1/*
2 * Copyright 2014, The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *     http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include "bcc/Renderscript/RSTransforms.h"
18#include "bcc/Support/Log.h"
19#include "RSStubsWhiteList.h"
20
21#include <cstdlib>
22
23#include <llvm/IR/Instructions.h>
24#include <llvm/IR/Module.h>
25#include <llvm/IR/Function.h>
26#include <llvm/Pass.h>
27
28namespace { // anonymous namespace
29
30// Create a Module pass that screens all the global functions in the
31// module and check if any disallowed external function is accessible
32// and potentially callable.
33class RSScreenFunctionsPass : public llvm::ModulePass {
34private:
35  static char ID;
36
37  std::vector<std::string> &whiteList = stubList;
38
39  bool isPresent(std::vector<std::string> &list, std::string name) {
40    auto lower = std::lower_bound(list.begin(),
41                                  list.end(),
42                                  name);
43
44    if (lower != list.end() && name.compare(*lower) == 0)
45      return true;
46    return false;
47  }
48
49  bool isLegal(llvm::Function &F) {
50    // A global function symbol is legal if
51    // a. it has a body, i.e. is not empty or
52    // b. its name starts with "llvm." or
53    // c. it is present in the whitelist
54
55    if (!F.empty())
56      return true;
57
58    llvm::StringRef FName = F.getName();
59    if (FName.startswith("llvm."))
60      return true;
61
62    if (isPresent(whiteList, FName.str()))
63      return true;
64
65    return false;
66  }
67
68public:
69  RSScreenFunctionsPass()
70    : ModulePass (ID) {
71      std::sort(whiteList.begin(), whiteList.end());
72  }
73
74  virtual void getAnalysisUsage(llvm::AnalysisUsage &AU) const override {
75    AU.setPreservesAll();
76  }
77
78  bool runOnModule(llvm::Module &M) override {
79    bool failed = false;
80
81    auto &FunctionList(M.getFunctionList());
82    for(auto &F: FunctionList) {
83      if (!isLegal(F)) {
84        ALOGE("Call to function %s from RenderScript is disallowed\n",
85              F.getName().str().c_str());
86        failed = true;
87      }
88    }
89
90    if (failed) {
91      llvm::report_fatal_error("Use of undefined external function");
92    }
93
94    return false;
95  }
96
97};
98
99}
100
101char RSScreenFunctionsPass::ID = 0;
102
103namespace bcc {
104
105llvm::ModulePass *
106createRSScreenFunctionsPass() {
107  return new RSScreenFunctionsPass();
108}
109
110}
111