d15f96fe4b
Extend llvm-objdump to show CO-RE relocations when `-r` option is
passed and object file has .BTF and .BTF.ext sections.
For example, the following C program:
#define __pai __attribute__((preserve_access_index))
struct foo { int i; int j;} __pai;
struct bar { struct foo f[7]; } __pai;
extern void sink(void *);
void root(struct bar *bar) {
sink(&bar[2].f[3].j);
}
Should lead to the following objdump output:
$ clang --target=bpf -O2 -g t.c -c -o - | \
llvm-objdump --no-addresses --no-show-raw-insn -dr -
...
r2 = 0x94
CO-RE <byte_off> [2] struct bar::[2].f[3].j (2:0:3:1)
r1 += r2
call -0x1
R_BPF_64_32 sink
exit
...
More examples could be found in unit tests, see BTFParserTest.cpp.
To achieve this:
- Move CO-RE relocation kinds definitions from BPFCORE.h to BTF.h.
- Extend BTF.h with types derived from BTF::CommonType, e.g.
BTF::IntType and BTF::StrutType, to allow dyn_cast() and access to
type additional data.
- Extend BTFParser to load BTF type and relocation data.
- Modify llvm-objdump.cpp to create instance of BTFParser when
disassembly of object file with BTF sections is processed and `-r`
flag is supplied.
Additional information about CO-RE is available at [1].
[1] https://docs.kernel.org/bpf/llvm_reloc.html
Depends on D149058
Differential Revision: https://reviews.llvm.org/D150079
87 lines
3.9 KiB
LLVM
87 lines
3.9 KiB
LLVM
; REQUIRES: bpf-registered-target
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;; Verify that llvm-objdump can use .BTF.ext to show CO-RE relocation data.
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; RUN: llc --mtriple bpfel %s --filetype=obj -o - | \
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; RUN: llvm-objdump --no-addresses --no-show-raw-insn -dr - | \
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; RUN: FileCheck %s
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; RUN: llc --mtriple bpfeb %s --filetype=obj -o - | \
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; RUN: llvm-objdump --no-addresses --no-show-raw-insn -dr - | \
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; RUN: FileCheck %s
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;; Input generated from the following C code:
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;;
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;; #define __pai __attribute__((preserve_access_index))
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;;
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;; enum bar { U, V };
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;; volatile unsigned long g;
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;; void root(void) {
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;; g = __builtin_preserve_enum_value(*(enum bar *)U, 0);
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;; g = __builtin_preserve_enum_value(*(enum bar *)V, 1);
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;; }
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;;
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;; Using the following command:
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;;
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;; clang --target=bpf -g -O2 -emit-llvm -S t.c
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; CHECK: CO-RE <enumval_exists> [[[#]]] enum bar::U = 0
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; CHECK: CO-RE <enumval_value> [[[#]]] enum bar::V = 1
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@g = dso_local global i64 0, align 8, !dbg !0
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@"llvm.bar:11:1$1" = external global i64, !llvm.preserve.access.index !5 #0
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@"llvm.bar:10:1$0" = external global i64, !llvm.preserve.access.index !5 #0
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; Function Attrs: nofree nounwind memory(readwrite, argmem: none)
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define dso_local void @root() local_unnamed_addr #1 !dbg !18 {
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entry:
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%0 = load i64, ptr @"llvm.bar:10:1$0", align 8
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%1 = tail call i64 @llvm.bpf.passthrough.i64.i64(i32 1, i64 %0)
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store volatile i64 %1, ptr @g, align 8, !dbg !22, !tbaa !23
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%2 = load i64, ptr @"llvm.bar:11:1$1", align 8
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%3 = tail call i64 @llvm.bpf.passthrough.i64.i64(i32 0, i64 %2)
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store volatile i64 %3, ptr @g, align 8, !dbg !27, !tbaa !23
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ret void, !dbg !28
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}
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; Function Attrs: nofree nosync nounwind memory(none)
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declare i64 @llvm.bpf.passthrough.i64.i64(i32, i64) #2
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attributes #0 = { "btf_ama" }
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attributes #1 = { nofree nounwind memory(readwrite, argmem: none) "frame-pointer"="all" "no-trapping-math"="true" "stack-protector-buffer-size"="8" }
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attributes #2 = { nofree nosync nounwind memory(none) }
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!llvm.dbg.cu = !{!2}
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!llvm.module.flags = !{!13, !14, !15, !16}
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!llvm.ident = !{!17}
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!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
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!1 = distinct !DIGlobalVariable(name: "g", scope: !2, file: !3, line: 4, type: !11, isLocal: false, isDefinition: true)
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!2 = distinct !DICompileUnit(language: DW_LANG_C11, file: !3, producer: "clang version 17.0.0 (/home/eddy/work/llvm-project/clang 2f8c5c0afd1d79a771dd74c8fb1e5bbae6d04eb7)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !10, splitDebugInlining: false, nameTableKind: None)
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!3 = !DIFile(filename: "t.c", directory: "/home/eddy/work/tmp", checksumkind: CSK_MD5, checksum: "5423aa9ef48cb61e948b5c2bd75fd1df")
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!4 = !{!5}
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!5 = !DICompositeType(tag: DW_TAG_enumeration_type, name: "bar", file: !3, line: 3, baseType: !6, size: 32, elements: !7)
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!6 = !DIBasicType(name: "unsigned int", size: 32, encoding: DW_ATE_unsigned)
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!7 = !{!8, !9}
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!8 = !DIEnumerator(name: "U", value: 0)
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!9 = !DIEnumerator(name: "V", value: 1)
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!10 = !{!0}
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!11 = !DIDerivedType(tag: DW_TAG_volatile_type, baseType: !12)
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!12 = !DIBasicType(name: "unsigned long", size: 64, encoding: DW_ATE_unsigned)
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!13 = !{i32 7, !"Dwarf Version", i32 5}
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!14 = !{i32 2, !"Debug Info Version", i32 3}
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!15 = !{i32 1, !"wchar_size", i32 4}
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!16 = !{i32 7, !"frame-pointer", i32 2}
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!17 = !{!"clang version 17.0.0 (/home/eddy/work/llvm-project/clang 2f8c5c0afd1d79a771dd74c8fb1e5bbae6d04eb7)"}
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!18 = distinct !DISubprogram(name: "root", scope: !3, file: !3, line: 5, type: !19, scopeLine: 5, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !21)
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!19 = !DISubroutineType(types: !20)
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!20 = !{null}
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!21 = !{}
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!22 = !DILocation(line: 6, column: 5, scope: !18)
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!23 = !{!24, !24, i64 0}
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!24 = !{!"long", !25, i64 0}
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!25 = !{!"omnipotent char", !26, i64 0}
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!26 = !{!"Simple C/C++ TBAA"}
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!27 = !DILocation(line: 7, column: 5, scope: !18)
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!28 = !DILocation(line: 8, column: 1, scope: !18)
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