[lld] 12d8654 - [COFF] Use the more accurate GuardFlags definition everywhere

[Martin Storsjö via llvm-commits]

Author: Alvin Wong
Date: 2022-08-31T15:11:34+03:00
New Revision: 12d865415ff3b9c95eaf3b3d92258d7ef77d2e76

URL: https://github.com/llvm/llvm-project/commit/12d865415ff3b9c95eaf3b3d92258d7ef77d2e76
DIFF: https://github.com/llvm/llvm-project/commit/12d865415ff3b9c95eaf3b3d92258d7ef77d2e76.diff

LOG: [COFF] Use the more accurate GuardFlags definition everywhere

This also modifies llvm-readobj to be more future-proof when printing
the guard FIDs table by calculating the entry size correctly according
to MS docs.

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D132924

Added: 
    

Modified: 
    lld/COFF/Writer.cpp
    llvm/include/llvm/Object/COFF.h
    llvm/tools/llvm-readobj/COFFDumper.cpp

Removed: 
    


################################################################################
diff  --git a/lld/COFF/Writer.cpp b/lld/COFF/Writer.cpp
index d6981e4e7e1a..c530b21b4686 100644
--- a/lld/COFF/Writer.cpp
+++ b/lld/COFF/Writer.cpp
@@ -24,6 +24,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/ADT/StringSwitch.h"
+#include "llvm/BinaryFormat/COFF.h"
 #include "llvm/Support/BinaryStreamReader.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Endian.h"
@@ -1702,12 +1703,12 @@ void Writer::createGuardCFTables() {
 
   // Set __guard_flags, which will be used in the load config to indicate that
   // /guard:cf was enabled.
-  uint32_t guardFlags = uint32_t(coff_guard_flags::CFInstrumented) |
-                        uint32_t(coff_guard_flags::HasFidTable);
+  uint32_t guardFlags = uint32_t(GuardFlags::CF_INSTRUMENTED) |
+                        uint32_t(GuardFlags::CF_FUNCTION_TABLE_PRESENT);
   if (config->guardCF & GuardCFLevel::LongJmp)
-    guardFlags |= uint32_t(coff_guard_flags::HasLongJmpTable);
+    guardFlags |= uint32_t(GuardFlags::CF_LONGJUMP_TABLE_PRESENT);
   if (config->guardCF & GuardCFLevel::EHCont)
-    guardFlags |= uint32_t(coff_guard_flags::HasEHContTable);
+    guardFlags |= uint32_t(GuardFlags::EH_CONTINUATION_TABLE_PRESENT);
   Symbol *flagSym = ctx.symtab.findUnderscore("__guard_flags");
   cast<DefinedAbsolute>(flagSym)->setVA(guardFlags);
 }

diff  --git a/llvm/include/llvm/Object/COFF.h b/llvm/include/llvm/Object/COFF.h
index 0b6975b9590f..8a110078ffdf 100644
--- a/llvm/include/llvm/Object/COFF.h
+++ b/llvm/include/llvm/Object/COFF.h
@@ -597,17 +597,6 @@ struct coff_tls_directory {
 using coff_tls_directory32 = coff_tls_directory<support::little32_t>;
 using coff_tls_directory64 = coff_tls_directory<support::little64_t>;
 
-/// Bits in control flow guard flags as we understand them.
-enum class coff_guard_flags : uint32_t {
-  CFInstrumented = 0x00000100,
-  HasFidTable = 0x00000400,
-  ProtectDelayLoadIAT = 0x00001000,
-  DelayLoadIATSection = 0x00002000, // Delay load in separate section
-  HasLongJmpTable = 0x00010000,
-  HasEHContTable = 0x00400000,
-  FidTableHasFlags = 0x10000000, // Indicates that fid tables are 5 bytes
-};
-
 enum class frame_type : uint16_t { Fpo = 0, Trap = 1, Tss = 2, NonFpo = 3 };
 
 struct coff_load_config_code_integrity {

diff  --git a/llvm/tools/llvm-readobj/COFFDumper.cpp b/llvm/tools/llvm-readobj/COFFDumper.cpp
index ba772d102a28..67889f4deb64 100644
--- a/llvm/tools/llvm-readobj/COFFDumper.cpp
+++ b/llvm/tools/llvm-readobj/COFFDumper.cpp
@@ -852,11 +852,18 @@ void COFFDumper::printCOFFLoadConfig() {
 
   if (Tables.GuardFidTableVA) {
     ListScope LS(W, "GuardFidTable");
-    if (Tables.GuardFlags & uint32_t(coff_guard_flags::FidTableHasFlags))
-      printRVATable(Tables.GuardFidTableVA, Tables.GuardFidTableCount, 5,
+    if (uint32_t Size =
+            Tables.GuardFlags &
+            uint32_t(COFF::GuardFlags::CF_FUNCTION_TABLE_SIZE_MASK)) {
+      // The size mask gives the number of extra bytes in addition to the 4-byte
+      // RVA of each entry in the table. As of writing only a 1-byte extra flag
+      // has been defined.
+      Size = (Size >> 28) + 4;
+      printRVATable(Tables.GuardFidTableVA, Tables.GuardFidTableCount, Size,
                     PrintGuardFlags);
-    else
+    } else {
       printRVATable(Tables.GuardFidTableVA, Tables.GuardFidTableCount, 4);
+    }
   }
 
   if (Tables.GuardIatTableVA) {