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[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
This commit is contained in:
George Rimar 2017-02-21 15:08:18 +00:00
parent 0c094f504c
commit ae4761c186
3 changed files with 107 additions and 3 deletions
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6
lld/ELF/LinkerScript.cpp
View File

@ -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;

2
lld/ELF/LinkerScript.h
View File

@ -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;

102
lld/test/ELF/linkerscript/at-addr.s Normal file
View File

@ -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