1 //===-- BPFELFObjectWriter.cpp - BPF ELF Writer ---------------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "MCTargetDesc/BPFMCTargetDesc.h"
11 #include "llvm/MC/MCELFObjectWriter.h"
12 #include "llvm/MC/MCFixup.h"
13 #include "llvm/Support/ELF.h"
14 #include "llvm/Support/ErrorHandling.h"
15 #include <cstdint>
16 
17 using namespace llvm;
18 
19 namespace {
20 
21 class BPFELFObjectWriter : public MCELFObjectTargetWriter {
22 public:
23   BPFELFObjectWriter(uint8_t OSABI);
24   ~BPFELFObjectWriter() override = default;
25 
26 protected:
27   unsigned getRelocType(MCContext &Ctx, const MCValue &Target,
28                         const MCFixup &Fixup, bool IsPCRel) const override;
29 };
30 
31 } // end anonymous namespace
32 
33 BPFELFObjectWriter::BPFELFObjectWriter(uint8_t OSABI)
34     : MCELFObjectTargetWriter(/*Is64Bit*/ true, OSABI, ELF::EM_BPF,
35                               /*HasRelocationAddend*/ false) {}
36 
37 unsigned BPFELFObjectWriter::getRelocType(MCContext &Ctx, const MCValue &Target,
38                                           const MCFixup &Fixup,
39                                           bool IsPCRel) const {
40   // determine the type of the relocation
41   switch ((unsigned)Fixup.getKind()) {
42   default:
43     llvm_unreachable("invalid fixup kind!");
44   case FK_SecRel_8:
45     return ELF::R_BPF_64_64;
46   case FK_SecRel_4:
47     return ELF::R_BPF_64_32;
48   case FK_Data_8:
49     return ELF::R_BPF_64_64;
50   case FK_Data_4:
51     return ELF::R_BPF_64_32;
52   }
53 }
54 
55 MCObjectWriter *llvm::createBPFELFObjectWriter(raw_pwrite_stream &OS,
56                                                uint8_t OSABI, bool IsLittleEndian) {
57   MCELFObjectTargetWriter *MOTW = new BPFELFObjectWriter(OSABI);
58   return createELFObjectWriter(MOTW, OS, IsLittleEndian);
59 }
60