CPUs which support RDRAND do not necessarily support RDSEED. This
introduces a flag g_cpu_supports_rdseed which is set appropriately
by CPUID. This causes Haswell CPUs in particular (and probably a lot
of AMD chips) to now fail to boot with #2634, rather than an illegal
instruction.
It seems like the KernelRng needs either an initial reseed call or
more random events added before the first call to get_good_random,
but I don't feel qualified to make that kind of change.
We were getting a little overly memey in some places, so let's scale
things back to business-casual.
Informal language is fine in comments, commits and debug logs,
but let's keep the runtime nice and presentable. :^)
This patch adds a MappedROM abstraction to the Kernel VM subsystem.
It's basically the read-only byte buffer equivalent of a TypedMapping.
We use this in the ACPI and MP table parsers to scan for interesting
stuff in low memory instead of doing a bunch of address arithmetic.
Let's not be paying the function call overhead for these tiny ops.
Maybe there's an argument for having fewer gadgets in the kernel but
for now we're actually seeing stac() in profiles so let's put
that above theoretical security issues.
This was supposed to be the foundation for some kind of pre-kernel
environment, but nobody is working on it right now, so let's move
everything back into the kernel and remove all the confusion.
This patch adds PageFaultResponse::OutOfMemory which informs the fault
handler that we were unable to allocate a necessary physical page and
cannot continue.
In response to this, the kernel will crash the current process. Because
we are OOM, we can't symbolicate the crash like we normally would
(since the ELF symbolication code needs to allocate), so we also
communicate to Process::crash() that we're out of memory.
Now we can survive "allocate 300 MB" (only the allocate process dies.)
This is definitely not perfect and can easily end up killing a random
innocent other process who happened to allocate one page at the wrong
time, but it's a *lot* better than panicking on OOM. :^)
We currently only care about debug exceptions that are triggered
by the single-step execution mode.
The debug exception is translated to a SIGTRAP, which can be caught
and handled by the tracing thread.
Also, duplicate data in dbg() and klog() calls were removed.
In addition, leakage of virtual address to kernel log is prevented.
This is done by replacing kprintf() calls to dbg() calls with the
leaked data instead.
Also, other kprintf() calls were replaced with klog().
Now we use the GenericInterruptHandler class instead of IRQHandler in
the CPU functions.
This commit adds an include to the ISR stub macros header file.
Also, this commit adds support for IRQ sharing, so when an IRQHandler
will try to register to already-assigned IRQ number, a SharedIRQHandler
will be created to register both IRQHandlers.
The kernel sampling profiler will walk thread stacks during the timer
tick handler. Since it's not safe to trigger page faults during IRQ's,
we now avoid this by checking the page tables manually before accessing
each stack location.
We're not equipped to deal with page faults during an IRQ handler,
so add an assertion so we can immediately tell what's wrong.
This is why profiling sometimes hangs the system -- walking the stack
of the profiled thread causes a page fault and things fall apart.
Since we scrub both kmalloc() and kfree() with predictable values, we
can log a helpful message when hitting a crash that looks like it might
be a dereference of such scrubbed data.
System components that need an IRQ handling are now inheriting the
InterruptHandler class.
In addition to that, the initialization process of PATAChannel was
changed to fit the changes.
PATAChannel, E1000NetworkAdapter and RTL8139NetworkAdapter are now
inheriting from PCI::Device instead of InterruptHandler directly.
We don't need to have this method anymore. It was a hack that was used
in many components in the system but currently we use better methods to
create virtual memory mappings. To prevent any further use of this
method it's best to just remove it completely.
Also, the APIC code is disabled for now since it doesn't help booting
the system, and is broken since it relies on identity mapping to exist
in the first 1MB. Any call to the APIC code will result in assertion
failed.
In addition to that, the name of the method which is responsible to
create an identity mapping between 1MB to 2MB was changed, to be more
precise about its purpose.
uintptr_t is 32-bit or 64-bit depending on the target platform.
This will help us write pointer size agnostic code so that when the day
comes that we want to do a 64-bit port, we'll be in better shape.
