[PATCH] D14199: [compiler-rt] [tsan] Unify aarch64 mapping

[Adhemerval Zanella via llvm-commits]

zatrazz added inline comments.

================
Comment at: lib/tsan/rtl/tsan_platform.h:129
@@ +128,3 @@
+  static const uptr kVdsoBeg       = 0x7f00000000ull;
+};
+
----------------
eugenis wrote:
> I've noticed that this mapping does not have an application region at 0x55...
> That's where PIE executables are mapped by the newer kernels.
> Did you test this on an older kernel (I don't know exactly when the transition happened; it was around 4.1 for X86 and AFAIK a bit earlier for AArch 64)?
> 
> See http://reviews.llvm.org/D15308 for more context.
> 
I did check the PIE executable with a full TSAN test built with '-pie -fpic' and I saw no issue. Analyzing the trace for 39-bits using the mutexset1.cc (I picked it at random) I see:

* Non-pie build:

00400000-004d1000 r-xp 00000000 08:02 21008174                           /home/adhemerval.zanella/llvm/llvm-git-aarch64-build-release/mutexset1
004e0000-004e3000 r--p 000d0000 08:02 21008174                           /home/adhemerval.zanella/llvm/llvm-git-aarch64-build-release/mutexset1
004e3000-004e6000 rw-p 000d3000 08:02 21008174                           /home/adhemerval.zanella/llvm/llvm-git-aarch64-build-release/mutexset1

* PIE build:

7fae119000-7fae1ee000 r-xp 00000000 08:02 21008174                       /home/adhemerval.zanella/llvm/llvm-git-aarch64-build-release/mutexset1
7fae1ee000-7fae1fb000 rw-p 00000000 00:00 0
7fae1fd000-7fae200000 r--p 000d4000 08:02 21008174                       /home/adhemerval.zanella/llvm/llvm-git-aarch64-build-release/mutexset1
7fae200000-7fae203000 rw-p 000d7000 08:02 21008174                       /home/adhemerval.zanella/llvm/llvm-git-aarch64-build-release/mutexset1

So at least for  39-bit PIE addresses are being covered. I will check again on 42-bit VMA.


http://reviews.llvm.org/D14199