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Don't print empty PT_LOAD. 

If we do, the freebsd dynamic linker tries to call mmap with a size 0,
which fails.

It is hard to avoid creating them when linker scripts are used, so we
just delete empty PT_LOADs at the end.

llvm-svn: 288808
This commit is contained in:
Rafael Espindola 2016-12-06 13:43:34 +00:00
parent e633741c3a
commit 074ba93ceb
3 changed files with 27 additions and 13 deletions
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16
lld/ELF/Writer.cpp
View File

@ -62,6 +62,7 @@ private:
void addPredefinedSections();
std::vector<Phdr> createPhdrs();
void removeEmptyPTLoad();
void addPtArmExid(std::vector<Phdr> &Phdrs);
void assignAddresses();
void assignFileOffsets();
@ -134,6 +135,16 @@ template <class ELFT> static bool needsInterpSection() {
template <class ELFT> void elf::writeResult() { Writer<ELFT>().run(); }
template <class ELFT> void Writer<ELFT>::removeEmptyPTLoad() {
auto I = std::remove_if(Phdrs.begin(), Phdrs.end(), [&](const Phdr &P) {
if (P.H.p_type != PT_LOAD)
return false;
uintX_t Size = P.Last->Addr + P.Last->Size - P.First->Addr;
return Size == 0;
});
Phdrs.erase(I, Phdrs.end());
}
// The main function of the writer.
template <class ELFT> void Writer<ELFT>::run() {
// Create linker-synthesized sections such as .got or .plt.
@ -198,6 +209,11 @@ template <class ELFT> void Writer<ELFT>::run() {
assignAddresses();
}
// Remove empty PT_LOAD to avoid causing the dynamic linker to try to mmap a
// 0 sized region. This has to be done late since only after assignAddresses
// we know the size of the sections.
removeEmptyPTLoad();
if (!Config->OFormatBinary)
assignFileOffsets();
else

11
lld/test/ELF/empty-pt-load.s Normal file
View File

@ -0,0 +1,11 @@
// REQUIRES: x86
// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
// RUN: ld.lld %t.o -o %t.so -shared
// RUN: llvm-readobj -l --elf-output-style=GNU %t.so | FileCheck %s
// Test that we don't create an empty executable PT_LOAD.
// CHECK: PHDR {{.*}} R 0x8
// CHECK-NEXT: LOAD {{.*}} R 0x1000
// CHECK-NEXT: LOAD {{.*}} RW 0x1000
// CHECK-NEXT: DYNAMIC {{.*}} RW 0x8

13
lld/test/ELF/program-header-layout.s
View File

@ -61,19 +61,6 @@ _start:
# CHECK-NEXT: Offset:
# CHECK-NEXT: VirtualAddress:
# CHECK-NEXT: PhysicalAddress:
# CHECK-NEXT: FileSize: 0
# CHECK-NEXT: MemSize: 0
# 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:
# CHECK-NEXT: VirtualAddress:
# CHECK-NEXT: PhysicalAddress:
# CHECK-NEXT: FileSize: 16
# CHECK-NEXT: MemSize: 16
# CHECK-NEXT: Flags [