commit fdd72fd5225dedb4431473fb3ac7b3d45fc8ed00
author Oren Ben Simhon <oren.ben.simhon@intel.com> Sat Mar 17 13:29:46 2018 +0000
committer Oren Ben Simhon <oren.ben.simhon@intel.com> Sat Mar 17 13:29:46 2018 +0000
tree b1819bd5c756e40209091ea07d752efab4cf83ac
parent dbcf1bf503880084e33e57e9fb916a66703d18d7

[X86] Added support for nocf_check attribute for indirect Branch Tracking

X86 Supports Indirect Branch Tracking (IBT) as part of Control-Flow Enforcement Technology (CET).
IBT instruments ENDBR instructions used to specify valid targets of indirect call / jmp.
The `nocf_check` attribute has two roles in the context of X86 IBT technology:
	1. Appertains to a function - do not add ENDBR instruction at the beginning of the function.
	2. Appertains to a function pointer - do not track the target function of this pointer by adding nocf_check prefix to the indirect-call instruction.

This patch implements `nocf_check` context for Indirect Branch Tracking.
It also auto generates `nocf_check` prefixes before indirect branchs to jump tables that are guarded by range checks.

Differential Revision: https://reviews.llvm.org/D41879

llvm-svn: 327767

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index 5822981..74b57a8 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -1160,6 +1160,7 @@
   case Attribute::Speculatable:    return 1ULL << 54;
   case Attribute::StrictFP:        return 1ULL << 55;
   case Attribute::SanitizeHWAddress: return 1ULL << 56;
+  case Attribute::NoCfCheck:       return 1ULL << 57;
   case Attribute::Dereferenceable:
     llvm_unreachable("dereferenceable attribute not supported in raw format");
     break;
@@ -1338,6 +1339,8 @@
     return Attribute::NoRedZone;
   case bitc::ATTR_KIND_NO_RETURN:
     return Attribute::NoReturn;
+  case bitc::ATTR_KIND_NOCF_CHECK:
+    return Attribute::NoCfCheck;
   case bitc::ATTR_KIND_NO_UNWIND:
     return Attribute::NoUnwind;
   case bitc::ATTR_KIND_OPTIMIZE_FOR_SIZE:

llvm/lib/Bitcode/Writer/BitcodeWriter.cpp

diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index 0738b90..d82101b 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -638,6 +638,8 @@
     return bitc::ATTR_KIND_NO_RED_ZONE;
   case Attribute::NoReturn:
     return bitc::ATTR_KIND_NO_RETURN;
+  case Attribute::NoCfCheck:
+    return bitc::ATTR_KIND_NOCF_CHECK;
   case Attribute::NoUnwind:
     return bitc::ATTR_KIND_NO_UNWIND;
   case Attribute::OptimizeForSize: