Allow clients to specify search order of DynamicLibraries.

Summary: Different JITs and other clients of LLVM may have different needs in how symbol resolution should occur.

Reviewers: v.g.vassilev, lhames, karies

Reviewed By: v.g.vassilev

Subscribers: pcanal, llvm-commits

Differential Revision: https://reviews.llvm.org/D33529

llvm-svn: 307849
This commit is contained in:
Frederich Munch 2017-07-12 21:22:45 +00:00
parent 5680b0ca9f
commit 5fdd2cbae8
5 changed files with 63 additions and 11 deletions

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@ -88,6 +88,22 @@ namespace sys {
return !getPermanentLibrary(Filename, ErrMsg).isValid(); return !getPermanentLibrary(Filename, ErrMsg).isValid();
} }
enum SearchOrdering {
/// SO_Linker - Search as a call to dlsym(dlopen(NULL)) would when
/// DynamicLibrary::getPermanentLibrary(NULL) has been called or
/// search the list of explcitly loaded symbols if not.
SO_Linker,
/// SO_LoadedFirst - Search all loaded libraries, then as SO_Linker would.
SO_LoadedFirst,
/// SO_LoadedLast - Search as SO_Linker would, then loaded libraries.
/// Only useful to search if libraries with RTLD_LOCAL have been added.
SO_LoadedLast,
/// SO_LoadOrder - Or this in to search libraries in the ordered loaded.
/// The default bahaviour is to search loaded libraries in reverse.
SO_LoadOrder = 4
};
static SearchOrdering SearchOrder; // = SO_Linker
/// This function will search through all previously loaded dynamic /// This function will search through all previously loaded dynamic
/// libraries for the symbol \p symbolName. If it is found, the address of /// libraries for the symbol \p symbolName. If it is found, the address of
/// that symbol is returned. If not, null is returned. Note that this will /// that symbol is returned. If not, null is returned. Note that this will

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@ -14,6 +14,7 @@
#include "llvm/Support/DynamicLibrary.h" #include "llvm/Support/DynamicLibrary.h"
#include "llvm-c/Support.h" #include "llvm-c/Support.h"
#include "llvm/ADT/DenseSet.h" #include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringMap.h" #include "llvm/ADT/StringMap.h"
#include "llvm/Config/config.h" #include "llvm/Config/config.h"
#include "llvm/Support/ManagedStatic.h" #include "llvm/Support/ManagedStatic.h"
@ -73,19 +74,37 @@ public:
return true; return true;
} }
void *Lookup(const char *Symbol) { void *LibLookup(const char *Symbol, DynamicLibrary::SearchOrdering Order) {
// Process handle gets first try. if (Order & SO_LoadOrder) {
for (void *Handle : Handles) {
if (void *Ptr = DLSym(Handle, Symbol))
return Ptr;
}
} else {
for (void *Handle : llvm::reverse(Handles)) {
if (void *Ptr = DLSym(Handle, Symbol))
return Ptr;
}
}
return nullptr;
}
void *Lookup(const char *Symbol, DynamicLibrary::SearchOrdering Order) {
assert(!((Order & SO_LoadedFirst) && (Order & SO_LoadedLast)) &&
"Invalid Ordering");
if (!Process || (Order & SO_LoadedFirst)) {
if (void *Ptr = LibLookup(Symbol, Order))
return Ptr;
}
if (Process) { if (Process) {
// Use OS facilities to search the current binary and all loaded libs.
if (void *Ptr = DLSym(Process, Symbol)) if (void *Ptr = DLSym(Process, Symbol))
return Ptr; return Ptr;
#ifndef NDEBUG
for (void *Handle : Handles) // Search any libs that might have been skipped because of RTLD_LOCAL.
assert(!DLSym(Handle, Symbol) && "Symbol exists in non process handle"); if (Order & SO_LoadedLast) {
#endif if (void *Ptr = LibLookup(Symbol, Order))
} else {
// Iterate in reverse, so newer libraries/symbols override older.
for (auto &&I = Handles.rbegin(), E = Handles.rend(); I != E; ++I) {
if (void *Ptr = DLSym(*I, Symbol))
return Ptr; return Ptr;
} }
} }
@ -113,6 +132,8 @@ static llvm::ManagedStatic<llvm::sys::SmartMutex<true>> SymbolsMutex;
#endif #endif
char DynamicLibrary::Invalid; char DynamicLibrary::Invalid;
DynamicLibrary::SearchOrdering DynamicLibrary::SearchOrder =
DynamicLibrary::SO_Linker;
namespace llvm { namespace llvm {
void *SearchForAddressOfSpecialSymbol(const char *SymbolName) { void *SearchForAddressOfSpecialSymbol(const char *SymbolName) {
@ -170,7 +191,7 @@ void *DynamicLibrary::SearchForAddressOfSymbol(const char *SymbolName) {
// Now search the libraries. // Now search the libraries.
if (OpenedHandles.isConstructed()) { if (OpenedHandles.isConstructed()) {
if (void *Ptr = OpenedHandles->Lookup(SymbolName)) if (void *Ptr = OpenedHandles->Lookup(SymbolName, SearchOrder))
return Ptr; return Ptr;
} }
} }

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@ -20,6 +20,9 @@ DynamicLibrary::HandleSet::~HandleSet() {
::dlclose(Handle); ::dlclose(Handle);
if (Process) if (Process)
::dlclose(Process); ::dlclose(Process);
// llvm_shutdown called, Return to default
DynamicLibrary::SearchOrder = DynamicLibrary::SO_Linker;
} }
void *DynamicLibrary::HandleSet::DLOpen(const char *File, std::string *Err) { void *DynamicLibrary::HandleSet::DLOpen(const char *File, std::string *Err) {

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@ -28,6 +28,8 @@ DynamicLibrary::HandleSet::~HandleSet() {
// 'Process' should not be released on Windows. // 'Process' should not be released on Windows.
assert((!Process || Process==this) && "Bad Handle"); assert((!Process || Process==this) && "Bad Handle");
// llvm_shutdown called, Return to default
DynamicLibrary::SearchOrder = DynamicLibrary::SO_Linker;
} }
void *DynamicLibrary::HandleSet::DLOpen(const char *File, std::string *Err) { void *DynamicLibrary::HandleSet::DLOpen(const char *File, std::string *Err) {

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@ -77,6 +77,7 @@ TEST(DynamicLibrary, Overload) {
EXPECT_TRUE(DL.isValid()); EXPECT_TRUE(DL.isValid());
EXPECT_TRUE(Err.empty()); EXPECT_TRUE(Err.empty());
// Test overloading local symbols does not occur by default
GS = FuncPtr<GetString>(DynamicLibrary::SearchForAddressOfSymbol("TestA")); GS = FuncPtr<GetString>(DynamicLibrary::SearchForAddressOfSymbol("TestA"));
EXPECT_TRUE(GS != nullptr && GS == &TestA); EXPECT_TRUE(GS != nullptr && GS == &TestA);
EXPECT_EQ(StdString(GS()), "ProcessCall"); EXPECT_EQ(StdString(GS()), "ProcessCall");
@ -85,6 +86,12 @@ TEST(DynamicLibrary, Overload) {
EXPECT_TRUE(GS != nullptr && GS == &TestA); EXPECT_TRUE(GS != nullptr && GS == &TestA);
EXPECT_EQ(StdString(GS()), "ProcessCall"); EXPECT_EQ(StdString(GS()), "ProcessCall");
// Test overloading by forcing library priority when searching for a symbol
DynamicLibrary::SearchOrder = DynamicLibrary::SO_LoadedFirst;
GS = FuncPtr<GetString>(DynamicLibrary::SearchForAddressOfSymbol("TestA"));
EXPECT_TRUE(GS != nullptr && GS != &TestA);
EXPECT_EQ(StdString(GS()), "LibCall");
DynamicLibrary::AddSymbol("TestA", PtrFunc(&OverloadTestA)); DynamicLibrary::AddSymbol("TestA", PtrFunc(&OverloadTestA));
GS = FuncPtr<GetString>(DL.getAddressOfSymbol("TestA")); GS = FuncPtr<GetString>(DL.getAddressOfSymbol("TestA"));
EXPECT_TRUE(GS != nullptr && GS != &OverloadTestA); EXPECT_TRUE(GS != nullptr && GS != &OverloadTestA);
@ -95,6 +102,9 @@ TEST(DynamicLibrary, Overload) {
} }
EXPECT_TRUE(FuncPtr<GetString>(DynamicLibrary::SearchForAddressOfSymbol( EXPECT_TRUE(FuncPtr<GetString>(DynamicLibrary::SearchForAddressOfSymbol(
"TestA")) == nullptr); "TestA")) == nullptr);
// Check serach ordering is reset to default after call to llvm_shutdown
EXPECT_TRUE(DynamicLibrary::SearchOrder == DynamicLibrary::SO_Linker);
} }
TEST(DynamicLibrary, Shutdown) { TEST(DynamicLibrary, Shutdown) {