[PATCH] D22564: [ELF] Support FLAGS attribute in PHDR definition

[Eugene Leviant via llvm-commits]

evgeny777 created this revision.
evgeny777 added a reviewer: ruiu.
evgeny777 added subscribers: grimar, ikudrin, llvm-commits.
evgeny777 set the repository for this revision to rL LLVM.
evgeny777 added a project: lld.

Allows user to specify flags for each program header

Repository:
  rL LLVM

https://reviews.llvm.org/D22564

Files:
  ELF/LinkerScript.cpp
  ELF/LinkerScript.h
  test/ELF/linkerscript-phdrs-flags.s

Index: test/ELF/linkerscript-phdrs-flags.s
===================================================================
--- test/ELF/linkerscript-phdrs-flags.s
+++ test/ELF/linkerscript-phdrs-flags.s
@@ -0,0 +1,36 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
+# RUN: echo "PHDRS {all PT_LOAD FILEHDR PHDRS FLAGS (7);} \
+# RUN:       SECTIONS { \
+# RUN:           . = 0x10000200; \
+# RUN:           .text : {*(.text.*)} :all \
+# RUN:           .foo : {*(.foo.*)} :all \
+# RUN:           .data : {*(.data.*)} :all}" > %t.script
+
+# RUN: ld.lld -o %t1 --script %t.script %t
+# RUN: llvm-readobj -program-headers %t1 | FileCheck %s
+# CHECK:     ProgramHeaders [
+# CHECK-NEXT:  ProgramHeader {
+# CHECK-NEXT:    Type: PT_LOAD (0x1)
+# CHECK-NEXT:    Offset: 0x0
+# CHECK-NEXT:    VirtualAddress: 0x10000000
+# CHECK-NEXT:    PhysicalAddress: 0x10000000
+# CHECK-NEXT:    FileSize: 521
+# CHECK-NEXT:    MemSize: 521
+# CHECK-NEXT:    Flags [ (0x7)
+# CHECK-NEXT:      PF_R (0x4)
+# CHECK-NEXT:      PF_W (0x2)
+# CHECK-NEXT:      PF_X (0x1)
+# CHECK-NEXT:    ]
+
+.global _start
+_start:
+ nop
+
+.section .foo.1,"a"
+foo1:
+ .long 0
+
+.section .foo.2,"a"
+foo2:
+ .long 0
Index: ELF/LinkerScript.h
===================================================================
--- ELF/LinkerScript.h
+++ ELF/LinkerScript.h
@@ -55,6 +55,8 @@
   unsigned Type;
   bool HasFilehdr;
   bool HasPhdrs;
+  bool HasFlags;
+  unsigned Flags;
 };
 
 // ScriptConfiguration holds linker script parse results.
Index: ELF/LinkerScript.cpp
===================================================================
--- ELF/LinkerScript.cpp
+++ ELF/LinkerScript.cpp
@@ -285,7 +285,7 @@
   std::vector<Phdr> Phdrs;
 
   for (const PhdrsCommand &Cmd : Opt.PhdrsCommands) {
-    Phdrs.emplace_back(Cmd.Type, PF_R);
+    Phdrs.emplace_back(Cmd.Type, Cmd.HasFlags ? Cmd.Flags : PF_R);
     Phdr &Added = Phdrs.back();
 
     if (Cmd.HasFilehdr)
@@ -338,7 +338,8 @@
       // Assign headers specified by linker script
       for (size_t Id : PhdrIds) {
         Phdrs[Id].AddSec(Sec);
-        Phdrs[Id].H.p_flags |= toPhdrFlags(Sec->getFlags());
+        if (!Opt.PhdrsCommands[Id].HasFlags)
+          Phdrs[Id].H.p_flags |= toPhdrFlags(Sec->getFlags());
       }
     } else {
       // If we have no load segment or flags've changed then we want new load
@@ -616,7 +617,7 @@
   expect("{");
   while (!Error && !skip("}")) {
     StringRef Tok = next();
-    Opt.PhdrsCommands.push_back({Tok, PT_NULL, false, false});
+    Opt.PhdrsCommands.push_back({Tok, PT_NULL, false, false, false, 0});
     PhdrsCommand &PhdrCmd = Opt.PhdrsCommands.back();
 
     PhdrCmd.Type = readPhdrType();
@@ -628,6 +629,12 @@
         PhdrCmd.HasFilehdr = true;
       else if (Tok == "PHDRS")
         PhdrCmd.HasPhdrs = true;
+      else if (Tok == "FLAGS") {
+        PhdrCmd.HasFlags = true;
+        expect("(");
+        next().getAsInteger(0, PhdrCmd.Flags);
+        expect(")"); 
+      }
       else
         setError("unexpected header attribute: " + Tok);
     } while (!Error);


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