[ELF] - Disable relro when -omagic specified.

--omagic is an option to create old-fashioned executables in which
.text segments are writable. Today, the option is still in use to
create special-purpose programs such as boot loaders. It doesn't
make sense to create PT_GNU_RELRO for such executables.

DIfferential revision: https://reviews.llvm.org/D27297

llvm-svn: 288579

diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
index b179347..48e5ad7 100644 (file)
--- a/lld/ELF/Driver.cpp
+++ b/lld/ELF/Driver.cpp
@@ -575,6 +575,13 @@ void LinkerDriver::readConfigs(opt::InputArgList &Args) {
   Config->Target2 = getTarget2Option(Args);
   Config->UnresolvedSymbols = getUnresolvedSymbolOption(Args);
 
+  // --omagic is an option to create old-fashioned executables in which
+  // .text segments are writable. Today, the option is still in use to
+  // create special-purpose programs such as boot loaders. It doesn't
+  // make sense to create PT_GNU_RELRO for such executables.
+  if (Config->OMagic)
+    Config->ZRelro = false;
+
   if (!Config->Relocatable)
     Config->Strip = getStripOption(Args);
 

diff --git a/lld/test/ELF/relro-omagic.s b/lld/test/ELF/relro-omagic.s
new file mode 100644 (file)
index 0000000..35a92db
--- /dev/null
+++ b/lld/test/ELF/relro-omagic.s
@@ -0,0 +1,34 @@
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %p/Inputs/shared.s -o %t2.o
+# RUN: ld.lld -shared %t2.o -o %t2.so
+# RUN: ld.lld -N %t.o %t2.so -o %t
+# RUN: llvm-objdump -section-headers %t | FileCheck --check-prefix=NORELRO %s
+# RUN: llvm-readobj --program-headers %t | FileCheck --check-prefix=NOPHDRS %s
+
+# NORELRO:      Sections:
+# NORELRO-NEXT: Idx Name          Size      Address          Type
+# NORELRO-NEXT:   0               00000000 0000000000000000
+# NORELRO-NEXT:   1 .dynsym       00000048 0000000000200120
+# NORELRO-NEXT:   2 .hash         00000020 0000000000200168
+# NORELRO-NEXT:   3 .dynstr       00000021 0000000000200188
+# NORELRO-NEXT:   4 .rela.dyn     00000018 00000000002001b0
+# NORELRO-NEXT:   5 .rela.plt     00000018 00000000002001c8
+# NORELRO-NEXT:   6 .text         0000000a 00000000002001e0 TEXT DATA
+# NORELRO-NEXT:   7 .plt          00000020 00000000002001f0 TEXT DATA
+# NORELRO-NEXT:   8 .data         00000008 0000000000200210 DATA
+# NORELRO-NEXT:   9 .foo          00000004 0000000000200218 DATA
+# NORELRO-NEXT:  10 .dynamic      000000f0 0000000000200220
+# NORELRO-NEXT:  11 .got          00000008 0000000000200310 DATA
+# NORELRO-NEXT:  12 .got.plt      00000020 0000000000200318 DATA
+
+# NOPHDRS:     ProgramHeaders [
+# NOPHDRS-NOT: PT_GNU_RELRO
+
+.long bar
+jmp *bar2@GOTPCREL(%rip)
+
+.section .data,"aw"
+.quad 0
+
+.section .foo,"aw"
+.zero 4