From f7a17448034721548bf26884df9349acd6e149a2 Mon Sep 17 00:00:00 2001 From: Rafael Espindola Date: Mon, 14 Nov 2016 15:39:38 +0000 Subject: [PATCH] Fix program header propagation. Propagate program headers by walking the commands, not the sections. This allows us to propagate program headers even from sections that don't end up in the output. Fixes pr30997. llvm-svn: 286837 --- lld/ELF/LinkerScript.cpp | 48 ++++++++++++++-------- lld/ELF/LinkerScript.h | 1 + lld/ELF/Writer.cpp | 2 + .../Inputs/implicit-program-header.script | 12 ++++++ .../ELF/linkerscript/implicit-program-header.s | 13 ++++++ 5 files changed, 58 insertions(+), 18 deletions(-) create mode 100644 lld/test/ELF/linkerscript/Inputs/implicit-program-header.script create mode 100644 lld/test/ELF/linkerscript/implicit-program-header.s diff --git a/lld/ELF/LinkerScript.cpp b/lld/ELF/LinkerScript.cpp index 2cf088e..c8ca74a 100644 --- a/lld/ELF/LinkerScript.cpp +++ b/lld/ELF/LinkerScript.cpp @@ -563,6 +563,35 @@ template void LinkerScript::adjustSectionsBeforeSorting() { auto *OutSec = make>(Cmd->Name, Type, Flags); OutputSections->push_back(OutSec); } +} + +template void LinkerScript::adjustSectionsAfterSorting() { + placeOrphanSections(); + + // If output section command doesn't specify any segments, + // and we haven't previously assigned any section to segment, + // then we simply assign section to the very first load segment. + // Below is an example of such linker script: + // PHDRS { seg PT_LOAD; } + // SECTIONS { .aaa : { *(.aaa) } } + std::vector DefPhdrs; + auto FirstPtLoad = + std::find_if(Opt.PhdrsCommands.begin(), Opt.PhdrsCommands.end(), + [](const PhdrsCommand &Cmd) { return Cmd.Type == PT_LOAD; }); + if (FirstPtLoad != Opt.PhdrsCommands.end()) + DefPhdrs.push_back(FirstPtLoad->Name); + + // Walk the commands and propagate the program headers to commands that don't + // explicitly specify them. + for (const std::unique_ptr &Base : Opt.Commands) { + auto *Cmd = dyn_cast(Base.get()); + if (!Cmd) + continue; + if (Cmd->Phdrs.empty()) + Cmd->Phdrs = DefPhdrs; + else + DefPhdrs = Cmd->Phdrs; + } removeEmptyCommands(); } @@ -630,8 +659,6 @@ void LinkerScript::placeOrphanSections() { template void LinkerScript::assignAddresses(std::vector> &Phdrs) { - placeOrphanSections(); - // Assign addresses as instructed by linker script SECTIONS sub-commands. Dot = 0; @@ -711,7 +738,6 @@ std::vector> LinkerScript::createPhdrs() { // Process PHDRS and FILEHDR keywords because they are not // real output sections and cannot be added in the following loop. - std::vector DefPhdrIds; for (const PhdrsCommand &Cmd : Opt.PhdrsCommands) { Ret.emplace_back(Cmd.Type, Cmd.Flags == UINT_MAX ? PF_R : Cmd.Flags); PhdrEntry &Phdr = Ret.back(); @@ -725,15 +751,6 @@ std::vector> LinkerScript::createPhdrs() { Phdr.H.p_paddr = Cmd.LMAExpr(0); Phdr.HasLMA = true; } - - // If output section command doesn't specify any segments, - // and we haven't previously assigned any section to segment, - // then we simply assign section to the very first load segment. - // Below is an example of such linker script: - // PHDRS { seg PT_LOAD; } - // SECTIONS { .aaa : { *(.aaa) } } - if (DefPhdrIds.empty() && Phdr.H.p_type == PT_LOAD) - DefPhdrIds.push_back(Ret.size() - 1); } // Add output sections to program headers. @@ -741,17 +758,12 @@ std::vector> LinkerScript::createPhdrs() { if (!(Sec->Flags & SHF_ALLOC)) break; - std::vector PhdrIds = getPhdrIndices(Sec->getName()); - if (PhdrIds.empty()) - PhdrIds = std::move(DefPhdrIds); - // Assign headers specified by linker script - for (size_t Id : PhdrIds) { + for (size_t Id : getPhdrIndices(Sec->getName())) { Ret[Id].add(Sec); if (Opt.PhdrsCommands[Id].Flags == UINT_MAX) Ret[Id].H.p_flags |= Sec->getPhdrFlags(); } - DefPhdrIds = std::move(PhdrIds); } return Ret; } diff --git a/lld/ELF/LinkerScript.h b/lld/ELF/LinkerScript.h index 6bd02f1..ce64526 100644 --- a/lld/ELF/LinkerScript.h +++ b/lld/ELF/LinkerScript.h @@ -221,6 +221,7 @@ public: void createSections(OutputSectionFactory &Factory); void removeEmptyCommands(); void adjustSectionsBeforeSorting(); + void adjustSectionsAfterSorting(); std::vector> createPhdrs(); bool ignoreInterpSection(); diff --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp index 9776f62..2117e47 100644 --- a/lld/ELF/Writer.cpp +++ b/lld/ELF/Writer.cpp @@ -856,6 +856,8 @@ template void Writer::sortSections() { std::rotate(BestPos, NonScriptI, NonScriptI + 1); ++NonScriptI; } + + Script::X->adjustSectionsAfterSorting(); } // Create output section objects and add them to OutputSections. diff --git a/lld/test/ELF/linkerscript/Inputs/implicit-program-header.script b/lld/test/ELF/linkerscript/Inputs/implicit-program-header.script new file mode 100644 index 0000000..27dbea8 --- /dev/null +++ b/lld/test/ELF/linkerscript/Inputs/implicit-program-header.script @@ -0,0 +1,12 @@ +PHDRS +{ + ph_write PT_LOAD FLAGS(2); + ph_exec PT_LOAD FLAGS(1); +} + +SECTIONS +{ + .bar : { *(.bar) } : ph_exec + .foo : { *(.foo) } + .text : { *(.text) } : ph_write +} diff --git a/lld/test/ELF/linkerscript/implicit-program-header.s b/lld/test/ELF/linkerscript/implicit-program-header.s new file mode 100644 index 0000000..9598a6a --- /dev/null +++ b/lld/test/ELF/linkerscript/implicit-program-header.s @@ -0,0 +1,13 @@ +# REQUIRES: x86 +# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o +# RUN: ld.lld -o %t1 --script %S/Inputs/implicit-program-header.script \ +# RUN: %t.o -shared +# RUN: llvm-readobj -elf-output-style=GNU -l %t1 | FileCheck %s + +# CHECK: Segment Sections... +# CHECK-NEXT: 00 .text .dynsym .hash .dynstr .dynamic +# CHECK-NEXT: 01 .foo + +.quad 0 +.section .foo,"ax" +.quad 0 -- 2.7.4