I wanted to clarify the semantics around SBProgress. Given the nature of
Progress events, copying seems like the wrong idea. Making SBProgress
move-only (like SBStream) seems like the better choice here.
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.
The improved error reporting in #120162 revealed that we were missing
opcodes in GetOpcodeDataSize. I changed the function to remove the
default case and switch over the enum type which will cause the compiler
to emit a warning if there are unhandled operations in the future.
rdar://139705570
.. 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.
Using a "random" name for an "anonymous" pipe seems to be the state of
the art on windows (according to stack overflow, new windows versions
may have something better, but it involves calling kernel APIs directly
and generally a lot of dark magic).
The problem with the current method was that is does not produce unique
names if one has two copies of the pipe code in the same process, which
is what happened with #120457 (because liblldb only exposes the public
api, and we've started using the pipe code in lldb-dap as well).
This patch works around the problem by adding the address of the counter
variable to the pipe name.
Replicating the multiple-copies setup in a test would be very difficult,
which is why I'm not adding a test for this scenario.
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.
Implement ansi::StripAnsiTerminalCodes and fix a long standing bug where
using format strings in lldb's prompt resulted in an incorrect prompt
column width.
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)
Recently I've been working on a lot of internal Python tooling, and in
certain cases I want to report async to the script over DAP. Progress.h
already handles this, so I've exposed Progress via the SB API so Python
scripts can also update progress objects.
I actually have no idea how to test this, so I just wrote a [toy command
to test
it](https://gist.github.com/Jlalond/48d85e75a91f7a137e3142e6a13d0947)
I also copied the first section of the extensive Progress.h class
documentation to the docstrings.
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.
I think the only issue here was that we would erroneously consider
functions which are "in the middle" of the function were stepping to as
a part of the function, and would try to step into them (likely stepping
out of the function instead) instead of giving up early.
We still have GetDescription and DumpStopContext which serve a similar
purpose.
(The main reason this is bothering me is because I'm working through the
uses of (deprecated) Function::GetAddressRange.)
This patch rewords some of the user expression diagnostics.
- Differentiate between being interrupted and hitting a breakpoint.
- Use "expression execution" to make it more obvious that the diagnostic
is associated with the user expression.
- Consistently use a colon instead of semicolons and commas.
rdar://143059974
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.
Revert to the state after d7796855b879 and use the underlying buffer
directly. I was still under the impression that was unsafe, so I did a
drive-by fix, which this commit reverts.
Rename `lldb_assert` to `_lldb_assert` to make it more obvious that you
shouldn't be using this function directly. Instead, you should use the
`lldbassert` macro which becomes a regular assert in a debug/asserts
build.
This patch adds the ability to get a thread at a give index, based on
insertion order, for SBSaveCore Options. This is primarily to benefit
scripts using SBSaveCore, and remove the need to have both options and a
second collection if your script is tracking what threads need to be
saved. Such as if you want to collect the source of all the threads to
be saved after the Core is generated.
