We can now properly initialize all processors without
crashing by sending SMP IPI messages to synchronize memory
between processors.
We now initialize the APs once we have the scheduler running.
This is so that we can process IPI messages from the other
cores.
Also rework interrupt handling a bit so that it's more of a
1:1 mapping. We need to allocate non-sharable interrupts for
IPIs.
This also fixes the occasional hang/crash because all
CPUs now synchronize memory with each other.
The short-circuit path added for waiting on a queue that already had a
pending wake was able to return with interrupts disabled, which breaks
the API contract of wait_on() always returning with IF=1.
Fix this by adding a way to override the restored IF in ScopedCritical.
If WaitQueue::wake_all, WaitQueue::wake_one, or WaitQueue::wake_n
is called but nobody is currently waiting, we should remember that
fact and prevent someone from waiting after such a request. This
solves a race condition where the Finalizer thread is notified
to finalize a thread, but it is not (yet) waiting on this queue.
Fixes#2693
These changes solve a number of problems with the software
context swithcing:
* The scheduler lock really should be held throughout context switches
* Transitioning from the initial (idle) thread to another needs to
hold the scheduler lock
* Transitioning from a dying thread to another also needs to hold
the scheduler lock
* Dying threads cannot necessarily be finalized if they haven't
switched out of it yet, so flag them as active while a processor
is running it (the Running state may be switched to Dying while
it still is actually running)
We need to be able to prevent a WaitQueue from being
modified by another CPU. So, add a SpinLock to it.
Because this pushes some other class over the 64 byte
limit, we also need to add another 128-byte bucket to
the slab allocator.
The Lock class still permits no reason, but for everything else
require a reason to be passed to Thread::wait_on. This makes it
easier to diagnose why a Thread is in Queued state.
FileBackedFileSystem is one that's backed by (mounted from) a file, in other
words one that has a "source" of the mount; that doesn't mean it deals in
blocks. The hierarchy now becomes:
* FS
* ProcFS
* DevPtsFS
* TmpFS
* FileBackedFS
* (future) Plan9FS
* BlockBasedFS
* Ext2FS
There isn't an easy way to retreive all register contents anymore,
so remove this functionality. We do have the ability to trace
processes, so it shouldn't really be needed anymore.
If we're trying to walk the stack for another thread, we can
no longer retreive the EBP register from Thread::m_tss. Instead,
we need to look at the top of the kernel stack, because all threads
not currently running were last in kernel mode. Context switches
now always trigger a brief switch to kernel mode, and Thread::m_tss
only is used to save ESP and EIP.
Fixes#2678
When delivering urgent signals to the current thread
we need to check if we should be unblocked, and if not
we need to yield to another process.
We also need to make sure that we suppress context switches
during Process::exec() so that we don't clobber the registers
that it sets up (eip mainly) by a context switch. To be able
to do that we add the concept of a critical section, which are
similar to Process::m_in_irq but different in that they can be
requested at any time. Calls to Scheduler::yield and
Scheduler::donate_to will return instantly without triggering
a context switch, but the processor will then asynchronously
trigger a context switch once the critical section is left.
If a partial write succeeded, we could then be in an unexpected state
where the file description was non-blocking, but we could no longer
write to it.
Previously, the kernel would block in that state, but instead we now
handle this as a proper short write and return the number of bytes
we were able to write.
Fixes#2645.
The run script is not in Kernel/ anymore, let's move `.bochsrc` in Meta/
so that it can be used with the new build system.
Also make bochs use `grub_disk_image` instead of `_disk_image`
- If rdseed is not available, fallback to rdrand.
- If rdrand is not available, block for entropy, or use insecure prng
depending on if user wants fast or good random.
CPUs which support RDRAND do not necessarily support RDSEED. This
introduces a flag g_cpu_supports_rdseed which is set appropriately
by CPUID. This causes Haswell CPUs in particular (and probably a lot
of AMD chips) to now fail to boot with #2634, rather than an illegal
instruction.
It seems like the KernelRng needs either an initial reseed call or
more random events added before the first call to get_good_random,
but I don't feel qualified to make that kind of change.
Random now gets entropy from the following drivers:
- KeyboardDevice
- PATAChannel
- PS2MouseDevice
- E1000NetworkAdapter
- RTL8139NetworkAdapter
Of these devices, PS2MouseDevice and PATAChannel provide the vast
majority of the entropy.
These APIs were clearly modeled after Ext2FS internals, and make perfect sense
in Ext2FS context. The new APIs are more generic, and map better to the
semantics exported to the userspace, where inode identifiers only appear in
stat() and readdir() output, but never in any input.
This will also hopefully reduce the potential for races (see commit c44b4d61f3).
Lastly, this makes it way more viable to implement a filesystem that only
synthesizes its inodes lazily when queried, and destroys them when they are no
longer in use. With inode identifiers being used to reference inodes, the only
choice for such a filesystem is to persist any inode it has given out the
identifier for, because it might be queried at any later time. With direct
references to inodes, the filesystem will know when the last reference is
dropped and the inode can be safely destroyed.
