_PATH` to point to it):
0 SymbolFileDWARFTests 0x0000560271ee5ba7
1 SymbolFileDWARFTests 0x0000560271ee3a2c
2 SymbolFileDWARFTests 0x0000560271ee63ea
3 libc.so.6 0x00007f3e54e5b050
4 libc.so.6 0x00007f3e54ea9e2c
5 libc.so.6 0x00007f3e54e5afb2 gsignal + 18
6 libc.so.6 0x00007f3e54e45472 abort + 211
7 SymbolFileDWARFTests 0x0000560271e79d51
8 SymbolFileDWARFTests 0x0000560271e724f7
9 SymbolFileDWARFTests 0x0000560271f39e2c
10 SymbolFileDWARFTests 0x0000560271f3b368
11 SymbolFileDWARFTests 0x0000560271f3c053
12 SymbolFileDWARFTests 0x0000560271f4cf67
13 SymbolFileDWARFTests 0x0000560271f4c18a
14 SymbolFileDWARFTests 0x0000560271f2561c
15 libc.so.6 0x00007f3e54e4624a
16 libc.so.6 0x00007f3e54e46305 __libc_start_main + 133
17 SymbolFileDWARFTests 0x0000560271e65161
```
LLDB deduces the CV-qualifiers and storage class of a C++ method from
the object parameter. Currently it assumes that parameter is implicit
(and is a pointer type with the name "this"). This isn't true anymore in
C++23 with explicit object parameters. To support those we can simply
check the `DW_AT_object_pointer` of the subprogram DIE (works for both
declarations and definitions) when searching for the object parameter.
We can also remove the check for `eEncodingIsPointerUID`, because in C++
an artificial parameter called `this` is only ever the implicit object
parameter (at least for all the major compilers).
Now that we have a dedicated abstraction for string tables, switch the
option parser library's string table over to it rather than using a raw
`const char*`. Also try to use the `StringTable::Offset` type rather
than a raw `unsigned` where we can to avoid accidental increments or
other issues.
This is based on review feedback for the initial switch of options to a
string table. Happy to tweak or adjust if desired here.
This patch continues simplifying `ParseChildParameters` by moving out
the logic that parses the first parameter of a function DIE into a
helper function. Since with GCC (and lately Clang) function declarations
have `DW_AT_object_pointer`s, we should be able to check for the
attribute's existence to determine if a function is static (and also
deduce CV-qualifiers from it). This will be useful for cases where the
object parameter is explicit (which is possible since C++23).
This should be NFC. I added a FIXME to places where we assume an
implicit object parameter (which will be addressed in a follow-up
patch).
We used to guard parsing of the CV-qualifiers of the "this" parameter
with a `encoding_mask & Type::eEncodingIsPointerUID`, which is
incorrect, because `eEncodingIsPointerUID` cannot be used as a bitmask
directly (see https://github.com/llvm/llvm-project/issues/120856). This
patch corrects this, but it should still be NFC because any parameter in
C++ called "this" *is* an implicit object parameter.
This patch refactors `ParseChildParameters` in a way which makes it (in
my opinion) more readable, removing some redundant local variables in
the process and reduces the scope of some variables.
**Motivation**
Since `DW_AT_object_pointer`s are now attached to declarations, we can
test for their existence to check whether a C++ method is static or not
(whereas currently we're deducing this from `ParseChildParameters` based
on some heuristics we know are true for most compilers). So my plan is
to move the code for determining `type_quals` and `is_static` out of
`ParseChildParameters`. The refactoring in this PR will make this
follow-up patch hopefully easier to review.
**Testing**
* This should be NFC. The main change is that we now no longer iterate
over `GetAttributes()` but instead retrieve the name, type and
is_artificial attributes of the parameters individually.
This commit adds support for a
`SBProcess::ContinueInDirection()` API. A user-accessible command for
this will follow in a later commit.
This feature depends on a gdbserver implementation (e.g. `rr`) providing
support for the `bc` and `bs` packets. `lldb-server` does not support
those packets, and there is no plan to change that. For testing
purposes, this commit adds a Python implementation of *very limited*
record-and-reverse-execute functionality, implemented as a proxy between
lldb and lldb-server in `lldbreverse.py`. This should not (and in
practice cannot) be used for anything except testing.
The tests here are quite minimal but we test that simple breakpoints and
watchpoints work as expected during reverse execution, and that
conditional breakpoints and watchpoints work when the condition calls a
function that must be executed in the forward direction.
This will be sent by Arm's Guarded Control Stack extension when an
invalid return is executed.
The signal does have an address we could show, but it's the PC at which
the fault occured. The debugger has plenty of ways to show you that
already, so I've left it out.
```
(lldb) c
Process 460 resuming
Process 460 stopped
* thread #1, name = 'test', stop reason = signal SIGSEGV: control protection fault
frame #0: 0x0000000000400784 test`main at main.c:57:1
54 afunc();
55 printf("return from main\n");
56 return 0;
-> 57 }
(lldb) dis
<...>
-> 0x400784 <+100>: ret
```
The new test case generates the signal by corrupting the link register
then attempting to return. This will work whether we manually enable GCS
or the C library does it for us.
(in the former case you could just return from main and it would fault)
In https://github.com/llvm/llvm-project/pull/122742 we will start
attaching DW_AT_object_pointer to method declarations (in addition to
definitions).
Currently when LLDB parses a `DW_TAG_subprogram` definition, it will
parse all the attributes of the declaration as well. If we have
`DW_AT_object_pointer` on both, then we would overwrite the more
specific attribute that we got from the defintion with the one from the
specification. This is problematic because LLDB relies on getting the
`DW_AT_name` from the `DW_AT_object_pointer`, which doesn't exist on the
specification.
Note GCC does attach `DW_AT_object_pointer` on declarations *and*
definitions already (see https://godbolt.org/z/G1GvddY48), so there's
definitely some expressions that will fail for GCC compiled binaries.
This patch will fix those cases (e.g., I would expect `TestConstThis.py`
to fail with GCC).
`GetAttributes` returns all attributes on a given DIE, including any
attributes that the DIE references via `DW_AT_abstract_origin` and
`DW_AT_specification`. However, if an attribute exists on both the
referring DIE and the referenced DIE, the first one encountered will be
the one that takes precendence when querying the returned
`DWARFAttributes`. But there was no guarantee in which order those
attributes get visited. That means there's no convenient way of ensuring
that an attribute of a definition doesn't get shadowed by one found on
the declaration. One use-case where we don't want this to happen is for
`DW_AT_object_pointer` (which can exist on both definitions and
declarations, see https://github.com/llvm/llvm-project/pull/123089).
This patch makes sure we visit the current DIE's attributes before
following DIE references. I tried keeping as much of the original
`GetAttributes` unchanged and just add an outer `GetAttributes` that
keeps track of the DIEs we need to visit next.
There's precendent for this iteration order in
`llvm::DWARFDie::findRecursively` and also
`lldb_private::ElaboratingDIEIterator`. We could use the latter to
implement `GetAttributes`, though it also follows `DW_AT_signature` so I
decided to leave it for follow-up.
Currently, an LLDB target option controls whether plugins report all
threads. However, it seems natural for this knowledge could come from
the plugin itself. To support this, this commits adds a virtual method
to the plugin base class, making the Python OS query the target option
to preserve existing behavior.
Anonymous namespaces are supposed to be optional when looking up types.
This was not working in combination with -gsimple-template-names,
because the way it was constructing the complete (with template args)
name scope (i.e., by generating thescope as a string and then reparsing
it) did not preserve the information about the scope kinds.
Essentially what the code wants here is to call `GetTypeLookupContext`
(that's the function used to get the context in the "regular" code
path), but to embelish each name with the template arguments (if they
don't have them already). This PR implements exactly that by adding an
argument to control which kind of names are we interested in. This
should also make the lookup faster as it avoids parsing of the long
string, but I haven't attempted to benchmark that.
I believe this function can also be used in some other places where
we're manually appending template names, but I'm leaving that for
another patch.
There was a bug in both the GNU and libc++ library synthetic child
providers when a typedef was used in the type of the variable. Previous
code was looking at the top level typename to try and determine if
std::unordered_ was a map or set and this failed when typedefs were
being used. This patch fixes both C++ library synthetic child providers
with updated tests.
Close https://github.com/llvm/llvm-project/issues/90154
This patch is also an optimization to the lookup process to utilize the
information provided by `export` keyword.
Previously, in the lookup process, the `export` keyword only takes part
in the check part, it doesn't get involved in the lookup process. That
said, previously, in a name lookup for 'name', we would load all of
declarations with the name 'name' and check if these declarations are
valid or not. It works well. But it is inefficient since it may load
declarations that may not be wanted.
Note that this patch actually did a trick in the lookup process instead
of bring module information to DeclarationName or considering module
information when deciding if two declarations are the same. So it may
not be a surprise to me if there are missing cases. But it is not a
regression. It should be already the case. Issue reports are welcomed.
In this patch, I tried to split the big lookup table into a lookup table
as before and a module local lookup table, which takes a combination of
the ID of the DeclContext and hash value of the primary module name as
the key. And refactored `DeclContext::lookup()` method to take the
module information. So that a lookup in a DeclContext won't load
declarations that are local to **other** modules.
And also I think it is already beneficial to split the big lookup table
since it may reduce the conflicts during lookups in the hash table.
BTW, this patch introduced a **regression** for a reachability rule in
C++20 but it was false-negative. See
'clang/test/CXX/module/module.interface/p7.cpp' for details.
This patch is not expected to introduce any other
regressions for non-c++20-modules users since the module local lookup
table should be empty for them.
---
On the API side, this patch unfortunately add a maybe-confusing argument
`Module *NamedModule` to
`ExternalASTSource::FindExternalVisibleDeclsByName()`. People may think
we can get the information from the first argument `const DeclContext
*DC`. But sadly there are declarations (e.g., namespace) can appear in
multiple different modules as a single declaration. So we have to add
additional information to indicate this.
Lots of code around LLDB was directly accessing the target's section
load list. This NFC patch makes the section load list private so the
Target class can access it, but everyone else now uses accessor
functions. This allows us to control the resolving of addresses and will
allow for functionality in LLDB which can lazily resolve addresses in
JIT plug-ins with a future patch.
In the presence of OS plugins, StopInfoMachException currently
propagates breakpoint stop reasons even if those breakpoints were not
intended for a specific thread, effectively removing our ability to set
thread-specific breakpoints.
This was originally added in [1], but the motivation provided in the
comment does not seem strong enough to remove the ability to set
thread-specific breakpoints. The only way to break thread specific
breakpoints would be if a user set such a breakpoint and _then_ loaded
an OS plugin, a scenario which we would likely not want to support.
[1]:
ab745c2ad8 (diff-8ec6e41b1dffa7ac4b5841aae24d66442ef7ebc62c8618f89354d84594f91050R501)
This is intended for use with Arm's Guarded Control Stack extension
(GCS). Which reuses some existing shadow stack support in Linux. It
should also work with the x86 equivalent.
A "ss" flag is added to the "VmFlags" line of shadow stack memory
regions in `/proc/<pid>/smaps`. To keep the naming generic I've called
it shadow stack instead of guarded control stack.
Also the wording is "shadow stack: yes" because the shadow stack region
is just where it's stored. It's enabled for the whole process or it
isn't. As opposed to memory tagging which can be enabled per region, so
"memory tagging: enabled" fits better for that.
I've added a test case that is also intended to be the start of a set of
tests for GCS. This should help me avoid duplicating the inline assembly
needed.
Note that no special compiler support is needed for the test. However,
for the intial enabling of GCS (assuming the libc isn't doing it) we do
need to use an inline assembly version of prctl.
This is because as soon as you enable GCS, all returns are checked
against the GCS. If the GCS is empty, the program will fault. In other
words, you can never return from the function that enabled GCS, unless
you push values onto it (which is possible but not needed here).
So you cannot use the libc's prctl wrapper for this reason. You can use
that wrapper for anything else, as we do to check if GCS is enabled.
This doesn't make much of a difference now, but it makes it easier to
add -gsimple-template-names support to these functions (the idea is to
add an argument to say whether you want the name as spelled in the debug
info, or the one embellished with template arguments -- we have use
cases for both).
With this patch, vector registers can be read and written when debugging a live process.
Note: We currently assume that all LoongArch64 processors include the
LSX and LASX extensions.
To add test cases, the following modifications were also made:
lldb/packages/Python/lldbsuite/test/lldbtest.py
lldb/packages/Python/lldbsuite/test/make/Makefile.rules
Reviewed By: DavidSpickett, SixWeining
Pull Request: https://github.com/llvm/llvm-project/pull/120664
This reverts commit 7b808e73aa0193c8a42eae8f2420a803f424bee1.
Previous commit which change default debuginfod cache path and pruning
policy settings is problematic. It broke multiple tests across lldb and
llvm. Reverting for now.
Co-authored-by: George Hu <georgehuyubo@gmail.com>
This PR include two changes:
1. Change debuginfod cache file name to include origin file name, the
new file name would be something like:
llvmcache-13267c5f5d2e3df472c133c8efa45fb3331ef1ea-liblzma.so.5.2.2.debuginfo.dwp
So it will provide more information in image list instead of a plain
llvmcache-123
2. Switch debuginfod cache to use lldb index cache settings. Currently
we don't have proper settings for setting the cache path or the cache
expiration time for debuginfod cache. We want to use the lldb index
cache settings, as they make sense to be in the same place and have the
same TTL.
---------
Co-authored-by: George Hu <georgehuyubo@gmail.com>
Note that PointerUnion::{is,get} have been soft deprecated in
PointerUnion.h:
// FIXME: Replace the uses of is(), get() and dyn_cast() with
// isa<T>, cast<T> and the llvm::dyn_cast<T>
Many calls to Function::GetAddressRange() were not interested in the
range itself. Instead they wanted to find the address of the function
(its entry point) or the base address for relocation of function-scoped
entities (technically, the two don't need to be the same, but there's
isn't good reason for them not to be). This PR creates a separate
function for retrieving this, and changes the existing
(non-controversial) uses to call that instead.
The functions call GetName for everything except variables, where they
call GetPubname instead. The difference is that the latter prefers to
return the linkage name, if it is available.
This doesn't seem particularly useful given that the linkage name
already kind of contains the context of the variable, and I doubt that
anything depends on it as these functions are currently called on type
and subprogram DIEs -- not variables.
This makes it easier to simplify/deduplicate these functions later.
### Issue:
Currently lldb `platform connect unix-connect://localhost:43045/` is
failing and showing "Failed to connect port" error message.
### Cause:
TCPSocket(bool should_close, bool child_processes_inherit) constructor
was removed in commit
[c1dff71](c1dff71525 (diff-91817651b505a466ea94ddc44eca856f62073e03b05d0d0d2f4a55dcfea0002eL20)).
However, the tcp_socket object creation still passes the deleted
constructor parameters, which causes the invocation of the wrong
constructor. As a result, the `FindUnusedPort` method is unable to
resolve the local port and always returns 0.
This commit addresses a bug introduced in commit bcf654c, which
prevented LLDB from parsing the GNU build ID for the main executable
from a core file. The fix finds the `p_vaddr` of the first `PT_LOAD`
segment as the `base_addr` and subtract this `base_addr` from the
virtual address being read.
Co-authored-by: George Hu <hyubo@meta.com>
Use `Address` (instead of `addr_t`) to setup
breakpoint in `ReportRetriever::SetupBreakpoint`.
This is cleaner and the breakpoint should now
survive re-running of the binary.
rdar://124399066
