Author: zbrid Date: Mon Nov 26 16:03:44 2018 New Revision: 347617 URL: http://llvm.org/viewvc/llvm-project?rev=347617&view=rev Log: [clang][slh] add attribute for speculative load hardening
Summary: The prior diff had to be reverted because there were two tests that failed. I updated the two tests in this diff clang/test/Misc/pragma-attribute-supported-attributes-list.test clang/test/SemaCXX/attr-speculative-load-hardening.cpp ----- Summary from Previous Diff (Still Accurate) ----- LLVM IR already has an attribute for speculative_load_hardening. Before this commit, when a user passed the -mspeculative-load-hardening flag to Clang, every function would have this attribute added to it. This Clang attribute will allow users to opt into SLH on a function by function basis. This can be applied to functions and Objective C methods. Reviewers: chandlerc, echristo, kristof.beyls, aaron.ballman Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D54915 Added: cfe/trunk/test/CodeGen/attr-speculative-load-hardening.cpp cfe/trunk/test/CodeGen/attr-speculative-load-hardening.m cfe/trunk/test/SemaCXX/attr-speculative-load-hardening.cpp Modified: cfe/trunk/include/clang/Basic/Attr.td cfe/trunk/include/clang/Basic/AttrDocs.td cfe/trunk/lib/CodeGen/CGCall.cpp cfe/trunk/lib/Sema/SemaDeclAttr.cpp cfe/trunk/test/Misc/pragma-attribute-supported-attributes-list.test Modified: cfe/trunk/include/clang/Basic/Attr.td URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/Attr.td?rev=347617&r1=347616&r2=347617&view=diff ============================================================================== --- cfe/trunk/include/clang/Basic/Attr.td (original) +++ cfe/trunk/include/clang/Basic/Attr.td Mon Nov 26 16:03:44 2018 @@ -3091,3 +3091,9 @@ def AlwaysDestroy : InheritableAttr { let Subjects = SubjectList<[Var]>; let Documentation = [AlwaysDestroyDocs]; } + +def SpeculativeLoadHardening : InheritableAttr { + let Spellings = [Clang<"speculative_load_hardening">]; + let Subjects = SubjectList<[Function, ObjCMethod], ErrorDiag>; + let Documentation = [SpeculativeLoadHardeningDocs]; +} Modified: cfe/trunk/include/clang/Basic/AttrDocs.td URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/AttrDocs.td?rev=347617&r1=347616&r2=347617&view=diff ============================================================================== --- cfe/trunk/include/clang/Basic/AttrDocs.td (original) +++ cfe/trunk/include/clang/Basic/AttrDocs.td Mon Nov 26 16:03:44 2018 @@ -3629,3 +3629,27 @@ GNU inline semantics are the default beh ``-std=c89``, ``-std=c94``, or ``-fgnu89-inline``. }]; } + +def SpeculativeLoadHardeningDocs : Documentation { + let Category = DocCatFunction; + let Content = [{ + This attribute can be applied to a function declaration in order to indicate + that `Speculative Load Hardening <https://llvm.org/docs/SpeculativeLoadHardening.html>`_ + should be enabled for the function body. This can also be applied to a method + in Objective C. + + Speculative Load Hardening is a best-effort mitigation against + information leak attacks that make use of control flow + miss-speculation - specifically miss-speculation of whether a branch + is taken or not. Typically vulnerabilities enabling such attacks are + classified as "Spectre variant #1". Notably, this does not attempt to + mitigate against miss-speculation of branch target, classified as + "Spectre variant #2" vulnerabilities. + + When inlining, the attribute is sticky. Inlining a function that + carries this attribute will cause the caller to gain the + attribute. This is intended to provide a maximally conservative model + where the code in a function annotated with this attribute will always + (even after inlining) end up hardened. + }]; +} Modified: cfe/trunk/lib/CodeGen/CGCall.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGCall.cpp?rev=347617&r1=347616&r2=347617&view=diff ============================================================================== --- cfe/trunk/lib/CodeGen/CGCall.cpp (original) +++ cfe/trunk/lib/CodeGen/CGCall.cpp Mon Nov 26 16:03:44 2018 @@ -1791,6 +1791,8 @@ void CodeGenModule::ConstructDefaultFnAt if (CodeGenOpts.Backchain) FuncAttrs.addAttribute("backchain"); + // FIXME: The interaction of this attribute with the SLH command line flag + // has not been determined. if (CodeGenOpts.SpeculativeLoadHardening) FuncAttrs.addAttribute(llvm::Attribute::SpeculativeLoadHardening); } @@ -1854,6 +1856,8 @@ void CodeGenModule::ConstructAttributeLi FuncAttrs.addAttribute(llvm::Attribute::NoDuplicate); if (TargetDecl->hasAttr<ConvergentAttr>()) FuncAttrs.addAttribute(llvm::Attribute::Convergent); + if (TargetDecl->hasAttr<SpeculativeLoadHardeningAttr>()) + FuncAttrs.addAttribute(llvm::Attribute::SpeculativeLoadHardening); if (const FunctionDecl *Fn = dyn_cast<FunctionDecl>(TargetDecl)) { AddAttributesFromFunctionProtoType( Modified: cfe/trunk/lib/Sema/SemaDeclAttr.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDeclAttr.cpp?rev=347617&r1=347616&r2=347617&view=diff ============================================================================== --- cfe/trunk/lib/Sema/SemaDeclAttr.cpp (original) +++ cfe/trunk/lib/Sema/SemaDeclAttr.cpp Mon Nov 26 16:03:44 2018 @@ -6373,6 +6373,9 @@ static void ProcessDeclAttribute(Sema &S case ParsedAttr::AT_Section: handleSectionAttr(S, D, AL); break; + case ParsedAttr::AT_SpeculativeLoadHardening: + handleSimpleAttribute<SpeculativeLoadHardeningAttr>(S, D, AL); + break; case ParsedAttr::AT_CodeSeg: handleCodeSegAttr(S, D, AL); break; Added: cfe/trunk/test/CodeGen/attr-speculative-load-hardening.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/attr-speculative-load-hardening.cpp?rev=347617&view=auto ============================================================================== --- cfe/trunk/test/CodeGen/attr-speculative-load-hardening.cpp (added) +++ cfe/trunk/test/CodeGen/attr-speculative-load-hardening.cpp Mon Nov 26 16:03:44 2018 @@ -0,0 +1,18 @@ +// RUN: %clang_cc1 -std=c++11 -disable-llvm-passes -emit-llvm %s -o - | FileCheck %s --check-prefix=CHECK1 +// RUN: %clang_cc1 -std=c++11 -disable-llvm-passes -emit-llvm %s -o - | FileCheck %s --check-prefix=CHECK2 +// +// Check that we set the attribute on each function. + +[[clang::speculative_load_hardening]] +int test1() { + return 42; +} + +int __attribute__((speculative_load_hardening)) test2() { + return 42; +} +// CHECK1: @{{.*}}test1{{.*}}[[SLH1:#[0-9]+]] +// CHECK1: attributes [[SLH1]] = { {{.*}}speculative_load_hardening{{.*}} } + +// CHECK2: @{{.*}}test2{{.*}}[[SLH2:#[0-9]+]] +// CHECK2: attributes [[SLH2]] = { {{.*}}speculative_load_hardening{{.*}} } Added: cfe/trunk/test/CodeGen/attr-speculative-load-hardening.m URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/attr-speculative-load-hardening.m?rev=347617&view=auto ============================================================================== --- cfe/trunk/test/CodeGen/attr-speculative-load-hardening.m (added) +++ cfe/trunk/test/CodeGen/attr-speculative-load-hardening.m Mon Nov 26 16:03:44 2018 @@ -0,0 +1,9 @@ +// RUN: %clang -emit-llvm %s -o - -S | FileCheck %s -check-prefix=SLH + +int main() __attribute__((speculative_load_hardening)) { + return 0; +} + +// SLH: @{{.*}}main{{.*}}[[SLH:#[0-9]+]] + +// SLH: attributes [[SLH]] = { {{.*}}speculative_load_hardening{{.*}} } Modified: cfe/trunk/test/Misc/pragma-attribute-supported-attributes-list.test URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Misc/pragma-attribute-supported-attributes-list.test?rev=347617&r1=347616&r2=347617&view=diff ============================================================================== --- cfe/trunk/test/Misc/pragma-attribute-supported-attributes-list.test (original) +++ cfe/trunk/test/Misc/pragma-attribute-supported-attributes-list.test Mon Nov 26 16:03:44 2018 @@ -2,7 +2,7 @@ // The number of supported attributes should never go down! -// CHECK: #pragma clang attribute supports 129 attributes: +// CHECK: #pragma clang attribute supports 130 attributes: // CHECK-NEXT: AMDGPUFlatWorkGroupSize (SubjectMatchRule_function) // CHECK-NEXT: AMDGPUNumSGPR (SubjectMatchRule_function) // CHECK-NEXT: AMDGPUNumVGPR (SubjectMatchRule_function) @@ -116,6 +116,7 @@ // CHECK-NEXT: ScopedLockable (SubjectMatchRule_record) // CHECK-NEXT: Section (SubjectMatchRule_function, SubjectMatchRule_variable_is_global, SubjectMatchRule_objc_method, SubjectMatchRule_objc_property) // CHECK-NEXT: SetTypestate (SubjectMatchRule_function_is_member) +// CHECK-NEXT: SpeculativeLoadHardening (SubjectMatchRule_function, SubjectMatchRule_objc_method) // CHECK-NEXT: SwiftContext (SubjectMatchRule_variable_is_parameter) // CHECK-NEXT: SwiftErrorResult (SubjectMatchRule_variable_is_parameter) // CHECK-NEXT: SwiftIndirectResult (SubjectMatchRule_variable_is_parameter) Added: cfe/trunk/test/SemaCXX/attr-speculative-load-hardening.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/attr-speculative-load-hardening.cpp?rev=347617&view=auto ============================================================================== --- cfe/trunk/test/SemaCXX/attr-speculative-load-hardening.cpp (added) +++ cfe/trunk/test/SemaCXX/attr-speculative-load-hardening.cpp Mon Nov 26 16:03:44 2018 @@ -0,0 +1,34 @@ +// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify %s + +int i __attribute__((speculative_load_hardening)); // expected-error {{'speculative_load_hardening' attribute only applies to functions}} + +void f1() __attribute__((speculative_load_hardening)); +void f2() __attribute__((speculative_load_hardening(1))); // expected-error {{'speculative_load_hardening' attribute takes no arguments}} + +template <typename T> +void tf1() __attribute__((speculative_load_hardening)); + +int f3(int __attribute__((speculative_load_hardening)), int); // expected-error {{'speculative_load_hardening' attribute only applies to functions}} + +struct A { + int f __attribute__((speculative_load_hardening)); // expected-error {{'speculative_load_hardening' attribute only applies to functions}} + void mf1() __attribute__((speculative_load_hardening)); + static void mf2() __attribute__((speculative_load_hardening)); +}; + +int ci [[clang::speculative_load_hardening]]; // expected-error {{'speculative_load_hardening' attribute only applies to functions}} + +[[clang::speculative_load_hardening]] void cf1(); +[[clang::speculative_load_hardening(1)]] void cf2(); // expected-error {{'speculative_load_hardening' attribute takes no arguments}} + +template <typename T> +[[clang::speculative_load_hardening]] +void ctf1(); + +int cf3(int c[[clang::speculative_load_hardening]], int); // expected-error {{'speculative_load_hardening' attribute only applies to functions}} + +struct CA { + int f [[clang::speculative_load_hardening]]; // expected-error {{'speculative_load_hardening' attribute only applies to functions}} + [[clang::speculative_load_hardening]] void mf1(); + [[clang::speculative_load_hardening]] static void mf2(); +}; _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
