diff options
Diffstat (limited to 'meta/recipes-devtools/patchelf/patchelf/avoidholes.patch')
-rw-r--r-- | meta/recipes-devtools/patchelf/patchelf/avoidholes.patch | 163 |
1 files changed, 0 insertions, 163 deletions
diff --git a/meta/recipes-devtools/patchelf/patchelf/avoidholes.patch b/meta/recipes-devtools/patchelf/patchelf/avoidholes.patch deleted file mode 100644 index 0b45c39bda..0000000000 --- a/meta/recipes-devtools/patchelf/patchelf/avoidholes.patch +++ /dev/null @@ -1,163 +0,0 @@ -Different types of binaries create challenges for patchelf. In order to extend -sections they need to be moved within the binary. The current approach to -handling ET_DYN binaries is to move the INTERP section to the end of the file. -This means changing PT_PHDR to add an extra PT_LOAD section so that the new section -is mmaped into memory by the elf loader in the kernel. In order to extend PHDR, -this means moving it to the end of the file. - -Its documented in patchelf there is a kernel 'bug' which means that if you have holes -in memory between the base load address and the PT_LOAD segment that contains PHDR, -it will pass an incorrect PHDR address to ld.so and fail to load the binary, segfaulting. - -To avoid this, the code currently inserts space into the binary to ensure that when -loaded into memory there are no holes between the PT_LOAD sections. This inflates the -binaries by many MBs in some cases. Whilst we could make them sparse, there is a second -issue which is that strip can fail to process these binaries: - -$ strip fixincl -Not enough room for program headers, try linking with -N -[.note.ABI-tag]: Bad value - -This turns out to be due to libbfd not liking the relocated PHDR section either -(https://github.com/NixOS/patchelf/issues/10). - -Instead this patch implements a different approach, leaving PHDR where it is but extending -it in place to allow addition of a new PT_LOAD section. This overwrites sections in the -binary but those get moved to the end of the file in the new PT_LOAD section. - -This is based on patches linked from the above github issue, however whilst the idea -was good, the implementation wasn't correct and they've been rewritten here. - -RP -2017/3/7 - -Upstream-Status: Accepted - -Index: patchelf-0.9/src/patchelf.cc -=================================================================== ---- patchelf-0.9.orig/src/patchelf.cc -+++ patchelf-0.9/src/patchelf.cc -@@ -146,6 +146,8 @@ private: - string & replaceSection(const SectionName & sectionName, - unsigned int size); - -+ bool haveReplacedSection(const SectionName & sectionName); -+ - void writeReplacedSections(Elf_Off & curOff, - Elf_Addr startAddr, Elf_Off startOffset); - -@@ -497,6 +499,16 @@ unsigned int ElfFile<ElfFileParamNames>: - return 0; - } - -+template<ElfFileParams> -+bool ElfFile<ElfFileParamNames>::haveReplacedSection(const SectionName & sectionName) -+{ -+ ReplacedSections::iterator i = replacedSections.find(sectionName); -+ -+ if (i != replacedSections.end()) -+ return true; -+ return false; -+} -+ - - template<ElfFileParams> - string & ElfFile<ElfFileParamNames>::replaceSection(const SectionName & sectionName, -@@ -595,52 +607,52 @@ void ElfFile<ElfFileParamNames>::rewrite - - debug("last page is 0x%llx\n", (unsigned long long) startPage); - -+ /* Because we're adding a new section header, we're necessarily increasing -+ the size of the program header table. This can cause the first section -+ to overlap the program header table in memory; we need to shift the first -+ few segments to someplace else. */ -+ /* Some sections may already be replaced so account for that */ -+ unsigned int i = 1; -+ Elf_Addr pht_size = sizeof(Elf_Ehdr) + (phdrs.size() + 1)*sizeof(Elf_Phdr); -+ while( shdrs[i].sh_addr <= pht_size && i < rdi(hdr->e_shnum) ) { -+ if (not haveReplacedSection(getSectionName(shdrs[i]))) -+ replaceSection(getSectionName(shdrs[i]), shdrs[i].sh_size); -+ i++; -+ } - -- /* Compute the total space needed for the replaced sections and -- the program headers. */ -- off_t neededSpace = (phdrs.size() + 1) * sizeof(Elf_Phdr); -+ /* Compute the total space needed for the replaced sections */ -+ off_t neededSpace = 0; - for (ReplacedSections::iterator i = replacedSections.begin(); - i != replacedSections.end(); ++i) - neededSpace += roundUp(i->second.size(), sectionAlignment); - debug("needed space is %d\n", neededSpace); - -- - size_t startOffset = roundUp(fileSize, getPageSize()); - - growFile(startOffset + neededSpace); - -- - /* Even though this file is of type ET_DYN, it could actually be - an executable. For instance, Gold produces executables marked -- ET_DYN. In that case we can still hit the kernel bug that -- necessitated rewriteSectionsExecutable(). However, such -- executables also tend to start at virtual address 0, so -+ ET_DYN as does LD when linking with pie. If we move PT_PHDR, it -+ has to stay in the first PT_LOAD segment or any subsequent ones -+ if they're continuous in memory due to linux kernel constraints -+ (see BUGS). Since the end of the file would be after bss, we can't -+ move PHDR there, we therefore choose to leave PT_PHDR where it is but -+ move enough following sections such that we can add the extra PT_LOAD -+ section to it. This PT_LOAD segment ensures the sections at the end of -+ the file are mapped into memory for ld.so to process. -+ We can't use the approach in rewriteSectionsExecutable() -+ since DYN executables tend to start at virtual address 0, so - rewriteSectionsExecutable() won't work because it doesn't have -- any virtual address space to grow downwards into. As a -- workaround, make sure that the virtual address of our new -- PT_LOAD segment relative to the first PT_LOAD segment is equal -- to its offset; otherwise we hit the kernel bug. This may -- require creating a hole in the executable. The bigger the size -- of the uninitialised data segment, the bigger the hole. */ -+ any virtual address space to grow downwards into. */ - if (isExecutable) { - if (startOffset >= startPage) { - debug("shifting new PT_LOAD segment by %d bytes to work around a Linux kernel bug\n", startOffset - startPage); -- } else { -- size_t hole = startPage - startOffset; -- /* Print a warning, because the hole could be very big. */ -- fprintf(stderr, "warning: working around a Linux kernel bug by creating a hole of %zu bytes in ā%sā\n", hole, fileName.c_str()); -- assert(hole % getPageSize() == 0); -- /* !!! We could create an actual hole in the file here, -- but it's probably not worth the effort. */ -- growFile(fileSize + hole); -- startOffset += hole; - } - startPage = startOffset; - } - -- -- /* Add a segment that maps the replaced sections and program -- headers into memory. */ -+ /* Add a segment that maps the replaced sections into memory. */ - phdrs.resize(rdi(hdr->e_phnum) + 1); - wri(hdr->e_phnum, rdi(hdr->e_phnum) + 1); - Elf_Phdr & phdr = phdrs[rdi(hdr->e_phnum) - 1]; -@@ -653,15 +665,12 @@ void ElfFile<ElfFileParamNames>::rewrite - - - /* Write out the replaced sections. */ -- Elf_Off curOff = startOffset + phdrs.size() * sizeof(Elf_Phdr); -+ Elf_Off curOff = startOffset; - writeReplacedSections(curOff, startPage, startOffset); - assert(curOff == startOffset + neededSpace); - -- -- /* Move the program header to the start of the new area. */ -- wri(hdr->e_phoff, startOffset); -- -- rewriteHeaders(startPage); -+ /* Write out the updated program and section headers */ -+ rewriteHeaders(hdr->e_phoff); - } - - |