In QtCreator (and under weird configurations with gcc), this used to
fail with the error messages like: "error: member of anonymous union
redeclares '___'".
This patch gives each member a unique name.
Previously, getauxval() got the address of the auxiliary vector by
traversing to the end of the `environ` pointer.
The assumption that the auxiliary vector comes after the environment
array is true at program startup, however the environment array may
be re-allocated and change its address during runtime which would cause
getauxval() to work with an incorrect auxiliary vector address.
To fix this, we now get the address of the auxiliary vector once in
__libc_init and store it in a libc-internal pointer which is then used
by getauxval().
Fixes#10087.
If we hit an assertion while the heap isn't in a stable state, we can't
rely on dynamic memory allocation because the malloc mutex is already
held and the heap is most likely corrupted. Instead, we need to bail
out fast before we make the situation even worse.
Two new ioctl requests are used to get and set the sample rate of the
sound card. The SB16 device keeps track of the sample rate separately,
because I don't want to figure out how to read the sample rate from the
device; it's easier that way.
The soundcard write doesn't set the sample rate to 44100 Hz every time
anymore, as we want to change it externally.
This patch begins the work of sharing types and macros between Kernel
and LibC instead of duplicating them via the kludge in UnixTypes.h.
The basic idea is that the Kernel vends various POSIX headers via
Kernel/API/POSIX/ and LibC simply #include's them to get the macros.
The `nonnull` attribute may delete null checks in the generated code, as
per the [GCC documentation]:
> The compiler may also perform optimizations based on the knowledge
> that nonnul parameters cannot be null. This can currently not be
> disabled other than by removing the nonnull attribute.
Disassembling the function as compiled by GCC, we can see that there is
no branch based on if `tv` is null. This means that `gettimeofday`
would produce UB if passed a null parameter, even if we wanted to
predictably return an error. Clang refuses to compile this due to a
`pointer-bool-conversion` warning.
In this commit, `settimeofday` is changed as well to match
`gettimeofday`'s null argument handling.
[GCC documentation]:
https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-nonnull-function-attribute
Since the InodeIndex encapsulates a 64 bit value, it is correct to
ensure that the Kernel is exposing the entire value and the LibC is
aware of it.
This commit requires an entire re-compile because it's essentially a
change in the Kernel ABI, together with a corresponding change in LibC.
When the system calls return `NumericLimits<ptrdiff_t>::min()`, negating
the return code would produce `NumericLimits<ptrdiff_t>::max() + 1`
since we are on a two's complement architecture. Because this value
cannot be stored, signed overflow occurs which is UB. This can be fixed
by applying the negation to `EMAXERRNO` since that's known to contain a
relatively small value.
Found when running tests with Clang.
This implements bits and pieces to get the debugging functionality to
build. No testing has been done to check whether it actually works
because GCC doesn't currently work.
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. :^) :^)
This patch changes the semantics of purgeable memory.
- AnonymousVMObject now has a "purgeable" flag. It can only be set when
constructing the object. (Previously, all anonymous memory was
effectively purgeable.)
- AnonymousVMObject now has a "volatile" flag. It covers the entire
range of physical pages. (Previously, we tracked ranges of volatile
pages, effectively making it a page-level concept.)
- Non-volatile objects maintain a physical page reservation via the
committed pages mechanism, to ensure full coverage for page faults.
- When an object is made volatile, it relinquishes any unused committed
pages immediately. If later made non-volatile again, we then attempt
to make a new committed pages reservation. If this fails, we return
ENOMEM to userspace.
mmap() now creates purgeable objects if passed the MAP_PURGEABLE option
together with MAP_ANONYMOUS. anon_create() memory is always purgeable.
As we've opted to make these inline functions and not macros, let's at
least make sure that the users don't *observe* multiple definitions of
these functions.
This implementation features a fast path for pthread_cond_signal() and
pthread_cond_broadcast() for the case there's no thread waiting, and
does not exhibit the "thundering herd" issue in
pthread_cond_broadcast().
Fixes https://github.com/SerenityOS/serenity/issues/8432
Depending on the driver, the second buffer may not be located right
after the first, e.g. it may be page aligned. This removes this
assumption and queries the driver for the appropriate offset.
Some devices may require DMA transfers to flush the updated buffer
areas prior to flipping. For those devices we track the areas that
require flushing prior to the next flip. For devices that do not
support flipping, but require flushing, we'll simply flush after
updating the front buffer.
This also adds a small optimization that skips these steps entirely for
a screen that doesn't have any updates that need to be rendered.
We regularily need to flush many rectangles, so instead of making many
expensive ioctl() calls to the framebuffer driver, collect the
rectangles and only make one call. And if we have too many rectangles
then it may be cheaper to just update the entire region, in which case
we simply convert them all into a union and just flush that one
rectangle instead.
