We have many places in the kernel code that we have boolean flags that
are only set once, and never reset again but are checked multiple times
before and after the time they're being set, which matches the purpose
of the SetOnce class.
This removes the allocate_tls syscall and adds an archctl option to set
the fs_base for the current thread on x86-64, since you can't set that
register from userspace. enter_thread_context loads the fs_base for the
next thread on each context switch.
This also moves tpidr_el0 (the thread pointer register on AArch64) to
the register state, so it gets properly saved/restored on context
switches.
The userspace TLS allocation code is kept pretty similar to the original
kernel TLS code, aside from a couple of style changes.
We also have to add a new argument "tls_pointer" to
SC_create_thread_params, as we otherwise can't prevent race conditions
between setting the thread pointer register and signal handling code
that might be triggered before the thread pointer was set, which could
use TLS.
Sticking this to the function source has multiple benefits:
- We instrument more code, by not excluding entire files.
- NO_SANITIZE_COVERAGE can be used in Header files.
- Keeping the info with the source code, means if a function or
file is moved around, the NO_SANITIZE_COVERAGE moves with it.
About half of the Processor code is common across architectures, so
let's share it with a templated base class. Also, other code that can be
shared in some ways, like FPUState and TrapFrame functions, is adjusted
here. Functions which cannot be shared trivially (without internal
refactoring) are left alone for now.
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.
This has been broken on x86_64 since its introduction, as it features
more registers to be saved, and we never held up the "rbp has to be the
last pushed register" there.
Instead, just copy rbp from the thread structure, which is now properly
updated since the last commit.
The details of the specific interrupt bits that must be turned on are
irrelevant to the sys$execve implementation. Abstract it away to the
Processor implementations using the InterruptsState enum.
This commit adds Processor::set_thread_specific_data, and this function
is used to factor out architecture specific implementation of setting
the thread specific data. This function is implemented for
aarch64 and x86_64, and the callsites are changed to use this function
instead.
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.
Various places in the kernel were manually checking the cs register for
x86_64, however to share this with aarch64 a function in RegisterState
is added, and the call-sites are updated. While we're here the
PreviousMode enum is renamed to ExecutionMode.
This file does not contain any architecture specific implementations,
so we can move it to the Kernel base directory. Also update the relevant
include paths.
