The ASHMEM_SET_SIZE ioctl() call accepts a size as a parameter, not a pointer, which is not recognized by Valgrind on ARM64, and results in errors such as:

==2040== Syscall param ioctl(generic) points to unaddressable byte(s)
==2040==    at 0x496F768: __ioctl (in /system/lib64/libc.so)
==2040==    by 0x492530B: ioctl (in /system/lib64/libc.so)
==2040==    by 0x5A9B04B: ashmem_create_region (in /system/lib64/libcutils.so)
==2040==    by 0x5768BA3: art::MemMap::MapAnonymous(char const*, unsigned char*, unsigned long, int, bool, bool, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*, bool) (in /system/lib64/libart.so)
==2040==    by 0x5612247: art::gc::Heap::Heap(unsigned long, unsigned long, unsigned long, unsigned long, double, double, unsigned long, unsigned long, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, art::InstructionSet, art::gc::CollectorType, art::gc::CollectorType, art::gc::space::LargeObjectSpaceType, unsigned long, unsigned long, unsigned long, bool, unsigned long, unsigned long, bool, bool, bool, bool, bool, bool, bool, bool, bool, bool, unsigned long) (in /system/lib64/libart.so)
==2040==    by 0x583BCFB: art::Runtime::Init(art::RuntimeArgumentMap&&) (in /system/lib64/libart.so)
==2040==    by 0x583E823: art::Runtime::Create(std::__1::vector<std::__1::pair<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, void const*>, std::__1::allocator<std::__1::pair<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, void const*> > > const&, bool) (in /system/lib64/libart.so)
==2040==    by 0x5705093: JNI_CreateJavaVM (in /system/lib64/libart.so)
==2040==    by 0x109377: main (in /system/bin/dalvikvm64)
==2040==  Address 0x10000000 is not stack'd, malloc'd or (recently) free'd

I have seen the issue with a build of the master branch of the Android Open Source Project, but it is reproducible on older versions as well (e.g. the 6.0 release).

Reproducible: Always

Steps to Reproduce:
1. Install the ARM64 version of Valgrind on the Android device as documented in the README.android file; assume that the installation directory is /data/local/tmp/valgrind.
2. Get an APK or a DEX file; let its name be Test.dex, and let the name of the class containing the main() method be Test as well.
3. adb push Test.dex /data/local/tmp
4. adb shell /data/local/tmp/valgrind/bin/valgrind dalvikvm64 -cp /data/local/tmp/Test.dex Test

Actual Results:  
Errors similar to the one above are displayed.

Expected Results:  
No errors of that type are shown.

Note that Valgrind is not affected by the same issue on a 32-bit ARM platform.

I have been using a suppression rule as a workaround:

{
  ashmem ioctl
  Memcheck:Param
  ioctl(generic)
  ...
  fun:ioctl
  fun:ashmem_create_region
}