9a67245d88
kernel verifier is becoming smarter and soon will support direct and indirect function calls. Remove obsolete error from BPF backend. Make call to use PCRel_4 fixup. 'bpf to bpf' calls are distinguished from 'bpf to kernel' calls by insn->src_reg == BPF_PSEUDO_CALL == 1 which is used as relocation indicator similar to ld_imm64->src_reg == BPF_PSEUDO_MAP_FD == 1 The actual 'call' instruction remains the same for both 'bpf to kernel' and 'bpf to bpf' calls. Signed-off-by: Alexei Starovoitov <ast@kernel.org> llvm-svn: 318614
63 lines
1.9 KiB
C++
63 lines
1.9 KiB
C++
//===-- BPFELFObjectWriter.cpp - BPF ELF Writer ---------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "MCTargetDesc/BPFMCTargetDesc.h"
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#include "llvm/BinaryFormat/ELF.h"
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#include "llvm/MC/MCELFObjectWriter.h"
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#include "llvm/MC/MCFixup.h"
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#include "llvm/MC/MCObjectWriter.h"
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#include "llvm/Support/ErrorHandling.h"
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#include <cstdint>
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using namespace llvm;
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namespace {
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class BPFELFObjectWriter : public MCELFObjectTargetWriter {
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public:
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BPFELFObjectWriter(uint8_t OSABI);
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~BPFELFObjectWriter() override = default;
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protected:
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unsigned getRelocType(MCContext &Ctx, const MCValue &Target,
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const MCFixup &Fixup, bool IsPCRel) const override;
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};
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} // end anonymous namespace
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BPFELFObjectWriter::BPFELFObjectWriter(uint8_t OSABI)
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: MCELFObjectTargetWriter(/*Is64Bit*/ true, OSABI, ELF::EM_BPF,
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/*HasRelocationAddend*/ false) {}
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unsigned BPFELFObjectWriter::getRelocType(MCContext &Ctx, const MCValue &Target,
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const MCFixup &Fixup,
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bool IsPCRel) const {
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// determine the type of the relocation
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switch ((unsigned)Fixup.getKind()) {
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default:
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llvm_unreachable("invalid fixup kind!");
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case FK_SecRel_8:
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return ELF::R_BPF_64_64;
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case FK_PCRel_4:
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case FK_SecRel_4:
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return ELF::R_BPF_64_32;
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case FK_Data_8:
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return ELF::R_BPF_64_64;
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case FK_Data_4:
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return ELF::R_BPF_64_32;
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}
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}
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std::unique_ptr<MCObjectWriter>
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llvm::createBPFELFObjectWriter(raw_pwrite_stream &OS, uint8_t OSABI,
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bool IsLittleEndian) {
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return createELFObjectWriter(llvm::make_unique<BPFELFObjectWriter>(OSABI), OS,
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IsLittleEndian);
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}
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