ELF headers were read unconditionally because doing so was assumed to be cheap
(as the guest app would read them anyway shortly after). However, relocation
parsing was added since then, which has less predictable performance due to
crossing page boundaries and reading larger amounts of memory. It might be
possible to make the underlying code more efficient, but until that's done
it's better to skip this logic unless needed.
Closes#5390
Disables THP on some key locations that are fairly sparse
- rpmalloc
- This is the big one as this allocates some heavy sparse buffers.
- CallRet stacks
- These get in the hundreds of megabytes, while not being sparse they
trend towards only using a handful of pages and ballooning to 2MB
per thread is quite heavy.
- Lookup cache
- L1 specifically gets hit here which adds a decent chunk of overhead
due to sparsity.
Win32 for all of these also aren't handled, but that will need to be a
followup.
Add a no-op for zero length in ChangeProtectionFlags.
This fixes AMD Vivado 2025.2 which tries to mprotect with 0 as size and merge strategies fails:
```
Unexpected ChangeProtectionFlags Merge strategy! [0x400000, 0x401000) Versus [0x0, 0x0)
```
We were passing through 32-bit signed values to the 64-bit handler,
which isn't valid and we need to make sure to sign extend.
I don't think this fixes anything because negative values aren't valid,
but a negative could have been interpreted as a large positive without
this.
So WTF can see their usage. Previously didn't add this due to some weird
madvise bug that delete anon names, but that seems to be fixed in a
newer kernel.
rpmalloc is currently very aggressively configured which causes
significant reductions in resident memory over jemalloc.
In Bayonetta's title screen it went from 963MB down to 834MB resident.
Mesa uses this to determine what the executable name is in a process for
application profiles. Without thunking, the guest glibc sets this
correctly, with thunking mesa would pick up `FEX` instead of the app.
With this fixed, it fixes Dead Island rendering when thunks are enabled.
Plenty of other games in Mesa's application profiles that it would fix
as well.
When an anonymous FD is passed to execveat that has the CLOEXEC flag
set, then binfmt_misc fails with ENOENT.
Workaround this limitation by duplicating the FD, stripping its CLOEXEC
flag in the process.
For #5234
On 36-bit VA systems the stack was ending up /wherever/ when it should
be at the top of the VA space (usually).
Additionally VDSO was getting mapped anywhere on 64-bit, so push that to
the top of the VA space as well.
Also removes a check for old kernels not supporting MAP_FIXED_NOREPLACE.
This was a nasty race condition where each thread could be accessing the
DRM cache at any given moment. Move it over to a per thread object that
is only allocated once it gets used.
Also removes an `atexit` registration that contributes to crashing on
exit.
Tony Wasserka