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Accept sh_entsize = 0. 

This surfaced again with Rust. As per bug 30435, rustc creates a
mergeable section with a sh_entsize zero. It bit us before, too.
I think we should relax the input check rather than being too picky.

Differential Revision: https://reviews.llvm.org/D24789

llvm-svn: 282049
This commit is contained in:
Rui Ueyama 2016-09-21 03:22:18 +00:00
parent e3cef93727
commit c75ef85e84
3 changed files with 17 additions and 10 deletions
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16
lld/ELF/InputFiles.cpp
View File

@ -184,15 +184,23 @@ bool elf::ObjectFile<ELFT>::shouldMerge(const Elf_Shdr &Sec) {
if (Sec.sh_size == 0)
return false;
// Check for sh_entsize. The ELF spec is not clear about the zero
// sh_entsize. It says that "the member [sh_entsize] contains 0 if
// the section does not hold a table of fixed-size entries". We know
// that Rust 1.13 produces a string mergeable section with a zero
// sh_entsize. Here we just accept it rather than being picky about it.
uintX_t EntSize = Sec.sh_entsize;
if (EntSize == 0)
return false;
if (Sec.sh_size % EntSize)
fatal(getFilename(this) +
": SHF_MERGE section size must be a multiple of sh_entsize");
uintX_t Flags = Sec.sh_flags;
if (!(Flags & SHF_MERGE))
return false;
if (Flags & SHF_WRITE)
fatal(getFilename(this) + ": writable SHF_MERGE section is not supported");
uintX_t EntSize = Sec.sh_entsize;
if (!EntSize || Sec.sh_size % EntSize)
fatal(getFilename(this) +
": SHF_MERGE section size must be a multiple of sh_entsize");
// Don't try to merge if the alignment is larger than the sh_entsize and this
// is not SHF_STRINGS.

4
lld/test/ELF/invalid-elf.test
View File

@ -24,10 +24,6 @@
# RUN: FileCheck --check-prefix=INVALID-SECTION-INDEX %s
# INVALID-SECTION-INDEX: Invalid section index
# RUN: not ld.lld %p/Inputs/invalid-shentsize-zero.elf -o %t2 2>&1 | \
# RUN: FileCheck --check-prefix=INVALID-SHENTSIZE-ZERO %s
# INVALID-SHENTSIZE-ZERO: SHF_MERGE section size must be a multiple of sh_entsize
# RUN: not ld.lld %p/Inputs/invalid-multiple-eh-relocs.elf -o %t2 2>&1 | \
# RUN: FileCheck --check-prefix=INVALID-EH-RELOCS %s
# INVALID-EH-RELOCS: multiple relocation sections to .eh_frame are not supported

7
lld/test/ELF/merge-invalid-size.s
View File

@ -3,5 +3,8 @@
// RUN: not ld.lld %t.o -o %t.so 2>&1 | FileCheck %s
// CHECK: SHF_MERGE section size must be a multiple of sh_entsize
.section .foo,"aM",@progbits,4
.short 42
// Test that we accept a zero sh_entsize.
// RUN: ld.lld %p/Inputs/invalid-shentsize-zero.elf -o %t2
.section .foo,"aM",@progbits,4
.short 42