forked from OSchip/llvm-project
[LLD][ELF] Add support for INPUT_SECTION_FLAGS
The INPUT_SECTION_FLAGS linker script command is used to constrain the
section pattern matching to sections that match certain combinations of
flags.
There are two ways to express the constraint.
withFlags: Section must have these flags.
withoutFlags: Section must not have these flags.
The syntax of the command is:
INPUT_SECTION_FLAGS '(' sect_flag_list ')'
sect_flag_list: NAME
| sect_flag_list '&' NAME
Where NAME matches a section flag name such as SHF_EXECINSTR, or the
integer value of a section flag. If the first character of NAME is ! then
it means must not contain flag.
We do not support the rare case of { INPUT_SECTION_FLAGS(flags) filespec }
where filespec has no input section description like (.text).
As an example from the ld man page:
SECTIONS {
.text : { INPUT_SECTION_FLAGS (SHF_MERGE & SHF_STRINGS) *(.text) }
.text2 : { INPUT_SECTION_FLAGS (!SHF_WRITE) *(.text) }
}
.text will match sections called .text that have both the SHF_MERGE and
SHF_STRINGS flag.
.text2 will match sections called .text that don't have the SHF_WRITE flag.
The flag names accepted are the generic to all targets and SHF_ARM_PURECODE
as it is very useful to filter all the pure code sections into a single
program header that can be marked execute never.
fixes PR44265
Differential Revision: https://reviews.llvm.org/D72756
This commit is contained in:
Peter Smith
parent
6b4f86f65f
commit
dbd0ad3366
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@ -335,7 +335,9 @@ bool LinkerScript::shouldKeep(InputSectionBase *s) {
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for (InputSectionDescription *id : keptSections)
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if (id->filePat.match(filename))
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for (SectionPattern &p : id->sectionPatterns)
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if (p.sectionPat.match(s->name))
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if (p.sectionPat.match(s->name) &&
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(s->flags & id->withFlags) == id->withFlags &&
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(s->flags & id->withoutFlags) == 0)
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return true;
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return false;
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}
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@ -431,7 +433,10 @@ LinkerScript::computeInputSections(const InputSectionDescription *cmd) {
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continue;
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std::string filename = getFilename(sec->file);
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if (!cmd->filePat.match(filename) || pat.excludedFilePat.match(filename))
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if (!cmd->filePat.match(filename) ||
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pat.excludedFilePat.match(filename) ||
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(sec->flags & cmd->withFlags) != cmd->withFlags ||
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(sec->flags & cmd->withoutFlags) != 0)
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continue;
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ret.push_back(sec);
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@ -155,8 +155,10 @@ struct SectionPattern {
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};
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struct InputSectionDescription : BaseCommand {
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InputSectionDescription(StringRef filePattern)
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: BaseCommand(InputSectionKind), filePat(filePattern) {}
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InputSectionDescription(StringRef filePattern, uint64_t withFlags = 0,
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uint64_t withoutFlags = 0)
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: BaseCommand(InputSectionKind), filePat(filePattern),
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withFlags(withFlags), withoutFlags(withoutFlags) {}
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static bool classof(const BaseCommand *c) {
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return c->kind == InputSectionKind;
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@ -180,6 +182,10 @@ struct InputSectionDescription : BaseCommand {
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// they were created in. This is used to insert newly created ThunkSections
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// into Sections at the end of a createThunks() pass.
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std::vector<std::pair<ThunkSection *, uint32_t>> thunkSections;
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// SectionPatterns can be filtered with the INPUT_SECTION_FLAGS command.
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uint64_t withFlags;
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uint64_t withoutFlags;
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};
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// Represents BYTE(), SHORT(), LONG(), or QUAD().
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@ -30,6 +30,7 @@
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/FileSystem.h"
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#include "llvm/Support/Path.h"
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#include "llvm/Support/ScopedPrinter.h"
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#include <cassert>
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#include <limits>
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#include <vector>
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@ -91,10 +92,13 @@ private:
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OutputSection *readOutputSectionDescription(StringRef outSec);
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std::vector<BaseCommand *> readOverlay();
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std::vector<StringRef> readOutputSectionPhdrs();
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std::pair<uint64_t, uint64_t> readInputSectionFlags();
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InputSectionDescription *readInputSectionDescription(StringRef tok);
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StringMatcher readFilePatterns();
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std::vector<SectionPattern> readInputSectionsList();
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InputSectionDescription *readInputSectionRules(StringRef filePattern);
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InputSectionDescription *readInputSectionRules(StringRef filePattern,
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uint64_t withFlags,
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uint64_t withoutFlags);
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unsigned readPhdrType();
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SortSectionPolicy readSortKind();
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SymbolAssignment *readProvideHidden(bool provide, bool hidden);
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@ -657,8 +661,10 @@ std::vector<SectionPattern> ScriptParser::readInputSectionsList() {
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//
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// <section-list> is parsed by readInputSectionsList().
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InputSectionDescription *
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ScriptParser::readInputSectionRules(StringRef filePattern) {
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auto *cmd = make<InputSectionDescription>(filePattern);
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ScriptParser::readInputSectionRules(StringRef filePattern, uint64_t withFlags,
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uint64_t withoutFlags) {
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auto *cmd =
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make<InputSectionDescription>(filePattern, withFlags, withoutFlags);
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expect("(");
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while (!errorCount() && !consume(")")) {
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@ -694,15 +700,23 @@ InputSectionDescription *
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ScriptParser::readInputSectionDescription(StringRef tok) {
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// Input section wildcard can be surrounded by KEEP.
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// https://sourceware.org/binutils/docs/ld/Input-Section-Keep.html#Input-Section-Keep
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uint64_t withFlags = 0;
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uint64_t withoutFlags = 0;
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if (tok == "KEEP") {
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expect("(");
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StringRef filePattern = next();
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InputSectionDescription *cmd = readInputSectionRules(filePattern);
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if (consume("INPUT_SECTION_FLAGS"))
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std::tie(withFlags, withoutFlags) = readInputSectionFlags();
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InputSectionDescription *cmd =
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readInputSectionRules(next(), withFlags, withoutFlags);
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expect(")");
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script->keptSections.push_back(cmd);
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return cmd;
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}
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return readInputSectionRules(tok);
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if (tok == "INPUT_SECTION_FLAGS") {
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std::tie(withFlags, withoutFlags) = readInputSectionFlags();
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tok = next();
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}
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return readInputSectionRules(tok, withFlags, withoutFlags);
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}
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void ScriptParser::readSort() {
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@ -781,9 +795,14 @@ OutputSection *ScriptParser::readOverlaySectionDescription() {
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script->createOutputSection(next(), getCurrentLocation());
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cmd->inOverlay = true;
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expect("{");
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while (!errorCount() && !consume("}"))
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cmd->sectionCommands.push_back(readInputSectionRules(next()));
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cmd->phdrs = readOutputSectionPhdrs();
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while (!errorCount() && !consume("}")) {
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uint64_t withFlags = 0;
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uint64_t withoutFlags = 0;
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if (consume("INPUT_SECTION_FLAGS"))
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std::tie(withFlags, withoutFlags) = readInputSectionFlags();
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cmd->sectionCommands.push_back(
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readInputSectionRules(next(), withFlags, withoutFlags));
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}
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return cmd;
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}
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@ -841,6 +860,9 @@ OutputSection *ScriptParser::readOutputSectionDescription(StringRef outSec) {
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// We have a file name and no input sections description. It is not a
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// commonly used syntax, but still acceptable. In that case, all sections
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// from the file will be included.
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// FIXME: GNU ld permits INPUT_SECTION_FLAGS to be used here. We do not
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// handle this case here as it will already have been matched by the
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// case above.
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auto *isd = make<InputSectionDescription>(tok);
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isd->sectionPatterns.push_back({{}, StringMatcher({"*"})});
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cmd->sectionCommands.push_back(isd);
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@ -1102,6 +1124,63 @@ ByteCommand *ScriptParser::readByteCommand(StringRef tok) {
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return make<ByteCommand>(e, size, commandString);
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}
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static llvm::Optional<uint64_t> parseFlag(StringRef tok) {
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if (llvm::Optional<uint64_t> asInt = parseInt(tok))
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return asInt;
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#define CASE_ENT(enum) #enum, ELF::enum
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return StringSwitch<llvm::Optional<uint64_t>>(tok)
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.Case(CASE_ENT(SHF_WRITE))
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.Case(CASE_ENT(SHF_ALLOC))
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.Case(CASE_ENT(SHF_EXECINSTR))
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.Case(CASE_ENT(SHF_MERGE))
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.Case(CASE_ENT(SHF_STRINGS))
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.Case(CASE_ENT(SHF_INFO_LINK))
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.Case(CASE_ENT(SHF_LINK_ORDER))
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.Case(CASE_ENT(SHF_OS_NONCONFORMING))
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.Case(CASE_ENT(SHF_GROUP))
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.Case(CASE_ENT(SHF_TLS))
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.Case(CASE_ENT(SHF_COMPRESSED))
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.Case(CASE_ENT(SHF_EXCLUDE))
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.Case(CASE_ENT(SHF_ARM_PURECODE))
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.Default(None);
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#undef CASE_ENT
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}
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// Reads the '(' <flags> ')' list of section flags in
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// INPUT_SECTION_FLAGS '(' <flags> ')' in the
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// following form:
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// <flags> ::= <flag>
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// | <flags> & flag
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// <flag> ::= Recognized Flag Name, or Integer value of flag.
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// If the first character of <flag> is a ! then this means without flag,
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// otherwise with flag.
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// Example: SHF_EXECINSTR & !SHF_WRITE means with flag SHF_EXECINSTR and
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// without flag SHF_WRITE.
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std::pair<uint64_t, uint64_t> ScriptParser::readInputSectionFlags() {
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uint64_t withFlags = 0;
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uint64_t withoutFlags = 0;
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expect("(");
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while (!errorCount()) {
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StringRef tok = unquote(next());
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bool without = tok.consume_front("!");
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if (llvm::Optional<uint64_t> flag = parseFlag(tok)) {
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if (without)
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withoutFlags |= *flag;
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else
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withFlags |= *flag;
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} else {
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setError("unrecognised flag: " + tok);
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}
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if (consume(")"))
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break;
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if (!consume("&")) {
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next();
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setError("expected & or )");
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}
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}
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return std::make_pair(withFlags, withoutFlags);
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}
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StringRef ScriptParser::readParenLiteral() {
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expect("(");
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bool orig = inExpr;
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@ -0,0 +1,13 @@
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# REQUIRES: x86
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# RUN: llvm-mc -filetype=obj -triple=x86_64 /dev/null -o %t.o
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# RUN: not ld.lld -shared %t.o -o /dev/null --script %s 2>&1 | FileCheck -strict-whitespace %s
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## Check that the section flag is recognized.
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SECTIONS {
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.text : { INPUT_SECTION_FLAGS(UNKNOWN_FLAG) *(.text) }
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}
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# CHECK: unrecognised flag: UNKNOWN_FLAG
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# CHECK-NEXT: >>> .text : { INPUT_SECTION_FLAGS(UNKNOWN_FLAG) *(.text) }
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# CHECK-NEXT: >>> ^
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@ -0,0 +1,13 @@
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# REQUIRES: x86
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# RUN: llvm-mc -filetype=obj -triple=x86_64 /dev/null -o %t.o
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# RUN: not ld.lld -shared %t.o -o /dev/null --script %s 2>&1 | FileCheck -strict-whitespace %s
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## Check that we start with a flag
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SECTIONS {
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.text : { INPUT_SECTION_FLAGS(& SHF_ALLOC) *(.text) }
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}
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# CHECK: unrecognised flag: &
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# CHECK-NEXT: >>> .text : { INPUT_SECTION_FLAGS(& SHF_ALLOC) *(.text) }
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# CHECK-NEXT: >>> ^
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@ -0,0 +1,13 @@
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# REQUIRES: x86
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# RUN: llvm-mc -filetype=obj -triple=x86_64 /dev/null -o %t.o
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# RUN: not ld.lld -shared %t.o -o /dev/null --script %s 2>&1 | FileCheck -strict-whitespace %s
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## Check that flags are separated by &
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SECTIONS {
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.text : { INPUT_SECTION_FLAGS(SHF_ALLOC SHF_EXECINSTR) *(.text) }
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}
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// CHECK: expected & or )
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// CHECK-NEXT: >>> .text : { INPUT_SECTION_FLAGS(SHF_ALLOC SHF_EXECINSTR) *(.text) }
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// CHECK-NEXT: >>> ^
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@ -0,0 +1,27 @@
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# REQUIRES: x86
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# RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t.o
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# RUN: echo "SECTIONS { \
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# RUN: . = SIZEOF_HEADERS; \
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# RUN: .keep : { KEEP( INPUT_SECTION_FLAGS(!SHF_WRITE) *(.sec*)) } \
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# RUN: }" > %t.script
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# RUN: ld.lld --gc-sections -o %t --script %t.script %t.o
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# RUN: llvm-readobj --symbols %t | FileCheck %s
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## Check that INPUT_SECTION_FLAGS can be used within KEEP, and affects what
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## is kept.
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# CHECK: Name: keep
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# CHECK-NOT: NAME: collect
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.text
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.global _start
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_start:
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.long 0
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.section .sec1, "a"
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.global keep
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keep:
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.long 1
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.section .sec2, "aw"
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.global collect
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collect:
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.long 2
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@ -0,0 +1,115 @@
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# REQUIRES: x86
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# RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t.o
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## Test the INPUT_SECTION_FLAGS feature. It prefixes an input section list and
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## restricts matches to sections that have the required flags and do not have
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## any of the must not have flags.
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## Uniquely identify each .sec section by flag alone, with .text going into
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## to the SHF_EXECINSTR requiring .outsec2
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# RUN: echo "SECTIONS { \
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# RUN: .outsec1 : { INPUT_SECTION_FLAGS(SHF_ALLOC & !SHF_EXECINSTR & \
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# RUN: !SHF_WRITE & !SHF_MERGE) *(.sec.*) } \
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# RUN: .outsec2 : { INPUT_SECTION_FLAGS(SHF_ALLOC & SHF_EXECINSTR & !SHF_WRITE\
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# RUN: & !SHF_MERGE) *(.sec.* .text) } \
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# RUN: .outsec3 : { INPUT_SECTION_FLAGS(SHF_WRITE) *(.sec.*) } \
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# RUN: .outsec4 : { INPUT_SECTION_FLAGS(SHF_MERGE & !SHF_STRINGS) *(.sec.*) } \
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# RUN: .outsec5 : { INPUT_SECTION_FLAGS(SHF_STRINGS) *(.sec.*) } \
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# RUN: } " > %t.script
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# RUN: ld.lld -o %t1 --script %t.script %t.o
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# RUN: llvm-readobj --symbols %t1 | FileCheck %s
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# CHECK: Name: _start
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# CHECK: Section: .outsec2
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# CHECK: Name: s1
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# CHECK: Section: .outsec1
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# CHECK: Name: s2
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# CHECK: Section: .outsec2
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# CHECK: Name: s3
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# CHECK: Section: .outsec3
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# CHECK: Name: s4
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# CHECK: Section: .outsec4
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# CHECK: Name: s5
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# CHECK: Section: .outsec5
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## Same test but using OVERLAY.
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# RUN: echo "SECTIONS { \
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# RUN: OVERLAY 0x1000 : AT ( 0x4000 ) { \
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# RUN: .outsec1 { INPUT_SECTION_FLAGS(SHF_ALLOC & !SHF_EXECINSTR & \
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# RUN: !SHF_WRITE & !SHF_MERGE) *(.sec.*) }\
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# RUN: .outsec2 { INPUT_SECTION_FLAGS(SHF_ALLOC & SHF_EXECINSTR & !SHF_WRITE \
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# RUN: & !SHF_MERGE) *(.sec.* .text) } \
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# RUN: .outsec3 { INPUT_SECTION_FLAGS(SHF_WRITE) *(.sec.*) } \
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# RUN: .outsec4 { INPUT_SECTION_FLAGS(SHF_MERGE & !SHF_STRINGS) *(.sec.*) } \
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# RUN: .outsec5 { INPUT_SECTION_FLAGS(SHF_STRINGS) *(.sec.*) } \
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# RUN: } } " > %t2.script
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# RUN: ld.lld -o %t2 --script %t2.script %t.o
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# RUN: llvm-readobj --symbols %t2 | FileCheck %s
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## Same test but using hex representations of the flags.
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# RUN: echo "SECTIONS { \
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# RUN: .outsec1 : { INPUT_SECTION_FLAGS(0x2 & !0x4 & !0x1 & !0x10) *(.sec.*) }\
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# RUN: .outsec2 : { INPUT_SECTION_FLAGS(0x2 & 0x4 & !0x1 & !0x10) \
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# RUN: *(.sec.* .text) } \
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# RUN: .outsec3 : { INPUT_SECTION_FLAGS(0x1) *(.sec.*) } \
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# RUN: .outsec4 : { INPUT_SECTION_FLAGS(0x10 & !0x20) *(.sec.*) } \
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# RUN: .outsec5 : { INPUT_SECTION_FLAGS(0x20) *(.sec.*) } \
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# RUN: } " > %t3.script
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# RUN: ld.lld -o %t3 --script %t3.script %t.o
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# RUN: llvm-readobj --symbols %t3 | FileCheck %s
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## Check that we can handle multiple InputSectionDescriptions in a single
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## OutputSection
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# RUN: echo "SECTIONS { \
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# RUN: .outsec1 : { INPUT_SECTION_FLAGS(SHF_ALLOC & !SHF_EXECINSTR & \
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# RUN: !SHF_WRITE & !SHF_MERGE) *(.sec.*) ; \
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# RUN: INPUT_SECTION_FLAGS(SHF_ALLOC & SHF_EXECINSTR & !SHF_WRITE\
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# RUN: & !SHF_MERGE) *(.sec.* *.text) }\
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# RUN: } " > %t4.script
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# RUN: ld.lld -o %t4 --script %t4.script %t.o
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# RUN: llvm-readobj --symbols %t4 | FileCheck --check-prefix MULTIPLE %s
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# MULTIPLE: Name: _start
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# MULTIPLE: Section: .outsec1
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# MULTIPLE: Name: s1
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# MULTIPLE: Section: .outsec1
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# MULTIPLE: Name: s2
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# MULTIPLE: Section: .outsec1
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# MULTIPLE: Name: s3
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# MULTIPLE: Section: .sec.aw
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# MULTIPLE: Name: s4
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# MULTIPLE: Section: .sec.aM
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# MULTIPLE: Name: s5
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# MULTIPLE: Section: .sec.aMS
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.text
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.global _start
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_start:
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nop
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.section .sec.a, "a", @progbits
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.globl s1
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s1:
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.long 1
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.section .sec.ax, "ax", @progbits
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.globl s2
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s2:
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.long 2
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.section .sec.aw, "aw", @progbits
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.globl s3
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s3:
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.long 3
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.section .sec.aM, "aM", @progbits, 4
|
||||
.globl s4
|
||||
s4:
|
||||
.long 4
|
||||
|
||||
.section .sec.aMS, "aMS", @progbits, 1
|
||||
.globl s5
|
||||
s5:
|
||||
.asciz "a"
|
||||
Loading…
Reference in New Issue