This isn't a complete conversion to ErrorOr<void>, but a good chunk.
The end goal here is to propagate buffer allocation failures to the
caller, and allow the use of TRY() with formatting functions.
... In files included from Kernel/Thread.cpp or Kernel/Process.cpp
Some places the warning is suppressed, because we do not want a const
object do have non-const access to the returned sub-object.
This small change simplifies the function a bit but also fixes a problem
with it.
Let's take an example to see this:
Let's say we have a reserved range between 0xe0000 to 0xfffff (EBDA),
then we want to map from the memory device (/dev/mem) the entire
EBDA to a program. If a program tries to map more than 131072 bytes,
the current logic will work - the start address is 0xe0000, and ofcourse
it's below the limit, hence it passes the first two restrictions.
Then, the third if statement will fail if we try to mmap more than
the said allowed bytes.
However, let's take another scenario, where we try to mmap from
0xf0000 - but we try to mmap less than 131072 - but more than 65536.
In such case, we again pass the first two if statements, but the third
one is passed two, because it doesn't take into account the offseted
address from the start of the reserved range (0xe0000). In such case,
a user can easily mmap 65535 bytes above 0x100000. This might
seem negligible. However, it's still a severe bug that can theoretically
be exploited into a info leak or tampering with important kernel
structures.
By moving the PhysicalPage classes out of the kernel heap into a static
array, one for each physical page, we can avoid the added overhead and
easily find them by indexing into an array.
This also wraps the PhysicalPage into a PhysicalPageEntry, which allows
us to re-use each slot with information where to find the next free
page.
We already use PAE for the NX bit, but this changes the PhysicalAddress
structure to be able to hold 64 bit physical addresses. This allows us
to use all the available physical memory.
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 *
This may seem like a no-op change, however it shrinks down the Kernel by a bit:
.text -432
.unmap_after_init -60
.data -480
.debug_info -673
.debug_aranges 8
.debug_ranges -232
.debug_line -558
.debug_str -308
.debug_frame -40
With '= default', the compiler can do more inlining, hence the savings.
I intentionally omitted some opportunities for '= default', because they
would increase the Kernel size.
There is no reason to call a getter without observing the result, doing
so indicates an error in the code. Mark these methods as [[nodiscard]]
to find these cases.
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.
Also run it across the whole tree to get everything using the One True Style.
We don't yet run this in an automated fashion as it's a little slow, but
there is a snippet to do so in makeall.sh.
