[compiler-rt] e1e2635 - [HWASan] Use tagged-globals feature on x86.

[Matt Morehouse via llvm-commits]

Author: Matt Morehouse
Date: 2021-10-19T05:56:50-07:00
New Revision: e1e2635327d74b6404d30521f9e09928e3919cec

URL: https://github.com/llvm/llvm-project/commit/e1e2635327d74b6404d30521f9e09928e3919cec
DIFF: https://github.com/llvm/llvm-project/commit/e1e2635327d74b6404d30521f9e09928e3919cec.diff

LOG: [HWASan] Use tagged-globals feature on x86.

Allows us to use the small code model when we disable relocation
relaxation.

Reviewed By: eugenis

Differential Revision: https://reviews.llvm.org/D111344

Added: 
    

Modified: 
    clang/lib/Driver/SanitizerArgs.cpp
    compiler-rt/test/hwasan/TestCases/global.c
    compiler-rt/test/hwasan/lit.cfg.py

Removed: 
    


################################################################################
diff  --git a/clang/lib/Driver/SanitizerArgs.cpp b/clang/lib/Driver/SanitizerArgs.cpp
index 8770fb1cf9fef..bef0dec64d4e1 100644
--- a/clang/lib/Driver/SanitizerArgs.cpp
+++ b/clang/lib/Driver/SanitizerArgs.cpp
@@ -1146,7 +1146,7 @@ void SanitizerArgs::addArgs(const ToolChain &TC, const llvm::opt::ArgList &Args,
     CmdArgs.push_back(Args.MakeArgString("hwasan-abi=" + HwasanAbi));
   }
 
-  if (Sanitizers.has(SanitizerKind::HWAddress) && TC.getTriple().isAArch64()) {
+  if (Sanitizers.has(SanitizerKind::HWAddress) && !HwasanUseAliases) {
     CmdArgs.push_back("-target-feature");
     CmdArgs.push_back("+tagged-globals");
   }

diff  --git a/compiler-rt/test/hwasan/TestCases/global.c b/compiler-rt/test/hwasan/TestCases/global.c
index 5df828e571acc..23fefd0eccebe 100644
--- a/compiler-rt/test/hwasan/TestCases/global.c
+++ b/compiler-rt/test/hwasan/TestCases/global.c
@@ -5,6 +5,15 @@
 // RUN: not %run %t -1 2>&1 | FileCheck --check-prefixes=CHECK,LSYM %s
 // RUN: not %env_hwasan_opts=symbolize=0 %run %t -1 2>&1 | FileCheck --check-prefixes=CHECK,LNOSYM %s
 
+// Test with and without optimizations, with and without PIC, since 
diff erent
+// backend passes run depending on these flags.
+// RUN: %clang_hwasan -fno-pic %s -o %t
+// RUN: not %run %t 1 2>&1 | FileCheck --check-prefixes=CHECK,RSYM %s
+// RUN: %clang_hwasan -fno-pic -O2 %s -o %t
+// RUN: not %run %t 1 2>&1 | FileCheck --check-prefixes=CHECK,RSYM %s
+// RUN: %clang_hwasan -O2 %s -o %t
+// RUN: not %run %t 1 2>&1 | FileCheck --check-prefixes=CHECK,RSYM %s
+
 // REQUIRES: pointer-tagging
 
 int x = 1;

diff  --git a/compiler-rt/test/hwasan/lit.cfg.py b/compiler-rt/test/hwasan/lit.cfg.py
index dcae2b2932815..2cd6d641f2cf9 100644
--- a/compiler-rt/test/hwasan/lit.cfg.py
+++ b/compiler-rt/test/hwasan/lit.cfg.py
@@ -18,10 +18,12 @@
 else:
   config.available_features.add('pointer-tagging')
 if config.target_arch == 'x86_64':
-  # This does basically the same thing as tagged-globals on aarch64. Because
-  # the x86_64 implementation is for testing purposes only there is no
-  # equivalent target feature implemented on x86_64.
-  clang_hwasan_common_cflags += ["-mcmodel=large"]
+  # By default the assembler uses R_X86_64_REX_GOTPCRELX relocations, which can
+  # be relaxed to direct references.  When tagged globals are enabled, these
+  # references fail to link since they have more than a 32-bit offset from RIP.
+  # As a workaround, we disable the relaxation.
+  # TODO: Implement a way to disable for the affected relocations only.
+  clang_hwasan_common_cflags += ["-Wa,-mrelax-relocations=no"]
 
   # The callback instrumentation used on x86_64 has a 1/64 chance of choosing a
   # stack tag of 0.  This causes stack tests to become flaky, so we force tags