This was a premature optimization from the early days of SerenityOS.
The eternal heap was a simple bump pointer allocator over a static
byte array. My original idea was to avoid heap fragmentation and improve
data locality, but both ideas were rooted in cargo culting, not data.
We would reserve 4 MiB at boot and only ended up using ~256 KiB, wasting
the rest.
This patch replaces all kmalloc_eternal() usage by regular kmalloc().
This class was misusing the outdate Lockable template and didn't take
advantage of the lock/resource separation mechanism fully anyway.
Since the underlying PRNG has its own SpinLock, and we already use that
for synchronization everywhere anyway, we can simply remove the Lockable
inheritance from this class.
The default template argument is only used in one place, and it
looks like it was probably just an oversight. The rest of the Kernel
code all uses u8 as the type. So lets make that the default and remove
the unused template argument, as there doesn't seem to be a reason to
allow the size to be customizable.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
Alot of code is shared between i386/i686/x86 and x86_64
and a lot probably will be used for compatability modes.
So we start by moving the headers into one Directory.
We will probalby be able to move some cpp files aswell.
(...and ASSERT_NOT_REACHED => VERIFY_NOT_REACHED)
Since all of these checks are done in release builds as well,
let's rename them to VERIFY to prevent confusion, as everyone is
used to assertions being compiled out in release.
We can introduce a new ASSERT macro that is specifically for debug
checks, but I'm doing this wholesale conversion first since we've
accumulated thousands of these already, and it's not immediately
obvious which ones are suitable for ASSERT.
This adds an optional argument to get_good_random_bytes that can be
used to only return randomness if it doesn't have to block.
Also add a SpinLock around using FortunaPRNG.
Fixes#5132
Booting old computers without RDRAND/RDSEED and without a disk makes
the system severely starved for entropy. Uses interrupts as a source
to side-step that issue.
Also warn whenever the system is starved of entropy, because that's
a non-obvious failure mode.
MemoryManager cannot use the Singleton class because
MemoryManager::initialize is called before the global constructors
are run. That caused the Singleton to be re-initialized, causing
it to create another MemoryManager instance.
Fixes#3226
I originally defined the bytes() method for the String class, because it
made it obvious that it's a span of bytes instead of span of characters.
This commit makes this more consistent by defining a bytes() method when
the type of the span is known to be u8.
Additionaly, the cast operator to Bytes is overloaded for ByteBuffer and
such.
- If rdseed is not available, fallback to rdrand.
- If rdrand is not available, block for entropy, or use insecure prng
depending on if user wants fast or good random.
Random now gets entropy from the following drivers:
- KeyboardDevice
- PATAChannel
- PS2MouseDevice
- E1000NetworkAdapter
- RTL8139NetworkAdapter
Of these devices, PS2MouseDevice and PATAChannel provide the vast
majority of the entropy.
As suggested by Joshua, this commit adds the 2-clause BSD license as a
comment block to the top of every source file.
For the first pass, I've just added myself for simplicity. I encourage
everyone to add themselves as copyright holders of any file they've
added or modified in some significant way. If I've added myself in
error somewhere, feel free to replace it with the appropriate copyright
holder instead.
Going forward, all new source files should include a license header.
We now have these API's in <Kernel/Random.h>:
- get_fast_random_bytes(u8* buffer, size_t buffer_size)
- get_good_random_bytes(u8* buffer, size_t buffer_size)
- get_fast_random<T>()
- get_good_random<T>()
Internally they both use x86 RDRAND if available, otherwise they fall
back to the same LCG we had in RandomDevice all along.
The main purpose of this patch is to give kernel code a way to better
express its needs for random data.
Randomness is something that will require a lot more work, but this is
hopefully a step in the right direction.
