When we were taking a signal that had a misaligned stack, we would store
the host stack at a weird offset.
After that point when we were trying to sigreturn we wouldn't know the
alignment of the stack coming back and we would try loading the host
stack from the wrong offset. Easy fix is to just align the host stack
location.
Fixes Ender Lilies, which was consistently crashing from a SIGCHLD due
to having a misaligned stack.
Side-change: Move the cookie check to the start of the restore. Doesn't
make sense to check the cookie after restoring state since it could be
quite wrong.
Now that we've moved MOVHPS over to sharing the implementation of
MOVHPD, the FLAGS_SF_HIGH_XMM_REG is now unused.
Since we're supporting AVX, this flag is kind of weird in terms of
behavior, since what determines the high part of a register is now
situationally different.
Also it's much more explicit to perform the insert directly in the
implementation of instructions, than relying on a flag to do it for us.
So, instead of keeping it around, we can reclaim it as unused for use
with any necessary behavior that we would require in the future.
These instructions essentially have the same behavior. This also allows
us to remove the only used instance of FLAGS_SF_HIGH_XMM_REG, which,
given that we now support AVX, has ambiguous use.
While we're at it, we can expand the tests to make use of the store to
memory variant.
Also removes an erroneous copy-pasted comment about ZEXTing. This is
from the MOVQ implementation function. MOVHPS/MOVHPD don't do any
ZEXTing, they either store to memory or insert into a register.
Will catch cases where registers aren't consecutive in the constructive
variant. While we're at it, we can also amend EXT's similar but slightly wrong
consecutive check.
Also adds tests to ensure these corner-cases hold.
Performance stats up front:
This improves pressure-vessel startup time on my test device by 10.1%
Improving the startup time from 9.71425 seconds to 8.7421 seconds.
Most filesystem based syscalls support a file descriptor version with an
*at suffix. This allows us to do these syscalls with pathnames that are
relative to the directory FD that is passed to the syscall.
This is pretty much exactly what we want when we are searching for files
inside of our rootfs. The only quirk ends up being that we are getting
passed absolute paths. This ends up being very simple to workaround by
stripping off the front '/' character. Doing this is just offsetting the
pointer passed to the syscall by one byte.
This does require having two temporary buffers of size PATH_MAX passed
to the handler since just like in the other implementation, we need to
keep the previous result around. The difference being now that we aren't
doing a bunch of std::string temporary manipulation and now we are
returning one of the passed in buffers back depending on the result.
Lioncache