2020-04-03 02:54:05 +08:00
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//===- InputSection.cpp ---------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "InputSection.h"
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2020-08-13 10:50:09 +08:00
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#include "InputFiles.h"
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2020-04-28 03:50:59 +08:00
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#include "OutputSegment.h"
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2020-04-03 02:54:05 +08:00
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#include "Symbols.h"
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#include "Target.h"
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#include "lld/Common/Memory.h"
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#include "llvm/Support/Endian.h"
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2020-05-19 06:46:33 +08:00
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using namespace llvm;
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2020-04-03 02:54:05 +08:00
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using namespace llvm::MachO;
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using namespace llvm::support;
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using namespace lld;
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using namespace lld::macho;
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std::vector<InputSection *> macho::inputSections;
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2020-04-28 03:50:59 +08:00
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uint64_t InputSection::getFileOffset() const {
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2020-05-02 07:29:06 +08:00
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return parent->fileOff + outSecFileOff;
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2020-04-28 03:50:59 +08:00
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}
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2020-05-02 07:29:06 +08:00
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uint64_t InputSection::getVA() const { return parent->addr + outSecOff; }
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2020-04-03 02:54:05 +08:00
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void InputSection::writeTo(uint8_t *buf) {
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[lld-macho] Ensure __bss sections we output have file offset of zero
Summary:
llvm-mc emits `__bss` sections with an offset of zero, but we weren't expecting
that in our input, so we were copying non-zero data from the start of the file and
putting it in `__bss`, with obviously undesirable runtime results. (It appears that
the kernel will copy those nonzero bytes as long as the offset is nonzero, regardless
of whether S_ZERO_FILL is set.)
I debated on whether to make a special ZeroFillSection -- separate from a
regular InputSection -- but it seemed like too much work for now. But I'm happy
to refactor if anyone feels strongly about having it as a separate class.
Depends on D80857.
Reviewers: ruiu, pcc, MaskRay, smeenai, alexshap, gkm, Ktwu, christylee
Reviewed By: smeenai
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D80859
2020-06-14 11:00:36 +08:00
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if (getFileSize() == 0)
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return;
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memcpy(buf, data.data(), data.size());
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2020-04-03 02:54:05 +08:00
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for (Reloc &r : relocs) {
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uint64_t va = 0;
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2020-08-08 02:04:52 +08:00
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if (auto *s = r.target.dyn_cast<Symbol *>()) {
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va = target->resolveSymbolVA(buf + r.offset, *s, r.type);
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if (isThreadLocalVariables(flags)) {
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// References from thread-local variable sections are treated as
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// offsets relative to the start of the target section, instead of as
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// absolute addresses.
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if (auto *defined = dyn_cast<Defined>(s))
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va -= defined->isec->parent->addr;
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}
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} else if (auto *isec = r.target.dyn_cast<InputSection *>()) {
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2020-05-02 07:29:06 +08:00
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va = isec->getVA();
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2020-08-08 02:04:52 +08:00
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}
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2020-04-03 02:54:05 +08:00
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[lld-macho][re-land] Support .subsections_via_symbols
Summary:
This diff restores and builds upon @pcc and @ruiu's initial work on
subsections.
The .subsections_via_symbols directive indicates we can split each
section along symbol boundaries, unless those symbols have been marked
with `.alt_entry`.
We exercise this functionality in our tests by using order files that
rearrange those symbols.
Depends on D79668.
Reviewers: ruiu, pcc, MaskRay, smeenai, alexshap, gkm, Ktwu, christylee
Reviewed By: smeenai
Subscribers: thakis, llvm-commits, pcc, ruiu
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D79926
2020-05-19 23:46:07 +08:00
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uint64_t val = va + r.addend;
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2020-05-19 23:53:53 +08:00
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if (r.pcrel)
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2020-05-02 07:29:06 +08:00
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val -= getVA() + r.offset;
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2020-06-14 10:52:20 +08:00
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target->relocateOne(buf + r.offset, r, val);
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2020-04-03 02:54:05 +08:00
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}
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}
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2020-08-13 10:50:09 +08:00
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std::string lld::toString(const InputSection *isec) {
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return (toString(isec->file) + ":(" + isec->name + ")").str();
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}
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