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

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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
This commit is contained in:
Oren Ben Simhon
2018-03-17 13:29:46 +00:00
parent dbcf1bf503
commit fdd72fd522
34 changed files with 302 additions and 76 deletions
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3
llvm/lib/Bitcode/Reader/BitcodeReader.cpp
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@@ -1160,6 +1160,7 @@ static uint64_t getRawAttributeMask(Attribute::AttrKind Val) {
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 @@ static Attribute::AttrKind getAttrFromCode(uint64_t Code) {
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: