On 10/29/18 06:24, Jakub Jelinek wrote:
On Mon, Oct 29, 2018 at 12:13:04PM +0100, Martin Liška wrote:
Just for the record: am I right that any system using 44 bit of VMA will fail
because
anything + (1 << 44) will be out of process address space?
Yes.
And I noticed that documentation in sanitizer_linux.cc is misleading:
...
uptr GetMaxVirtualAddress() {
#if (SANITIZER_NETBSD || SANITIZER_OPENBSD) && defined(__x86_64__)
return 0x7f7ffffff000ULL; // (0x00007f8000000000 - PAGE_SIZE)
#elif SANITIZER_WORDSIZE == 64
# if defined(__powerpc64__) || defined(__aarch64__)
// On PowerPC64 we have two different address space layouts: 44- and 46-bit.
// We somehow need to figure out which one we are using now and choose
// one of 0x00000fffffffffffUL and 0x00003fffffffffffUL.
...
That should be adjusted.
Apparently for ppc64 there are many different layouts now, 44, 46, 47, 49, 52
at least depending on which kernel and page size you choose.
So, ideally we want some choice that works with all of them. Shadow offset
1ULL<<44 is not that choice.
We (llvm team) tried to get it to work on all the different kernels but
didn't find anything that worked. Finally we just went with a value
that worked on the newer kernels as the 44 bit one was not a target of
concern.
--
-Bill Seurer
