Taking a reference or a pointer to a value that's not aligned properly
is undefined behavior. While `[[gnu::packed]]` ensures that reads from
and writes to fields of packed structs is a safe operation, the
information about the reduced alignment is lost when creating pointers
to these values.
Weirdly enough, GCC's undefined behavior sanitizer doesn't flag these,
even though the doc of `-Waddress-of-packed-member` says that it usually
leads to UB. In contrast, x86_64 Clang does flag these, which renders
the 64-bit kernel unable to boot.
For now, the `address-of-packed-member` warning will only be enabled in
the kernel, as it is absolutely crucial there because of KUBSAN, but
might get excessively noisy for the userland in the future.
Also note that we can't append to `CMAKE_CXX_FLAGS` like we do for other
flags in the kernel, because flags added via `add_compile_options` come
after these, so the `-Wno-address-of-packed-member` in the root would
cancel it out.
This contains all the bits and pieces necessary to build a Clang binary
that will correctly compile SerenityOS.
I had some trouble with getting LLVM building with a single command, so
for now, I decided to build each LLVM component in a separate command
invocation. In the future, we can also make the main llvm build step
architecture-independent, but that would come with extra work to make
library and include paths work.
The binutils build invocation and related boilerplate is duplicated
because we only use `objdump` from GNU binutils in the Clang toolchain,
so most features can be disabled.
Kernels built with Clang seem to be quite allocation-heavy compared to
their GCC counterparts. We would sometimes end up crashing during boot
because the eternal ranges had no free capacity.
... segment
This happens with binaries build with Clang or with a custom linker
script. If this is the case, offsets should be calculated not from the
base address of `.text`, but from the first section loaded for the
library.
This commit moves all UserspaceEmulator symbolication into a common
helper function and fixes a FIXME.
This helps us avoid weird truncation issues and fixes a bug on Clang
builds where truncation while reading caused the DIE offsets following
large LEB128 numbers to be incorrect. This removes the need for the
separate `LongUnsignedNumber` type.
On i686, reading integers larger than `2^32 - 1` would fail as the
32-bit `size_t` parameter would overflow. This caused us to read too few
bytes in LibDebug's DWARF parser. Making this method templated solves
this issue, as we now can call this API with a `u64` parameter.
This LineProgram instruction is emitted by Clang. Although we currently
have no use for it (it's mostly a debugger feature), we need to handle
this opcode, as otherwise CrashReporter wouldn't work.
Due to a bug in Clang 12, the compilation would fail with an 'unexpected
end-of-file' error when it encounters some of the nested generic lambdas
in `Compositor.cpp`.
Co-authored-by: Peter Bindels <dascandy@gmail.com>
The Clang error message reads like this (`-Wdeprecated-array-compare`):
> error: comparison between two arrays is deprecated; to compare
> array addresses, use unary '+' to decay operands to pointers.
Since C99 and C++20 have a standardized syntax for designated
initializer, we should use that instead of this GCC-specific extension.
While this currently works both in Clang and GCC, the former emits a
warning for it, while the latter has an [issue] open that plans to
deprecate it.
[issue]: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88144
Clang is a bit more pedantic than GCC when diagnosing implicit
fallthroughs, and doesn't care if the succeeding label only contains a
single break statement.
When exiting the terminal settings window, the opacity, bell and
maximum history size will be saved to the application config file.
Because the color scheme is neither configurable nor
will it be loaded on startup, it will not get saved for now.
This seemed like a good idea at the time to avoid an unnecessary
dependency on qemu-system-i386. However this makes debugging the
kernel with GDB more difficult because GDB assumes that the QEMU
architectures matches the kernel architecture.
The text was painted with the assumption that no other column would be
present after the tree column, which won't always be true. Additionally,
some alignment and focus rect-related issues have been fixed.
The maximum number of virtual consoles is determined at compile time,
so we can pre-allocate that many slots, dodging some heap allocations.
Furthermore, virtual consoles are never destroyed, so it's fine to
simply store a raw pointer to the currently active one.
Previously in Browser, when we navigate back from a page that has an
icon to a page that does not have an icon, the icon does not update and
the old icon is displayed because FrameLoader does not set the default
favicon when the favicon cannot be loaded. This patch ensures that
Browser receives a new icon bitmap every time a load takes place.
This pattern is no good:
kmalloc(elements * sizeof(T));
Since it silently swallows any multiplication overflow.
This patch adds a simple kmalloc_array() that stops the program if
overflow occurs:
kmalloc_array(elements, sizeof(T));
When the preprocessor encounters an #include statement it now adds
the preprocessor definitions that exist in the included header to its
own set of definitions.
We previously only aggregated the definitions from headers after
processing the source, which was less correct. (For example, there
could be an #ifdef that depends on a definition from another header).
We now call Preprocessor::process_and_lex() and pass the result to the
parser.
Doing the lexing in the preprocessor will allow us to maintain the
original position information of tokens after substituting definitions.
We need test-js for the parser tests for test262, but we don't need to
rebuild all of Lagom twice. This was missed when we did the initial
change to shared libraries. Before #9017, the Lagom build for test-js
is what built libLagom.a for the libjs-test262-runner to link against.
Now that we are building libjs.so and its dependencies in the runner's
build directory, we should build test-js there as well.
Requires linusg/libjs-test262#32 in order to properly find the built
test-js.
Before Libraries was moved to Userland/Libraries syslog.h had a bunch
of manually aligned defines and array initializations.
Andreas seems to have formatted the file with clang-format as part of
that file move. Since syslog.h is now properly formatted, we don't
need to exclude it from the linter list.
