From fdd72fd5225dedb4431473fb3ac7b3d45fc8ed00 Mon Sep 17 00:00:00 2001 From: Oren Ben Simhon Date: Sat, 17 Mar 2018 13:29:46 +0000 Subject: [X86] Added support for nocf_check attribute for indirect Branch Tracking MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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/Writer/BitcodeWriter.cpp | 2 ++ 1 file changed, 2 insertions(+) (limited to '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 @@ static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) { 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: -- cgit v1.1