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[lld][COFF] Provide unwinding information for Chunk injected by /delayloaded

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For each symbol in a /delayloaded library, lld injects a small piece of
code to handle the symbol lazy loading. This code doesn't have unwind
information, which may be troublesome.

Provide these information for AMD64.

Thanks to Yannis Juglaret <yjuglaret@mozilla.com> for contributing the
unwinding info and for his support while crafting this patch.

Fix #59639

Differential Revision: https://reviews.llvm.org/D141691
This commit is contained in:
serge-sans-paille 2023-01-13 14:25:54 +01:00
parent 48e862d06d
commit c512eda38e
No known key found for this signature in database
GPG Key ID: 7B24DA8C9551659F
6 changed files with 117 additions and 7 deletions
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77
lld/COFF/DLL.cpp
View File

@ -229,6 +229,19 @@ static const uint8_t tailMergeX64[] = {
0xFF, 0xE0, // jmp rax
};
static const uint8_t tailMergeUnwindInfoX64[] = {
0x01, // Version=1, Flags=UNW_FLAG_NHANDLER
0x0a, // Size of prolog
0x05, // Count of unwind codes
0x00, // No frame register
0x0a, 0x82, // Offset 0xa: UWOP_ALLOC_SMALL(0x48)
0x06, 0x02, // Offset 6: UWOP_ALLOC_SMALL(8)
0x04, 0x02, // Offset 4: UWOP_ALLOC_SMALL(8)
0x02, 0x02, // Offset 2: UWOP_ALLOC_SMALL(8)
0x01, 0x02, // Offset 1: UWOP_ALLOC_SMALL(8)
0x00, 0x00 // Padding to align on 32-bits
};
static const uint8_t thunkX86[] = {
0xB8, 0, 0, 0, 0, // mov eax, offset ___imp__<FUNCNAME>
0xE9, 0, 0, 0, 0, // jmp __tailMerge_<lib>
@ -332,6 +345,41 @@ public:
Defined *helper = nullptr;
};
class TailMergePDataChunkX64 : public NonSectionChunk {
public:
TailMergePDataChunkX64(Chunk *tm, Chunk *unwind) : tm(tm), unwind(unwind) {
// See
// https://learn.microsoft.com/en-us/cpp/build/exception-handling-x64#struct-runtime_function
setAlignment(4);
}
size_t getSize() const override { return 3 * sizeof(uint32_t); }
void writeTo(uint8_t *buf) const override {
write32le(buf + 0, tm->getRVA()); // TailMergeChunk start RVA
write32le(buf + 4, tm->getRVA() + tm->getSize()); // TailMergeChunk stop RVA
write32le(buf + 8, unwind->getRVA()); // UnwindInfo RVA
}
Chunk *tm = nullptr;
Chunk *unwind = nullptr;
};
class TailMergeUnwindInfoX64 : public NonSectionChunk {
public:
TailMergeUnwindInfoX64() {
// See
// https://learn.microsoft.com/en-us/cpp/build/exception-handling-x64#struct-unwind_info
setAlignment(4);
}
size_t getSize() const override { return sizeof(tailMergeUnwindInfoX64); }
void writeTo(uint8_t *buf) const override {
memcpy(buf, tailMergeUnwindInfoX64, sizeof(tailMergeUnwindInfoX64));
}
};
class ThunkChunkX86 : public NonSectionChunk {
public:
ThunkChunkX86(COFFLinkerContext &ctx, Defined *i, Chunk *tm)
@ -672,6 +720,8 @@ void DelayLoadContents::create(Defined *h) {
helper = h;
std::vector<std::vector<DefinedImportData *>> v = binImports(ctx, imports);
Chunk *unwind = newTailMergeUnwindInfoChunk();
// Create .didat contents for each DLL.
for (std::vector<DefinedImportData *> &syms : v) {
// Create the delay import table header.
@ -680,6 +730,7 @@ void DelayLoadContents::create(Defined *h) {
size_t base = addresses.size();
Chunk *tm = newTailMergeChunk(dir);
Chunk *pdataChunk = unwind ? newTailMergePDataChunk(tm, unwind) : nullptr;
for (DefinedImportData *s : syms) {
Chunk *t = newThunkChunk(s, tm);
auto *a = make<DelayAddressChunk>(ctx, t);
@ -692,7 +743,7 @@ void DelayLoadContents::create(Defined *h) {
auto *c = make<HintNameChunk>(extName, 0);
names.push_back(make<LookupChunk>(ctx, c));
hintNames.push_back(c);
// Add a syntentic symbol for this load thunk, using the "__imp___load"
// Add a synthetic symbol for this load thunk, using the "__imp___load"
// prefix, in case this thunk needs to be added to the list of valid
// call targets for Control Flow Guard.
StringRef symName = saver().save("__imp___load_" + extName);
@ -701,6 +752,8 @@ void DelayLoadContents::create(Defined *h) {
}
}
thunks.push_back(tm);
if (pdataChunk)
pdata.push_back(pdataChunk);
StringRef tmName =
saver().save("__tailMerge_" + syms[0]->getDLLName().lower());
ctx.symtab.addSynthetic(tmName, tm);
@ -720,6 +773,9 @@ void DelayLoadContents::create(Defined *h) {
dir->nameTab = names[base];
dirs.push_back(dir);
}
if (unwind)
unwindinfo.push_back(unwind);
// Add null terminator.
dirs.push_back(make<NullChunk>(sizeof(delay_import_directory_table_entry)));
}
@ -739,6 +795,25 @@ Chunk *DelayLoadContents::newTailMergeChunk(Chunk *dir) {
}
}
Chunk *DelayLoadContents::newTailMergeUnwindInfoChunk() {
switch (ctx.config.machine) {
case AMD64:
return make<TailMergeUnwindInfoX64>();
// FIXME: Add support for other architectures.
default:
return nullptr; // Just don't generate unwind info.
}
}
Chunk *DelayLoadContents::newTailMergePDataChunk(Chunk *tm, Chunk *unwind) {
switch (ctx.config.machine) {
case AMD64:
return make<TailMergePDataChunkX64>(tm, unwind);
// FIXME: Add support for other architectures.
default:
return nullptr; // Just don't generate unwind info.
}
}
Chunk *DelayLoadContents::newThunkChunk(DefinedImportData *s,
Chunk *tailMerge) {
switch (ctx.config.machine) {

6
lld/COFF/DLL.h
View File

@ -44,6 +44,8 @@ public:
std::vector<Chunk *> getChunks();
std::vector<Chunk *> getDataChunks();
ArrayRef<Chunk *> getCodeChunks() { return thunks; }
ArrayRef<Chunk *> getCodePData() { return pdata; }
ArrayRef<Chunk *> getCodeUnwindInfo() { return unwindinfo; }
uint64_t getDirRVA() { return dirs[0]->getRVA(); }
uint64_t getDirSize();
@ -51,6 +53,8 @@ public:
private:
Chunk *newThunkChunk(DefinedImportData *s, Chunk *tailMerge);
Chunk *newTailMergeChunk(Chunk *dir);
Chunk *newTailMergePDataChunk(Chunk *tm, Chunk *unwind);
Chunk *newTailMergeUnwindInfoChunk();
Defined *helper;
std::vector<DefinedImportData *> imports;
@ -60,6 +64,8 @@ private:
std::vector<Chunk *> names;
std::vector<Chunk *> hintNames;
std::vector<Chunk *> thunks;
std::vector<Chunk *> pdata;
std::vector<Chunk *> unwindinfo;
std::vector<Chunk *> dllNames;
COFFLinkerContext &ctx;

4
lld/COFF/Writer.cpp
View File

@ -1121,6 +1121,10 @@ void Writer::appendImportThunks() {
dataSec->addChunk(c);
for (Chunk *c : delayIdata.getCodeChunks())
textSec->addChunk(c);
for (Chunk *c : delayIdata.getCodePData())
pdataSec->addChunk(c);
for (Chunk *c : delayIdata.getCodeUnwindInfo())
rdataSec->addChunk(c);
}
}

27
lld/test/COFF/delayimports.test
View File

@ -3,13 +3,14 @@
# RUN: /alternatename:__delayLoadHelper2=main
# RUN: llvm-readobj --coff-imports %t.exe | FileCheck -check-prefix=IMPORT %s
# RUN: llvm-readobj --coff-basereloc %t.exe | FileCheck -check-prefix=BASEREL %s
# RUN: llvm-readobj --unwind %t.exe | FileCheck -check-prefix=UNWIND %s
IMPORT: DelayImport {
IMPORT-NEXT: Name: std64.dll
IMPORT-NEXT: Attributes: 0x1
IMPORT-NEXT: ModuleHandle: 0x3018
IMPORT-NEXT: ImportAddressTable: 0x3020
IMPORT-NEXT: ImportNameTable: 0x2040
IMPORT-NEXT: ImportNameTable: 0x2050
IMPORT-NEXT: BoundDelayImportTable: 0x0
IMPORT-NEXT: UnloadDelayImportTable: 0x0
IMPORT-NEXT: Import {
@ -39,3 +40,27 @@ BASEREL-NEXT: Entry {
BASEREL-NEXT: Type: DIR64
BASEREL-NEXT: Address: 0x3030
BASEREL-NEXT: }
UNWIND: UnwindInformation [
UNWIND-NEXT: RuntimeFunction {
UNWIND-NEXT: StartAddress: (0x14000108A)
UNWIND-NEXT: EndAddress: (0x1400010DD)
UNWIND-NEXT: UnwindInfoAddress: (0x140002000)
UNWIND-NEXT: UnwindInfo {
UNWIND-NEXT: Version: 1
UNWIND-NEXT: Flags [ (0x0)
UNWIND-NEXT: ]
UNWIND-NEXT: PrologSize: 10
UNWIND-NEXT: FrameRegister: -
UNWIND-NEXT: FrameOffset: -
UNWIND-NEXT: UnwindCodeCount: 5
UNWIND-NEXT: UnwindCodes [
UNWIND-NEXT: 0x0A: ALLOC_SMALL size=72
UNWIND-NEXT: 0x06: ALLOC_SMALL size=8
UNWIND-NEXT: 0x04: ALLOC_SMALL size=8
UNWIND-NEXT: 0x02: ALLOC_SMALL size=8
UNWIND-NEXT: 0x01: ALLOC_SMALL size=8
UNWIND-NEXT: ]
UNWIND-NEXT: }
UNWIND-NEXT: }
UNWIND-NEXT: ]

4
lld/test/COFF/delayimporttables.yaml
View File

@ -14,7 +14,7 @@
# CHECK-NEXT: Attributes: 0x1
# CHECK-NEXT: ModuleHandle: 0x3000
# CHECK-NEXT: ImportAddressTable: 0x3010
# CHECK-NEXT: ImportNameTable: 0x2060
# CHECK-NEXT: ImportNameTable: 0x2070
# CHECK-NEXT: BoundDelayImportTable: 0x0
# CHECK-NEXT: UnloadDelayImportTable: 0x0
# CHECK-NEXT: Import {
@ -31,7 +31,7 @@
# CHECK-NEXT: Attributes: 0x1
# CHECK-NEXT: ModuleHandle: 0x3008
# CHECK-NEXT: ImportAddressTable: 0x3028
# CHECK-NEXT: ImportNameTable: 0x2078
# CHECK-NEXT: ImportNameTable: 0x2088
# CHECK-NEXT: BoundDelayImportTable: 0x0
# CHECK-NEXT: UnloadDelayImportTable: 0x0
# CHECK-NEXT: Import {

6
lld/test/COFF/giats.s
View File

@ -37,14 +37,14 @@
# DELAY-CHECK: ImageBase: 0x140000000
# DELAY-CHECK: LoadConfig [
# DELAY-CHECK: GuardCFFunctionTable: 0x140002114
# DELAY-CHECK: GuardCFFunctionTable: 0x140002124
# DELAY-CHECK: GuardCFFunctionCount: 2
# DELAY-CHECK: GuardFlags [ (0x10500)
# DELAY-CHECK: CF_FUNCTION_TABLE_PRESENT (0x400)
# DELAY-CHECK: CF_INSTRUMENTED (0x100)
# DELAY-CHECK: CF_LONGJUMP_TABLE_PRESENT (0x10000)
# DELAY-CHECK: ]
# DELAY-CHECK: GuardAddressTakenIatEntryTable: 0x14000211C
# DELAY-CHECK: GuardAddressTakenIatEntryTable: 0x14000212C
# DELAY-CHECK: GuardAddressTakenIatEntryCount: 1
# DELAY-CHECK: ]
# DELAY-CHECK: GuardFidTable [
@ -122,4 +122,4 @@ _load_config_used:
.quad __guard_iat_count
.quad __guard_longjmp_table
.quad __guard_fids_count
.fill 84, 1, 0
.fill 84, 1, 0