Date: Thu, 5 Sep 2019 17:53:42 +0000 (UTC) From: Dimitry Andric <dim@FreeBSD.org> To: src-committers@freebsd.org, svn-src-projects@freebsd.org Subject: svn commit: r351879 - projects/clang900-import/contrib/llvm/tools/lld/ELF Message-ID: <201909051753.x85HrgAi036673@repo.freebsd.org>
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Author: dim Date: Thu Sep 5 17:53:41 2019 New Revision: 351879 URL: https://svnweb.freebsd.org/changeset/base/351879 Log: Pull in r369828 from upstream lld trunk (by Fāng-ruì Sòng): [ELF] Align the first section of a PT_LOAD even if its type is SHT_NOBITS Reported at https://reviews.llvm.org/D64930#1642223 If the only section of a PT_LOAD is a SHT_NOBITS section (e.g. .bss), we may not align its sh_offset. p_offset of the PT_LOAD will be set to sh_offset, and we will get p_offset!=p_vaddr (mod p_align). If such executable is mapped by the Linux kernel, it will segfault. After D64906, this may happen the non-linker script case. The linker script case has had this issue for a long time. This was fixed by rL321657 (but the test linkerscript/nobits-offset.s failed to test a SHT_NOBITS section), but broken by rL345154. Reviewed By: peter.smith Differential Revision: https://reviews.llvm.org/D66658 Pull in r371013 from upstream lld trunk (by Rui Ueyama): Align output segments correctly Previously, segments were aligned according to their first section's alignment requirements. That was not correct, but segments are also aligned to a page boundary, and a page boundary is usually much larger than a section alignment requirement, so no one noticed this bug before. Now, lld has --nmagic option which sets maxPageSize to 1 to effectively disable page alignment, which reveals the issue. Fixes https://bugs.llvm.org/show_bug.cgi?id=43212 Differential Revision: https://reviews.llvm.org/D67152 Together, these should ensure gpboot.out gets a correctly aligned offset for its .rodata section, and fix "layout constraint violation" errors from objcopy. Modified: projects/clang900-import/contrib/llvm/tools/lld/ELF/Writer.cpp Modified: projects/clang900-import/contrib/llvm/tools/lld/ELF/Writer.cpp ============================================================================== --- projects/clang900-import/contrib/llvm/tools/lld/ELF/Writer.cpp Thu Sep 5 17:48:39 2019 (r351878) +++ projects/clang900-import/contrib/llvm/tools/lld/ELF/Writer.cpp Thu Sep 5 17:53:41 2019 (r351879) @@ -2230,25 +2230,27 @@ template <class ELFT> void Writer<ELFT>::fixSectionAli // same with its virtual address modulo the page size, so that the loader can // load executables without any address adjustment. static uint64_t computeFileOffset(OutputSection *os, uint64_t off) { - // File offsets are not significant for .bss sections. By convention, we keep - // section offsets monotonically increasing rather than setting to zero. - if (os->type == SHT_NOBITS) - return off; - - // If the section is not in a PT_LOAD, we just have to align it. - if (!os->ptLoad) - return alignTo(off, os->alignment); - // The first section in a PT_LOAD has to have congruent offset and address // module the page size. - OutputSection *first = os->ptLoad->firstSec; - if (os == first) { - uint64_t alignment = std::max<uint64_t>(os->alignment, config->maxPageSize); + if (os->ptLoad && os->ptLoad->firstSec == os) { + uint64_t alignment = + std::max<uint64_t>(os->ptLoad->p_align, config->maxPageSize); return alignTo(off, alignment, os->addr); } + // File offsets are not significant for .bss sections other than the first one + // in a PT_LOAD. By convention, we keep section offsets monotonically + // increasing rather than setting to zero. + if (os->type == SHT_NOBITS) + return off; + + // If the section is not in a PT_LOAD, we just have to align it. + if (!os->ptLoad) + return alignTo(off, os->alignment); + // If two sections share the same PT_LOAD the file offset is calculated // using this formula: Off2 = Off1 + (VA2 - VA1). + OutputSection *first = os->ptLoad->firstSec; return first->offset + os->addr - first->addr; }
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