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Fix incorrect physical address on self-referencing AT command. 

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.

The problem was diagnosed and the first version of the patch written
by Erick Reyes.

llvm-svn: 322421
This commit is contained in:
Rafael Espindola 2018-01-12 23:26:25 +00:00
parent 5923a6da05
commit 75702389bd
2 changed files with 71 additions and 8 deletions
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16
lld/ELF/LinkerScript.cpp
View File

@ -608,13 +608,6 @@ void LinkerScript::switchTo(OutputSection *Sec) {
Ctx->OutSec = Sec;
Ctx->OutSec->Addr = advance(0, Ctx->OutSec->Alignment);
// If neither AT nor AT> is specified for an allocatable section, the linker
// 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
if (Ctx->LMAOffset)
Ctx->OutSec->LMAOffset = Ctx->LMAOffset();
}
// This function searches for a memory region to place the given output
@ -662,6 +655,8 @@ void LinkerScript::assignOffsets(OutputSection *Sec) {
if (Ctx->MemRegion)
Dot = Ctx->MemRegionOffset[Ctx->MemRegion];
switchTo(Sec);
if (Sec->LMAExpr) {
uint64_t D = Dot;
Ctx->LMAOffset = [=] { return Sec->LMAExpr().getValue() - D; };
@ -676,7 +671,12 @@ void LinkerScript::assignOffsets(OutputSection *Sec) {
}
}
switchTo(Sec);
// If neither AT nor AT> is specified for an allocatable section, the linker
// 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
if (Ctx->LMAOffset)
Ctx->OutSec->LMAOffset = Ctx->LMAOffset();
// The Size previously denoted how many InputSections had been added to this
// section, and was used for sorting SHF_LINK_ORDER sections. Reset it to

63
lld/test/ELF/linkerscript/at-self-reference.s Normal file
View File

@ -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