[PATCH] D41403: [ELF] Fix incorrect physical address on self-referencing AT command

[Erick Reyes via Phabricator via llvm-commits]

erickreyes created this revision.
erickreyes added a reviewer: lld.
erickreyes added a project: lld.
Herald added subscribers: llvm-commits, emaste.

When a section placement (AT) command references the section itself, the physical address of the section in the ELF header was calculated incorrectly due to alignment happening right after the location pointer's value was captured.


Repository:
  rLLD LLVM Linker

https://reviews.llvm.org/D41403

Files:
  ELF/LinkerScript.cpp
  test/ELF/linkerscript/at-self-reference.s


Index: test/ELF/linkerscript/at-self-reference.s
===================================================================
--- test/ELF/linkerscript/at-self-reference.s
+++ test/ELF/linkerscript/at-self-reference.s
@@ -0,0 +1,63 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
+# RUN: echo "SECTIONS { \
+# RUN:  . = 0x1000; \
+# RUN:  .aaa : AT(ADDR(.aaa)) { *(.aaa) } \
+# RUN:  .bbb : AT(ADDR(.bbb)) { *(.bbb) } \
+# RUN: }" > %t.script
+# RUN: ld.lld %t --script %t.script -o %t2
+# RUN: llvm-readobj -program-headers %t2 | FileCheck %s
+
+# CHECK:      ProgramHeaders [
+# CHECK-NEXT:  ProgramHeader {
+# CHECK-NEXT:    Type: PT_LOAD (0x1)
+# CHECK-NEXT:    Offset: 0x1000
+# CHECK-NEXT:    VirtualAddress: 0x1000
+# CHECK-NEXT:    PhysicalAddress: 0x1000
+# CHECK-NEXT:    FileSize: 3
+# CHECK-NEXT:    MemSize: 3
+# CHECK-NEXT:    Flags [ (0x5)
+# CHECK-NEXT:      PF_R (0x4)
+# CHECK-NEXT:      PF_X (0x1)
+# CHECK-NEXT:    ]
+# CHECK-NEXT:    Alignment: 4096
+# CHECK-NEXT:  }
+# CHECK-NEXT:  ProgramHeader {
+# CHECK-NEXT:    Type: PT_LOAD (0x1)
+# CHECK-NEXT:    Offset: 0x1008
+# CHECK-NEXT:    VirtualAddress: 0x1008
+# CHECK-NEXT:    PhysicalAddress: 0x1008
+# CHECK-NEXT:    FileSize: 9
+# CHECK-NEXT:    MemSize: 9
+# CHECK-NEXT:    Flags [ (0x5)
+# CHECK-NEXT:      PF_R (0x4)
+# CHECK-NEXT:      PF_X (0x1)
+# CHECK-NEXT:    ]
+# CHECK-NEXT:    Alignment: 4096
+# CHECK-NEXT:  }
+# CHECK-NEXT:  ProgramHeader {
+# CHECK-NEXT:    Type: PT_GNU_STACK (0x6474E551)
+# CHECK-NEXT:    Offset: 0x0
+# CHECK-NEXT:    VirtualAddress: 0x0
+# CHECK-NEXT:    PhysicalAddress: 0x0
+# CHECK-NEXT:    FileSize: 0
+# CHECK-NEXT:    MemSize: 0
+# CHECK-NEXT:    Flags [ (0x6)
+# CHECK-NEXT:      PF_R (0x4)
+# CHECK-NEXT:      PF_W (0x2)
+# CHECK-NEXT:    ]
+# CHECK-NEXT:    Alignment: 0
+# CHECK-NEXT:  }
+# CHECK-NEXT:]
+
+.global _start
+_start:
+ nop
+
+
+.section .aaa, "a"
+.asciz "aa"
+
+.section .bbb, "a"
+.align 8
+.quad 0
Index: ELF/LinkerScript.cpp
===================================================================
--- ELF/LinkerScript.cpp
+++ ELF/LinkerScript.cpp
@@ -663,7 +663,7 @@
     Dot = Ctx->MemRegionOffset[Ctx->MemRegion];
 
   if (Sec->LMAExpr) {
-    uint64_t D = Dot;
+    uint64_t D = alignTo(Dot, Sec->Alignment);
     Ctx->LMAOffset = [=] { return Sec->LMAExpr().getValue() - D; };
   }
 


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