From 32bd10b1a33df2cc4d067a16901d56665f4ba085 Mon Sep 17 00:00:00 2001 From: Andrew Kaylor Date: Mon, 19 Aug 2013 19:38:06 +0000 Subject: [PATCH] Adding comments to document RuntimeDyld relocation handling git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188697 91177308-0d34-0410-b5e6-96231b3b80d8 --- .../RuntimeDyld/RuntimeDyld.cpp | 3 +++ .../RuntimeDyld/RuntimeDyldELF.cpp | 22 ++++++++++++++++++- .../RuntimeDyld/RuntimeDyldMachO.cpp | 20 +++++++++++++++++ 3 files changed, 44 insertions(+), 1 deletion(-) diff --git a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp index 943622fba87..a00b951e0a8 100644 --- a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp +++ b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp @@ -41,6 +41,9 @@ void RuntimeDyldImpl::resolveRelocations() { // Just iterate over the sections we have and resolve all the relocations // in them. Gross overkill, but it gets the job done. for (int i = 0, e = Sections.size(); i != e; ++i) { + // The Section here (Sections[i]) refers to the section in which the + // symbol for the relocation is located. The SectionID in the relocation + // entry provides the section to which the relocation will be applied. uint64_t Addr = Sections[i].LoadAddress; DEBUG(dbgs() << "Resolving relocations Section #" << i << "\t" << format("%p", (uint8_t *)Addr) diff --git a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp index 16fd52de590..6ce4f672bf8 100644 --- a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp +++ b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp @@ -734,8 +734,28 @@ void RuntimeDyldELF::resolveSystemZRelocation(const SectionEntry &Section, } } +// The target location for the relocation is described by RE.SectionID and +// RE.Offset. RE.SectionID can be used to find the SectionEntry. Each +// SectionEntry has three members describing its location. +// SectionEntry::Address is the address at which the section has been loaded +// into memory in the current (host) process. SectionEntry::LoadAddress is the +// address that the section will have in the target process. +// SectionEntry::ObjAddress is the address of the bits for this section in the +// original emitted object image (also in the current address space). +// +// Relocations will be applied as if the section were loaded at +// SectionEntry::LoadAddress, but they will be applied at an address based +// on SectionEntry::Address. SectionEntry::ObjAddress will be used to refer to +// Target memory contents if they are required for value calculations. +// +// The Value parameter here is the load address of the symbol for the +// relocation to be applied. For relocations which refer to symbols in the +// current object Value will be the LoadAddress of the section in which +// the symbol resides (RE.Addend provides additional information about the +// symbol location). For external symbols, Value will be the address of the +// symbol in the target address space. void RuntimeDyldELF::resolveRelocation(const RelocationEntry &RE, - uint64_t Value) { + uint64_t Value) { const SectionEntry &Section = Sections[RE.SectionID]; return resolveRelocation(Section, RE.Offset, Value, RE.RelType, RE.Addend); } diff --git a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp index a2320584d19..2f4df6b9622 100644 --- a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp +++ b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp @@ -84,6 +84,26 @@ StringRef RuntimeDyldMachO::getEHFrameSection() { return StringRef((char*)EHFrame->Address, EHFrame->Size); } +// The target location for the relocation is described by RE.SectionID and +// RE.Offset. RE.SectionID can be used to find the SectionEntry. Each +// SectionEntry has three members describing its location. +// SectionEntry::Address is the address at which the section has been loaded +// into memory in the current (host) process. SectionEntry::LoadAddress is the +// address that the section will have in the target process. +// SectionEntry::ObjAddress is the address of the bits for this section in the +// original emitted object image (also in the current address space). +// +// Relocations will be applied as if the section were loaded at +// SectionEntry::LoadAddress, but they will be applied at an address based +// on SectionEntry::Address. SectionEntry::ObjAddress will be used to refer to +// Target memory contents if they are required for value calculations. +// +// The Value parameter here is the load address of the symbol for the +// relocation to be applied. For relocations which refer to symbols in the +// current object Value will be the LoadAddress of the section in which +// the symbol resides (RE.Addend provides additional information about the +// symbol location). For external symbols, Value will be the address of the +// symbol in the target address space. void RuntimeDyldMachO::resolveRelocation(const RelocationEntry &RE, uint64_t Value) { const SectionEntry &Section = Sections[RE.SectionID]; -- 2.34.1