[PATCH] D18526: [tsan] Disable randomized address space on aarch64 linux.

[Yabin Cui via llvm-commits]

yabinc added a comment.

At Diff1 of this patch, I made it Android specific. And zatrazz recommended
to use VReport() instead of Report() to avoid breaking tests. It doesn't break tests any more when I run make check-tsan.

> This patch broke not *all* AArch64 buildbots, but "some".


Can you specify what build it may break? As far as I know, export TSAN_OPTIONS="verbosity=1" makes tsan print the verbose warning. But make check-tsan doesn't fail, I think it may be because make check-tsan clears environment variable TSAN_OPTIONS. Maybe you want me to fix the tests, comment on http://reviews.llvm.org/D18378?

> if this fix is *guaranteed* to work on *every* possible Android configuration on the planet, present and future, than I'm ok with the change.


I think this is an unresonable promise for me. I have tested on the aarch64 android devices I have: N5X, N9, and N6P, which are all 39-VMAs,
without and with the kernel patch. Unless you have specific considerations or actionable suggests, I can't do anything further.

> The previous change was *guaranteed* to work with any Linux kernel, so we accepted for all AArch64, but that was a false assumption. So forgive me if I don't trust this new assumption as well.


I don't think that was a false assumption. The previous change broken the test because of the tests. There is no sense so far that the change doesn't work with any Linux kernel.

> Concretely, what I'm asking is proof that this is true for all Android configurations. Virtual address randomization is a crucial security feature, and I'd be surprised if Google never uses it as we move into 64-bit land, especially as Android takes on more roles in automotive, home automation and small laptops.


I think the current plan on android is only using tsan for debugging by platform developers and app developers, so security issue isn't involved so far (or never will be). If the tsan maintainers determine that they don't want to disable virtual address randomization, android developers have to disable virtual address space manually before tsan has a workable solution. The only way to make something true for all Android configurations is to write a Compatibility Test Suite for it, but I can't do it before I make tsan usable by platform developers (because how can you test that something is true before you can't run the test).


http://reviews.llvm.org/D18526