Steam's webhelper has started enabling its sandbox which completely
breaks under FEX since we don't support seccomp.
Curiously the Chromium code is actually supposed to support a fallback
namespace only mode, which is used in glibc 2.34 environments.
The startup script for this will try to use this namespace only mode,
but Chromium developers never tested this in an environment that doesn't
support seccomp.
Due to an early check in their sandbox code, it checks for bpf support
before checking for which sandbox mode it is entering. This returns
early with a false statement which brings the entire browser instance
down with an assert.
Inject the --no-sandbox argument so we get around this and the sandbox
is disabled.
The pause instruction is architecturally defined to be the `REP NOP`
instruction.
This allows people to use this instruction as a backwards compatible
pause without checking for CPUID support. In fact there is no way to
check if the hardware implements this as a `REP NOP` or a `PAUSE`.
If you have new enough hardware then this just ends up being a PAUSE.
Pass this PAUSE over to our host to help out applications that are
writing spin loops with a PAUSE in it, which we were deleting
previously.
This is an IR op that produces nor consumes any SSA values, but has side
effects.
Turns in to the pause instruction on x86 and yield instruction on
AArch64.
Previously if the instruction was encoded to use rsp, rbp, rsi, or rdi
then due to how these were encoded in modrm this would hit the frontend
path for writing to the high 8 bits of a 16bit register.
This is because it's instruction specific if an 8-bit modrm instruction
chooses to use the high 8-bit region or the upper 4 registers.
See the ModRM.reg section of `ModRM.reg and .r/m Field Encodings`
specifically to see what each encoding stands for. Has four different
meanings per encoding depending on instruction.
This instruction doesn't actually write to registers at 8-bit size, it
extracts an element at 8-bit size and then zero extends it to the full
GPR.
When storing to memory it always stores to memory at the size of the
element extracted.
I grepped around the instruction tables to see if there were any other
instances of this mistake. This was the only one.
Fixes#1472 and also gets Psychonauts 2 running.
Fixes a regression in fa87c73b9ee60a334eace2cdc3097725cbaf5b88; curl complains "curl: option -: is unknown" when trying to fetch a RootFS without this.
std::erase_if shouldn't allow you to modify the object passed in to the
predicate.
libstdc++ hasn't always enforced this but now it does with libstdc++12
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.
Ryan Houdek