//===-- Intercept.cpp - System function interception routines -------------===//
//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
// If a function call occurs to an external function, the JIT is designed to use
-// dlsym on the current process to find a function to call. This is useful for
+// the dynamic loader interface to find a function to call. This is useful for
// calling system calls and library functions that are not available in LLVM.
// Some system calls, however, need to be handled specially. For this reason,
// we intercept some of them here and use our own stubs to handle them.
//
//===----------------------------------------------------------------------===//
-#include "VM.h"
-#include "Config/dlfcn.h" // dlsym access
-#include <iostream>
+#include "JIT.h"
+#include "llvm/System/DynamicLibrary.h"
+#include "llvm/Config/config.h"
+using namespace llvm;
-// AtExitList - List of functions registered with the at_exit function
-static std::vector<void (*)()> AtExitList;
+// AtExitHandlers - List of functions to call when the program exits,
+// registered with the atexit() library function.
+static std::vector<void (*)()> AtExitHandlers;
-void VM::runAtExitHandlers() {
- while (!AtExitList.empty()) {
- void (*Fn)() = AtExitList.back();
- AtExitList.pop_back();
+/// runAtExitHandlers - Run any functions registered by the program's
+/// calls to atexit(3), which we intercept and store in
+/// AtExitHandlers.
+///
+static void runAtExitHandlers() {
+ while (!AtExitHandlers.empty()) {
+ void (*Fn)() = AtExitHandlers.back();
+ AtExitHandlers.pop_back();
Fn();
}
}
//===----------------------------------------------------------------------===//
-// Function stubs that are invoked instead of raw system calls
+// Function stubs that are invoked instead of certain library calls
//===----------------------------------------------------------------------===//
-// NoopFn - Used if we have nothing else to call...
-static void NoopFn() {}
+// Force the following functions to be linked in to anything that uses the
+// JIT. This is a hack designed to work around the all-too-clever Glibc
+// strategy of making these functions work differently when inlined vs. when
+// not inlined, and hiding their real definitions in a separate archive file
+// that the dynamic linker can't see. For more info, search for
+// 'libc_nonshared.a' on Google, or read http://llvm.org/PR274.
+#if defined(__linux__)
+#if defined(HAVE_SYS_STAT_H)
+#include <sys/stat.h>
+#endif
+void *FunctionPointers[] = {
+ (void *)(intptr_t) stat,
+ (void *)(intptr_t) fstat,
+ (void *)(intptr_t) lstat,
+ (void *)(intptr_t) stat64,
+ (void *)(intptr_t) fstat64,
+ (void *)(intptr_t) lstat64,
+ (void *)(intptr_t) atexit,
+ (void *)(intptr_t) mknod
+};
+#endif // __linux__
+
+// __mainFunc - If the program does not have a linked in __main function, allow
+// it to run, but print a warning.
+static void __mainFunc() {
+ fprintf(stderr, "WARNING: Program called __main but was not linked to "
+ "libcrtend.a.\nThis probably won't hurt anything unless the "
+ "program is written in C++.\n");
+}
-// jit_exit - Used to intercept the "exit" system call.
+// jit_exit - Used to intercept the "exit" library call.
static void jit_exit(int Status) {
- VM::runAtExitHandlers(); // Run at_exit handlers...
+ runAtExitHandlers(); // Run atexit handlers...
exit(Status);
}
-// jit_atexit - Used to intercept the "at_exit" system call.
+// jit_atexit - Used to intercept the "atexit" library call.
static int jit_atexit(void (*Fn)(void)) {
- AtExitList.push_back(Fn); // Take note of at_exit handler...
+ AtExitHandlers.push_back(Fn); // Take note of atexit handler...
return 0; // Always successful
}
//===----------------------------------------------------------------------===//
-//
+//
/// getPointerToNamedFunction - This method returns the address of the specified
-/// function by using the dlsym function call. As such it is only useful for
-/// resolving library symbols, not code generated symbols.
+/// function by using the dynamic loader interface. As such it is only useful
+/// for resolving library symbols, not code generated symbols.
///
-void *VM::getPointerToNamedFunction(const std::string &Name) {
- // Check to see if this is one of the functions we want to intercept...
- if (Name == "exit") return (void*)&jit_exit;
- if (Name == "atexit") return (void*)&jit_atexit;
+void *JIT::getPointerToNamedFunction(const std::string &Name) {
+ // Check to see if this is one of the functions we want to intercept. Note,
+ // we cast to intptr_t here to silence a -pedantic warning that complains
+ // about casting a function pointer to a normal pointer.
+ if (Name == "exit") return (void*)(intptr_t)&jit_exit;
+ if (Name == "atexit") return (void*)(intptr_t)&jit_atexit;
+
+ // If the program does not have a linked in __main function, allow it to run,
+ // but print a warning.
+ if (Name == "__main") return (void*)(intptr_t)&__mainFunc;
+ const char *NameStr = Name.c_str();
+ // If this is an asm specifier, skip the sentinal.
+ if (NameStr[0] == 1) ++NameStr;
+
// If it's an external function, look it up in the process image...
- // On Sparc, RTLD_SELF is already defined and it's not zero
- // Linux/x86 wants to use a 0, other systems may differ
-#ifndef RTLD_SELF
-#define RTLD_SELF 0
-#endif
- void *Ptr = dlsym(RTLD_SELF, Name.c_str());
- if (Ptr == 0) {
- std::cerr << "WARNING: Cannot resolve fn '" << Name
- << "' using a dummy noop function instead!\n";
- Ptr = (void*)NoopFn;
- }
+ void *Ptr = sys::DynamicLibrary::SearchForAddressOfSymbol(NameStr);
+ if (Ptr) return Ptr;
- return Ptr;
+ // If it wasn't found and if it starts with an underscore ('_') character, and
+ // has an asm specifier, try again without the underscore.
+ if (Name[0] == 1 && NameStr[0] == '_') {
+ Ptr = sys::DynamicLibrary::SearchForAddressOfSymbol(NameStr+1);
+ if (Ptr) return Ptr;
+ }
+
+ cerr << "ERROR: Program used external function '" << Name
+ << "' which could not be resolved!\n";
+ abort();
+ return 0;
}
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