From f31f596152befc309a83f00f164b8145ca9485b3 Mon Sep 17 00:00:00 2001
From: Peter Smith <peter.smith@linaro.org>
Date: Thu, 13 Sep 2018 15:49:13 +0000
Subject: [PATCH] [ELF] Guard --fix-cortex-a53-843419 against --just-syms

If --just-syms is used the mapping symbols from the ELF file will be
absolute symbols with no section. The code to process mapping symbols in
--fix-cortex-a53-843419 assumes that these symbols have a defining section
so a crash will result when --just-syms is used. The simple fix is to not
process the symbol when it doesn't have a section.

Fixes PR37971

Differential Revision: https://reviews.llvm.org/D52038

llvm-svn: 342146
---
 lld/ELF/AArch64ErrataFix.cpp                       |  2 +-
 .../ELF/aarch64-cortex-a53-843419-abs-mapsyms.s    | 22 ++++++++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)
 create mode 100644 lld/test/ELF/aarch64-cortex-a53-843419-abs-mapsyms.s

diff --git a/lld/ELF/AArch64ErrataFix.cpp b/lld/ELF/AArch64ErrataFix.cpp
index 8a54ddd..27d9726 100644
--- a/lld/ELF/AArch64ErrataFix.cpp
+++ b/lld/ELF/AArch64ErrataFix.cpp
@@ -451,7 +451,7 @@ void AArch64Err843419Patcher::init() {
         continue;
       if (!IsCodeMapSymbol(Def) && !IsDataMapSymbol(Def))
         continue;
-      if (auto *Sec = dyn_cast<InputSection>(Def->Section))
+      if (auto *Sec = dyn_cast_or_null<InputSection>(Def->Section))
         if (Sec->Flags & SHF_EXECINSTR)
           SectionMap[Sec].push_back(Def);
     }
diff --git a/lld/test/ELF/aarch64-cortex-a53-843419-abs-mapsyms.s b/lld/test/ELF/aarch64-cortex-a53-843419-abs-mapsyms.s
new file mode 100644
index 0000000..608b1ac
--- /dev/null
+++ b/lld/test/ELF/aarch64-cortex-a53-843419-abs-mapsyms.s
@@ -0,0 +1,22 @@
+// REQUIRES: aarch64
+// RUN: llvm-mc -filetype=obj -triple=aarch64-linux-gnu %s -o %t
+// RUN: ld.lld --just-symbols %t -fix-cortex-a53-843419 -o %t.axf
+// RUN: llvm-readobj --symbols %t.axf | FileCheck %s
+
+// Check that we can gracefully handle --just-symbols, which gives a local
+// absolute mapping symbol (with no Section). Previously we assumed that all
+// mapping symbols were defined relative to a section and assert failed.
+
+        .text
+        .global _start
+        .type _start, %function
+_start: ret
+
+// CHECK:     Name: $x.0
+// CHECK-NEXT:     Value: 0x0
+// CHECK-NEXT:     Size: 0
+// CHECK-NEXT:     Binding: Local (0x0)
+// CHECK-NEXT:     Type: None (0x0)
+// CHECK-NEXT:     Other: 0
+// CHECK-NEXT:     Section: Absolute (0xFFF1)
+// CHECK-NEXT:   }
-- 
2.7.4