[llvm-branch-commits] [llvm] a5a6cfe - BPF: permit type modifiers for __builtin_btf_type_id() relocation
Tom Stellard via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Mon May 3 17:38:14 PDT 2021
Author: Yonghong Song
Date: 2021-05-03T17:37:51-07:00
New Revision: a5a6cfe2f030e81e689ed9af4e95ddf95c4d8675
URL: https://github.com/llvm/llvm-project/commit/a5a6cfe2f030e81e689ed9af4e95ddf95c4d8675
DIFF: https://github.com/llvm/llvm-project/commit/a5a6cfe2f030e81e689ed9af4e95ddf95c4d8675.diff
LOG: BPF: permit type modifiers for __builtin_btf_type_id() relocation
Lorenz Bauer from Cloudflare tried to use "const struct <name>"
as the type for __builtin_btf_type_id(*(const struct <name>)0, 1)
relocation and hit a llvm BPF fatal error.
https://lore.kernel.org/bpf/a3782f71-3f6b-1e75-17a9-1827822c2030@fb.com/
...
fatal error: error in backend: Empty type name for BTF_TYPE_ID_REMOTE reloc
Currently, we require the debuginfo type itself must have a name.
In this case, the debuginfo type is "const" which points to "struct <name>".
The "const" type does not have a name, hence the above fatal error
will be triggered.
Let us permit "const" and "volatile" type modifiers. We skip modifiers
in some other cases as well like structure member type tracing.
This can aviod the above fatal error.
Differential Revision: https://reviews.llvm.org/D97986
(cherry picked from commit 9c0274cdeae904089806be6faee72b9126d2cf5b)
Added:
llvm/test/CodeGen/BPF/BTF/builtin-btf-type-id-2.ll
Modified:
llvm/lib/Target/BPF/BPFPreserveDIType.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Target/BPF/BPFPreserveDIType.cpp b/llvm/lib/Target/BPF/BPFPreserveDIType.cpp
index 18a4f60c171ae..0348e2200acbc 100644
--- a/llvm/lib/Target/BPF/BPFPreserveDIType.cpp
+++ b/llvm/lib/Target/BPF/BPFPreserveDIType.cpp
@@ -85,8 +85,17 @@ static bool BPFPreserveDITypeImpl(Function &F) {
} else {
Reloc = BPFCoreSharedInfo::BTF_TYPE_ID_REMOTE;
DIType *Ty = cast<DIType>(MD);
+ while (auto *DTy = dyn_cast<DIDerivedType>(Ty)) {
+ unsigned Tag = DTy->getTag();
+ if (Tag != dwarf::DW_TAG_const_type &&
+ Tag != dwarf::DW_TAG_volatile_type)
+ break;
+ Ty = DTy->getBaseType();
+ }
+
if (Ty->getName().empty())
report_fatal_error("Empty type name for BTF_TYPE_ID_REMOTE reloc");
+ MD = Ty;
}
BasicBlock *BB = Call->getParent();
diff --git a/llvm/test/CodeGen/BPF/BTF/builtin-btf-type-id-2.ll b/llvm/test/CodeGen/BPF/BTF/builtin-btf-type-id-2.ll
new file mode 100644
index 0000000000000..63c56c4dfec57
--- /dev/null
+++ b/llvm/test/CodeGen/BPF/BTF/builtin-btf-type-id-2.ll
@@ -0,0 +1,73 @@
+; RUN: opt -O2 -mtriple=bpf-pc-linux -S -o %t1 %s
+; RUN: llc -filetype=asm -o - %t1 | FileCheck -check-prefixes=CHECK %s
+; RUN: llc -mattr=+alu32 -filetype=asm -o - %t1 | FileCheck -check-prefixes=CHECK %s
+; Source code:
+; struct s {
+; int a;
+; };
+; int test(void) {
+; return __builtin_btf_type_id(*(const struct s *)0, 1);
+; }
+; Compilation flag:
+; clang -target bpf -O2 -g -S -emit-llvm -Xclang -disable-llvm-passes test.c
+
+; Function Attrs: nounwind
+define dso_local i32 @test() #0 !dbg !7 {
+entry:
+ %0 = call i64 @llvm.bpf.btf.type.id(i32 0, i64 1), !dbg !11, !llvm.preserve.access.index !12
+ %conv = trunc i64 %0 to i32, !dbg !11
+ ret i32 %conv, !dbg !16
+}
+
+; CHECK: .long 1 # BTF_KIND_INT(id = 2)
+; CHECK-NEXT: .long 16777216 # 0x1000000
+; CHECK-NEXT: .long 4
+; CHECK-NEXT: .long 16777248 # 0x1000020
+
+; CHECK: .long 16 # BTF_KIND_STRUCT(id = 4)
+; CHECK-NEXT: .long 67108865 # 0x4000001
+; CHECK-NEXT: .long 4
+; CHECK-NEXT: .long 18
+; CHECK-NEXT: .long 2
+
+; CHECK: .ascii "int" # string offset=1
+; CHECK: .ascii ".text" # string offset=10
+; CHECK: .byte 115 # string offset=16
+; CHECK: .byte 97 # string offset=18
+; CHECK: .byte 48 # string offset=20
+
+; CHECK: .long 16 # FieldReloc
+; CHECK-NEXT: .long 10 # Field reloc section string offset=10
+; CHECK-NEXT: .long 1
+; CHECK-NEXT: .long .Ltmp{{[0-9]+}}
+; CHECK-NEXT: .long 4
+; CHECK-NEXT: .long 20
+; CHECK-NEXT: .long 7
+
+; Function Attrs: nounwind readnone
+declare i64 @llvm.bpf.btf.type.id(i32, i64) #1
+
+attributes #0 = { nounwind "frame-pointer"="all" "no-trapping-math"="true" "stack-protector-buffer-size"="8" }
+attributes #1 = { nounwind readnone }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 13.0.0 (https://github.com/llvm/llvm-project.git 9783e2098800b954c55ae598a1ce5c4b93444fc0)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.c", directory: "/tmp/home/yhs/bpf/test")
+!2 = !{}
+!3 = !{i32 7, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 13.0.0 (https://github.com/llvm/llvm-project.git 9783e2098800b954c55ae598a1ce5c4b93444fc0)"}
+!7 = distinct !DISubprogram(name: "test", scope: !1, file: !1, line: 4, type: !8, scopeLine: 4, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
+!8 = !DISubroutineType(types: !9)
+!9 = !{!10}
+!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!11 = !DILocation(line: 5, column: 10, scope: !7)
+!12 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !13)
+!13 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "s", file: !1, line: 1, size: 32, elements: !14)
+!14 = !{!15}
+!15 = !DIDerivedType(tag: DW_TAG_member, name: "a", scope: !13, file: !1, line: 2, baseType: !10, size: 32)
+!16 = !DILocation(line: 5, column: 3, scope: !7)
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