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Add a framework for intercepting system calls

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@6190 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2003-05-14 13:26:47 +00:00
parent 7cfee5b2bb
commit 6701a8603f
2 changed files with 54 additions and 21 deletions
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52
lib/ExecutionEngine/JIT/Intercept.cpp Normal file
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@ -0,0 +1,52 @@
//===-- Intercept.cpp - System function interception routines -------------===//
//
// 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
// 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 <dlfcn.h> // dlsym access
//===----------------------------------------------------------------------===//
// Function stubs that are invoked instead of raw system calls
//===----------------------------------------------------------------------===//
// NoopFn - Used if we have nothing else to call...
static void NoopFn() {}
// jit_exit - Used to intercept the "exit" system call.
static void jit_exit(int Status) {
exit(Status); // Do nothing for now.
}
// jit_atexit - Used to intercept the "at_exit" system call.
static int jit_atexit(void (*Fn)(void)) {
atexit(Fn); // Do nothing for now.
}
//===----------------------------------------------------------------------===//
//
/// 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.
///
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 jit_exit;
if (Name == "at_exit") return jit_atexit;
// If it's an external function, look it up in the process image...
void *Ptr = dlsym(0, Name.c_str());
if (Ptr == 0) {
std::cerr << "WARNING: Cannot resolve fn '" << Name
<< "' using a dummy noop function instead!\n";
Ptr = (void*)NoopFn;
}
return Ptr;
}

23
lib/ExecutionEngine/JIT/VM.cpp
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@ -1,4 +1,4 @@
//===-- jello.cpp - LLVM Just in Time Compiler ----------------------------===//
//===-- VM.cpp - LLVM Just in Time Compiler -------------------------------===//
//
// This tool implements a just-in-time compiler for LLVM, allowing direct
// execution of LLVM bytecode in an efficient manner.
@ -9,8 +9,6 @@
#include "llvm/Target/TargetMachine.h"
#include "llvm/CodeGen/MachineCodeEmitter.h"
#include "llvm/Function.h"
#include <dlfcn.h> // dlsym access
VM::~VM() {
delete MCE;
@ -50,27 +48,10 @@ void *VM::resolveFunctionReference(void *RefAddr) {
}
const std::string &VM::getFunctionReferencedName(void *RefAddr) {
assert(FunctionRefs[RefAddr] && "Function address unknown!");
return FunctionRefs[RefAddr]->getName();
}
static void NoopFn() {}
/// 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.
///
void *VM::getPointerToNamedFunction(const std::string &Name) {
// If it's an external function, look it up in the process image...
void *Ptr = dlsym(0, Name.c_str());
if (Ptr == 0) {
std::cerr << "WARNING: Cannot resolve fn '" << Name
<< "' using a dummy noop function instead!\n";
Ptr = (void*)NoopFn;
}
return Ptr;
}
/// getPointerToFunction - This method is used to get the address of the
/// specified function, compiling it if neccesary.
///