1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
|
//===------------ BPFCheckAndAdjustIR.cpp - Check and Adjust IR -----------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Check IR and adjust IR for verifier friendly codes.
// The following are done for IR checking:
// - no relocation globals in PHI node.
// The following are done for IR adjustment:
// - remove __builtin_bpf_passthrough builtins. Target independent IR
// optimizations are done and those builtins can be removed.
//
//===----------------------------------------------------------------------===//
#include "BPF.h"
#include "BPFCORE.h"
#include "BPFTargetMachine.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/User.h"
#include "llvm/IR/Value.h"
#include "llvm/Pass.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#define DEBUG_TYPE "bpf-check-and-opt-ir"
using namespace llvm;
namespace {
class BPFCheckAndAdjustIR final : public ModulePass {
bool runOnModule(Module &F) override;
public:
static char ID;
BPFCheckAndAdjustIR() : ModulePass(ID) {}
private:
void checkIR(Module &M);
bool adjustIR(Module &M);
bool removePassThroughBuiltin(Module &M);
};
} // End anonymous namespace
char BPFCheckAndAdjustIR::ID = 0;
INITIALIZE_PASS(BPFCheckAndAdjustIR, DEBUG_TYPE, "BPF Check And Adjust IR",
false, false)
ModulePass *llvm::createBPFCheckAndAdjustIR() {
return new BPFCheckAndAdjustIR();
}
void BPFCheckAndAdjustIR::checkIR(Module &M) {
// Ensure relocation global won't appear in PHI node
// This may happen if the compiler generated the following code:
// B1:
// g1 = @llvm.skb_buff:0:1...
// ...
// goto B_COMMON
// B2:
// g2 = @llvm.skb_buff:0:2...
// ...
// goto B_COMMON
// B_COMMON:
// g = PHI(g1, g2)
// x = load g
// ...
// If anything likes the above "g = PHI(g1, g2)", issue a fatal error.
for (Function &F : M)
for (auto &BB : F)
for (auto &I : BB) {
PHINode *PN = dyn_cast<PHINode>(&I);
if (!PN || PN->use_empty())
continue;
for (int i = 0, e = PN->getNumIncomingValues(); i < e; ++i) {
auto *GV = dyn_cast<GlobalVariable>(PN->getIncomingValue(i));
if (!GV)
continue;
if (GV->hasAttribute(BPFCoreSharedInfo::AmaAttr) ||
GV->hasAttribute(BPFCoreSharedInfo::TypeIdAttr))
report_fatal_error("relocation global in PHI node");
}
}
}
bool BPFCheckAndAdjustIR::removePassThroughBuiltin(Module &M) {
// Remove __builtin_bpf_passthrough()'s which are used to prevent
// certain IR optimizations. Now major IR optimizations are done,
// remove them.
bool Changed = false;
CallInst *ToBeDeleted = nullptr;
for (Function &F : M)
for (auto &BB : F)
for (auto &I : BB) {
if (ToBeDeleted) {
ToBeDeleted->eraseFromParent();
ToBeDeleted = nullptr;
}
auto *Call = dyn_cast<CallInst>(&I);
if (!Call)
continue;
auto *GV = dyn_cast<GlobalValue>(Call->getCalledOperand());
if (!GV)
continue;
if (!GV->getName().startswith("llvm.bpf.passthrough"))
continue;
Changed = true;
Value *Arg = Call->getArgOperand(1);
Call->replaceAllUsesWith(Arg);
ToBeDeleted = Call;
}
return Changed;
}
bool BPFCheckAndAdjustIR::adjustIR(Module &M) {
return removePassThroughBuiltin(M);
}
bool BPFCheckAndAdjustIR::runOnModule(Module &M) {
checkIR(M);
return adjustIR(M);
}
|
