dd6029ff3a
There are several bugfixes in this update, but the most important one is to ensure __start_ and __stop_ symbols for linker sets and kernel module metadata are always emitted in object files: http://llvm.org/bugs/show_bug.cgi?id=9292 Before this fix, if you compiled kernel modules with clang, they would not be properly processed by kldxref, and if they had any dependencies, the kernel would fail to load those. Another problem occurred when attempting to mount a tmpfs filesystem, which would result in 'operation not supported by device'.
300 lines
11 KiB
C++
300 lines
11 KiB
C++
//===- lib/MC/MCSectionMachO.cpp - MachO Code Section Representation ------===//
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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 "llvm/MC/MCSectionMachO.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/Support/raw_ostream.h"
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#include <cctype>
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using namespace llvm;
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/// SectionTypeDescriptors - These are strings that describe the various section
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/// types. This *must* be kept in order with and stay synchronized with the
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/// section type list.
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static const struct {
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const char *AssemblerName, *EnumName;
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} SectionTypeDescriptors[MCSectionMachO::LAST_KNOWN_SECTION_TYPE+1] = {
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{ "regular", "S_REGULAR" }, // 0x00
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{ 0, "S_ZEROFILL" }, // 0x01
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{ "cstring_literals", "S_CSTRING_LITERALS" }, // 0x02
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{ "4byte_literals", "S_4BYTE_LITERALS" }, // 0x03
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{ "8byte_literals", "S_8BYTE_LITERALS" }, // 0x04
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{ "literal_pointers", "S_LITERAL_POINTERS" }, // 0x05
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{ "non_lazy_symbol_pointers", "S_NON_LAZY_SYMBOL_POINTERS" }, // 0x06
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{ "lazy_symbol_pointers", "S_LAZY_SYMBOL_POINTERS" }, // 0x07
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{ "symbol_stubs", "S_SYMBOL_STUBS" }, // 0x08
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{ "mod_init_funcs", "S_MOD_INIT_FUNC_POINTERS" }, // 0x09
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{ "mod_term_funcs", "S_MOD_TERM_FUNC_POINTERS" }, // 0x0A
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{ "coalesced", "S_COALESCED" }, // 0x0B
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{ 0, /*FIXME??*/ "S_GB_ZEROFILL" }, // 0x0C
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{ "interposing", "S_INTERPOSING" }, // 0x0D
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{ "16byte_literals", "S_16BYTE_LITERALS" }, // 0x0E
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{ 0, /*FIXME??*/ "S_DTRACE_DOF" }, // 0x0F
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{ 0, /*FIXME??*/ "S_LAZY_DYLIB_SYMBOL_POINTERS" }, // 0x10
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{ "thread_local_regular", "S_THREAD_LOCAL_REGULAR" }, // 0x11
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{ "thread_local_zerofill", "S_THREAD_LOCAL_ZEROFILL" }, // 0x12
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{ "thread_local_variables", "S_THREAD_LOCAL_VARIABLES" }, // 0x13
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{ "thread_local_variable_pointers",
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"S_THREAD_LOCAL_VARIABLE_POINTERS" }, // 0x14
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{ "thread_local_init_function_pointers",
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"S_THREAD_LOCAL_INIT_FUNCTION_POINTERS"}, // 0x15
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};
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/// SectionAttrDescriptors - This is an array of descriptors for section
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/// attributes. Unlike the SectionTypeDescriptors, this is not directly indexed
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/// by attribute, instead it is searched. The last entry has an AttrFlagEnd
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/// AttrFlag value.
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static const struct {
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unsigned AttrFlag;
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const char *AssemblerName, *EnumName;
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} SectionAttrDescriptors[] = {
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#define ENTRY(ASMNAME, ENUM) \
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{ MCSectionMachO::ENUM, ASMNAME, #ENUM },
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ENTRY("pure_instructions", S_ATTR_PURE_INSTRUCTIONS)
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ENTRY("no_toc", S_ATTR_NO_TOC)
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ENTRY("strip_static_syms", S_ATTR_STRIP_STATIC_SYMS)
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ENTRY("no_dead_strip", S_ATTR_NO_DEAD_STRIP)
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ENTRY("live_support", S_ATTR_LIVE_SUPPORT)
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ENTRY("self_modifying_code", S_ATTR_SELF_MODIFYING_CODE)
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ENTRY("debug", S_ATTR_DEBUG)
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ENTRY(0 /*FIXME*/, S_ATTR_SOME_INSTRUCTIONS)
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ENTRY(0 /*FIXME*/, S_ATTR_EXT_RELOC)
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ENTRY(0 /*FIXME*/, S_ATTR_LOC_RELOC)
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#undef ENTRY
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{ 0, "none", 0 }, // used if section has no attributes but has a stub size
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#define AttrFlagEnd 0xffffffff // non legal value, multiple attribute bits set
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{ AttrFlagEnd, 0, 0 }
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};
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MCSectionMachO::MCSectionMachO(StringRef Segment, StringRef Section,
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unsigned TAA, unsigned reserved2, SectionKind K)
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: MCSection(SV_MachO, K), TypeAndAttributes(TAA), Reserved2(reserved2) {
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assert(Segment.size() <= 16 && Section.size() <= 16 &&
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"Segment or section string too long");
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for (unsigned i = 0; i != 16; ++i) {
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if (i < Segment.size())
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SegmentName[i] = Segment[i];
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else
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SegmentName[i] = 0;
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if (i < Section.size())
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SectionName[i] = Section[i];
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else
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SectionName[i] = 0;
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}
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}
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void MCSectionMachO::PrintSwitchToSection(const MCAsmInfo &MAI,
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raw_ostream &OS) const {
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OS << "\t.section\t" << getSegmentName() << ',' << getSectionName();
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// Get the section type and attributes.
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unsigned TAA = getTypeAndAttributes();
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if (TAA == 0) {
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OS << '\n';
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return;
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}
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unsigned SectionType = TAA & MCSectionMachO::SECTION_TYPE;
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assert(SectionType <= MCSectionMachO::LAST_KNOWN_SECTION_TYPE &&
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"Invalid SectionType specified!");
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if (SectionTypeDescriptors[SectionType].AssemblerName) {
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OS << ',';
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OS << SectionTypeDescriptors[SectionType].AssemblerName;
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} else {
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// If we have no name for the attribute, stop here.
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OS << '\n';
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return;
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}
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// If we don't have any attributes, we're done.
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unsigned SectionAttrs = TAA & MCSectionMachO::SECTION_ATTRIBUTES;
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if (SectionAttrs == 0) {
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// If we have a S_SYMBOL_STUBS size specified, print it along with 'none' as
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// the attribute specifier.
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if (Reserved2 != 0)
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OS << ",none," << Reserved2;
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OS << '\n';
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return;
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}
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// Check each attribute to see if we have it.
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char Separator = ',';
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for (unsigned i = 0;
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SectionAttrs != 0 && SectionAttrDescriptors[i].AttrFlag;
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++i) {
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// Check to see if we have this attribute.
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if ((SectionAttrDescriptors[i].AttrFlag & SectionAttrs) == 0)
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continue;
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// Yep, clear it and print it.
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SectionAttrs &= ~SectionAttrDescriptors[i].AttrFlag;
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OS << Separator;
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if (SectionAttrDescriptors[i].AssemblerName)
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OS << SectionAttrDescriptors[i].AssemblerName;
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else
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OS << "<<" << SectionAttrDescriptors[i].EnumName << ">>";
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Separator = '+';
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}
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assert(SectionAttrs == 0 && "Unknown section attributes!");
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// If we have a S_SYMBOL_STUBS size specified, print it.
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if (Reserved2 != 0)
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OS << ',' << Reserved2;
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OS << '\n';
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}
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bool MCSectionMachO::UseCodeAlign() const {
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return hasAttribute(MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS);
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}
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bool MCSectionMachO::isVirtualSection() const {
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return (getType() == MCSectionMachO::S_ZEROFILL ||
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getType() == MCSectionMachO::S_GB_ZEROFILL ||
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getType() == MCSectionMachO::S_THREAD_LOCAL_ZEROFILL);
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}
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/// StripSpaces - This removes leading and trailing spaces from the StringRef.
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static void StripSpaces(StringRef &Str) {
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while (!Str.empty() && isspace(Str[0]))
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Str = Str.substr(1);
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while (!Str.empty() && isspace(Str.back()))
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Str = Str.substr(0, Str.size()-1);
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}
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/// ParseSectionSpecifier - Parse the section specifier indicated by "Spec".
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/// This is a string that can appear after a .section directive in a mach-o
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/// flavored .s file. If successful, this fills in the specified Out
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/// parameters and returns an empty string. When an invalid section
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/// specifier is present, this returns a string indicating the problem.
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std::string MCSectionMachO::ParseSectionSpecifier(StringRef Spec, // In.
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StringRef &Segment, // Out.
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StringRef &Section, // Out.
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unsigned &TAA, // Out.
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unsigned &StubSize) { // Out.
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// Find the first comma.
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std::pair<StringRef, StringRef> Comma = Spec.split(',');
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// If there is no comma, we fail.
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if (Comma.second.empty())
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return "mach-o section specifier requires a segment and section "
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"separated by a comma";
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// Capture segment, remove leading and trailing whitespace.
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Segment = Comma.first;
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StripSpaces(Segment);
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// Verify that the segment is present and not too long.
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if (Segment.empty() || Segment.size() > 16)
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return "mach-o section specifier requires a segment whose length is "
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"between 1 and 16 characters";
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// Split the section name off from any attributes if present.
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Comma = Comma.second.split(',');
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// Capture section, remove leading and trailing whitespace.
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Section = Comma.first;
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StripSpaces(Section);
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// Verify that the section is present and not too long.
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if (Section.empty() || Section.size() > 16)
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return "mach-o section specifier requires a section whose length is "
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"between 1 and 16 characters";
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// If there is no comma after the section, we're done.
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StubSize = 0;
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if (Comma.second.empty())
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return "";
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// Otherwise, we need to parse the section type and attributes.
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Comma = Comma.second.split(',');
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// Get the section type.
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StringRef SectionType = Comma.first;
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StripSpaces(SectionType);
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// Figure out which section type it is.
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unsigned TypeID;
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for (TypeID = 0; TypeID !=MCSectionMachO::LAST_KNOWN_SECTION_TYPE+1; ++TypeID)
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if (SectionTypeDescriptors[TypeID].AssemblerName &&
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SectionType == SectionTypeDescriptors[TypeID].AssemblerName)
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break;
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// If we didn't find the section type, reject it.
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if (TypeID > MCSectionMachO::LAST_KNOWN_SECTION_TYPE)
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return "mach-o section specifier uses an unknown section type";
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// Remember the TypeID.
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TAA = TypeID;
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// If we have no comma after the section type, there are no attributes.
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if (Comma.second.empty()) {
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// S_SYMBOL_STUBS always require a symbol stub size specifier.
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if (TAA == MCSectionMachO::S_SYMBOL_STUBS)
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return "mach-o section specifier of type 'symbol_stubs' requires a size "
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"specifier";
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return "";
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}
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// Otherwise, we do have some attributes. Split off the size specifier if
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// present.
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Comma = Comma.second.split(',');
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StringRef Attrs = Comma.first;
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// The attribute list is a '+' separated list of attributes.
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std::pair<StringRef, StringRef> Plus = Attrs.split('+');
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while (1) {
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StringRef Attr = Plus.first;
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StripSpaces(Attr);
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// Look up the attribute.
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for (unsigned i = 0; ; ++i) {
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if (SectionAttrDescriptors[i].AttrFlag == AttrFlagEnd)
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return "mach-o section specifier has invalid attribute";
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if (SectionAttrDescriptors[i].AssemblerName &&
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Attr == SectionAttrDescriptors[i].AssemblerName) {
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TAA |= SectionAttrDescriptors[i].AttrFlag;
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break;
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}
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}
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if (Plus.second.empty()) break;
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Plus = Plus.second.split('+');
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};
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// Okay, we've parsed the section attributes, see if we have a stub size spec.
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if (Comma.second.empty()) {
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// S_SYMBOL_STUBS always require a symbol stub size specifier.
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if (TAA == MCSectionMachO::S_SYMBOL_STUBS)
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return "mach-o section specifier of type 'symbol_stubs' requires a size "
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"specifier";
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return "";
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}
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// If we have a stub size spec, we must have a sectiontype of S_SYMBOL_STUBS.
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if ((TAA & MCSectionMachO::SECTION_TYPE) != MCSectionMachO::S_SYMBOL_STUBS)
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return "mach-o section specifier cannot have a stub size specified because "
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"it does not have type 'symbol_stubs'";
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// Okay, if we do, it must be a number.
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StringRef StubSizeStr = Comma.second;
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StripSpaces(StubSizeStr);
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// Convert the stub size from a string to an integer.
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if (StubSizeStr.getAsInteger(0, StubSize))
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return "mach-o section specifier has a malformed stub size";
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return "";
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}
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