This means that userspace breakpoint traps no longer panic the kernel.
This also causes us to no longer panic on failed assertions in userspace
when using gcc, as gcc compiles __builtin_trap to breakpoint
instructions on RISC-V.
As MMIO is placed at fixed physical addressed, and does not need to be
backed by real RAM physical pages, there's no need to use PhysicalPage
instances to track their pages.
This results in slightly reduced allocations, but more importantly
makes MMIO addresses which end up after the normal RAM ranges work,
like 64-bit PCI BARs usually are.
Prepare to remove biglock on PCI::Access in a future commit, so we can
ensure we only lock a spinlock on a precise PCI HostController if needed
instead of the entire subsystem.
The new baked image is a Prekernel and a Kernel baked together now, so
essentially we no longer need to pass the Prekernel as -kernel and the
actual kernel image as -initrd to QEMU, leaving the option to pass an
actual initrd or initramfs module later on with multiboot.
Nobody uses this functionality. I used this code on my old 2007 ICH7
test machine about a year ago, but bare metal is a small aspect of the
project, so it's safe to assume that nobody really tests this piece of
code.
Therefore, let's drop this for good and focus on more modern hardware.
LLVM 18 otherwise throws errors, as we use '-mgeneral-regs-only' in the
kernel.
The functions had to be moved into a .S, as there is no
'-mno-general-regs-only' and also no nice way to remove
'-mgeneral-regs-only' for a single .cpp file.
Since CLINT interrupts are wired directly into the hart, instead of
going through an interrupt controller (the PLIC), trying to handle them
through the normal numbered-interrupt mechanism will just complicate it
for no reason.
Instead we now handle them directly in the trap handler.
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.
"register asm" variables don't preserve the register value, so the call
to calculate_physical_to_link_time_address_offset in the asm input
operands is allowed to clobber a0.
The following command was used to clang-format these files:
clang-format-18 -i $(find . \
-not \( -path "./\.*" -prune \) \
-not \( -path "./Base/*" -prune \) \
-not \( -path "./Build/*" -prune \) \
-not \( -path "./Toolchain/*" -prune \) \
-not \( -path "./Ports/*" -prune \) \
-type f -name "*.cpp" -o -name "*.mm" -o -name "*.h")
There are a couple of weird cases where clang-format now thinks that a
pointer access in an initializer list, e.g. `m_member(ptr->foo)`, is a
lambda return statement, and it puts spaces around the `->`.
This simply reads the current cycle count from the cycle CSR.
x86-64 uses the similar rdtsc instruction here, which also may or may
not tick at a constant rate.
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.
These changes are compatible with clang-format 16 and will be mandatory
when we eventually bump clang-format version. So, since there are no
real downsides, let's commit them now.
This otherwise caused a race condition between the signal dispatcher
(which sets sepc to the signal trampoline) and sepc being updated in the
trap handler.
We obviously have to keep the sepc set by the signal dispatcher and not
increment it afterwards.
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.
This simple delay loop uses the time CSR to wait for the given amount
of time. The tick frequency of the CSR is read from the
/cpus/timebase-frequency devicetree property.
Instead, rewrite the region page fault handling code to not use
PageFault::type() on RISC-V.
I split Region::handle_fault into having a RISC-V-specific
implementation, as I am not sure if I cover all page fault handling edge
cases by solely relying on MM's own region metadata.
We should probably also take the processor-provided page fault reason
into account, if we decide to merge these two implementations in the
future.
This commit also removes the unnecessary user_sp RegisterState member.
We never use the kernel stack pointer on entry, so we can simply always
store the stack pointer of the previous privilege mode in sp.
Also remove the sp member from mcontext, as RISC-V doesn't have a
dedicated stack pointer register.
sp is defined to be x2 (x[1] in our case) by the ABI.
I probably accidentally included sp while copying the struct from
aarch64.
sepc has to be incremented before the call to syscall_handler,
as we otherwise would return to the ecall instruction, resulting in an
infinite trap loop.
We can't increment it after syscall_handler, as sepc might get changed
while handling the syscall.
thread_context_first_enter reuses the context restoring code in the
trap handler, just like other arches already do.
The `ld x2, 1*8(sp)` is unnecessary in the trap handler, as the stack
pointer should be equal to the stack pointer slot in the RegisterState
if the trap is from supervisor mode (and we currently don't support
user traps).
This load will however make us unable to reuse that code for
thread_context_first_enter.
