[LLD][COFF] Follow up comments on pr146610 (#147152)
This is a follow-up PR for post-commit comments in https://github.com/llvm/llvm-project/pull/146610 - Changed "exporteddllmain" references to "importeddllmain". - Add support for x86 target and test coverage. - Changed a comment to better express why we're skipping importing `DllMain`.
This commit is contained in:
Alexandre Ganea
GitHub
parent
423cea7607
commit
fcacd4e880
@ -319,7 +319,7 @@ struct Configuration {
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bool warnDebugInfoUnusable = true;
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bool warnLongSectionNames = true;
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bool warnStdcallFixup = true;
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bool warnExportedDllMain = true;
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bool warnImportedDllMain = true;
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bool incremental = true;
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bool integrityCheck = false;
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bool killAt = false;
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@ -1643,8 +1643,8 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
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config->warnLocallyDefinedImported = false;
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else if (s == "longsections")
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config->warnLongSectionNames = false;
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else if (s == "exporteddllmain")
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config->warnExportedDllMain = false;
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else if (s == "importeddllmain")
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config->warnImportedDllMain = false;
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// Other warning numbers are ignored.
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}
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}
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@ -117,8 +117,6 @@ static coff_symbol_generic *cloneSymbol(COFFSymbolRef sym) {
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// Skip importing DllMain thunks from import libraries.
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static bool fixupDllMain(COFFLinkerContext &ctx, llvm::object::Archive *file,
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const Archive::Symbol &sym, bool &skipDllMain) {
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if (skipDllMain)
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return true;
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const Archive::Child &c =
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CHECK(sym.getMember(), file->getFileName() +
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": could not get the member for symbol " +
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@ -128,13 +126,13 @@ static bool fixupDllMain(COFFLinkerContext &ctx, llvm::object::Archive *file,
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file->getFileName() +
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": could not get the buffer for a child buffer of the archive");
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if (identify_magic(mb.getBuffer()) == file_magic::coff_import_library) {
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if (ctx.config.warnExportedDllMain) {
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if (ctx.config.warnImportedDllMain) {
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// We won't place DllMain symbols in the symbol table if they are
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// coming from a import library. This message can be ignored with the flag
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// '/ignore:exporteddllmain'
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// '/ignore:importeddllmain'
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Warn(ctx)
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<< file->getFileName()
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<< ": skipping exported DllMain symbol [exporteddllmain]\nNOTE: this "
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<< ": skipping imported DllMain symbol [importeddllmain]\nNOTE: this "
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"might be a mistake when the DLL/library was produced.";
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}
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skipDllMain = true;
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@ -204,14 +202,24 @@ void ArchiveFile::parse() {
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}
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}
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// Read the symbol table to construct Lazy objects.
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bool skipDllMain = false;
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StringRef mangledDllMain, impMangledDllMain;
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// The calls below will fail if we haven't set the machine type yet. Instead
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// of failing, it is preferable to skip this "imported DllMain" check if we
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// don't know the machine type at this point.
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if (!file->isEmpty() && ctx.config.machine != IMAGE_FILE_MACHINE_UNKNOWN) {
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mangledDllMain = archiveSymtab->mangle("DllMain");
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impMangledDllMain = uniqueSaver().save("__imp_" + mangledDllMain);
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}
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// Read the symbol table to construct Lazy objects.
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for (const Archive::Symbol &sym : file->symbols()) {
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// If the DllMain symbol was exported by mistake, skip importing it
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// otherwise we might end up with a import thunk in the final binary which
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// is wrong.
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if (sym.getName() == "__imp_DllMain" || sym.getName() == "DllMain") {
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if (fixupDllMain(ctx, file.get(), sym, skipDllMain))
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// If an import library provides the DllMain symbol, skip importing it, as
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// we should be using our own DllMain, not another DLL's DllMain.
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if (!mangledDllMain.empty() && (sym.getName() == mangledDllMain ||
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sym.getName() == impMangledDllMain)) {
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if (skipDllMain || fixupDllMain(ctx, file.get(), sym, skipDllMain))
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continue;
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}
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archiveSymtab->addLazyArchive(this, sym);
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58
lld/test/COFF/imported-dllmain-i386.test
Normal file
58
lld/test/COFF/imported-dllmain-i386.test
Normal file
@ -0,0 +1,58 @@
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REQUIRES: x86
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RUN: split-file %s %t.dir && cd %t.dir
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RUN: llvm-mc -filetype=obj -triple=i386-windows a.s -o a.obj
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RUN: llvm-mc -filetype=obj -triple=i386-windows b1.s -o b1.obj
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RUN: llvm-mc -filetype=obj -triple=i386-windows b2.s -o b2.obj
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### This is the line where our problem occurs. Here, we export the DllMain symbol which shouldn't happen normally.
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RUN: lld-link b1.obj b2.obj -out:b.dll -dll -implib:b.lib -entry:DllMain -export:bar -export:DllMain -safeseh:no
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RUN: llvm-mc -filetype=obj -triple=i386-windows c.s -o c.obj
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RUN: lld-link -lib c.obj -out:c.lib
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### Later, if b.lib is provided before other libs/objs that export DllMain statically, we previously were using the dllimported DllMain from b.lib, which is wrong.
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RUN: lld-link a.obj b.lib c.lib -dll -out:out.dll -entry:DllMain -safeseh:no 2>&1 | FileCheck -check-prefix=WARN %s
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RUN: lld-link a.obj b.lib c.lib -dll -out:out.dll -entry:DllMain -ignore:importeddllmain -safeseh:no 2>&1 | FileCheck -check-prefix=IGNORED --allow-empty %s
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RUN: llvm-objdump --private-headers -d out.dll | FileCheck -check-prefix=DISASM %s
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WARN: lld-link: warning: b.lib: skipping imported DllMain symbol [importeddllmain]
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IGNORED-NOT: lld-link: warning: b.lib: skipping imported DllMain symbol [importeddllmain]
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DISASM: The Import Tables:
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DISASM: DLL Name: b.dll
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DISASM-NOT: DllMain
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DISASM: bar
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DISASM: Disassembly of section .text:
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DISASM: b0 01 movb $0x1, %al
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DISASM-NEXT: c3 retl
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#--- a.s
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.text
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.globl _foo
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_foo:
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call *__imp__bar
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ret
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#--- b1.s
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.text
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.globl _bar
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_bar:
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ret
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#--- b2.s
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.intel_syntax noprefix
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.text
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.globl _DllMain
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_DllMain:
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xor al, al
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ret
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#--- c.s
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.intel_syntax noprefix
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.text
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.globl _DllMain
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_DllMain:
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mov al, 1
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ret
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@ -14,11 +14,11 @@ RUN: lld-link -lib c.obj -out:c.lib
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### Later, if b.lib is provided before other libs/objs that export DllMain statically, we previously were using the dllimported DllMain from b.lib, which is wrong.
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RUN: lld-link a.obj b.lib c.lib -dll -out:out.dll -entry:DllMain 2>&1 | FileCheck -check-prefix=WARN %s
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RUN: lld-link a.obj b.lib c.lib -dll -out:out.dll -entry:DllMain -ignore:exporteddllmain 2>&1 | FileCheck -check-prefix=IGNORED --allow-empty %s
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RUN: lld-link a.obj b.lib c.lib -dll -out:out.dll -entry:DllMain -ignore:importeddllmain 2>&1 | FileCheck -check-prefix=IGNORED --allow-empty %s
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RUN: llvm-objdump --private-headers -d out.dll | FileCheck -check-prefix=DISASM %s
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WARN: lld-link: warning: b.lib: skipping exported DllMain symbol [exporteddllmain]
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IGNORED-NOT: lld-link: warning: b.lib: skipping exported DllMain symbol [exporteddllmain]
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WARN: lld-link: warning: b.lib: skipping imported DllMain symbol [importeddllmain]
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IGNORED-NOT: lld-link: warning: b.lib: skipping imported DllMain symbol [importeddllmain]
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DISASM: The Import Tables:
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DISASM: DLL Name: b.dll
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