This feels like a pretty naive implementation, but I think it can work.
Basically each waiter creates an object on its stack that is then
added to a linked list inside by the pthread_cond_t.
Signalling is then done by walking the list and unsetting the "waiting"
flag on as many of the waiters as you like.
This extends the opportunistic protection of empty-but-kept-around to
also cover BigAllocationBlocks. Since we only cache 4KB BAB's at the
moment, this sees limited use, but it does work.
We now keep a separate queue of empty ChunkedBlocks in each allocator.
The underlying memory for each block is mprotect'ed with PROT_NONE to
provoke crashes on use-after-free.
This is not going to catch *all* use-after-frees, but if it catches
some, that's still pretty nice. :^)
The malloc memory region names are now updated to reflect their reuse
status: "malloc: ChunkedBlock(size) (free/reused)"
It's now possible to load a .o file into the kernel via a syscall.
The kernel will perform all the necessary ELF relocations, and then
call the "module_init" symbol in the loaded module.
Long ago, there was a fourth stdio default stream, stddbg, connected to the
debug console. It has since been replaced by the dbgputstr() and dbgputch()
syscalls.
3fce2fb205
Remove the last remains of stddbg, as fd 3 is soon going to be reused for socket
takeover.
Add an initial implementation of pthread attributes for:
* detach state (joinable, detached)
* schedule params (just priority)
* guard page size (as skeleton) (requires kernel support maybe?)
* stack size and user-provided stack location (4 or 8 MB only, must be aligned)
Add some tests too, to the thread test program.
Also, LibC: Move pthread declarations to sys/types.h, where they belong.
This can be implemented entirely in userspace by calling tcgetattr().
To avoid screwing up the syscall indexes, this patch also adds a
mechanism for removing a syscall without shifting the index of other
syscalls.
Note that ports will still have to be rebuilt after this change,
as their LibC code will try to make the isatty() syscall on startup.
Have pthread_create() allocate a stack and passing it to the kernel
instead of this work happening in the kernel. The more of this we can
do in userspace, the better.
This patch also unexposes the raw create_thread() and exit_thread()
syscalls since they are now only used by LibPthread anyway.
VM regions can now be marked as stack regions, which is then validated
on syscall, and on page fault.
If a thread is caught with its stack pointer pointing into anything
that's *not* a Region with its stack bit set, we'll crash the whole
process with SIGSTKFLT.
Userspace must now allocate custom stacks by using mmap() with the new
MAP_STACK flag. This mechanism was first introduced in OpenBSD, and now
we have it too, yay! :^)
This patch adds pthread_create() and pthread_exit(), which currently
simply wrap our existing create_thread() and exit_thread() syscalls.
LibThread is also ported to using LibPthread.
POSIX's openat() is very similar to open(), except you also provide a
file descriptor referring to a directory from which relative paths
should be resolved.
Passing it the magical fd number AT_FDCWD means "resolve from current
directory" (which is indeed also what open() normally does.)
This fixes libarchive's bsdtar, since it was trying to do something
extremely wrong in the absence of openat() support. The issue has
recently been fixed upstream in libarchive:
https://github.com/libarchive/libarchive/issues/1239
However, we should have openat() support anyway, so I went ahead and
implemented it. :^)
Fixes#748.
This just copies the short char into the wide char without any decoding
whatsoever. A proper implementation should look at the current LC_CTYPE
and implement multi-byte decoding.
Files opened with O_DIRECT will now bypass the disk cache in read/write
operations (though metadata operations will still hit the disk cache.)
This will allow us to test actual disk performance instead of testing
disk *cache* performance, if that's what we want. :^)
There's room for improvment here, we're very aggressively flushing any
dirty cache entries for the specific block before reading/writing that
block. This is done by walking the entire cache, which may be slow.
`atof()` has now been implemented as part of the standard C library.
It supports scientific notation such as `1.2e-3` etc, ala the version
found as part of `glibc`.
It's a bit chunky, so there's probably room for optimisations here
and there, however, for now it works as intended (and allows Quake
to run).
Ports/.port_include.sh, Toolchain/BuildIt.sh, Toolchain/UseIt.sh
have been left largely untouched due to use of Bash-exclusive
functions and variables such as $BASH_SOURCE, pushd and popd.
When using the bounded string operations (e.g. snprintf), the null
terminator was always being written even if there was no space for
it (or indeed any valid buffer at all)
This overwriting caused segmentation faults and memory corruption
Thread::make_userspace_stack_for_main_thread is only ever called from
Process::do_exec, after all the fun ELF loading and TSS setup has
occured.
The calculations in there that check if the combined argv + envp
size will exceed the default stack size are not used in the rest of
the stack setup. So, it should be safe to move this to the beginning
of do_exec and bail early with -E2BIG, just like the man pages say.
Additionally, advertise this limit in limits.h to be a good POSIX.1
citizen. :)
