From 9748eae3dd471d16c4c8cde3e7b8a8575db925bb Mon Sep 17 00:00:00 2001
From: clc5q <clc5q@git.zephyr-software.com>
Date: Wed, 20 Jan 2016 00:58:22 +0000
Subject: [PATCH] Apply computed-goto pattern detection to functions just as it
was applied to orphaned code to emit IBT annotations.
Former-commit-id: a9d8aace7a5d1070e2741697a7a265883c22764d
---
src/base/SMPFunction.cpp | 27 ++++++++++++++++++++++++++-
1 file changed, 26 insertions(+), 1 deletion(-)
diff --git a/src/base/SMPFunction.cpp b/src/base/SMPFunction.cpp
index 25cf054f..e959fce1 100644
--- a/src/base/SMPFunction.cpp
+++ b/src/base/SMPFunction.cpp
@@ -9558,7 +9558,9 @@ void SMPFunction::EmitAnnotations(FILE *AnnotFile, FILE *InfoAnnotFile) {
#endif
bool AllocSeen = false; // Reached LocalVarsAllocInstr yet?
bool DeallocTrigger = false;
- for ( ; InstIter != Instrs.end(); ++InstIter) {
+ bool PrefetchInstSeenLast = false; // inst before current inst was a prefetch
+ bool UndefinedOpcodeSeenLast = false; // inst before current inst was an undefined opcode
+ for (; InstIter != Instrs.end(); ++InstIter) {
SMPInstr *CurrInst = (*InstIter);
STARS_ea_t addr = CurrInst->GetAddr();
if (CurrInst->IsFloatNop()) {
@@ -9634,6 +9636,29 @@ void SMPFunction::EmitAnnotations(FILE *AnnotFile, FILE *InfoAnnotFile) {
if (CurrInst->MDIsReturnInstr() && this->GetReturnAddressStatus() == FUNC_SAFE)
CurrInst->EmitSafeReturn(AnnotFile);
+
+ // Emit IBT annotations for instructions that fit computed-goto patterns in libc/glibc, such
+ // as prefetch instructions and the instructions that follow them (computed goto often chooses
+ // between going to the prefetch or jumping just past it, and IDA Pro cannot analyze these libc
+ // macro-generated computed gotos even if they are not orphaned code). Likewise, an undefined opcode
+ // often separates an indirect jump and its first target, so inst after undefined opcode is IBT.
+ bool EmitIBTAnnotation = (PrefetchInstSeenLast || UndefinedOpcodeSeenLast);
+ if (CurrInst->MDIsPrefetchOpcode()) {
+ PrefetchInstSeenLast = true;
+ UndefinedOpcodeSeenLast = false;
+ EmitIBTAnnotation = true;
+ }
+ else if (CurrInst->MDIsUndefinedOpcode()) {
+ UndefinedOpcodeSeenLast = true;
+ PrefetchInstSeenLast = false;
+ }
+ else {
+ PrefetchInstSeenLast = false;
+ UndefinedOpcodeSeenLast = false;
+ }
+ if (EmitIBTAnnotation) {
+ global_STARS_program->PrintUnknownCodeXref(addr, CurrInst->GetSize());
+ }
} // end for all instructions
// Loop through all basic blocks and emit profiling request annotations
--
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