When the shift amount is >= 16-bytes then we need to zero the register.
We had a bug where we were assigning `Result.High` to itself, which
effectively made the top 128-bits of the ymm register not modify itself.
Adds a unit test to ensure that doesn't happen again.
more efficient to pool the output of constant folding and such. but we need to
avoid that becoming accidentally quadratic, so rework that too
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
it's only really load bearing for pf/af, which is handled as a global flag opt
now. this mitigates some of the compile time hit from globalizing flag opts.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
another global CFG-based optimization -- if we know that the raw PF is already
1-bit we can skip parity evaluation, saving work with floating point compares.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
This works fine on real Windows and is relied on by wine as SystemCall
is set to 1 in KUSER_SHARED_DATA, which causes the ntdll thunks to use
it over `syscall`
Because we already pooled the _Constants, there's no benefit to also pooling inline constants. the robin map to do so just adds extra overhead for no benefit - drop it.
without multiblock, shaves around 2% off node. with multiblock, a bit less than
1% but still a win.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
When I implemented TSC scaling originally, I chose a scale factor of 128
because it basically covered the range of devices we cared about without
going too high. I also only tested devices that had a TSC scale factor
from 19.2Mhz to 34Mhz. Turns out there is hardware that also has a 48Mhz
cycle counter, which cause them to effectively have a 6.1Ghz cycle
counter, which is kind of absurd.
Instead of a fixed scale, just calculate the amount of scaling we need
to get >= the minimum threshold of 1Ghz. This will change the shift from
7 to 5 or 6 for the faster cycle counter devices.
Of course if someone wants to know the scale factor they can still use
cpuid function 15h to know it.
Fixes#4026
Seccomp is a relatively complex feature that was added to Linux back in
2005, and was further extended in 2013 to support BPF based protections.
Once seccomp is enabled, you can no longer disable seccomp but
additional protections can be placed on top of existing seccomp filters.
Additionally seccomp filters are inherited in child processes, which
ensures the process tree can't escape from the secure computing
environment through child processes.
The basis of this feature is a shim that lives between userspace and the
kernel at the syscall entrypoint.
In "strict" mode, seccomp only allows read, write, exit, exit_group, and {rt_,}sigreturn to function.
When in "filter" mode, a BPF filter is run on syscall entrypoint and
returns state about if the syscall should be allowed or not. Multiple
filters can be installed in this mode, all of which get executed. The
result that is the most restricted is the action that occurs at the end.
There are some significant limitations in filter mode that must be
adhered to which makes executing this code inside of kernel space a
non-issue and effectively limits how much cpu time is spent in the filters.
Although these filters are free to do basically anything with the
provided data, just can't do any loops.
FEX needs to implement seccomp because there are multiple applications
using the feature, the primary one being Chromium which some games embed
without disabling the sandbox. WINE also uses seccomp for capturing
games that do raw Windows system calls. Apparently Red Dead Redemption
is one of the games that requires this.
While FEX implements seccomp, it is not yet all encompassing, which is
one of the reasons why it isn't enabled by default and requires a config
option.
**seccomp_unotify is not implemented**
This is a relatively new feature for seccomp which lets the seccomp
filter signal an FD for multiple things. Luckily Chromium and WINE don't
use this. This will be tricky to implement under FEX since it
requires ioctl trapping and some other behaviour
**ptrace isn't supported**
One feature of seccomp is that it can raise ptrace events. Since FEX
doesn't support ptrace at all, this isn't handled. Again Chromium and
WINE don't use this.
**kill-thread not quite correct**
This isn't directly related to seccomp but more about how we do thread
shutdown in FEX. This will require some more changes around thread state
tracking before fully supporting this. Chromium and WINE don't use this.
kill-process also falls under this
Features that are supported:
- Strict mode and seccomp-bpf mode supported
- All BFP instructions that seccomp-bpf understands
- Inheriting seccomp through execve
- This means we serialize and deserialize the calling thread's
seccomp filters
- An execve that escapes FEX will also escape seccomp. Not much we
can do about it
- TSync - Allowing post-mortem seccomp insertion which allows threads to
synchronize seccomp filters after the fact
Features that are not supported:
- Different arch qualifiers depending on syscall entrypoint
- Just like our syscall handler, we are hardcoded to the arch that the
application starts with
- user_notif
- ptrace
- Runtime code cache invalidation when seccomp is installed
- Currently we must ensure all syscalls go through the frontend
syscall handler
- Runtime invalidation of code cache with inline syscalls will get
fixed in the future.
This currently isn't enabled by default because of the minor feature
problems that haven't been resolved. Currently the Linux Kernel's test
application works for the features that FEX supports, and WINE's usage
can be handled by FEX. Chromium's sandbox doesn't yet work with this PR,
but it only fails due to features unrelated to seccomp.
Having this open for merging now so we can work to resolve the remaining
issues without this bitrotting.
The Ultra-class SoCs are two Max-class SoCs connected via
Apple's fabric, and thus use the same core revisions as the
Max-class SoCs for both big and LITTLE cores.
Signed-off-by: James Calligeros <jcalligeros99@gmail.com>
These are a Linux construct and should live here. Removes a weird
passthrough API from FEXCore and keeps it in the frontend instead.
This isn't even typically allocated in a real setup, as it's only a
fallback for if VDSO isn't loaded.
The CallbackReturn function stays in FEXCore because it would have
caused an API in the other direction instead.
This variable can't be constexpr initialized since it requires linker
fix-ups, which changes it in to a global static initializer instead.
While this benign as it doesn't allocate any memory, just move it next
to its single use. Removes the static initializer that was there for no
reason.
Ryan Houdek