From 2724b7ef5a4987ba382d4a3c934b1d42dfcff8c1 Mon Sep 17 00:00:00 2001
From: Jakob Botsch Nielsen <Jakob.botsch.nielsen@gmail.com>
Date: Wed, 23 Mar 2022 18:13:00 +0100
Subject: [PATCH] Give end-marker symbols their own addresses to work around a
 linker bug (#66999)

It seems there is a linker bug related to control-flow guard that is
causing #66969. In eb8460f a thunktemplates.asm file was added that has
a LEAF_END_MARKED at the end of the file. This creates two symbols for
the same upcoming address. Normally that should be fine, but in this
case it causes the linker to place the same address twice in a CFG table
in the PE file. This causes the kernel to fail while loading the image.

A simple workaround would be to add a nop at the end of
thunktemplates.asm, but @janvorli suggested giving these symbols their
own address in all cases for goodness when debugging. We already do so
for Windows x64 it looks like.

Fix #66969
---
 src/coreclr/pal/inc/unixasmmacrosamd64.inc | 2 ++
 src/coreclr/pal/inc/unixasmmacrosarm.inc   | 2 ++
 src/coreclr/pal/inc/unixasmmacrosarm64.inc | 2 ++
 src/coreclr/pal/inc/unixasmmacrosx86.inc   | 2 ++
 src/coreclr/vm/amd64/AsmMacros.inc         | 5 +++--
 src/coreclr/vm/arm/asmmacros.h             | 3 +++
 src/coreclr/vm/arm64/asmmacros.h           | 3 +++
 src/coreclr/vm/i386/AsmMacros.inc          | 2 ++
 8 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/src/coreclr/pal/inc/unixasmmacrosamd64.inc b/src/coreclr/pal/inc/unixasmmacrosamd64.inc
index 2aca375faa8383..bb1e70a27bef02 100644
--- a/src/coreclr/pal/inc/unixasmmacrosamd64.inc
+++ b/src/coreclr/pal/inc/unixasmmacrosamd64.inc
@@ -52,6 +52,8 @@ C_FUNC(\Name):
 C_FUNC(\Name\()_End):
         .global C_FUNC(\Name\()_End)
         LEAF_END \Name, \Section
+        // make sure this symbol gets its own address
+        nop
 .endm
 
 .macro NOP_6_BYTE
diff --git a/src/coreclr/pal/inc/unixasmmacrosarm.inc b/src/coreclr/pal/inc/unixasmmacrosarm.inc
index d323ccc49fbd2d..f5eb32656cd3ae 100644
--- a/src/coreclr/pal/inc/unixasmmacrosarm.inc
+++ b/src/coreclr/pal/inc/unixasmmacrosarm.inc
@@ -40,6 +40,8 @@ C_FUNC(\Name):
         .global C_FUNC(\Name\()_End)
 C_FUNC(\Name\()_End):
         LEAF_END \Name, \Section
+        // make sure this symbol gets its own address
+        nop
 .endm
 
 .macro PREPARE_EXTERNAL_VAR Name, HelperReg
diff --git a/src/coreclr/pal/inc/unixasmmacrosarm64.inc b/src/coreclr/pal/inc/unixasmmacrosarm64.inc
index 9545afb9f8e584..8b3c5803b7d71f 100644
--- a/src/coreclr/pal/inc/unixasmmacrosarm64.inc
+++ b/src/coreclr/pal/inc/unixasmmacrosarm64.inc
@@ -44,6 +44,8 @@ C_FUNC(\Name):
 C_FUNC(\Name\()_End):
         .global C_FUNC(\Name\()_End)
         LEAF_END \Name, \Section
+        // make sure this symbol gets its own address
+        nop
 .endm
 
 .macro PREPARE_EXTERNAL_VAR Name, HelperReg
diff --git a/src/coreclr/pal/inc/unixasmmacrosx86.inc b/src/coreclr/pal/inc/unixasmmacrosx86.inc
index 87cbddd6eda204..7bc994a779c356 100644
--- a/src/coreclr/pal/inc/unixasmmacrosx86.inc
+++ b/src/coreclr/pal/inc/unixasmmacrosx86.inc
@@ -33,6 +33,8 @@ C_FUNC(\Name):
 C_FUNC(\Name\()_End):
         .global C_FUNC(\Name\()_End)
         LEAF_END \Name, \Section
+        // make sure this symbol gets its own address
+        nop
 .endm
 
 .macro PROLOG_BEG
diff --git a/src/coreclr/vm/amd64/AsmMacros.inc b/src/coreclr/vm/amd64/AsmMacros.inc
index 32d8ecb4fe70ed..2d14b9c31e8fca 100644
--- a/src/coreclr/vm/amd64/AsmMacros.inc
+++ b/src/coreclr/vm/amd64/AsmMacros.inc
@@ -133,12 +133,13 @@ Section ends
 LEAF_END_MARKED macro Name, section
         public Name&_End
 Name&_End label qword
+
+Name    endp
+
         ; this nop is important to keep the label in
         ; the right place in the face of BBT
         nop
 
-Name    endp
-
 Section ends
 
         endm
diff --git a/src/coreclr/vm/arm/asmmacros.h b/src/coreclr/vm/arm/asmmacros.h
index ad3826cd8b2e1d..2c07bfb3fd00c8 100644
--- a/src/coreclr/vm/arm/asmmacros.h
+++ b/src/coreclr/vm/arm/asmmacros.h
@@ -29,6 +29,9 @@ __EndLabelName SETS "$FuncName":CC:"_End"
 
     LEAF_END $FuncName
 
+    ; Make sure this symbol gets its own address
+    nop
+
     MEND
 
 ;-----------------------------------------------------------------------------
diff --git a/src/coreclr/vm/arm64/asmmacros.h b/src/coreclr/vm/arm64/asmmacros.h
index fae7ec3309aeec..bd19b9e6dc3dc5 100644
--- a/src/coreclr/vm/arm64/asmmacros.h
+++ b/src/coreclr/vm/arm64/asmmacros.h
@@ -147,6 +147,9 @@ __EndLabelName SETS "$FuncName":CC:"_End"
 
     LEAF_END $FuncName
 
+    ; make sure this symbol gets its own address
+    nop
+
     MEND
 ;-----------------------------------------------------------------------------
 ; Macro use for enabling C++ to know where to patch code at runtime.
diff --git a/src/coreclr/vm/i386/AsmMacros.inc b/src/coreclr/vm/i386/AsmMacros.inc
index ac77064f0da5cc..ba6cc7e81a2854 100644
--- a/src/coreclr/vm/i386/AsmMacros.inc
+++ b/src/coreclr/vm/i386/AsmMacros.inc
@@ -38,6 +38,8 @@ LEAF_END_MARKED macro functionName
     %endMarkerName:
     PUBLIC endMarkerName
     functionName ENDP
+    ; make sure this symbol gets its own address
+    nop
 endm
 
 PATCH_LABEL macro labelName