When keeping track of addresses to give to the kernel for channel shared
memory, double the channel's size since the kernel will double-map the
area as a ring buffer.
These are some changes I made to debug tooling while tracking down the
bugfix in the previous commit.
Each `scripts/debug_*_alloc.gdb` script has gdb output a `*_allocs.txt`
file, which in turn can be parsed by the `scripts/parse_*_allocs.py`
script to find errors.
In the heap allocator, new blocks allocated directly for an allocate
request (instead of indirectly as part of a block split) would only set
their order in the tracking map, not their free flag. This left
uninitialized data in the block info map, which thus meant it was marked
as free for looking up for merges. (Not for allocations, since the block
didn't actually appear in the free list.)
I spent some time getting VSCode debugging working. Now I can use VSCode
on windows to work on jsix in Linux (WSL) and launch and debug it within
QEMU. So many layers but it works pretty nicely!
Now threads inherit their MXCSR (sans exception state bits) SIMD
settings from their creator. By default, all exceptions are masked, and
both "to zero" flags are set.
Initial support for XSAVE, but not XSAVEOPT or XSAVEC:
- Enable XSAVE and set up xcr0 for all CPUs
- Allocate XSAVE area for all non-kernel threads
- Call XSAVE and XRSTOR on task switch
Well god damnit, when i converted the `cpu::cpu_id::regs` struct to a
union, i was super sloppy and forgot to wrap the existing fields in
their own anonymous struct. I have been wrong about CPUID vales for
ages.
The libc CRT _start function had a stray pop left in it, which was
causing the stack to never be 16-byte aligned and thus causing crashes
when SSE instructions were called.
When used in kernel vs. non-kernel code the assert macros were not
working as expected. Other util code does not use assert like this, so
I'm just dropping it from bitset.
This commit does a number of things to start the transition of channels
from kernel to user space:
- Remove channel objects / syscalls from the kernel
- Add mutex type in libj6
- Add condition type in libj6
- Add a `ring` type flag for VMA syscalls to create ring buffers
- Implement a rudimentary shared memory channel using all of the above
Add the syscalls j6_futex_wait and j6_futex_wake. Currently marking this
as WIP as they need more testing.
Added to support futexes:
- vm_area and vm_space support for looking up physical address for a
virtual address
- libj6 mutex implementation using futex system calls
The upcoming futex syscalls will be easier to use (and to auto verify)
if passed a pointer instead of an address, this allows for changing a
`Primitive` to a `PrimitiveRef` by adding a `*` to the end.
There are some SSE instructions (moveaps, moveups) in userland code that
QEMU software emulation seems to be fine with but generate `#UD` on KVM.
So let's finally get floating-point support working. This is the first
step, just setting the control regs to try to fix that error.
This was kept in the kernel as a way to keep exercising the code, but it
doesn't belong there. This moves it to init, which doesn't do anything
but probe for devices currently - but at least it's executing the code
in userspace now.
For now, using VNC, I want to keep the framebuffer mode small, so I'm
commenting out the bootloader's loop to pick the biggest video mode.
I'll revisit this as a bootconfig option later.
init still uses a custom _start to set up the stack, but then jumps to
_libc_crt0_start. The modules data passed to it is taken from the
j6_init_args instead of having it stashed into a global variable.
Also replace several uses of snprintf/j6_log with j6::syslog.
Clang will complain if main() is not declared with 0, 2, or 3 arguments.
In order to allow an extra 4th parameter, a new weak main() symbol which
just jumps to driver_main is defined, and _start passes the extra init
pointer to main.
Additionally, libc's crt0.s _start is made weak, and a matching
_libc_crt0_start symbol is defined for implementations that wish to
override _start but still call libc's _start. (Will be used by init.)
Previously processes and threads would be deleted by the scheduler. Now,
only delete them based on refcounts - this allows joining an
already-exited thread, for instance.
Previously event tried to read its value in event::wake_observer, which
required jumping through some hoops in how wait_queue was designed, so
that a value wouldn't be wasted if the wait_queue was empty. Now, read
the event value in event::wait after returning from the thread::block
call instead, which simplifies the whole process and lets us simplify
the wait_queue API as well.
For the coming switch to cap/handle ref-counting being the main lifetime
determiner of objects, get rid of self handles for threads and processes
to avoid circular references. Instead, passing 0 to syscalls expecting a
thread or process handle signifies "this process/thread".
There was an inverted boolean logic in determining how many consecutive
pages were available.
Also adding some memory debugging tools I added to track down the recent
memory bugs:
- A direct debugcon::write call, for logging to the debugcon without the
possible page faults with the logger.
- A new vm_space::lock call, to make a page not fillable in memory
debugging mode
- A mode in heap_allocator to always alloc new pages, and lock freed
pages to cause page faults for use-after-free bugs.
- Logging in kobject on creation and deletion
- Page table cache structs are now page-sized for easy pointer math
Yet again burned by the fack that integer literals are assumed to be of
type int, so `1 << n` is 0 for any n >= 32. This burned me in the frame
allocator, but I also grepped for all instances of `1 <<` and fixed
those too.
