This has KString, KBuffer, DoubleBuffer, KBufferBuilder, IOWindow,
UserOrKernelBuffer and ScopedCritical classes being moved to the
Kernel/Library subdirectory.
Also, move the panic and assertions handling code to that directory.
Enabling these will fix the Unsupported Exclusive or Atomic access data
fault we get on bare metal Raspberry Pi 3. On A53/A57 chips (and newer),
atomic compare-exchange operations require the data cache to be enabled.
Setting the kernel_load_base variable caused backtracking to regress, so
to have proper backtracing the calculation of the symbol address in
KSyms.cpp needs to keep into account that the aarch64 kernel is linked
at a high virtual memory address.
The handling of page tables is very architecture specific, so belongs
in the Arch directory. Some parts were already architecture-specific,
however this commit moves the rest of the PageDirectory class into the
Arch directory.
While we're here the aarch64/PageDirectory.{h,cpp} files are updated to
be aarch64 specific, by renaming some members and removing x86_64
specific code.
This is the same address that the x86_64 kernel runs at, and allows us
to run the kernel at a high virtual memory address. Since we now run
completely in high virtual memory, we can also unmap the identity
mapping. Additionally some changes in MMU.cpp are required to
successfully boot.
Since we link the kernel at a high virtual memory address, the addresses
of global variables are also at virtual addresses. To be able to access
them without the MMU enabled, we have to subtract the
KERNEL_MAPPING_BASE.
This function will be used once the kernel runs in high virtual memory
to unmap the identity mapping as userspace will later on use this memory
range instead.
And use it the code that will be part of the early boot process.
The PANIC macro and dbgln functions cannot be used as it accesses global
variables, which in the early boot process do not work, since the MMU is
not yet enabled.
In the upcoming commits, we'll change the kernel to run at a virtual
address in high memory. This commit prepares for that by making sure the
kernel and mmio are mapped into high virtual memory.
For the initial page tables we only need to identity map the kernel
image, the rest of the memory will be managed by the MemoryManager. The
linker script is updated to get the kernel image start and end
addresses.
The page table and page directory formats are architecture specific, so
move the headers into the Arch directory. Also move the aarch64 page
table constants from aarch64/MMU.cpp to aarch64/PageDirectory.h.
By default these 2 fields were zero, which made it rely on
implementation defined behavior whether these fields internally would be
set to the correct value. The ARM processor in the Raspberry PI (and
QEMU 6.x) would actually fixup these values, whereas QEMU 7.x now does
not do that anymore, and a translation fault would be generated instead.
For more context see the relevant QEMU issue:
- https://gitlab.com/qemu-project/qemu/-/issues/1157Fixes#14856
