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Put the header in the first PT_LOAD even if that PT_LOAD has a LMAExpr. 

This should fix PR36017.

The root problem is that we were creating a PT_LOAD just for the
header. That was technically valid, but inconvenient: we should not be
making the ELF discontinuous.

The solution is to allow a section with LMAExpr to be added to a
PT_LOAD if that PT_LOAD doesn't already have a LMAExpr.

llvm-svn: 323625
This commit is contained in:
Rafael Espindola 2018-01-29 03:44:44 +00:00
parent b839f1590e
commit a0d7df3988
3 changed files with 32 additions and 2 deletions
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7
lld/ELF/Writer.cpp
View File

@ -822,6 +822,8 @@ void PhdrEntry::add(OutputSection *Sec) {
p_align = std::max(p_align, Sec->Alignment);
if (p_type == PT_LOAD)
Sec->PtLoad = this;
if (Sec->LMAExpr)
ASectionHasLMA = true;
}
// The beginning and the ending of .rel[a].plt section are marked
@ -1626,8 +1628,9 @@ template <class ELFT> std::vector<PhdrEntry *> Writer<ELFT>::createPhdrs() {
// different flags or is loaded at a discontiguous address using AT linker
// script command.
uint64_t NewFlags = computeFlags(Sec->getPhdrFlags());
if (Sec->LMAExpr || Sec->MemRegion != Load->FirstSec->MemRegion ||
Flags != NewFlags) {
if ((Sec->LMAExpr && Load->ASectionHasLMA) ||
Sec->MemRegion != Load->FirstSec->MemRegion || Flags != NewFlags) {
Load = AddHdr(PT_LOAD, NewFlags);
Flags = NewFlags;
}

6
lld/ELF/Writer.h
View File

@ -44,6 +44,12 @@ struct PhdrEntry {
OutputSection *FirstSec = nullptr;
OutputSection *LastSec = nullptr;
bool HasLMA = false;
// True if one of the sections in this program header has a LMA specified via
// linker script: AT(addr). We never allow 2 or more sections with LMA in the
// same program header.
bool ASectionHasLMA = false;
uint64_t LMAOffset = 0;
};

21
lld/test/ELF/linkerscript/merge-header-load.s Normal file
View File

@ -0,0 +1,21 @@
# REQUIRES: x86
# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
# RUN: echo "SECTIONS { \
# RUN: . = 0xffffffff80000200; \
# RUN: .text : AT (0x4200) { *(.text) } \
# RUN: }" > %t.script
# RUN: ld.lld %t.o --script %t.script -o %t
# RUN: llvm-readelf -program-headers %t | FileCheck %s
# Test that we put the header in the first PT_LOAD. We used to create a PT_LOAD
# just for it and it would have a different virtual to physical address delta.
# CHECK: Program Headers:
# CHECK: Type Offset VirtAddr PhysAddr
# CHECK-NEXT: PHDR 0x000040 0xffffffff80000040 0x0000000000004040
# CHECK-NEXT: LOAD 0x000000 0xffffffff80000000 0x0000000000004000
# CHECK-NOT: LOAD
.global _start
_start:
nop