[PATCH] D41640: [ELF] - Do not ignore discarding of .rela.plt/.rela.dyn, allow doing custom layout for them.

[George Rimar via Phabricator via llvm-commits]

grimar updated this revision to Diff 129228.
grimar retitled this revision from "[ELF] - Do not ignore discarding of .rela.plt/.rela.dyn" to "[ELF] - Do not ignore discarding of .rela.plt/.rela.dyn, allow doing custom layout for them.".
grimar added a comment.

- Changed comment.
- Added testcase showing we are able to do custom layout for synthetic .rel[a] sections with this patch.


https://reviews.llvm.org/D41640

Files:
  ELF/LinkerScript.cpp
  test/ELF/linkerscript/discard-section-err.s
  test/ELF/linkerscript/synthetic-relsec-layout.s


Index: test/ELF/linkerscript/synthetic-relsec-layout.s
===================================================================
--- test/ELF/linkerscript/synthetic-relsec-layout.s
+++ test/ELF/linkerscript/synthetic-relsec-layout.s
@@ -0,0 +1,16 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
+# RUN: echo "SECTIONS { .foo : { *(.rela.dyn) } }" > %t.script
+# RUN: ld.lld -T %t.script --emit-relocs %t.o -o %t.so -shared
+# RUN: llvm-readobj -r %t.so | FileCheck %s
+
+# Check we are able to do custom layout for synthetic sections.
+# (here we check we can place synthetic .rela.dyn into .foo).
+
+# CHECK: Relocations [
+# CHECK:   Section ({{.*}}) .foo {
+# CHECK:     R_X86_64_64 .foo 0x0
+# CHECK:   }
+
+.data
+.quad .foo
Index: test/ELF/linkerscript/discard-section-err.s
===================================================================
--- test/ELF/linkerscript/discard-section-err.s
+++ test/ELF/linkerscript/discard-section-err.s
@@ -22,4 +22,14 @@
 # RUN:   FileCheck -check-prefix=DYNSTR %s
 # DYNSTR: discarding .dynstr section is not allowed
 
+# RUN: echo "SECTIONS { /DISCARD/ : { *(.rela.plt) } }" > %t.script
+# RUN: not ld.lld -pie -o %t --script %t.script %t.o 2>&1 | \
+# RUN:   FileCheck -check-prefix=RELAPLT %s
+# RELAPLT: discarding .rela.plt section is not allowed
+
+# RUN: echo "SECTIONS { /DISCARD/ : { *(.rela.dyn) } }" > %t.script
+# RUN: not ld.lld -pie -o %t --script %t.script %t.o 2>&1 | \
+# RUN:   FileCheck -check-prefix=RELADYN %s
+# RELADYN: discarding .rela.dyn section is not allowed
+
 .comm foo,4,4
Index: ELF/LinkerScript.cpp
===================================================================
--- ELF/LinkerScript.cpp
+++ ELF/LinkerScript.cpp
@@ -290,7 +290,10 @@
       // For -emit-relocs we have to ignore entries like
       //   .rela.dyn : { *(.rela.data) }
       // which are common because they are in the default bfd script.
-      if (Sec->Type == SHT_REL || Sec->Type == SHT_RELA)
+      // We do not ignore SHT_REL[A] linker-synthesized sections here because
+      // want to support scripts that do custom layout for them.
+      if (!isa<SyntheticSection>(Sec) &&
+          (Sec->Type == SHT_REL || Sec->Type == SHT_RELA))
         continue;
 
       std::string Filename = getFilename(Sec->File);
@@ -315,7 +318,7 @@
 void LinkerScript::discard(ArrayRef<InputSection *> V) {
   for (InputSection *S : V) {
     if (S == InX::ShStrTab || S == InX::Dynamic || S == InX::DynSymTab ||
-        S == InX::DynStrTab)
+        S == InX::DynStrTab || S == InX::RelaPlt || S == InX::RelaDyn)
       error("discarding " + S->Name + " section is not allowed");
 
     S->Assigned = false;


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D41640.129228.patch
Type: text/x-patch
Size: 2678 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20180110/d94c725a/attachment.bin>