Instead of allocating a temporary copy of the string, return a view of
it instead. Should improve the performance of system calls that take
file paths. Since it was allocating a string for every single syscall
that uses them in this case.
This will allow investigating the Arm64 directly next to the test, plus
publicly linking directly to badly behaving tests.
Perfect for nerdsniping implementations.
Implements CI for tracking instruction counts for generate blocks of
code when transforming from x86 to ARM64 assembly.
This will end up encompassing every instruction in our instruction
tables similarly to how our assembly tests try to test everything in our
instruction tables.
Incidentally, the data for this CI is generated using our assembly
tests. By enabling disassembly and instruction stats when executing a
suite of instructions, this gives the stats that can be added to a json
file.
The current implementation only implements the SecondGroup table of
instructions because it is a relatively small table and has known
inefficiencies in the instruction implementations. As this gets merged I
will be adding more tables of instructions to additional json files for
testing.
These JSON files will support adjusting CPU features regardless of the
host features so it can test implementations depending on different CPU
features. This will let us test things like one instruction having
different "optimal" implementations depending on if it supports SVE128,
SVE256, SVEI8MM, etc.
This initial instruction auditing is what found the bug in our vector
shift instructions by size of zero. If inspecting the result of the CI
run, you can tell that these instructions still aren't "optimal" because
they are doing loads and stores that can be eliminated.
The "Optimal" in the JSON is purely for human readable and grepping
ability to see what is optimal versus not. Same with the "Comment"
section.
According to my auditing spreadsheet, the total number of instructions
that will end up in these json files will be about 1000, but we will
likely end up with more since there will be edge cases that can be more
optimal depending on arguments.
Moves the dummy handlers over to this library. This will end up getting
used for more than the mingw test harness runner once the instruction
count CI is operational.
Allows us to consume an array of strings and convert it to an mask of
enum values. This is a quality of life change that allows us to specify
a mask of options.
The first configuration option added to support this is to control the
vixl disassembler. Now by default the vixl disassembler doesn't
disassemble any blocks and needs to be enabled individually.
eg:
```
FEXLoader --disassemble=blocks <args>
FEXLoader --disassemble=dispatcher <args>
FEXLoader --disassemble=blocks,dispatcher <args>
```
Has the additional convenience option of just passing in numbers as
well.
```
FEXLoader --disassemble=2 <args>
FEXLoader --disassemble=1 <args>
FEXLoader --disassemble=3 <args>
```
Also of course all of this works through environment variables.
```
FEX_DISASSEMBLE=blocks FEXInterpreter <args>
FEX_DISASSEMBLE=dispatcher FEXInterpreter <args>
FEX_DISASSEMBLE=blocks,dispatcher FEXInterpreter <args>
```
While only used fairly sparingly now, this is likely to have some
additional configurations using this in the future. Since we already
have some configs that are basically using enums, but just by doing
string comparisons.
This was asked for by a developer, so I figured I would throw it
together quick.
There was one holdout variable that was in a TLS object in FEXCore. Move
it to the frontend with the rest of the TLS variables.
Allows us to remove "Frontend" TLS management to be the only TLS
management.
Removes the @PREFIX_ARCH@ replacement string in the thunks path.
The library prefix paths now get generated upfront and everything gets
replaced to handle the differences between multiarch distros.
Fixes Thunks on Arch and Fedora.
When a fork occurs FEX needs to be incredibly careful as any thread
(that isn't forking) that holds a lock will vanish when the fork occurs.
At this point if the newly forked process tries to use these mutexes
then the process hangs indefinitely.
The three major mutexes that need to be held during a fork:
- Code Invalidation mutex
- This is the highest priority and causes us to hang frequently.
- This is highly likely to occur when one thread is loading shared
libraries and another thread is forking.
- Happens frequently with Wine and steam.
- VMA tracking mutex
- This one happens when one thread is allocating memory while a fork
occurs.
- This closely relates to the code invalidation mutex, just happens at
the syscall layer instead of the FEXCore layer.
- Happens as frequently as the code invalidation mutex.
- Allocation mutex
- This mutex is used for FEX's 64-bit Allocator, this happens when FEX
is allocating memory on one thread and a fork occurs.
- Fairly infrequent because jemalloc doesn't allocate VMA regions that
often.
While this likely doesn't hit all of the FEX mutexes, this hits the ones
that are burning fires and are happening frequently.
- FEXCore: Adds forkable mutex/locks
Necessary since we have a few locations in FEX that need to be locked
before and after a fork.
When a fork occurs the locks must be locked prior to the fork. Then
afterwards they either need to unlock or be set to default
initialization state.
- Parent
- Does an unlock
- Child
- Sets the lock to default initialization state
- This is because it pthreads does TID based ownership checking on
unique locks and refcount based waiting for shared locks.
- No way to "unlock" after fork in this case other than default
initializing.
Fixes a spurious `No such file or directory` error when `ls` is trying
to query a path's xattributes that come from the emulated rootfs.
These syscalls don't support the *at variants, so it can't use the optimized `GetEmulatedFDPath` implementation.
It must also return an error on a found file path, which makes their
implementation be slightly different than the other user of of
`GetEmulatedPath`. In the case of error, it must only return an error
from the emulated path if it is /not/ ENOENT.
Before:
```
$ FEXInterpreter /usr/bin/ls -alth /usr/bin/wine-stable
/usr/bin/ls: /usr/bin/wine-stable: No such file or directory
-rwxr-xr-x 1 ryanh ryanh 1.1K Sep 24 2022 /usr/bin/wine-stable
```
After:
```
$ FEXInterpreter /usr/bin/ls -alth /usr/bin/wine-stable
-rwxr-xr-x 1 ryanh ryanh 1.1K Sep 24 2022 /usr/bin/wine-stable
```
istringstream is a very slow way to parse this, let's make it a bit
quicker.
Some implementation numbers:
1. Original implementation - 1833556 calculations per second
2. std::strtoul implementation - 4666818 calculations per second
- 2.54x the istringstream implementation
3. str::from_chars implementation - 5120718 calculations per second
- 1.09x the std::strtoul implementation
- 2.79x th istringstream implementation
This message is complaining each time VFORK was using with clone, but we
are handling VFORK here now.
This is just causing debug messages for no reason.
Remove the message and remove the flag removal option.
Not sure how this ever managed to work before this point actually. We
were returning a 64-bit pointer when we were supposed to be returning a
32-bit pointer.
Seemingly this was overwriting the len stack variable so then Steam's
chromehtml.so library was checking the results thoroughly and detecting
that the robust list wasn't setup before this point.
SOMEHOW this worked if FEX was built locally, but broke from the PPA
builders? Not sure how that happened, but theoretically on the next PPA
release this is now fixed and Steam can run from those builds.
Also when setting the robust list, make sure to return EINVAL if the
size doesn't match what's expected there.
FEXCore has no need to understand how to load these layers. Which
requires json parsing.
Move these to the frontend which is already doing the configuration
layer setup and initialization tasks anyway.
Means FEXCore itself no longer needs to link to tiny-json which can be
left to the frontend.
This is just confusing end users these days and no longer matters as a
debug option.
Remove from the GUI initially, maybe afterwards we will even remove
setting this at all and always auto-detect.
This basically just means that we detect ArchLinux and set a flag that
it is a rolling release, skipping doing the version check for an "exact"
match in that instance.
When a signal handler is not installed and is a terminal failure, make
sure to save telemetry before faulting.
We know when an application is going down in this case so we can make
sure to have the telemetry data saved.
Adds a telemetry signal mask data point as well to know which signal
took it down.
Noticed this while debugging Proton Experimental hanging and thought
this could be related. Didn't solve that issue but this should be merged
anyway.
vfork doesn't fork the host's process space in to the child process.
Saving Copy-On-Write overhead problems. It also puts the parent process
to sleep until the fork terminates or executes.
This is a major issue under FEX where we can't emulate vfork correctly
because we need to do other work before this process terminates or
executes a new process. We have been treating `vfork` as a `fork` this
entire time.
This can likely cause problems for applications that actually use vfork
to wait for a process to complete. So let's actually emulate that
feature by using a pipe with poll to determine when that FD gets
removed.
FEX can't use waitpid to wait for this process to terminate since we
would affect the guest also wanted to use a waitpid.
I originally wrote this emulation prior to me fully understanding how
the syscall works. So there are two optimizations here.
1) No need to consume the incoming buffer at all.
- Originally I thought the incoming dirent structures were used to
calculate offset.
- This is not the case, the FD's file position is used instead.
- This means we can remove the incoming buffer consuming overhead
entirely.
2) No need to allocate a temporary buffer at all.
- With getdents and getdents64 we are guaranteed to be dealing with
structures that are the same size or smaller than the host
structure.
- This lets us encode the real host dirents in to the provided
buffer.
- After the `getdents64` host syscall, we then iterate forward
through the list, modifying as we go.
- Need to make sure to shift the elements of the structure in order.
- Need to make sure to use memmove on the `d_name` member since the
movement region can overlap.
These two optimizations significantly reduce the amount of time spent in
getdents, which has a noticeable impact on load times.
Side-tangent: I noticed a fun quirk of how NFS operates with getdents.
If the FSCache hasn't populated the metadata for that folder, then it
will early return with "some" data, not fully maxing out the buffer. The
kernel will start prefetching metadata assuming directory iterating is
happening. The next `getdents` happens and it should return a larger
number of elements.
Very neat.
Billy Laws