This commit adds support for building the SerenityOS userland with the
new [mold linker].
This is not enabled by default yet; to link using mold, run the
`Toolchain/BuildMold.sh` script to build the latest release of mold, and
set the `ENABLE_MOLD_LINKER` CMake variable to ON. This option relies on
toolchain support that has been added just recently, so you might need
to rebuild your toolchain for mold to work.
[mold linker]: https://github.com/rui314/mold
If this option is set, we will not build all components.
Instead, we include an external CMake file passed in via a variable
named HACKSTUDIO_BUILD_CMAKE_FILE.
This will be used to build serenity components from Hack Studio.
The `--allow-shlib-undefined` option is a bit of a misnomer. It actually
controls whether we should be allowed to have undefined references after
symbols from all dependencies have been resolved, so it applies both to
shared libraries and executables.
LLD defaults to allowing undefined references in shared libraries, but
not in executables. Previously, we had to disable this check for
executables too, as it caused a build failure due to the
LibC-LibPthread-libc++ and the LibCore-LibCrypto circular dependencies.
Now that those have been resolved, we can enable this warning, in the
hopes that it will prevent us from introducing circular libraries and
missing dependencies that might cause unexpected breakage.
There's only two places where we're using the C99 feature of array
designated initalizers. This feature seemingly wasn't included with
C++20 designated initalizers for classes and structs. The only two
places we were using this feature are suitably old and isolated that
it makes sense to just suppress the warning at the usage sites while
discouraging future array designated intializers in new code.
Enable the warning project-wide. It catches when a non-virtual method
creates an overload set with a virtual method. This might cause
surprising overload resolution depending on how the method is invoked.
The Clang implementation of this warning protects against some undefined
pre-processor behavior while ignoring function-like macros. The gcc
implementation also warns on function-like macros, and is therefore
noisy.
These were removed in the Superbuild conversion. Re-add the checks that
make sure that if there's a toolchain update, developers re-build their
toolchain.
gzip -c is supported in both Linux and BSD flavors of gzip. The -o flag
was introduced in a previous commit which is present in OpenBSD, but not
other flavors of Linux. -c will write to stdout which is redirected to
the target files. As a side benefit, we no longer need to copy files
anywhere
OpenBSD gzip does not have the -k flag to keep the original after
extraction. Work around this by copying the original gzip to the dest
and then extracting. A bit of a hack, but only needs to be done for the
first-time or rebuilds
OpenBSD provides crypt in libc, not libcrypt. Adjust if/else to check
for either and proceed accordingly
Remove outdated OpenBSD checks when building the toolchain
This option is already enabled when building Lagom, so let's enable it
for the main build too. We will no longer be surprised by Lagom Clang
CI builds failing while everything compiles locally.
Furthermore, the stronger `-Wsuggest-override` warning is enabled in
this commit, which enforces the use of the `override` keyword in all
classes, not just those which already have some methods marked as
`override`. This works with both GCC and Clang.
This commit updates the Clang toolchain's version to 13.0.0, which comes
with better C++20 support and improved handling of new features by
clang-format. Due to the newly enabled `-Bsymbolic-functions` flag, our
Clang binaries will only be 2-4% slower than if we dynamically linked
them, but we save hundreds of megabytes of disk space.
The `BuildClang.sh` script has been reworked to build the entire
toolchain in just three steps: one for the compiler, one for GNU
binutils, and one for the runtime libraries. This reduces the complexity
of the build script, and will allow us to modify the CI configuration to
only rebuild the libraries when our libc headers change.
Most of the compile flags have been moved out to a separate CMake cache
file, similarly to how the Android and Fuchsia toolchains are
implemented within the LLVM repo. This provides a nicer interface than
the heaps of command-line arguments.
We no longer build separate toolchains for each architecture, as the
same Clang binary can compile code for multiple targets.
The horrible mess that `SERENITY_CLANG_ARCH` was, has been removed in
this commit. Clang happily accepts an `i686-pc-serenity` target triple,
which matches what our GCC toolchain accepts.
Replace the old logic where we would start with a host build, and swap
all the CMake compiler and target variables underneath it to trick
CMake into building for Serenity after we configured and built the Lagom
code generators.
The SuperBuild creates two ExternalProjects, one for Lagom and one for
Serenity. The Serenity project depends on the install stage for the
Lagom build. The SuperBuild also generates a CMakeToolchain file for the
Serenity build to use that replaces the old toolchain file that was only
used for Ports.
To ensure that code generators are rebuilt when core libraries such as
AK and LibCore are modified, developers will need to direct their manual
`ninja` invocations to the SuperBuild's binary directory instead of the
Serenity binary directory.
This commit includes warning coalescing and option style cleanup for the
affected CMakeLists in the Kernel, top level, and runtime support
libraries. A large part of the cleanup is replacing USE_CLANG_TOOLCHAIN
with the proper CMAKE_CXX_COMPILER_ID variable, which will no longer be
confused by a host clang compiler.
This common strategy of having a serenity_option() macro defined in
either the Lagom or top level CMakeLists.txt allows us to do two things:
First, we can more clearly see which options are Serenity-specific,
Lagom-specific, or common between the target and host builds.
Second, it enables the upcoming SuperBuild changes to set() the options
in the SuperBuild's CMake cache and forward each target's options to the
corresponding ExternalProject.
This makes it so we don't need to specify the full path to all the
helper scripts we include() from different places in the codebase and
feels a lot cleaner.
This prevents GCC and Clang from deleting null pointer checks for
optimization purposes. I think we're strictly better off crashing
in those cases instead of the compiler hiding errors from us.
This tells the linker to not combine read-only data and executable code,
instead favoring multiple PT_LOAD headers with more precise permissions.
This greatly reduces the amount of executable pages in all our programs
and libraries.
/usr/lib/libjs.so before:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
LOAD 0x000000 0x00000000 0x00000000 0x2fc77c 0x2fc77c R E 0x1000
LOAD 0x2fc900 0x002fd900 0x002fd900 0x0c708 0x0dd1c RW 0x1000
/usr/lib/libjs.so after:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
LOAD 0x000000 0x00000000 0x00000000 0x80e60 0x80e60 R 0x1000
LOAD 0x081000 0x00081000 0x00081000 0x25f6c9 0x25f6c9 R E 0x1000
LOAD 0x2e1000 0x002e1000 0x002e1000 0x1c27c 0x1c27c R 0x1000
LOAD 0x2fd900 0x002fe900 0x002fe900 0x0c708 0x0dd1c RW 0x1000
As you can see, we go from 0x2fc77c bytes of executable memory down to
0x25f6c9 (a ~20% reduction!) The memory that was previous executable is
now simply read-only instead. :^)
This is needed so all headers and files exist on disk, so that
the sonar cloud analyzer can find them when executing the compilation
commands contained in compile_commands.json, without actually building.
Co-authored-by: Andrew Kaster <akaster@serenityos.org>
This allows us to remove all the add_subdirectory calls from the top
level CMakeLists.txt that referred to targets linking LagomCore.
Segregating the host tools and Serenity targets helps us get to a place
where the main Serenity build can simply use a CMake toolchain file
rather than swapping all the compiler/sysroot variables after building
host libraries and tools.
By using SerenityOS_SOURCE_DIR we can make custom targets and commands
agnostic to the actual location of the root CMakeLists directory.
All we care about is the root of the SerenityOS project.
The `-z,text` linker flag causes the linker to reject shared libraries
and PIE executables that have textrels. Our code mostly did not use
these except in one place in LibC, which is changed in this commit.
This makes GNU ld match LLD's behavior, which has this option enabled by
default.
TEXTRELs pose a security risk, as performing these relocations require
executable pages to be written to by the dynamic linker. This can
significantly weaken W^X hardening mitigations.
Note that after this change, TEXTRELs can still be used in ports, as the
dynamic loader code is not changed. There are also uses of it in the
kernel, removing which are outside the scope of this PR. To allow those,
`-z,notext` is added.
Previously, this was disabled because GCC flagged seemingly correct and
well-defined code. This was however not the case because GCC implicitly
marked some pointers non-null, even if we wanted to handle them
ourselves, and deleted null checks on them. By re-introducing this
warning, we will know if the compiler tries to discard our code again.
This is primarily to allow using LibUnicode within LibJS and its REPL.
Note: this seems to be the first time that a Lagom dependency requires
generated source files. For this to work, some of Lagom's CMakeLists.txt
commands needed to be re-organized to include the CMake files that fetch
and parse UnicodeData.txt. The paths required to invoke the generator
also differ depending on what is currently building (SerenityOS vs.
Lagom as part of the Serenity build vs. a standalone Lagom build).
The Unicode standard publishes the Unicode Character Database (UCD) with
information about every code point, such as each code point's upper case
mapping. LibUnicode exists to download and parse UCD files at build time
and to provide accessors to that data.
As a start, LibUnicode includes upper- and lower-case code point
converters.
GCC and Clang allow us to inject a call to a function named
__sanitizer_cov_trace_pc on every edge. This function has to be defined
by us. By noting down the caller in that function we can trace the code
we have encountered during execution. Such information is used by
coverage guided fuzzers like AFL and LibFuzzer to determine if a new
input resulted in a new code path. This makes fuzzing much more
effective.
Additionally this adds a basic KCOV implementation. KCOV is an API that
allows user space to request the kernel to start collecting coverage
information for a given user space thread. Furthermore KCOV then exposes
the collected program counters to user space via a BlockDevice which can
be mmaped from user space.
This work is required to add effective support for fuzzing SerenityOS to
the Syzkaller syscall fuzzer. :^) :^)
The GCC documentation says that since it's officially a part of C++20,
this flag does nothing. Clang, however, does complain that it does not
recognize it, so it's better to just remove it.
This adds a utility program which is essentially a command generator for
CMake. It reads the 'components.ini' file generated by CMake in the
build directory, prompts the user to select a build type and optionally
customize it, generates and runs a CMake command as well as 'ninja
clean' and 'rm -rf Root', which are needed to properly remove system
components.
The program uses whiptail(1) for user interaction.
Neither the kernel nor LibELF support loading libraries with larger
PT_LOAD alignment. The default on x86 is 4096 while it's 2MiB on x86_64.
This changes the alignment to 4096 on all platforms.
