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Merging r369199:
------------------------------------------------------------------------ r369199 | yhs | 2019-08-18 00:12:00 +0200 (Sun, 18 Aug 2019) | 26 lines [BPF] Fix bpf llvm-objdump issues. Commit https://reviews.llvm.org/D57939 ("[DWARF] Refactor RelocVisitor and fix computation of SHT_RELA-typed relocation entries) made a change for relocation resolution when operating on an object file. The change unfortunately broke BPF as given SymbolValue (S) and Addent (A), previously relocation is resolved to S + A and after the change, it is resolved to S This patch fixed the issue by resolving relocation correctly. It looks not all relocation resolution reaches here and I did not trace down exactly when. But I do find if the object file includes codes in two different ELF sections than default ".text", the above bug will be triggered. This patch included a trivial two function source code to demonstrate this issue. The relocation for .debug_loc is resolved incorrectly due to this and llvm-objdump cannot display source annotated assembly. Differential Revision: https://reviews.llvm.org/D66372 ------------------------------------------------------------------------ llvm-svn: 369359
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‎llvm/lib/Object/RelocationResolver.cpp

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -90,9 +90,9 @@ static bool supportsBPF(uint64_t Type) {
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static uint64_t resolveBPF(RelocationRef R, uint64_t S, uint64_t A) {
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switch (R.getType()) {
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case ELF::R_BPF_64_32:
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return S & 0xFFFFFFFF;
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return (S + A) & 0xFFFFFFFF;
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case ELF::R_BPF_64_64:
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return S;
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return S + A;
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default:
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llvm_unreachable("Invalid relocation type");
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}

‎llvm/test/CodeGen/BPF/objdump_two_funcs.ll

Lines changed: 69 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,69 @@
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; RUN: llc -march=bpfel -filetype=obj -o - %s | llvm-objdump -S - | FileCheck %s
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; RUN: llc -march=bpfeb -filetype=obj -o - %s | llvm-objdump -S - | FileCheck %s
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;
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; Source code:
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; __attribute__((section("s1")))
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; int func1(int a) {
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; return a * a;
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; }
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; __attribute__((section("s2")))
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; int func2(int a) {
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; return a * a * a;
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; }
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; Compiler flag to generate IR:
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; clang -target bpf -S -gdwarf-5 -gembed-source -emit-llvm -g -O2 bug.c
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; Function Attrs: norecurse nounwind readnone
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define dso_local i32 @func1(i32 %a) local_unnamed_addr #0 section "s1" !dbg !7 {
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entry:
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; CHECK: func1:
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call void @llvm.dbg.value(metadata i32 %a, metadata !12, metadata !DIExpression()), !dbg !13
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%mul = mul nsw i32 %a, %a, !dbg !14
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ret i32 %mul, !dbg !15
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; CHECK: ; return a * a;
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}
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; Function Attrs: norecurse nounwind readnone
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define dso_local i32 @func2(i32 %a) local_unnamed_addr #0 section "s2" !dbg !16 {
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entry:
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; CHECK: func2:
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call void @llvm.dbg.value(metadata i32 %a, metadata !18, metadata !DIExpression()), !dbg !19
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%mul = mul nsw i32 %a, %a, !dbg !20
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%mul1 = mul nsw i32 %mul, %a, !dbg !21
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ret i32 %mul1, !dbg !22
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; CHECK: ; return a * a * a;
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}
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; Function Attrs: nounwind readnone speculatable
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declare void @llvm.dbg.value(metadata, metadata, metadata) #1
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attributes #0 = { norecurse nounwind readnone "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
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attributes #1 = { nounwind readnone speculatable }
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!3, !4, !5}
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!llvm.ident = !{!6}
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!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 9.0.0 (trunk 366422) (llvm/trunk 366423)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
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!1 = !DIFile(filename: "bug.c", directory: "/tmp/home/yhs/work/tests/llvm/reloc", checksumkind: CSK_MD5, checksum: "c7c9938d4e6989ca33db748213aab194", source: "__attribute__((section(\22s1\22)))\0Aint func1(int a) {\0A return a * a;\0A}\0A__attribute__((section(\22s2\22)))\0Aint func2(int a) {\0A return a * a * a;\0A}\0A")
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!2 = !{}
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!3 = !{i32 2, !"Dwarf Version", i32 5}
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!4 = !{i32 2, !"Debug Info Version", i32 3}
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!5 = !{i32 1, !"wchar_size", i32 4}
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!6 = !{!"clang version 9.0.0 (trunk 366422) (llvm/trunk 366423)"}
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!7 = distinct !DISubprogram(name: "func1", scope: !1, file: !1, line: 2, type: !8, scopeLine: 2, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !11)
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!8 = !DISubroutineType(types: !9)
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!9 = !{!10, !10}
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!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
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!11 = !{!12}
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!12 = !DILocalVariable(name: "a", arg: 1, scope: !7, file: !1, line: 2, type: !10)
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!13 = !DILocation(line: 0, scope: !7)
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!14 = !DILocation(line: 3, column: 14, scope: !7)
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!15 = !DILocation(line: 3, column: 5, scope: !7)
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!16 = distinct !DISubprogram(name: "func2", scope: !1, file: !1, line: 6, type: !8, scopeLine: 6, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !17)
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!17 = !{!18}
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!18 = !DILocalVariable(name: "a", arg: 1, scope: !16, file: !1, line: 6, type: !10)
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!19 = !DILocation(line: 0, scope: !16)
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!20 = !DILocation(line: 7, column: 14, scope: !16)
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!21 = !DILocation(line: 7, column: 18, scope: !16)
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!22 = !DILocation(line: 7, column: 5, scope: !16)

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