Commit Graph

33 Commits

Author SHA1 Message Date
Andreas Kling
e9c0f4567d Kernel+ProcessManager: Expose the number of kmalloc/kfree calls.
This will be very helpful in tracking down unwanted kmalloc traffic. :^)
2019-04-15 19:43:12 +02:00
Andreas Kling
a58d7fd8bb Kernel: Get rid of Kernel/types.h, separate LinearAddress/PhysicalAddress. 2019-04-06 14:29:29 +02:00
Andreas Kling
39fd81174e Kernel: Tidy up kmalloc.cpp a tiny bit. 2019-04-03 14:41:40 +02:00
Andreas Kling
60d25f0f4a Kernel: Introduce threads, and refactor everything in support of it.
The scheduler now operates on threads, rather than on processes.
Each process has a main thread, and can have any number of additional
threads. The process exits when the main thread exits.

This patch doesn't actually spawn any additional threads, it merely
does all the plumbing needed to make it possible. :^)
2019-03-23 22:03:17 +01:00
Andreas Kling
a7a456002e LibC: Enough compat work to make binutils-2.32 build and run. 2019-02-23 17:24:50 +01:00
Andreas Kling
6788dcdb58 Start fixing things up to build with a proper cross-compiler. 2019-02-22 10:23:28 +01:00
Andreas Kling
e241f3a801 Kernel: Shrink kmalloc() chunk size from 128 to 64.
This sacrifices some speed for more space. I don't want to work on a new
allocator right this moment, so this buys me some time.
2019-02-17 13:41:15 +01:00
Andreas Kling
0730b3c15f Add ability to switch video modes from the system menu.
I had to change PhysicalPage around a bit for this. Physical pages can now
be instantiated for any arbitrary physical address without worrying that
such pages end up in the kernel page allocator when released.

Most of the pieces were already in place, I just glued everything together.
2019-02-17 13:12:59 +01:00
Andreas Kling
022f7790db Use modern C++ attributes instead of __attribute__ voodoo.
This is quite nice, although I wish [[gnu::always_inline]] implied inline.
Also "gnu::" is kind of a wart, but whatcha gonna do.
2019-02-15 12:30:48 +01:00
Andreas Kling
0e73aa36c8 Kernel: Unbreak symbolication yet another time. 2019-01-27 10:17:56 +01:00
Andreas Kling
a8baee4dcd Tidy up memory map a bit and write out the general map in MemoryManager.
There was a bug that given enough supervisor page allocation, we would
eventually start dipping into the kmalloc range.
2019-01-16 00:44:09 +01:00
Andreas Kling
3ac977f50b Paper over a race in DoubleBuffer.
I'm still somewhat okay throwing InterruptDisabler at races as they screw me.
Eventually I'm gonna have to devise a different strategy though.
2019-01-12 23:23:35 +01:00
Andreas Kling
2e2d883c09 Print process name and PID when kmalloc() panics. 2019-01-12 21:48:41 +01:00
Andreas Kling
f6179ad9f9 Add slightly better kmalloc_aligned() and kfree_aligned().
Process page directories can now actually be freed. This could definitely
be implemented in a nicer, less wasteful way, but this works for now.

The spawn stress test can now run for a lot longer but eventually dies
due to kmalloc running out of memory.
2018-12-26 21:47:15 +01:00
Andreas Kling
85b886c2e0 Make it possible to build the Kernel on a macOS host.
It still requires an ELF compiler and linker, but at least it builds.
I need to get rid of the "Unix" namespace. This does a lot of that.
2018-12-02 23:34:50 +01:00
Andreas Kling
9d05f6b7a7 Make bash-2.05b build with minimal changes.
This is really neat. :^)
2018-11-17 00:14:07 +01:00
Andreas Kling
5e8e554f94 Add a braindead 10x speedup to kmalloc().
Skip over entirely full buckets when scanning for a big-enough memory slot.
This means I can postpone writing a better kmalloc() for a while longer! :^)
2018-11-12 15:29:46 +01:00
Andreas Kling
2ac5e14c08 Merge VGA into VirtualConsole. 2018-11-10 16:26:18 +01:00
Andreas Kling
47b7eeda44 Fix all current build warnings in the kernel. 2018-11-09 10:03:21 +01:00
Andreas Kling
e71cb1c56b Fix some paging related bugs exposed by the spawn stress test.
- Process::exec() needs to restore the original paging scope when called
  on a non-current process.
- Add missing InterruptDisabler guards around g_processes access.
- Only flush the TLB when modifying the active page tables.
2018-11-09 01:25:31 +01:00
Andreas Kling
b59ce22fc5 Fix dumb-but-hard-to-find bug in paging.
This was the fix:

-process.m_page_directory[0] = m_kernel_page_directory[0];
-process.m_page_directory[1] = m_kernel_page_directory[1];
+process.m_page_directory->entries[0] = m_kernel_page_directory->entries[0];
+process.m_page_directory->entries[1] = m_kernel_page_directory->entries[1];

I spent a good two hours scratching my head, not being able to figure out why
user process page directories felt they had ownership of page tables in the
kernel page directory.

It was because I was copying the entire damn kernel page directory into
the process instead of only sharing the two first PDE's. Dang!
2018-11-03 00:35:57 +01:00
Andreas Kling
8accc92c3c Implement fork()!
This is quite cool! The syscall entry point plumbs the register dump
down to sys$fork(), which uses it to set up the child process's TSS
in order to resume execution right after the int 0x80 fork() call. :^)

This works pretty well, although there is some problem with the kernel
alias mappings used to clone the parent process's regions. If I disable
the MM::release_page_directory() code, there's no problem. Probably there's
a premature freeing of a physical page somehow.
2018-11-02 20:41:58 +01:00
Andreas Kling
c70afd045e Use a freelist for GDT entries.
Tweak the kmalloc space layout a bit. Get the spawn stress test up
and running again.
2018-11-01 16:23:12 +01:00
Andreas Kling
0f70b9105f Implement address validation by querying the task's page directory.
This is way better than walking the region lists. I suppose we could
even let the hardware trigger a page fault and handle that. That'll
be the next step in the evolution here I guess.
2018-11-01 12:45:51 +01:00
Andreas Kling
1da0a7c949 Give each task its own page directory.
This isn't finished but I'll commit as I go. We need to get to where context
switching only needs to change CR3 and everything's ready to go.

My basic idea is:
- The first 4 kB is off-limits. This catches null dereferences.
- Up to the 4 MB mark is identity-mapped and kernel-only.
- The rest is available to everyone!

While the first 4 MB is only available to the kernel, it's still mapped in
every process, for convenience when entering the kernel.
2018-11-01 09:01:51 +01:00
Andreas Kling
9a086b2d35 Add a kmalloc_eternal() for things that will never be destroyed. 2018-10-31 23:19:15 +01:00
Andreas Kling
e6284a8774 Fix broken SpinLock.
The SpinLock was all backwards and didn't actually work. Fixing it exposed
how wrong most of the locking here is.

I need to come up with a better granularity here.
2018-10-29 22:04:26 +01:00
Andreas Kling
2716a9e2d7 Greatly improve /proc/PID/stack by tracing the ebp frame chain.
I also added a generator cache to FileHandle. This way, multiple
reads to a generated file (i.e in a synthfs) can transparently
handle multiple calls to read() without the contents changing
between calls.

The cache is discarded at EOF (or when the FileHandle is destroyed.)
2018-10-27 00:14:24 +02:00
Andreas Kling
c928b06218 Add a very hackish /proc/PID/stack.
It walks the stack and identifies anything that looks like a kernel symbol.
This could be a lot more sophisticated.
2018-10-26 22:33:15 +02:00
Andreas Kling
0c5bbac86e Add an InterruptDisabler helper class and use that for kmalloc.
The naive spinlock was not nearly enough to protect kmalloc from
reentrancy problems.

I don't want to deal with coming up with a fancy lock for kmalloc
right now, so I made an InterruptDisabler thingy instead.
It does CLI and then STI iff interrupts were previously enabled.
2018-10-24 11:07:53 +02:00
Andreas Kling
a5caf7ca99 Make the kmalloc global stats variable volatile.
I know I'm praying for cargo here, but this does fix a weird issue
where logging the sum_alloc and sum_free globals wouldn't display
symmetric values all the time.
2018-10-24 01:04:06 +02:00
Andreas Kling
82dae8fc90 Add a kmalloc lock. This definitely reduces flakiness. 2018-10-24 00:51:19 +02:00
Andreas Kling
9396108034 Import the "gerbert" kernel I worked on earlier this year.
It's a lot crappier than I remembered it. It's gonna need a lot of work.
2018-10-16 11:02:00 +02:00