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Implement the stack protector stack accesses via intrinsics:

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- stackprotector_prologue creates a stack object and stores the guard there.

- stackprotector_epilogue reads the stack guard from the stack position created
  by stackprotector_prologue.

- The PrologEpilogInserter was changed to make sure that the stack guard is
  first on the stack frame.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58791 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bill Wendling
2008-11-06 02:29:10 +00:00
parent 9092213a5e
commit b2a4298ce4
5 changed files with 105 additions and 9 deletions
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lib/CodeGen/StackProtector.cpp
+11 -9
View File
@@ -20,6 +20,7 @@
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/Instructions.h"
#include "llvm/Intrinsics.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/ADT/APInt.h"
@@ -110,16 +111,15 @@ bool StackProtector::InsertStackProtectors() {
// onto the stack.
BasicBlock &Entry = F->getEntryBlock();
Instruction *InsertPt = &Entry.front();
const PointerType *GuardTy = PointerType::getUnqual(Type::Int8Ty);
// The global variable for the stack guard.
Constant *StackGuardVar = M->getOrInsertGlobal("__stack_chk_guard", GuardTy);
// The place on the stack that the stack protector guard is kept.
AllocaInst *StackProtFrameSlot =
new AllocaInst(GuardTy, "StackProt_Frame", InsertPt);
LoadInst *LI = new LoadInst(StackGuardVar, "StackGuard", false, InsertPt);
new StoreInst(LI, StackProtFrameSlot, false, InsertPt);
CallInst::
Create(Intrinsic::getDeclaration(M, Intrinsic::stackprotector_prologue),
LI, "", InsertPt);
// Create the basic block to jump to when the guard check fails.
BasicBlock *FailBB = CreateFailBB();
@@ -137,7 +137,7 @@ bool StackProtector::InsertStackProtectors() {
// %1 = load __stack_chk_guard
// %2 = load <stored stack guard>
// %3 = cmp i1 %1, %2
// br i1 %3, label %SPRet, label %CallStackCheckFailBlk
// br i1 %3, label %SP_return, label %CallStackCheckFailBlk
//
// SP_return:
// ret ...
@@ -161,9 +161,11 @@ bool StackProtector::InsertStackProtectors() {
F->getBasicBlockList().insert(InsPt, NewBB);
// Generate the stack protector instructions in the old basic block.
LoadInst *LI2 = new LoadInst(StackGuardVar, "", false, BB);
LoadInst *LI1 = new LoadInst(StackProtFrameSlot, "", true, BB);
ICmpInst *Cmp = new ICmpInst(CmpInst::ICMP_EQ, LI1, LI2, "", BB);
LoadInst *LI1 = new LoadInst(StackGuardVar, "", false, BB);
CallInst *CI = CallInst::
Create(Intrinsic::getDeclaration(M, Intrinsic::stackprotector_epilogue),
"", BB);
ICmpInst *Cmp = new ICmpInst(CmpInst::ICMP_EQ, CI, LI1, "", BB);
BranchInst::Create(NewBB, FailBB, Cmp, BB);
}