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Differential D83638

BPF: permit .maps section variables with typedef type
ClosedPublic

Authored by yonghong-song on Jul 11 2020, 11:02 PM.

Details

Reviewers
ast
anakryiko
Commits
rG152a9fef1b3b: BPF: permit .maps section variables with typedef type
Summary

Currently, llvm when see a global variable in .maps section,
it ensures its type must be a struct type. Then pointee
will be further evaluated for the structure members.
In normal cases, the pointee type will be skipped.

Although this is what current all bpf programs are doing,
but it is a little bit restrictive. For example, it is legitimate
for users to have:
typedef struct { int key_size; int value_size; } map_t;
map_t map attribute((section(".maps")));

This patch lifts this restriction and typedef of
a struct type is also allowed for .maps section variables.
To avoid create unnecessary fixup entries when traversal
started with typedef/struct type, the new implementation
first traverse all map struct members and then traverse
the typedef/struct type. This way, in internal BTFDebug
implementation, no fixup entries are generated.

Two new unit tests are added for typedef and const
struct in .maps section. Also tested with kernel bpf selftests.

Diff Detail

Event Timeline

yonghong-song created this revision.Jul 11 2020, 11:02 PM
Herald added a project: Restricted Project. · View Herald TranscriptJul 11 2020, 11:02 PM
Herald added subscribers: llvm-commits, hiraditya. · View Herald Transcript
anakryiko added a comment.Jul 11 2020, 11:17 PM

maybe let's just remove special-casing of .maps section? It's just like any other global variable, should be handled in exactly the same way, no?

Harbormaster completed remote builds in B63883: Diff 277274.Jul 11 2020, 11:33 PM
yonghong-song added a comment.Jul 11 2020, 11:50 PM
In D83638#2146167, @anakryiko wrote:

maybe let's just remove special-casing of .maps section? It's just like any other global variable, should be handled in exactly the same way, no?

for .maps, we need to trace pointee types. For general globals, functional arguments, etc., we do not trace pointee types like in struct t { struct task_struct *p; } the task_struct won't be traced. That is why we need to handle .maps specially.

anakryiko accepted this revision.Jul 12 2020, 12:31 AM

ah, makes sense. LGTM then :)

This revision is now accepted and ready to land.Jul 12 2020, 12:31 AM
Closed by commit rG152a9fef1b3b: BPF: permit .maps section variables with typedef type (authored by yonghong-song). · Explain WhyJul 12 2020, 9:46 AM
This revision was automatically updated to reflect the committed changes.

Revision Contents

PathSize
llvm/
lib/
Target/
BPF/
32 lines
test/
CodeGen/
BPF/
BTF/
90 lines
65 lines
58 lines

Diff 277294

llvm/lib/Target/BPF/BTFDebug.cpp

Show First 20 Lines • Show All 658 Lines • ▼ Show 20 Lines
} }
void BTFDebug::visitMapDefType(const DIType *Ty, uint32_t &TypeId) { void BTFDebug::visitMapDefType(const DIType *Ty, uint32_t &TypeId) {
if (!Ty || DIToIdMap.find(Ty) != DIToIdMap.end()) { if (!Ty || DIToIdMap.find(Ty) != DIToIdMap.end()) {
TypeId = DIToIdMap[Ty]; TypeId = DIToIdMap[Ty];
return; return;
} }
// MapDef type is a struct type // MapDef type may be a struct type or a non-pointer derived type
const DIType *OrigTy = Ty;
while (auto *DTy = dyn_cast<DIDerivedType>(Ty)) {
auto Tag = DTy->getTag();
if (Tag != dwarf::DW_TAG_typedef && Tag != dwarf::DW_TAG_const_type &&
Tag != dwarf::DW_TAG_volatile_type &&
Tag != dwarf::DW_TAG_restrict_type)
break;
Ty = DTy->getBaseType();
}
const auto *CTy = dyn_cast<DICompositeType>(Ty); const auto *CTy = dyn_cast<DICompositeType>(Ty);
if (!CTy) if (!CTy)
return; return;
auto Tag = CTy->getTag(); auto Tag = CTy->getTag();
if (Tag != dwarf::DW_TAG_structure_type || CTy->isForwardDecl()) if (Tag != dwarf::DW_TAG_structure_type || CTy->isForwardDecl())
return; return;
// Record this type // Visit all struct members to ensure pointee type is visited
const DINodeArray Elements = CTy->getElements(); const DINodeArray Elements = CTy->getElements();
bool HasBitField = false;
for (const auto *Element : Elements) {
auto E = cast<DIDerivedType>(Element);
if (E->isBitField()) {
HasBitField = true;
break;
}
}
auto TypeEntry =
std::make_unique<BTFTypeStruct>(CTy, true, HasBitField, Elements.size());
StructTypes.push_back(TypeEntry.get());
TypeId = addType(std::move(TypeEntry), CTy);
// Visit all struct members
for (const auto *Element : Elements) { for (const auto *Element : Elements) {
const auto *MemberType = cast<DIDerivedType>(Element); const auto *MemberType = cast<DIDerivedType>(Element);
visitTypeEntry(MemberType->getBaseType()); visitTypeEntry(MemberType->getBaseType());
} }
// Visit this type, struct or a const/typedef/volatile/restrict type
visitTypeEntry(OrigTy, TypeId, false, false);
} }
/// Read file contents from the actual file or from the source /// Read file contents from the actual file or from the source
std::string BTFDebug::populateFileContent(const DISubprogram *SP) { std::string BTFDebug::populateFileContent(const DISubprogram *SP) {
auto File = SP->getFile(); auto File = SP->getFile();
std::string FileName; std::string FileName;
if (!File->getFilename().startswith("/") && File->getDirectory().size()) if (!File->getFilename().startswith("/") && File->getDirectory().size())
▲ Show 20 Lines • Show All 598 Lines • Show Last 20 Lines

llvm/test/CodeGen/BPF/BTF/map-def-2.ll

  • This file was added.
; RUN: llc -march=bpfel -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
; RUN: llc -march=bpfeb -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
;
; Source code:
; struct key_type {
; int a1;
; };
; typedef struct map_type {
; struct key_type *key;
; } _map_type;
; typedef _map_type __map_type;
; __map_type __attribute__((section(".maps"))) hash_map;
; Compilation flag:
; clang -target bpf -O2 -g -S -emit-llvm t2.c
%struct.map_type = type { %struct.key_type* }
%struct.key_type = type { i32 }
@hash_map = dso_local local_unnamed_addr global %struct.map_type zeroinitializer, section ".maps", align 8, !dbg !0
; CHECK: .long 0 # BTF_KIND_PTR(id = 1)
; CHECK-NEXT: .long 33554432 # 0x2000000
; CHECK-NEXT: .long 2
; CHECK-NEXT: .long 1 # BTF_KIND_STRUCT(id = 2)
; CHECK-NEXT: .long 67108865 # 0x4000001
; CHECK-NEXT: .long 4
; CHECK-NEXT: .long 10
; CHECK-NEXT: .long 3
; CHECK-NEXT: .long 0 # 0x0
; CHECK-NEXT: .long 13 # BTF_KIND_INT(id = 3)
; CHECK-NEXT: .long 16777216 # 0x1000000
; CHECK-NEXT: .long 4
; CHECK-NEXT: .long 16777248 # 0x1000020
; CHECK-NEXT: .long 17 # BTF_KIND_TYPEDEF(id = 4)
; CHECK-NEXT: .long 134217728 # 0x8000000
; CHECK-NEXT: .long 5
; CHECK-NEXT: .long 28 # BTF_KIND_TYPEDEF(id = 5)
; CHECK-NEXT: .long 134217728 # 0x8000000
; CHECK-NEXT: .long 6
; CHECK-NEXT: .long 38 # BTF_KIND_STRUCT(id = 6)
; CHECK-NEXT: .long 67108865 # 0x4000001
; CHECK-NEXT: .long 8
; CHECK-NEXT: .long 47
; CHECK-NEXT: .long 1
; CHECK-NEXT: .long 0 # 0x0
; CHECK-NEXT: .long 51 # BTF_KIND_VAR(id = 7)
; CHECK-NEXT: .long 234881024 # 0xe000000
; CHECK-NEXT: .long 4
; CHECK-NEXT: .long 1
; CHECK-NEXT: .long 60 # BTF_KIND_DATASEC(id = 8)
; CHECK-NEXT: .long 251658241 # 0xf000001
; CHECK-NEXT: .long 0
; CHECK-NEXT: .long 7
; CHECK-NEXT: .long hash_map
; CHECK-NEXT: .long 8
; CHECK: .ascii "key_type" # string offset=1
; CHECK: .ascii "a1" # string offset=10
; CHECK: .ascii "int" # string offset=13
; CHECK: .ascii "__map_type" # string offset=17
; CHECK: .ascii "_map_type" # string offset=28
; CHECK: .ascii "map_type" # string offset=38
; CHECK: .ascii "key" # string offset=47
; CHECK: .ascii "hash_map" # string offset=51
; CHECK: .ascii ".maps" # string offset=60
!llvm.dbg.cu = !{!2}
!llvm.module.flags = !{!16, !17, !18}
!llvm.ident = !{!19}
!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
!1 = distinct !DIGlobalVariable(name: "hash_map", scope: !2, file: !3, line: 8, type: !6, isLocal: false, isDefinition: true)
!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 11.0.0 (https://github.com/llvm/llvm-project.git b8409c03ed90807f3d49c7d98dceea98cf461f7a)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5, splitDebugInlining: false, nameTableKind: None)
!3 = !DIFile(filename: "t2.c", directory: "/tmp/home/yhs/tmp1")
!4 = !{}
!5 = !{!0}
!6 = !DIDerivedType(tag: DW_TAG_typedef, name: "__map_type", file: !3, line: 7, baseType: !7)
!7 = !DIDerivedType(tag: DW_TAG_typedef, name: "_map_type", file: !3, line: 6, baseType: !8)
!8 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "map_type", file: !3, line: 4, size: 64, elements: !9)
!9 = !{!10}
!10 = !DIDerivedType(tag: DW_TAG_member, name: "key", scope: !8, file: !3, line: 5, baseType: !11, size: 64)
!11 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !12, size: 64)
!12 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "key_type", file: !3, line: 1, size: 32, elements: !13)
!13 = !{!14}
!14 = !DIDerivedType(tag: DW_TAG_member, name: "a1", scope: !12, file: !3, line: 2, baseType: !15, size: 32)
!15 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!16 = !{i32 7, !"Dwarf Version", i32 4}
!17 = !{i32 2, !"Debug Info Version", i32 3}
!18 = !{i32 1, !"wchar_size", i32 4}
!19 = !{!"clang version 11.0.0 (https://github.com/llvm/llvm-project.git b8409c03ed90807f3d49c7d98dceea98cf461f7a)"}

llvm/test/CodeGen/BPF/BTF/map-def-3.ll

  • This file was added.
; RUN: llc -march=bpfel -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
; RUN: llc -march=bpfeb -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
;
; Source code:
; struct key_type {
; int a1;
; };
; const struct key_type __attribute__((section(".maps"))) hash_map;
; Compilation flag:
; clang -target bpf -O2 -g -S -emit-llvm t3.c
%struct.key_type = type { i32 }
@hash_map = dso_local local_unnamed_addr constant %struct.key_type zeroinitializer, section ".maps", align 4, !dbg !0
; CHECK: .long 1 # BTF_KIND_INT(id = 1)
; CHECK-NEXT: .long 16777216 # 0x1000000
; CHECK-NEXT: .long 4
; CHECK-NEXT: .long 16777248 # 0x1000020
; CHECK-NEXT: .long 0 # BTF_KIND_CONST(id = 2)
; CHECK-NEXT: .long 167772160 # 0xa000000
; CHECK-NEXT: .long 3
; CHECK-NEXT: .long 5 # BTF_KIND_STRUCT(id = 3)
; CHECK-NEXT: .long 67108865 # 0x4000001
; CHECK-NEXT: .long 4
; CHECK-NEXT: .long 14
; CHECK-NEXT: .long 1
; CHECK-NEXT: .long 0 # 0x0
; CHECK-NEXT: .long 17 # BTF_KIND_VAR(id = 4)
; CHECK-NEXT: .long 234881024 # 0xe000000
; CHECK-NEXT: .long 2
; CHECK-NEXT: .long 1
; CHECK-NEXT: .long 26 # BTF_KIND_DATASEC(id = 5)
; CHECK-NEXT: .long 251658241 # 0xf000001
; CHECK-NEXT: .long 0
; CHECK-NEXT: .long 4
; CHECK-NEXT: .long hash_map
; CHECK-NEXT: .long 4
; CHECK: .ascii "int" # string offset=1
; CHECK: .ascii "key_type" # string offset=5
; CHECK: .ascii "a1" # string offset=14
; CHECK: .ascii "hash_map" # string offset=17
; CHECK: .ascii ".maps" # string offset=26
!llvm.dbg.cu = !{!2}
!llvm.module.flags = !{!11, !12, !13}
!llvm.ident = !{!14}
!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
!1 = distinct !DIGlobalVariable(name: "hash_map", scope: !2, file: !3, line: 4, type: !6, isLocal: false, isDefinition: true)
!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 11.0.0 (https://github.com/llvm/llvm-project.git 5bd074629f00d4798674b411cf00216f38016483)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5, splitDebugInlining: false, nameTableKind: None)
!3 = !DIFile(filename: "t3.c", directory: "/tmp/home/yhs/tmp1")
!4 = !{}
!5 = !{!0}
!6 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !7)
!7 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "key_type", file: !3, line: 1, size: 32, elements: !8)
!8 = !{!9}
!9 = !DIDerivedType(tag: DW_TAG_member, name: "a1", scope: !7, file: !3, line: 2, baseType: !10, size: 32)
!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!11 = !{i32 7, !"Dwarf Version", i32 4}
!12 = !{i32 2, !"Debug Info Version", i32 3}
!13 = !{i32 1, !"wchar_size", i32 4}
!14 = !{!"clang version 11.0.0 (https://github.com/llvm/llvm-project.git 5bd074629f00d4798674b411cf00216f38016483)"}

llvm/test/CodeGen/BPF/BTF/map-def.ll

Show All 22 Lines
; CHECK-NEXT: .short 60319 # 0xeb9f ; CHECK-NEXT: .short 60319 # 0xeb9f
; CHECK-NEXT: .byte 1 ; CHECK-NEXT: .byte 1
; CHECK-NEXT: .byte 0 ; CHECK-NEXT: .byte 0
; CHECK-NEXT: .long 24 ; CHECK-NEXT: .long 24
; CHECK-NEXT: .long 0 ; CHECK-NEXT: .long 0
; CHECK-NEXT: .long 168 ; CHECK-NEXT: .long 168
; CHECK-NEXT: .long 168 ; CHECK-NEXT: .long 168
; CHECK-NEXT: .long 65 ; CHECK-NEXT: .long 65
; CHECK-NEXT: .long 1 # BTF_KIND_STRUCT(id = 1) ; CHECK-NEXT: .long 0 # BTF_KIND_PTR(id = 1)
; CHECK-NEXT: .long 67108866 # 0x4000002
; CHECK-NEXT: .long 16
; CHECK-NEXT: .long 10
; CHECK-NEXT: .long 2
; CHECK-NEXT: .long 0 # 0x0
; CHECK-NEXT: .long 14
; CHECK-NEXT: .long 5
; CHECK-NEXT: .long 64 # 0x40
; CHECK-NEXT: .long 0 # BTF_KIND_PTR(id = 2)
; CHECK-NEXT: .long 33554432 # 0x2000000 ; CHECK-NEXT: .long 33554432 # 0x2000000
; CHECK-NEXT: .long 3 ; CHECK-NEXT: .long 2
; CHECK-NEXT: .long 20 # BTF_KIND_STRUCT(id = 3) ; CHECK-NEXT: .long 1 # BTF_KIND_STRUCT(id = 2)
; CHECK-NEXT: .long 67108866 # 0x4000002 ; CHECK-NEXT: .long 67108866 # 0x4000002
; CHECK-NEXT: .long 8 ; CHECK-NEXT: .long 8
; CHECK-NEXT: .long 29 ; CHECK-NEXT: .long 10
; CHECK-NEXT: .long 4 ; CHECK-NEXT: .long 3
; CHECK-NEXT: .long 0 # 0x0 ; CHECK-NEXT: .long 0 # 0x0
; CHECK-NEXT: .long 31 ; CHECK-NEXT: .long 12
; CHECK-NEXT: .long 4 ; CHECK-NEXT: .long 3
; CHECK-NEXT: .long 32 # 0x20 ; CHECK-NEXT: .long 32 # 0x20
; CHECK-NEXT: .long 33 # BTF_KIND_INT(id = 4) ; CHECK-NEXT: .long 14 # BTF_KIND_INT(id = 3)
; CHECK-NEXT: .long 16777216 # 0x1000000 ; CHECK-NEXT: .long 16777216 # 0x1000000
; CHECK-NEXT: .long 4 ; CHECK-NEXT: .long 4
; CHECK-NEXT: .long 16777248 # 0x1000020 ; CHECK-NEXT: .long 16777248 # 0x1000020
; CHECK-NEXT: .long 0 # BTF_KIND_PTR(id = 5) ; CHECK-NEXT: .long 0 # BTF_KIND_PTR(id = 4)
; CHECK-NEXT: .long 33554432 # 0x2000000 ; CHECK-NEXT: .long 33554432 # 0x2000000
; CHECK-NEXT: .long 6 ; CHECK-NEXT: .long 5
; CHECK-NEXT: .long 37 # BTF_KIND_INT(id = 6) ; CHECK-NEXT: .long 18 # BTF_KIND_INT(id = 5)
; CHECK-NEXT: .long 16777216 # 0x1000000 ; CHECK-NEXT: .long 16777216 # 0x1000000
; CHECK-NEXT: .long 4 ; CHECK-NEXT: .long 4
; CHECK-NEXT: .long 32 # 0x20 ; CHECK-NEXT: .long 32 # 0x20
; CHECK-NEXT: .long 31 # BTF_KIND_STRUCT(id = 6)
; CHECK-NEXT: .long 67108866 # 0x4000002
; CHECK-NEXT: .long 16
; CHECK-NEXT: .long 40
; CHECK-NEXT: .long 1
; CHECK-NEXT: .long 0 # 0x0
; CHECK-NEXT: .long 44
; CHECK-NEXT: .long 4
; CHECK-NEXT: .long 64 # 0x40
; CHECK-NEXT: .long 50 # BTF_KIND_VAR(id = 7) ; CHECK-NEXT: .long 50 # BTF_KIND_VAR(id = 7)
; CHECK-NEXT: .long 234881024 # 0xe000000 ; CHECK-NEXT: .long 234881024 # 0xe000000
; CHECK-NEXT: .long 1 ; CHECK-NEXT: .long 6
; CHECK-NEXT: .long 1 ; CHECK-NEXT: .long 1
; CHECK-NEXT: .long 59 # BTF_KIND_DATASEC(id = 8) ; CHECK-NEXT: .long 59 # BTF_KIND_DATASEC(id = 8)
; CHECK-NEXT: .long 251658241 # 0xf000001 ; CHECK-NEXT: .long 251658241 # 0xf000001
; CHECK-NEXT: .long 0 ; CHECK-NEXT: .long 0
; CHECK-NEXT: .long 7 ; CHECK-NEXT: .long 7
; CHECK-NEXT: .long hash_map ; CHECK-NEXT: .long hash_map
; CHECK-NEXT: .long 16 ; CHECK-NEXT: .long 16
; CHECK-NEXT: .byte 0 # string offset=0 ; CHECK-NEXT: .byte 0 # string offset=0
; CHECK-NEXT: .ascii "map_type" # string offset=1 ; CHECK-NEXT: .ascii "key_type" # string offset=1
; CHECK-NEXT: .byte 0 ; CHECK-NEXT: .byte 0
; CHECK-NEXT: .ascii "key" # string offset=10 ; CHECK-NEXT: .byte 97 # string offset=10
; CHECK-NEXT: .byte 0 ; CHECK-NEXT: .byte 0
; CHECK-NEXT: .ascii "value" # string offset=14 ; CHECK-NEXT: .byte 98 # string offset=12
; CHECK-NEXT: .byte 0 ; CHECK-NEXT: .byte 0
; CHECK-NEXT: .ascii "key_type" # string offset=20 ; CHECK-NEXT: .ascii "int" # string offset=14
; CHECK-NEXT: .byte 0 ; CHECK-NEXT: .byte 0
; CHECK-NEXT: .byte 97 # string offset=29 ; CHECK-NEXT: .ascii "unsigned int" # string offset=18
; CHECK-NEXT: .byte 0 ; CHECK-NEXT: .byte 0
; CHECK-NEXT: .byte 98 # string offset=31 ; CHECK-NEXT: .ascii "map_type" # string offset=31
; CHECK-NEXT: .byte 0 ; CHECK-NEXT: .byte 0
; CHECK-NEXT: .ascii "int" # string offset=33 ; CHECK-NEXT: .ascii "key" # string offset=40
; CHECK-NEXT: .byte 0 ; CHECK-NEXT: .byte 0
; CHECK-NEXT: .ascii "unsigned int" # string offset=37 ; CHECK-NEXT: .ascii "value" # string offset=44
; CHECK-NEXT: .byte 0 ; CHECK-NEXT: .byte 0
; CHECK-NEXT: .ascii "hash_map" # string offset=50 ; CHECK-NEXT: .ascii "hash_map" # string offset=50
; CHECK-NEXT: .byte 0 ; CHECK-NEXT: .byte 0
; CHECK-NEXT: .ascii ".maps" # string offset=59 ; CHECK-NEXT: .ascii ".maps" # string offset=59
; CHECK-NEXT: .byte 0 ; CHECK-NEXT: .byte 0
!llvm.dbg.cu = !{!2} !llvm.dbg.cu = !{!2}
!llvm.module.flags = !{!18, !19, !20} !llvm.module.flags = !{!18, !19, !20}
Show All 24 Lines