The hierarchy is AHCIController, AHCIPortHandler, AHCIPort and
SATADiskDevice. Each AHCIController has at least one AHCIPortHandler.
An AHCIPortHandler is an interrupt handler that takes care of
enumeration of handled AHCI ports when an interrupt occurs. Each
AHCIPort takes care of one SATADiskDevice, and later on we can add
support for Port multiplier.
When we implement support of Message signalled interrupts, we can spawn
many AHCIPortHandlers, and allow each one of them to be responsible for
a set of AHCIPorts.
As it turns out, Dr. POSIX doesn't require that post-mmap() changes
to a file are reflected in the memory mappings. So we don't actually
have to care about the file size changing (or the contents.)
IIUC, as long as all the MAP_SHARED mappings that refer to the same
inode are in sync, we're good.
This means that VMObjects don't need resizing capabilities. I'm sure
there are ways we can take advantage of this fact.
Add Bitmap::view() and forward most of the calls to BitmapView since
the code was identical.
Bitmap is now primarily concerned with its dynamically allocated
backing store and BitmapView deals with the rest.
Mostly due to the fact that clang-format allows aligned comments via
AlignTrailingComments.
We could also use raw string literals in inline asm, which clang-format
deals with properly (and would be nicer in a lot of places).
Instead of keeping AnonymousVMObject::m_cow_map in an OwnPtr<Bitmap>,
just make the Bitmap a regular value member. This increases the size
of the VMObject by 8 bytes, but removes some of the kmalloc/kfree spam
incurred by sys$fork().
Since we know for sure that the virtual memory regions in the new
process being created are not being used on any CPU, there's no need
to do TLB flushes for every mapped page.
Dynamic Vector allocations in sys$select() were showing up in the
full-system profile and since there will never be more than FD_SETSIZE
file descriptors to worry about, we can confidently add enough inline
capacity to this Vector that it never has to kmalloc.
To compensate for the increased stack usage, reduce the size of the
FDInfo struct while we're here. :^)
The full system profiling functionality is useful for profiling the
boot performance of the system. Add a new kernel boot option to start
the system with profiling enabled. This lets you disable and view a
profile once the system is booted.
You can use it by running:
```
$ run.sh qcmd boot_prof
```
Previously all of the CommandLine parsing was spread out around the
Kernel. Instead move it all into the Kernel CommandLine class, and
expose a strongly typed API for querying the state of options.
Previously, the instruction fetch flag of the page fault handler
did not have the currect binary representation, and would always
return false. This aligns these flags.
The perfcore file format was previously limited to a single process
since the pid/executable/regions data was top-level in the JSON.
This patch moves the process-specific data into a top-level array
named "processes" and we now add entries for each process that has
been sampled during the profile run.
This makes it possible to see samples from multiple threads when
viewing a perfcore file with Profiler. This is extremely cool! :^)
The superuser can now call sys$profiling_enable() with PID -1 to enable
profiling of all running threads in the system. The perf events are
collected in a global PerformanceEventBuffer (currently 32 MiB in size.)
The events can be accessed via /proc/profile
If we can't allocate a PerformanceEventBuffer to store the profiling
events, we now fail sys$profiling_enable() and sys$perf_event()
with ENOMEM instead of carrying on with a broken buffer.
This was the original approach before we switched to get_fast_random()
which wasn't fast enough, so we added a buffer.
Unfortunately that buffer is racy and we can actually skid past the end
of it and continue fetching "random" offsets from the adjacent memory
for a while, until we run out of kernel data segment and trip a fault.
Instead of making this even more convoluted, let's just go back to the
pleasantly simple (RDTSC & 0xff) approach. :^)
Fixes#4912.
I don't dare touch the multi-threading logic and locking mechanism, so it stays
timespec for now. However, this could and should be changed to AK::Time, and I
bet it will simplify the "increment_time_since_boot()" code.
This commit is very invasive, because Thread likes to take a pointer and write
to it. This means that translating between timespec/timeval/Time would have been
more difficult than just changing everything that hands a raw pointer to Thread,
in bulk.
These structs can be inconsistent, for example if the amount of microseconds is
negative or larger than 1'000'000. Therefore, they should not be copied as-is.
Use copy_time_from_user instead.
copy_from_user can fail, for example when the user-supplied pointer is just before
the end of mapped address space. In that case, the first few bytes would get copied,
permanently overwriting the internal state of the Socket, potentially leaving it
in an inconsistent or at least difficult-to-predict state.
