Fixes#2136
This is a fairly tricky edge case to support with FEX.
If execveat is used with AT_EMPTY_PATH then the application can pass an
FD to execve instead of a filename. This includes FDs that have been
deleted from the disk so the child process can't open it by filename
anymore.
To work around this limitation, we need to pass the FD to the new FEX
process and open it directly, similar to how binfmt_misc works with FDs.
The FD will get passed through environment variables, which the new
process will check for and then remove the variable from the
environment.
Lots of prickly edge cases to support here.
Without binfmt_misc:
- Passes the FD to FEXLoader directly.
- Requires duplicating the FD if it has O_CLOEXEC on the FD.
With binfmt_misc:
- Shebang file, pass directly to FEXLoader, just like without binfmt.
- x86 ELF Files, rely on the kernel's binfmt_misc support here.
- Unsupported ELF files, let kernel handle it through binfmt_misc
Argument handling:
- The application can pass in no arguments.
- Means our application configurations were failing to find a config
- Also various checks in the frontend were failing.
- If opened through an FD, find the symlink for that FD for the
application configuration instead.
Side note:
Fixed a performance issue in execve where when we were checking for file
format support. Either ELF or Shebang files, we were reading the /whole/
file upfront. We only need to read a header worth of ELF files, and only
257 bytes if it is potentially a shebang file. Should dramatically
reduce some application's execve times.
This is causing some heartburn with the hardlink.
- Removes some termux cmake list hacking.
- Removes the need to do post-install packaging fixups when hardlinks get dropped.
- Removes a custom uninstall target that was necessary before.
Fixes#2095
std::random_device can fail to find a random source and throw an assert
during initialization.
The constructor allows you to provide a token string to select an
explicit random source, but this is c++ library specific and will still
assert if the source isn't found. Also specific tokens are very much
target and library specific, so it is unsafe to use.
In the libstdc++ case, the default implementation will try to open
`/dev/urandom` which might not be available on all targets.
Instead of relying on this C++ object, use the `getrandom` syscall
directly to generate our RNG used in the ELFCodeLoader.
Resolves any sort of asserting case, blocks on RNG generation, and is
guaranteed to be available since this syscall has been available since a
very old kernel version.
On first FEXInterpreter execution, it is expected that `ConnectToServer`
will fail with `ECONNREFUSED` because FEXServer won't be running.
Skip printing this first messaage to stderr if configured.
If it is some other error message then ensure it is still printed.
`GetEmulatedPath` and `OpenAt` are called a /lot/ in applications.
std::filesystem::path handling here is quite heavy and costly for what
we are trying to achieve.
Remove this usage and instead use lstat, access, and readlink directly
which is a heck of a lot faster.
In particular this helps out pressure-vessel, shaving off launch times
by 1-2 seconds.
Going from ~22 seconds down to ~20 seconds.
`std::filesystem::exists` is particularly gnarly in how it checks to see
if the file exists.
It allocates memory, it creates lists, it splits things, then eventually
checking the status
Remove all this overhead to help out minorly for applications that
execve a lot.
Two changes here.
- Make the mount path follow server temp folder requirements.
- Will be mounted in `/tmp/` or `$XDG_RUNTIME_DIR/` now
- Switch the FEXServer socket to an "abstract" AF_UNIX socket.
- If the socket is in `/tmp/` then systemd will put the service in a
private `/tmp` folder that only exists for the service.
- If the socket is in `$XDG_RUNTIME_DIR` then pressure-vessel can't
chroot anymore since they make their own runtime directory.
- If it is in `$HOME/.fex-emu/` then it breaks usage where the
filesystem is a mount that doesn't support AF_UNIX like sshfs.
The only reasonable thing to do is to switch over to `abstract` sockets
which will work in all cases.
Tested with pressure-vessel and systemd and now it works in all
situations.
This will be useful for keying specific executables to steamids.
This is sadly required because a bunch of games end up naming themselves
"game.exe" so we can't safely enable thunks for all things shipping a
generic name.
In the case of a platform enabling PrivateTmp then the FEXServer and
FEXInterpreter won't have a tmp folder that shares the socket location.
The runtime directory is a perfect place to share these across
processes.
This is the last remaining auxv value that we were missing.
This requires a little bit of setup to match what we are doing in
FEXCore's Dispatcher.
This only tracks how much space is required by the kernel to store its
required state.
When we are installed as a binfmt_misc handler the Linux kernel will
assign us AT_SECURE for setuid binaries.
Ensure we are passing this through for any application that will end up
needing it.
AT_SYSINFO points to the vsyscall location that the kernel provides.
This AUXV value isn't used on x86-64.
If we have VDSO installed then we can use the one provided from there,
otherwise we need to provide a code page.
It seems like some behaviour changed with glibc provided in Ubuntu 22.10
that it now requires AT_SYSINFO.
Fixes wine 7.0 execution inside the Ubuntu 22.10 rootfs.
Segment registers are indexed significantly more than they are changed.
Pay the cost of indexing during the set and store rather than the per
register index.
Should be a fairly significant performance improvement for 32-bit
applications. At least on hardware that doesn't have a data dependent
prefetcher.
Breaks Steam atm and isn't clean.
Chrome seems to like sending us invalid packets of data sometimes. With
an invalid packet type just skip parsing the data entirely.
Fixes an infinite loop in Vampire Survivors.
This is a tricky situation that wine-preloader allocates the lower
32MB of stack space through fixed address mmap with MAP_FIXED.
They can't use mmap with an address hint nor MAP_FIXED_NOREPLACE because
it changes behaviour. mmap won't give you the allocation inside the
stack space even if you check `/proc/self/maps` that space isn't yet
allocated. The growable space of the stack blocks those allocations.
So the wine peeps might be SOL if they actually require this allocation
to exist.
To replicate this, allocate the application stack at the same location using an address hint.
This will give us the correct region on a 48-bit VA system, while also
letting it select a different region on a 36-bit VA system.
Previously the config options could only have ever enabled thunks rather than
disable them.
Now sort the code so it can enable thunks, then following configs can
redisable them. Allowing testing with global thunks enabled and
disabling problematic applications.
Also sorts the "ThunkConfigFile" config as lower priority than the
application configs. I wasn't thinking about ordering that hard for
these five configuration paths, but application configs should be higher
priority in this case.
This creates a generic interface that FEXCore can use for timeline
profiling. This allows us to create a generic interface which the
backend details are hidden so we can support multiple timeline profile
APIs.
The only API supported right now is ftrace/gpuvis. Which is extremely
lightweight of an interface with minimal overhead.
We must be careful here since in most cases will will have dozens of
FEX instances running at any given time. So a timeline profiler like
Microprofiler can have major issues since that only ever expects a
single process at a time.
Not enabled by default but just needs the `ENABLE_FEXCORE_PROFILER`
cmake option set to enable.
Implements AT_PLATFORM: Ends up being `i686` or `x86_64` depending on
ELF arch
Implements AT_HWCAP and AT_HWCAP2
AT_HWCAP is just CPUID function 01h EDX result
AT_HWCAP2 only has two defined bits in it, which we don't support
either.
Implements AT_RANDOM
Previously we were just sticking hardcoded values in to this.
Now we pass along the host's AT_RANDOM, or we generate our own if that
doesn't exist
Fixes#788
These should be using the real syscalls, not our provided allocators.
While not a problem currently since these redirect to host mmap and
munmap, it will become an issue once we have an allocator that lives
outside of x86-64 space.
Ryan Houdek