5dc8aaac39
With Control-Flow Integrity (CFI), the LowerTypeTests pass replaces function references with CFI jump table references, which is a problem for low-level code that needs the address of the actual function body. For example, in the Linux kernel, the code that sets up interrupt handlers needs to take the address of the interrupt handler function instead of the CFI jump table, as the jump table may not even be mapped into memory when an interrupt is triggered. This change adds the no_cfi constant type, which wraps function references in a value that LowerTypeTestsModule::replaceCfiUses does not replace. Link: https://github.com/ClangBuiltLinux/linux/issues/1353 Reviewed By: nickdesaulniers, pcc Differential Revision: https://reviews.llvm.org/D108478
38 lines
932 B
LLVM
38 lines
932 B
LLVM
; RUN: opt -S -lowertypetests %s | llc -asm-verbose=false | FileCheck %s
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target datalayout = "e-p:64:64"
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target triple = "x86_64-unknown-linux-gnu"
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; CHECK: a:
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; CHECK-NEXT: .quad f1
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; CHECK-NEXT: .quad .L.cfi.jumptable
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; CHECK-NEXT: .quad .L.cfi.jumptable
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; CHECK-NEXT: .quad f2
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; CHECK-NEXT: .quad f3
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; CHECK-NEXT: .quad f3.cfi
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@a = global [6 x void ()*] [void ()* no_cfi @f1, void ()* @f1, void ()* @f2, void ()* no_cfi @f2, void ()* @f3, void ()* no_cfi @f3]
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declare !type !0 void @f1()
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define internal void @f2() !type !0 {
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ret void
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}
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define void @f3() #0 !type !0 {
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ret void
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}
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declare i1 @llvm.type.test(i8* %ptr, metadata %bitset) nounwind readnone
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define i1 @foo(i8* %p) {
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%x = call i1 @llvm.type.test(i8* %p, metadata !"typeid1")
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ret i1 %x
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}
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!llvm.module.flags = !{!1}
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attributes #0 = { "cfi-canonical-jump-table" }
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!0 = !{i32 0, !"typeid1"}
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!1 = !{i32 4, !"CFI Canonical Jump Tables", i32 0}
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