[PATCH] D137921: [LLD][ELF] Add support for OpenBSD PT_OPENBSD_MUTABLE segment type

[Brad Smith via Phabricator via llvm-commits]

brad updated this revision to Diff 476658.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D137921/new/

https://reviews.llvm.org/D137921

Files:
  lld/ELF/ScriptParser.cpp
  lld/ELF/Writer.cpp
  lld/test/ELF/linkerscript/openbsd-mutable.s
  lld/test/ELF/openbsd-mutable.s


Index: lld/test/ELF/openbsd-mutable.s
===================================================================
--- /dev/null
+++ lld/test/ELF/openbsd-mutable.s
@@ -0,0 +1,20 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t
+# RUN: ld.lld %t -o %t.out
+# RUN: llvm-readobj --program-headers %t.out | FileCheck %s
+
+# CHECK:      ProgramHeader {
+# CHECK:        Type: PT_OPENBSD_MUTABLE (0x65A3DBE5)
+# CHECK-NEXT:   Offset:
+# CHECK-NEXT:   VirtualAddress:
+# CHECK-NEXT:   PhysicalAddress:
+# CHECK-NEXT:   FileSize: 8
+# CHECK-NEXT:   MemSize: 8
+# CHECK-NEXT:   Flags [
+# CHECK-NEXT:     PF_R (0x4)
+# CHECK-NEXT:   ]
+# CHECK-NEXT:   Alignment: 1
+# CHECK-NEXT: }
+
+.section .openbsd.mutable, "a"
+.quad 0
Index: lld/test/ELF/linkerscript/openbsd-mutable.s
===================================================================
--- /dev/null
+++ lld/test/ELF/linkerscript/openbsd-mutable.s
@@ -0,0 +1,24 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=i686-unknown-linux %s -o %t.o
+# RUN: echo "PHDRS { text PT_LOAD FILEHDR PHDRS; rand PT_OPENBSD_MUTABLE; } \
+# RUN:       SECTIONS { . = SIZEOF_HEADERS; \
+# RUN:         .text : { *(.text) } \
+# RUN:         .openbsd.mutable : { *(.openbsd.mutable) } : rand }" > %t.script
+# RUN: ld.lld --script %t.script %t.o -o %t
+# RUN: llvm-readobj --program-headers -S %t | FileCheck %s
+
+# CHECK:      ProgramHeader {
+# CHECK:        Type: PT_OPENBSD_MUTABLE (0x65A3DBE5)
+# CHECK-NEXT:   Offset: 0x74
+# CHECK-NEXT:   VirtualAddress: 0x74
+# CHECK-NEXT:   PhysicalAddress: 0x74
+# CHECK-NEXT:   FileSize: 8
+# CHECK-NEXT:   MemSize: 8
+# CHECK-NEXT:   Flags [ (0x4)
+# CHECK-NEXT:     PF_R (0x4)
+# CHECK-NEXT:   ]
+# CHECK-NEXT:   Alignment: 1
+# CHECK-NEXT: }
+
+.section .openbsd.mutable, "a"
+.quad 0
Index: lld/ELF/Writer.cpp
===================================================================
--- lld/ELF/Writer.cpp
+++ lld/ELF/Writer.cpp
@@ -2369,6 +2369,12 @@
     addHdr(PT_GNU_EH_FRAME, part.ehFrameHdr->getParent()->getPhdrFlags())
         ->add(part.ehFrameHdr->getParent());
 
+  // PT_OPENBSD_MUTABLE is an OpenBSD-specific feature. That makes
+  // the dynamic linker fill the segment with zero data, like bss, but
+  // it can be treated differently.
+  if (OutputSection *cmd = findSection(".openbsd.mutable", partNo))
+    addHdr(PT_OPENBSD_MUTABLE, cmd->getPhdrFlags())->add(cmd);
+
   // PT_OPENBSD_RANDOMIZE is an OpenBSD-specific feature. That makes
   // the dynamic linker fill the segment with random data.
   if (OutputSection *cmd = findSection(".openbsd.randomdata", partNo))
Index: lld/ELF/ScriptParser.cpp
===================================================================
--- lld/ELF/ScriptParser.cpp
+++ lld/ELF/ScriptParser.cpp
@@ -1575,6 +1575,7 @@
                      .Case("PT_GNU_EH_FRAME", PT_GNU_EH_FRAME)
                      .Case("PT_GNU_STACK", PT_GNU_STACK)
                      .Case("PT_GNU_RELRO", PT_GNU_RELRO)
+                     .Case("PT_OPENBSD_MUTABLE", PT_OPENBSD_MUTABLE)
                      .Case("PT_OPENBSD_RANDOMIZE", PT_OPENBSD_RANDOMIZE)
                      .Case("PT_OPENBSD_WXNEEDED", PT_OPENBSD_WXNEEDED)
                      .Case("PT_OPENBSD_BOOTDATA", PT_OPENBSD_BOOTDATA)


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D137921.476658.patch
Type: text/x-patch
Size: 3246 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20221119/ee471382/attachment-0001.bin>