https://github.com/scottconstable updated
https://github.com/llvm/llvm-project/pull/121070
>From 73b6f6332cf699b7fa1bcf7cae90ef828cfa9158 Mon Sep 17 00:00:00 2001
From: Scott D Constable <scott.d.consta...@intel.com>
Date: Mon, 23 Dec 2024 13:48:48 -0800
Subject: [PATCH] Implement a new kcfi_x86_arity feature that encodes an
indirect call target's arity (i.e., the number of live-in registers) in the
function's __cfi header.
---
clang/include/clang/Basic/Features.def | 1 +
llvm/lib/Target/X86/X86AsmPrinter.cpp | 19 +++++-
.../X86/kcfi-patchable-function-prefix.ll | 4 +-
llvm/test/CodeGen/X86/kcfi.ll | 63 ++++++++++++++++++-
4 files changed, 81 insertions(+), 6 deletions(-)
diff --git a/clang/include/clang/Basic/Features.def
b/clang/include/clang/Basic/Features.def
index c82b6d9b5f6c10..dca8f4dc0fbf76 100644
--- a/clang/include/clang/Basic/Features.def
+++ b/clang/include/clang/Basic/Features.def
@@ -254,6 +254,7 @@ FEATURE(is_trivially_constructible, LangOpts.CPlusPlus)
FEATURE(is_trivially_copyable, LangOpts.CPlusPlus)
FEATURE(is_union, LangOpts.CPlusPlus)
FEATURE(kcfi, LangOpts.Sanitize.has(SanitizerKind::KCFI))
+FEATURE(kcfi_x86_arity, LangOpts.Sanitize.has(SanitizerKind::KCFI))
FEATURE(modules, LangOpts.Modules)
FEATURE(safe_stack, LangOpts.Sanitize.has(SanitizerKind::SafeStack))
FEATURE(shadow_call_stack,
diff --git a/llvm/lib/Target/X86/X86AsmPrinter.cpp
b/llvm/lib/Target/X86/X86AsmPrinter.cpp
index f01e47b41cf5e4..fe2ce305dcf6e5 100644
--- a/llvm/lib/Target/X86/X86AsmPrinter.cpp
+++ b/llvm/lib/Target/X86/X86AsmPrinter.cpp
@@ -181,8 +181,25 @@ void X86AsmPrinter::emitKCFITypeId(const MachineFunction
&MF) {
// Embed the type hash in the X86::MOV32ri instruction to avoid special
// casing object file parsers.
EmitKCFITypePadding(MF);
+
+ // The ArityToRegMap assumes the 64-bit Linux kernel ABI, so verify the
target
+ const auto &Triple = MF.getTarget().getTargetTriple();
+ assert(Triple.isArch64Bit() && Triple.isOSLinux());
+
+ // Determine the function's arity (i.e., the number of arguments) at the ABI
+ // level by counting the number of parameters that are passed
+ // as registers, such as pointers and 64-bit (or smaller) integers. The
+ // Linux x86-64 ABI allows up to 6 parameters to be passed in GPRs.
+ // Additional parameters or parameters larger than 64 bits may be passed on
+ // the stack, in which case the arity is denoted as 7.
+ const unsigned ArityToRegMap[8] = {X86::EAX, X86::ECX, X86::EDX, X86::EBX,
+ X86::ESP, X86::EBP, X86::ESI, X86::EDI};
+ int Arity = MF.getInfo<X86MachineFunctionInfo>()->getArgumentStackSize() > 0
+ ? 7
+ : MF.getRegInfo().liveins().size();
+
EmitAndCountInstruction(MCInstBuilder(X86::MOV32ri)
- .addReg(X86::EAX)
+ .addReg(ArityToRegMap[Arity])
.addImm(MaskKCFIType(Type->getZExtValue())));
if (MAI->hasDotTypeDotSizeDirective()) {
diff --git a/llvm/test/CodeGen/X86/kcfi-patchable-function-prefix.ll
b/llvm/test/CodeGen/X86/kcfi-patchable-function-prefix.ll
index 1b7bd7835e890c..deababc7fd5379 100644
--- a/llvm/test/CodeGen/X86/kcfi-patchable-function-prefix.ll
+++ b/llvm/test/CodeGen/X86/kcfi-patchable-function-prefix.ll
@@ -3,7 +3,7 @@
; CHECK: .p2align 4
; CHECK-LABEL: __cfi_f1:
; CHECK-COUNT-11: nop
-; CHECK-NEXT: movl $12345678, %eax
+; CHECK-NEXT: movl $12345678, %ecx
; CHECK-LABEL: .Lcfi_func_end0:
; CHECK-NEXT: .size __cfi_f1, .Lcfi_func_end0-__cfi_f1
; CHECK-LABEL: f1:
@@ -26,7 +26,7 @@ define void @f2(ptr noundef %x) {
; CHECK: .p2align 4
; CHECK-LABEL: __cfi_f3:
; CHECK-NOT: nop
-; CHECK-NEXT: movl $12345678, %eax
+; CHECK-NEXT: movl $12345678, %ecx
; CHECK-COUNT-11: nop
; CHECK-LABEL: f3:
define void @f3(ptr noundef %x) #0 !kcfi_type !1 {
diff --git a/llvm/test/CodeGen/X86/kcfi.ll b/llvm/test/CodeGen/X86/kcfi.ll
index 059efcc71b0eb8..91d706796b8e99 100644
--- a/llvm/test/CodeGen/X86/kcfi.ll
+++ b/llvm/test/CodeGen/X86/kcfi.ll
@@ -16,7 +16,7 @@
; ASM-NEXT: nop
; ASM-NEXT: nop
; ASM-NEXT: nop
-; ASM-NEXT: movl $12345678, %eax
+; ASM-NEXT: movl $12345678, %ecx
; ASM-LABEL: .Lcfi_func_end0:
; ASM-NEXT: .size __cfi_f1, .Lcfi_func_end0-__cfi_f1
define void @f1(ptr noundef %x) !kcfi_type !1 {
@@ -90,7 +90,7 @@ define void @f4(ptr noundef %x) #0 {
;; Ensure we emit Value + 1 for unwanted values (e.g. endbr64 == 4196274163).
; ASM-LABEL: __cfi_f5:
-; ASM: movl $4196274164, %eax # imm = 0xFA1E0FF4
+; ASM: movl $4196274164, %ecx # imm = 0xFA1E0FF4
define void @f5(ptr noundef %x) !kcfi_type !2 {
; ASM-LABEL: f5:
; ASM: movl $98693132, %r10d # imm = 0x5E1F00C
@@ -100,7 +100,7 @@ define void @f5(ptr noundef %x) !kcfi_type !2 {
;; Ensure we emit Value + 1 for unwanted values (e.g. -endbr64 == 98693133).
; ASM-LABEL: __cfi_f6:
-; ASM: movl $98693134, %eax # imm = 0x5E1F00E
+; ASM: movl $98693134, %ecx # imm = 0x5E1F00E
define void @f6(ptr noundef %x) !kcfi_type !3 {
; ASM-LABEL: f6:
; ASM: movl $4196274162, %r10d # imm = 0xFA1E0FF2
@@ -138,6 +138,60 @@ define void @f8() {
ret void
}
+%struct.S9 = type { [10 x i64] }
+
+;; Ensure that functions with large (e.g., greater than 8 bytes) arguments
passed on the stack are assigned arity=7
+; ASM-LABEL: __cfi_f9:
+; ASM: movl $199571451, %edi # imm = 0xBE537FB
+define dso_local void @f9(ptr noundef byval(%struct.S9) align 8 %s) !kcfi_type
!4 {
+entry:
+ ret void
+}
+
+;; Ensure that functions with fewer than 7 register arguments and no stack
arguments are assigned arity<7
+; ASM-LABEL: __cfi_f10:
+; ASM: movl $1046421190, %esi # imm = 0x3E5F1EC6
+define dso_local void @f10(i32 noundef %v1, i32 noundef %v2, i32 noundef %v3,
i32 noundef %v4, i32 noundef %v5, i32 noundef %v6) #0 !kcfi_type !5 {
+entry:
+ %v1.addr = alloca i32, align 4
+ %v2.addr = alloca i32, align 4
+ %v3.addr = alloca i32, align 4
+ %v4.addr = alloca i32, align 4
+ %v5.addr = alloca i32, align 4
+ %v6.addr = alloca i32, align 4
+ store i32 %v1, ptr %v1.addr, align 4
+ store i32 %v2, ptr %v2.addr, align 4
+ store i32 %v3, ptr %v3.addr, align 4
+ store i32 %v4, ptr %v4.addr, align 4
+ store i32 %v5, ptr %v5.addr, align 4
+ store i32 %v6, ptr %v6.addr, align 4
+ ret void
+}
+
+;; Ensure that functions with greater than 7 register arguments and no stack
arguments are assigned arity=7
+; ASM-LABEL: __cfi_f11:
+; ASM: movl $1342488295, %edi # imm = 0x5004BEE7
+define dso_local void @f11(i32 noundef %v1, i32 noundef %v2, i32 noundef %v3,
i32 noundef %v4, i32 noundef %v5, i32 noundef %v6, i32 noundef %v7, i32 noundef
%v8) #0 !kcfi_type !6 {
+entry:
+ %v1.addr = alloca i32, align 4
+ %v2.addr = alloca i32, align 4
+ %v3.addr = alloca i32, align 4
+ %v4.addr = alloca i32, align 4
+ %v5.addr = alloca i32, align 4
+ %v6.addr = alloca i32, align 4
+ %v7.addr = alloca i32, align 4
+ %v8.addr = alloca i32, align 4
+ store i32 %v1, ptr %v1.addr, align 4
+ store i32 %v2, ptr %v2.addr, align 4
+ store i32 %v3, ptr %v3.addr, align 4
+ store i32 %v4, ptr %v4.addr, align 4
+ store i32 %v5, ptr %v5.addr, align 4
+ store i32 %v6, ptr %v6.addr, align 4
+ store i32 %v7, ptr %v7.addr, align 4
+ store i32 %v8, ptr %v8.addr, align 4
+ ret void
+}
+
attributes #0 = {
"target-features"="+retpoline-indirect-branches,+retpoline-indirect-calls" }
!llvm.module.flags = !{!0}
@@ -145,3 +199,6 @@ attributes #0 = {
"target-features"="+retpoline-indirect-branches,+retpoline-ind
!1 = !{i32 12345678}
!2 = !{i32 4196274163}
!3 = !{i32 98693133}
+!4 = !{i32 199571451}
+!5 = !{i32 1046421190}
+!6 = !{i32 1342488295}
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
