Currently thunk prefixes are mutally exclusive. No thunks database path
can currently have more than one prefix. If this is necessary then we
can add it in the future.
Most minor of optimizations here, we only scan the string once to find a
prefix, instead of searching for it on all four prefix replacements.
We weren't adjusting the guest stack size when using clone3.
If the clone comes from CLONE3 then we need to offset the RSP by the
provided stack size.
This also translates to fork/vfork through clone, so make sure to adjust
stack in that case as well.
Fixes Ender Lilies crashing with Ubuntu 22.04 rootfs
DRM ioctls are taking advantage of the fact that any ioctl structure
that is passed in to the kernel smaller than the expected value will
zero out the remaining members of the structure.
Some more ioctls coming down the pipe will also abuse this, so we might
as well as get started with the v3d ioctl that requires it.
Due to how this works, the kernel knows how big an ioctl structure
should be and if the userspace passes in a smaller struct, it will
memset the remaining size to zero.
std::filesystem::canonical is very heavyweight and walks the full path
to ensure that each folder in the path is not a symlink.
eg:
```
readlink("/proc", 0x7ffd5646e210, 1023) = -1 EINVAL (Invalid argument)
readlink("/proc/self", "880556", 1023) = 6
readlink("/proc/880556", 0x7ffd5646e210, 1023) = -1 EINVAL (Invalid argument)
readlink("/proc/880556/fd", 0x7ffd5646e210, 1023) = -1 EINVAL (Invalid argument)
readlink("/proc/880556/fd/5", "/home/ryanh/.fex-emu/RootFS/Ubuntu_22_04/usr/lib/x86_64-linux-gnu/ld-linux-x86-6"..., 1023) = 86
readlink("/home", 0x7ffd5646e210, 1023) = -1 EINVAL (Invalid argument)
readlink("/home/ryanh", 0x7ffd5646e210, 1023) = -1 EINVAL (Invalid argument)
readlink("/home/ryanh/.fex-emu", 0x7ffd5646e210, 1023) = -1 EINVAL (Invalid argument)
readlink("/home/ryanh/.fex-emu/RootFS", 0x7ffd5646e210, 1023) = -1 EINVAL (Invalid argument)
readlink("/home/ryanh/.fex-emu/RootFS/Ubuntu_22_04", 0x7ffd5646e210, 1023) = -1 EINVAL (Invalid argument)
readlink("/home/ryanh/.fex-emu/RootFS/Ubuntu_22_04/usr", 0x7ffd5646e210, 1023) = -1 EINVAL (Invalid argument)
readlink("/home/ryanh/.fex-emu/RootFS/Ubuntu_22_04/usr/lib", 0x7ffd5646e210, 1023) = -1 EINVAL (Invalid argument)
readlink("/home/ryanh/.fex-emu/RootFS/Ubuntu_22_04/usr/lib/x86_64-linux-gnu", 0x7ffd5646e210, 1023) = -1 EINVAL (Invalid argument)
readlink("/home/ryanh/.fex-emu/RootFS/Ubuntu_22_04/usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2", 0x7ffd5646e210, 1023) = -1 EINVAL (Invalid argument)
```
This is what was occuring for every single mmap that occurs. /really/
adding to the time for the syscall to take.
This also happens on a couple of other syscalls which are using this new
path now.
The primary reason why this works is that we know that every entry in
`/proc/self/fd/` is a symlink. So instead of asking for canonical, we
can just read the symlink and this will redirect us to the canonical
path.
So this previous example goes from 14 syscalls down to 1.
eg:
```
readlinkat(AT_FDCWD, "/proc/self/fd/5", "/home/ryanh/.fex-emu/RootFS/Ubuntu_22_04/usr/lib/x86_64-linux-gnu/ld-linux-x86-6"..., 4096) = 86
```
While this is only a minor improvement in the "typical" operating environment,
this significantly improves performance of FEX under proot or if the
rootfs lives on a network share.
Instead of duplicating prefixes in the ThunksDB json file even more,
just do a prefix replacement when the thunks database is being parsed.
Changes the JSON overlay arrays over to @PREFIX@ and reduce the
duplication.
Adds support for the pressure-vessel prefix `/usr/lib/pressure-vessel/overrides/lib`
This gets thunks ready for running under pressure-vessel, once vulkan
thunking switches from device libraries to the vulkan loader it should
just work.
32-bit allocations were scanning for available pages by shifting by the
length of allocation. This is incorrect since large allocations would
then only scan through the region in very large chunks. Especially if
MAP_32BIT was present. Instead scan by page size to ensure better fit.
This fixes X-Plane 11.
Also ensure we don't try to munmap a range unless the result is
MAP_FAILED, noticed we were trying to munmap ~0ULL
open is rarely used compared to openat and openat2, so this has been
just missed but nothing really got upset about it.
Fixes Proton Experimental while running under pressure-vessel.
clone2 stack pointer passed in points to the highest address for the
stack.
clone3 switches this around and gives us a base pointer and a size.
glibc started using clone3 for its thread cloning which finally caught
this bug. Necessary to run any application under the Ubuntu 22.04 rootfs
since that uses a new enough glibc to encounter this.
I accidentally committed a 32-bit range that was significantly smaller
than what it should be.
While the minimal range worked for simple cases, it didn't work for
anything complex.
Give it the full range it needs.
Fixes#1600
In the case of an AArch64 builder is using 16kb or 64kb pages like is
common on servers then it would fail to compile, even if the resulting
application would only ever run on 4k page hosts.
Resolve this by removing the build check and hardcoding 4kb pages for
each of our uses. We still require 4kb pages to run, so this mostly just
removes the weirdness where it is 16kb builder + 4k runner. Would have
broken some of our assumptions when running.
Ryan Houdek