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Support soft failure on DWP section overflow, producing a truncated but valid DWP(#71902)

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When 'ContinueOnCuIndexOverflow' enables without this modification, the
forcibly generated '.dwp' won't be recognized by Debugger(gdb 10.1)
correctly.
<img width="657" alt="image"
src="https://github.com/llvm/llvm-project/assets/150100070/31732775-2548-453a-a47a-fa04c6d05fe9">
it looks like there's a problem with processing the dwarf header, which
makes debugging completely impossible. (unless the consumer walks the debug_info section to rebuild that column (if that's the only section that overflowed - if it's another section, there's no recovery))

**About patch:**
When llvm-dwp enables option '--continue-on-cu-index-overflow=soft-stop'
and recognizes the overflow problem , it will stop packing and generate
the '.dwp' file at once, discarding any DWO files that would not fit
within the 32 bit/4GB limits of the format.
<img width="625" alt="image"
src="https://github.com/llvm/llvm-project/assets/150100070/77d6be24-262b-4f4c-afc0-9a6c49e133c7">
This commit is contained in:
Jinjie Huang 2023-12-02 04:01:22 +08:00 committed by GitHub
parent 481e9b3e0b
commit 4c44dcffd5
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 70 additions and 21 deletions
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8
llvm/include/llvm/DWP/DWP.h
View File

@ -15,6 +15,12 @@
#include <vector>
namespace llvm {
enum OnCuIndexOverflow {
HardStop,
SoftStop,
Continue,
};
struct UnitIndexEntry {
DWARFUnitIndex::Entry::SectionContribution Contributions[8];
std::string Name;
@ -61,7 +67,7 @@ struct CompileUnitIdentifiers {
};
Error write(MCStreamer &Out, ArrayRef<std::string> Inputs,
bool ContinueOnCuIndexOverflow);
OnCuIndexOverflow OverflowOptValue);
unsigned getContributionIndex(DWARFSectionKind Kind, uint32_t IndexVersion);

62
llvm/lib/DWP/DWP.cpp
View File

@ -183,14 +183,19 @@ static StringRef getSubsection(StringRef Section,
static Error sectionOverflowErrorOrWarning(uint32_t PrevOffset,
uint32_t OverflowedOffset,
StringRef SectionName,
bool ContinueOnCuIndexOverflow) {
OnCuIndexOverflow OverflowOptValue,
bool &AnySectionOverflow) {
std::string Msg =
(SectionName +
Twine(" Section Contribution Offset overflow 4G. Previous Offset ") +
Twine(PrevOffset) + Twine(", After overflow offset ") +
Twine(OverflowedOffset) + Twine("."))
.str();
if (ContinueOnCuIndexOverflow) {
if (OverflowOptValue == OnCuIndexOverflow::Continue) {
WithColor::defaultWarningHandler(make_error<DWPError>(Msg));
return Error::success();
} else if (OverflowOptValue == OnCuIndexOverflow::SoftStop) {
AnySectionOverflow = true;
WithColor::defaultWarningHandler(make_error<DWPError>(Msg));
return Error::success();
}
@ -201,7 +206,8 @@ static Error addAllTypesFromDWP(
MCStreamer &Out, MapVector<uint64_t, UnitIndexEntry> &TypeIndexEntries,
const DWARFUnitIndex &TUIndex, MCSection *OutputTypes, StringRef Types,
const UnitIndexEntry &TUEntry, uint32_t &TypesOffset,
unsigned TypesContributionIndex, bool ContinueOnCuIndexOverflow) {
unsigned TypesContributionIndex, OnCuIndexOverflow OverflowOptValue,
bool &AnySectionOverflow) {
Out.switchSection(OutputTypes);
for (const DWARFUnitIndex::Entry &E : TUIndex.getRows()) {
auto *I = E.getContributions();
@ -232,9 +238,14 @@ static Error addAllTypesFromDWP(
static_assert(sizeof(OldOffset) == sizeof(TypesOffset));
TypesOffset += C.getLength();
if (OldOffset > TypesOffset) {
if (Error Err = sectionOverflowErrorOrWarning(
OldOffset, TypesOffset, "Types", ContinueOnCuIndexOverflow))
if (Error Err = sectionOverflowErrorOrWarning(OldOffset, TypesOffset,
"Types", OverflowOptValue,
AnySectionOverflow))
return Err;
if (AnySectionOverflow) {
TypesOffset = OldOffset;
return Error::success();
}
}
}
return Error::success();
@ -244,7 +255,7 @@ static Error addAllTypesFromTypesSection(
MCStreamer &Out, MapVector<uint64_t, UnitIndexEntry> &TypeIndexEntries,
MCSection *OutputTypes, const std::vector<StringRef> &TypesSections,
const UnitIndexEntry &CUEntry, uint32_t &TypesOffset,
bool ContinueOnCuIndexOverflow) {
OnCuIndexOverflow OverflowOptValue, bool &AnySectionOverflow) {
for (StringRef Types : TypesSections) {
Out.switchSection(OutputTypes);
uint64_t Offset = 0;
@ -273,9 +284,14 @@ static Error addAllTypesFromTypesSection(
uint32_t OldOffset = TypesOffset;
TypesOffset += C.getLength32();
if (OldOffset > TypesOffset) {
if (Error Err = sectionOverflowErrorOrWarning(
OldOffset, TypesOffset, "types", ContinueOnCuIndexOverflow))
if (Error Err = sectionOverflowErrorOrWarning(OldOffset, TypesOffset,
"Types", OverflowOptValue,
AnySectionOverflow))
return Err;
if (AnySectionOverflow) {
TypesOffset = OldOffset;
return Error::success();
}
}
}
}
@ -583,7 +599,7 @@ Error handleSection(
}
Error write(MCStreamer &Out, ArrayRef<std::string> Inputs,
bool ContinueOnCuIndexOverflow) {
OnCuIndexOverflow OverflowOptValue) {
const auto &MCOFI = *Out.getContext().getObjectFileInfo();
MCSection *const StrSection = MCOFI.getDwarfStrDWOSection();
MCSection *const StrOffsetSection = MCOFI.getDwarfStrOffDWOSection();
@ -613,6 +629,7 @@ Error write(MCStreamer &Out, ArrayRef<std::string> Inputs,
uint32_t ContributionOffsets[8] = {};
uint16_t Version = 0;
uint32_t IndexVersion = 0;
bool AnySectionOverflow = false;
DWPStringPool Strings(Out, StrSection);
@ -687,12 +704,15 @@ Error write(MCStreamer &Out, ArrayRef<std::string> Inputs,
uint32_t SectionIndex = 0;
for (auto &Section : Obj.sections()) {
if (SectionIndex == Index) {
return sectionOverflowErrorOrWarning(
OldOffset, ContributionOffsets[Index], *Section.getName(),
ContinueOnCuIndexOverflow);
if (Error Err = sectionOverflowErrorOrWarning(
OldOffset, ContributionOffsets[Index], *Section.getName(),
OverflowOptValue, AnySectionOverflow))
return Err;
}
++SectionIndex;
}
if (AnySectionOverflow)
break;
}
}
@ -720,8 +740,14 @@ Error write(MCStreamer &Out, ArrayRef<std::string> Inputs,
C.getLength32()) {
if (Error Err = sectionOverflowErrorOrWarning(
InfoSectionOffset, InfoSectionOffset + C.getLength32(),
"debug_info", ContinueOnCuIndexOverflow))
"debug_info", OverflowOptValue, AnySectionOverflow))
return Err;
if (AnySectionOverflow) {
if (Header.Version < 5 ||
Header.UnitType == dwarf::DW_UT_split_compile)
FoundCUUnit = true;
break;
}
}
UnitOffset += C.getLength32();
@ -752,6 +778,8 @@ Error write(MCStreamer &Out, ArrayRef<std::string> Inputs,
Info.substr(UnitOffset - C.getLength32(), C.getLength32()));
InfoSectionOffset += C.getLength32();
}
if (AnySectionOverflow)
break;
}
if (!FoundCUUnit)
@ -762,9 +790,11 @@ Error write(MCStreamer &Out, ArrayRef<std::string> Inputs,
if (Error Err = addAllTypesFromTypesSection(
Out, TypeIndexEntries, TypesSection, CurTypesSection, CurEntry,
ContributionOffsets[getContributionIndex(DW_SECT_EXT_TYPES, 2)],
ContinueOnCuIndexOverflow))
OverflowOptValue, AnySectionOverflow))
return Err;
}
if (AnySectionOverflow)
break;
continue;
}
@ -860,9 +890,11 @@ Error write(MCStreamer &Out, ArrayRef<std::string> Inputs,
if (Error Err = addAllTypesFromDWP(
Out, TypeIndexEntries, TUIndex, OutSection, TypeInputSection,
CurEntry, ContributionOffsets[TypesContributionIndex],
TypesContributionIndex, ContinueOnCuIndexOverflow))
TypesContributionIndex, OverflowOptValue, AnySectionOverflow))
return Err;
}
if (AnySectionOverflow)
break;
}
if (Version < 5) {

6
llvm/tools/llvm-dwp/Opts.td
View File

@ -9,5 +9,7 @@ def version : F<"version", "Display the version of this program">;
def execFileNames : S<"e", "Specify the executable/library files to get the list of *.dwo from.">, MetaVarName<"<filename>">;
def outputFileName : S<"o", "Specify the output file.">, MetaVarName<"<filename>">;
def continueOnCuIndexOverflow: F<"continue-on-cu-index-overflow", "This turns an error when offset for .debug_*.dwo sections "
"overfolws into a warning.">, MetaVarName<"<filename>">;
def continueOnCuIndexOverflow : S<"continue-on-cu-index-overflow", "default = continue, This turns an error when offset "
"for .debug_*.dwo sections overfolws into a warning. = soft-stop, This produces a "
"truncated but valid DWP file, discarding any DWO files that would not fit within "
"the 32 bit/4GB limits of the format.">, MetaVarName<"<filename>">;

15
llvm/tools/llvm-dwp/llvm-dwp.cpp
View File

@ -71,7 +71,7 @@ public:
// Options
static std::vector<std::string> ExecFilenames;
static std::string OutputFilename;
static bool ContinueOnCuIndexOverflow;
static std::string ContinueOption;
static Expected<SmallVector<std::string, 16>>
getDWOFilenames(StringRef ExecFilename) {
@ -125,6 +125,7 @@ int llvm_dwp_main(int argc, char **argv, const llvm::ToolContext &) {
DwpOptTable Tbl;
llvm::BumpPtrAllocator A;
llvm::StringSaver Saver{A};
OnCuIndexOverflow OverflowOptValue = OnCuIndexOverflow::HardStop;
opt::InputArgList Args =
Tbl.parseArgs(argc, argv, OPT_UNKNOWN, Saver, [&](StringRef Msg) {
llvm::errs() << Msg << '\n';
@ -143,7 +144,15 @@ int llvm_dwp_main(int argc, char **argv, const llvm::ToolContext &) {
}
OutputFilename = Args.getLastArgValue(OPT_outputFileName, "");
ContinueOnCuIndexOverflow = Args.hasArg(OPT_continueOnCuIndexOverflow);
if (Args.hasArg(OPT_continueOnCuIndexOverflow)) {
ContinueOption =
Args.getLastArgValue(OPT_continueOnCuIndexOverflow, "continue");
if (ContinueOption == "soft-stop") {
OverflowOptValue = OnCuIndexOverflow::SoftStop;
} else {
OverflowOptValue = OnCuIndexOverflow::Continue;
}
}
for (const llvm::opt::Arg *A : Args.filtered(OPT_execFileNames))
ExecFilenames.emplace_back(A->getValue());
@ -255,7 +264,7 @@ int llvm_dwp_main(int argc, char **argv, const llvm::ToolContext &) {
if (!MS)
return error("no object streamer for target " + TripleName, Context);
if (auto Err = write(*MS, DWOFilenames, ContinueOnCuIndexOverflow)) {
if (auto Err = write(*MS, DWOFilenames, OverflowOptValue)) {
logAllUnhandledErrors(std::move(Err), WithColor::error());
return 1;
}