This patch adds a single "kernel info page" that is mappable read-only
by any process and contains the current time of day.
This is then used to implement a version of gettimeofday() that doesn't
have to make a syscall.
To protect against race condition issues, the info page also has a
serial number which is incremented whenever the kernel updates the
contents of the page. Make sure to verify that the serial number is the
same before and after reading the information you want from the page.
Currently only Ext2FS and TmpFS supports InodeWatchers. We now fail
with ENOTSUPP if watch_file() is called on e.g ProcFS.
This fixes an issue with FileManager chewing up all the CPU when /proc
was opened. Watchers don't keep the watched Inode open, and when they
close, the watcher FD will EOF.
Since nothing else kept /proc open in FileManager, the watchers created
for it would EOF immediately, causing a refresh over and over.
Fixes#879.
The kernel now supports basic profiling of all the threads in a process
by calling profiling_enable(pid_t). You finish the profiling by calling
profiling_disable(pid_t).
This all works by recording thread stacks when the timer interrupt
fires and the current thread is in a process being profiled.
Note that symbolication is deferred until profiling_disable() to avoid
adding more noise than necessary to the profile.
A simple "/bin/profile" command is included here that can be used to
start/stop profiling like so:
$ profile 10 on
... wait ...
$ profile 10 off
After a profile has been recorded, it can be fetched in /proc/profile
There are various limits (or "bugs") on this mechanism at the moment:
- Only one process can be profiled at a time.
- We allocate 8MB for the samples, if you use more space, things will
not work, and probably break a bit.
- Things will probably fall apart if the profiled process dies during
profiling, or while extracing /proc/profile
This patch makes SharedBuffer use a PurgeableVMObject as its underlying
memory object.
A new syscall is added to control the volatile flag of a SharedBuffer.
It's now possible to get purgeable memory by using mmap(MAP_PURGEABLE).
Purgeable memory has a "volatile" flag that can be set using madvise():
- madvise(..., MADV_SET_VOLATILE)
- madvise(..., MADV_SET_NONVOLATILE)
When in the "volatile" state, the kernel may take away the underlying
physical memory pages at any time, without notifying the owner.
This gives you a guilt discount when caching very large things. :^)
Setting a purgeable region to non-volatile will return whether or not
the memory has been taken away by the kernel while being volatile.
Basically, if madvise(..., MADV_SET_NONVOLATILE) returns 1, that means
the memory was purged while volatile, and whatever was in that piece
of memory needs to be reconstructed before use.
Using int was a mistake. This patch changes String, StringImpl,
StringView and StringBuilder to use size_t instead of int for lengths.
Obviously a lot of code needs to change as a result of this.
This patch adds pthread_key_create() and pthread_{get,set}specific().
There's a maximum of 64 thread-specific keys for simplicity.
Key destructors are not invoked on thread exit.
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.
