[ELF] - Postpone evaluation of LMA offset.

Previously we evaluated the values of LMA incorrectly for next cases:

.text : AT(ADDR(.text) - 0xffffffff80000000) { ... }
.data : AT(ADDR(.data) - 0xffffffff80000000) { ... }
.init.begin : AT(ADDR(.init.begin) - 0xffffffff80000000) { ... }

Reason was that we evaluated offset when VA was not assigned. For case above
we ended up with 3 loads that has similar LMA and it was incorrect.
That is critical for linux kernel.

Patch updates the offset after VA calculation. That fixes the issue.

Differential revision: https://reviews.llvm.org/D30163

llvm-svn: 295722

3 files changed, 107 insertions, 3 deletions

diff --git a/lld/ELF/LinkerScript.cpp b/lld/ELF/LinkerScript.cpp
index be42bec9f41..db7bb03568b 100644
--- a/lld/ELF/LinkerScript.cpp
+++ b/lld/ELF/LinkerScript.cpp
@@ -464,7 +464,9 @@ void LinkerScript<ELFT>::switchTo(OutputSectionBase *Sec) {
   // will set the LMA such that the difference between VMA and LMA for the
   // section is the same as the preceding output section in the same region
   // https://sourceware.org/binutils/docs-2.20/ld/Output-Section-LMA.html
-  CurOutSec->setLMAOffset(LMAOffset);
+  Expr LMAExpr = CurLMA.first;
+  if (LMAExpr)
+    CurOutSec->setLMAOffset(LMAExpr(CurLMA.second) - CurLMA.second);
 }
 
 template <class ELFT> void LinkerScript<ELFT>::process(BaseCommand &Base) {
@@ -563,7 +565,7 @@ MemoryRegion *LinkerScript<ELFT>::findMemoryRegion(OutputSectionCommand *Cmd,
 template <class ELFT>
 void LinkerScript<ELFT>::assignOffsets(OutputSectionCommand *Cmd) {
   if (Cmd->LMAExpr)
-    LMAOffset = Cmd->LMAExpr(Dot) - Dot;
+    CurLMA = {Cmd->LMAExpr, Dot};
   OutputSectionBase *Sec = findSection<ELFT>(Cmd->Name, *OutputSections);
   if (!Sec)
     return;
diff --git a/lld/ELF/LinkerScript.h b/lld/ELF/LinkerScript.h
index 8e5b67a980b..6b8598fdd06 100644
--- a/lld/ELF/LinkerScript.h
+++ b/lld/ELF/LinkerScript.h
@@ -298,7 +298,7 @@ private:
                                  OutputSectionBase *Sec);
 
   uintX_t Dot;
-  uintX_t LMAOffset = 0;
+  std::pair<Expr, uintX_t> CurLMA;
   OutputSectionBase *CurOutSec = nullptr;
   MemoryRegion *CurMemRegion = nullptr;
   uintX_t ThreadBssOffset = 0;
diff --git a/lld/test/ELF/linkerscript/at-addr.s b/lld/test/ELF/linkerscript/at-addr.s
new file mode 100644
index 00000000000..7d7907ccb11
--- /dev/null
+++ b/lld/test/ELF/linkerscript/at-addr.s
@@ -0,0 +1,102 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
+# RUN: echo "SECTIONS { . = 0x1000; \
+# RUN:  .aaa : AT(ADDR(.aaa) - 0x500) { *(.aaa) } \
+# RUN:  .bbb : AT(ADDR(.bbb) - 0x500) { *(.bbb) } \
+# RUN:  .ccc : AT(ADDR(.ccc) - 0x500) { *(.ccc) } \
+# 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_PHDR
+# CHECK-NEXT:     Offset: 0x40
+# CHECK-NEXT:     VirtualAddress: 0x40
+# CHECK-NEXT:     PhysicalAddress: 0x40
+# CHECK-NEXT:     FileSize:
+# CHECK-NEXT:     MemSize:
+# CHECK-NEXT:     Flags [
+# CHECK-NEXT:       PF_R
+# CHECK-NEXT:     ]
+# CHECK-NEXT:     Alignment: 8
+# CHECK-NEXT:   }
+# CHECK-NEXT:   ProgramHeader {
+# CHECK-NEXT:     Type: PT_LOAD
+# CHECK-NEXT:     Offset: 0x0
+# CHECK-NEXT:     VirtualAddress: 0x0
+# CHECK-NEXT:     PhysicalAddress: 0x0
+# CHECK-NEXT:     FileSize:
+# CHECK-NEXT:     MemSize:
+# CHECK-NEXT:     Flags [
+# CHECK-NEXT:       PF_R
+# CHECK-NEXT:       PF_X
+# CHECK-NEXT:     ]
+# CHECK-NEXT:     Alignment:
+# CHECK-NEXT:   }
+# CHECK-NEXT:   ProgramHeader {
+# CHECK-NEXT:     Type: PT_LOAD
+# CHECK-NEXT:     Offset: 0x1000
+# CHECK-NEXT:     VirtualAddress: 0x1000
+# CHECK-NEXT:     PhysicalAddress: 0xB00
+# CHECK-NEXT:     FileSize: 8
+# CHECK-NEXT:     MemSize: 8
+# CHECK-NEXT:     Flags [
+# CHECK-NEXT:       PF_R
+# CHECK-NEXT:       PF_X
+# CHECK-NEXT:     ]
+# CHECK-NEXT:     Alignment:
+# CHECK-NEXT:   }
+# CHECK-NEXT:   ProgramHeader {
+# CHECK-NEXT:     Type: PT_LOAD
+# CHECK-NEXT:     Offset: 0x1008
+# CHECK-NEXT:     VirtualAddress: 0x1008
+# CHECK-NEXT:     PhysicalAddress: 0xB08
+# CHECK-NEXT:     FileSize: 8
+# CHECK-NEXT:     MemSize: 8
+# CHECK-NEXT:     Flags [
+# CHECK-NEXT:       PF_R
+# CHECK-NEXT:       PF_X
+# CHECK-NEXT:     ]
+# CHECK-NEXT:     Alignment: 4096
+# CHECK-NEXT:   }
+# CHECK-NEXT:   ProgramHeader {
+# CHECK-NEXT:     Type: PT_LOAD
+# CHECK-NEXT:     Offset: 0x1010
+# CHECK-NEXT:     VirtualAddress: 0x1010
+# CHECK-NEXT:     PhysicalAddress: 0xB10
+# CHECK-NEXT:     FileSize: 9
+# CHECK-NEXT:     MemSize: 9
+# CHECK-NEXT:     Flags [
+# CHECK-NEXT:       PF_R
+# CHECK-NEXT:       PF_X
+# CHECK-NEXT:     ]
+# CHECK-NEXT:     Alignment: 4096
+# CHECK-NEXT:   }
+# CHECK-NEXT:   ProgramHeader {
+# CHECK-NEXT:     Type: PT_GNU_STACK
+# CHECK-NEXT:     Offset:
+# CHECK-NEXT:     VirtualAddress: 0x0
+# CHECK-NEXT:     PhysicalAddress: 0x0
+# CHECK-NEXT:     FileSize:
+# CHECK-NEXT:     MemSize:
+# CHECK-NEXT:     Flags [
+# CHECK-NEXT:       PF_R
+# CHECK-NEXT:       PF_W
+# CHECK-NEXT:     ]
+# CHECK-NEXT:     Alignment: 0
+# CHECK-NEXT:   }
+# CHECK-NEXT: ]
+
+.global _start
+_start:
+ nop
+
+.section .aaa, "a"
+.quad 0
+
+.section .bbb, "a"
+.quad 0
+
+.section .ccc, "a"
+.quad 0