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 "Log.h"
18 #include "RSTransforms.h"
19 #include "RSFunctionsList.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
28 namespace { // 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.
33 class RSScreenFunctionsPass : public llvm::ModulePass {
34 private:
35 static char ID;
36
isPresent(const std::string & name)37 bool isPresent(const std::string &name) {
38 auto lower = std::lower_bound(stubList.begin(),
39 stubList.end(),
40 name);
41
42 if (lower != stubList.end() && name.compare(*lower) == 0)
43 return true;
44 return false;
45 }
46
isLegal(llvm::Function & F)47 bool isLegal(llvm::Function &F) {
48 // A global function symbol is legal if
49 // a. it has a body, i.e. is not empty or
50 // b. its name starts with "llvm." or
51 // c. it is present in the RS Functions list.
52
53 if (!F.empty())
54 return true;
55
56 llvm::StringRef FName = F.getName();
57 if (FName.startswith("llvm."))
58 return true;
59
60 if (isPresent(FName.str()))
61 return true;
62
63 return false;
64 }
65
66 public:
RSScreenFunctionsPass()67 RSScreenFunctionsPass()
68 : ModulePass (ID) {
69 std::sort(stubList.begin(), stubList.end());
70 }
71
getAnalysisUsage(llvm::AnalysisUsage & AU) const72 virtual void getAnalysisUsage(llvm::AnalysisUsage &AU) const override {
73 AU.setPreservesAll();
74 }
75
runOnModule(llvm::Module & M)76 bool runOnModule(llvm::Module &M) override {
77 bool failed = false;
78
79 auto &FunctionList(M.getFunctionList());
80 for(auto &F: FunctionList) {
81 if (!isLegal(F)) {
82 ALOGE("Call to function %s from RenderScript is disallowed\n",
83 F.getName().str().c_str());
84 failed = true;
85 }
86 }
87
88 if (failed) {
89 llvm::report_fatal_error("Use of undefined external function");
90 }
91
92 return false;
93 }
94
95 };
96
97 }
98
99 char RSScreenFunctionsPass::ID = 0;
100
101 namespace bcc {
102
103 llvm::ModulePass *
createRSScreenFunctionsPass()104 createRSScreenFunctionsPass() {
105 return new RSScreenFunctionsPass();
106 }
107
108 }
109