Since this range is mapped in already in the kernel page directory, we
can initialize it before jumping into the first kernel process which
lets us avoid mapping in the range into init_stage2's address space.
This brings us half-way to removing the shared bottom 2 MiB mapping in
every process, leaving only the Prekernel.
The sa_family field in SIOCGIFHWADDR specifies the underlying network
interface's device type, this is hardcoded to generic "Ethernet" right
now, as we don't have a nice way to query it.
In order to reduce our reliance on __builtin_{ffs, clz, ctz, popcount},
this commit removes all calls to these functions and replaces them with
the equivalent functions in AK/BuiltinWrappers.h.
Not much to say here, this is an implementation of this call that
accesses the actual limit constant that's used by the VirtualFileSystem
class.
As a side note, this is required for my eventual Qt port.
As pointed out by BertalanD on Discord, POSIX specifies that
_SC_SYMLOOP_MAX (implemented in the following commit) always needs to be
equal or more than _POSIX_SYMLOOP_MAX (8, defined in
LibC/bits/posix1_lim.h), hence I've increased it to that value to
comply with the standard.
The move to header is required for the following commit - to make this
constant accessible outside of the VFS class, namely in sysconf.
For setreuid and setresuid syscalls, -1 means to set the current
uid/euid/gid/egid value, to be more convenient for programming.
However, for other syscalls where we pass only one argument, there's no
justification to specify -1.
This behavior is identical to how Linux handles the value -1, and is
influenced by the fact that the manual pages for the group of one
argument syscalls that handle ID operations is ambiguous about this
topic.
Unsurprisingly, the /proc/PID/stacks/TID stack walk had the same
arbitrary memory read problem as the perf event stack walk.
It would be nice if the kernel had a single stack walk implementation,
but that's outside the scope of this commit.
Since perfcore files can be generated during process finalization,
we can't just allow them to contain sensitive kernel information
if they're gonna be owned by the process's own UID+GID.
So instead, perfcores are now owned by 0:0. This is not the most
ergonomic solution, but I'm not sure what we could do to make it nicer.
We'll have to think more about that. In the meantime, this patches up
a kernel info leak. :^)
When walking the stack to generate a perf_event sample, we now check
if a userspace stack frame points back into kernel memory.
It was possible to use this as an arbitrary kernel memory read. :^)
We can leave the .ksyms section mapped-but-read-only and then have the
symbols index simply point into it.
Note that we manually insert null-terminators into the symbols section
while parsing it.
This gets rid of ~950 KiB of kmalloc_eternal() at startup. :^)
We used to build with -Os in order to fit within a certain size, but
there isn't really a good reason for that kind of restriction.
Switching to -O2 yields a significant improvement in throughput,
for example `test-js` is roughly 20% faster on my machine. :^)
This fixes at least half of our LibC includes in the kernel. The source
of truth for errno codes and their description strings now lives in
Kernel/API/POSIX/errno.h as an enumeration, which LibC includes.
Before this commit, we only checked the receive buffer on the socket,
which is unused on datagram streams. Now we return the actual size of
the datagram without the protocol headers, which required the protocol
to tell us what the size of the payload is.
This small change allows to use the IOAPIC by default without to enable
SMP mode, which emulates Uni-Processor setup with IOAPIC instead of
using the PIC.
This opens the opportunity to utilize other types of interrupts like MSI
and MSI-X interrupts.
The MADT data could be on unaligned boundary - for example, a GSI number
(u32) on unaligned address which leads to a KUBSAN error and halting the
system.
Using the phrase "create" doesn't give information on whether the object
must be allocated or a failure to do so can be handled gracefully.
Therefore, we must use better phrase for such purpose, so "must_create"
for the allocate-and-construct static methods is definitely good choice.
Instead, allocate before constructing the object and pass NonnullOwnPtr
of KString to the object if needed. Some classes can determine their
names as they have a known attribute to look for or have a static name.
- dump_backtrace was using ebp instead of rbp on x86_64, only using the
lower 32-bits of rbp.
- The symbol loader was only fetching half of the pointer from the
symbol table. (8 chars instead of 16 chars)
Since it's possible to determine where the small zones will start to
occur for each PhysicalRegion, we can use arithmetic so that the call
time for both large and small zones is identical.
This file refers to the controlling terminal associated with the current
process. It's specified by POSIX, and is used by ports like openssh to
interface with the terminal even if the standard input/output is
redirected to somewhere else.
Our implementation leverages ProcFS's existing facilities to create
process-specific symbolic links. In our setup, `/dev/tty` is a symbolic
link to `/proc/self/tty`, which itself is a symlink to the appropriate
`/dev/pts` entry. If no TTY is attached, `/dev/tty` is left dangling.
Now that the userland has a compatiblity wrapper for select(), the
kernel doesn't need to implement this syscall natively. The poll()
interface been around since 1987, any code still using select()
should be slapped silly.
Note: the SerenityOS source tree mostly uses select() and not poll()
despite SerenityOS having support for poll() since early 2019...
This includes a new Thread::Blocker called SignalBlocker which blocks
until a signal of a matching type is pending. The current Blocker
implementation in the Kernel is very complicated, but cleaning it up is
a different yak for a different day.
