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Use the largest segment alignment for libraries requiring non-standard alignments #474 #475

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merged 2 commits into from
Mar 11, 2023
Merged

Use the largest segment alignment for libraries requiring non-standard alignments #474 #475

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9f1c0af
Set the alignment of the new LOAD segment the same as others
brenoguim Mar 7, 2023
80f6866
Filter with awk instead of grep
brenoguim Mar 8, 2023
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2 changes: 1 addition & 1 deletion .github/workflows/publish.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -89,7 +89,7 @@ jobs:
rm -f dist/*
cd patchelf-*
./configure --prefix /patchelf
make check
make check || (cat tests/test-suite.log; exit 1)
make install-strip
cd -
tar -czf ./dist/patchelf-\$(cat patchelf-*/version)-\$(uname -m).tar.gz -C /patchelf .
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11 changes: 8 additions & 3 deletions src/patchelf.cc
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Expand Up @@ -800,12 +800,17 @@ void ElfFile<ElfFileParamNames>::rewriteSectionsLibrary()
page of other segments. */
Elf_Addr startPage = 0;
Elf_Addr firstPage = 0;
unsigned alignStartPage = getPageSize();
for (auto & phdr : phdrs) {
Elf_Addr thisPage = roundUp(rdi(phdr.p_vaddr) + rdi(phdr.p_memsz), getPageSize());
Elf_Addr thisPage = rdi(phdr.p_vaddr) + rdi(phdr.p_memsz);
if (thisPage > startPage) startPage = thisPage;
if (rdi(phdr.p_type) == PT_PHDR) firstPage = rdi(phdr.p_vaddr) - rdi(phdr.p_offset);
unsigned thisAlign = rdi(phdr.p_align);
alignStartPage = std::max(alignStartPage, thisAlign);
}

startPage = roundUp(startPage, alignStartPage);

debug("last page is 0x%llx\n", (unsigned long long) startPage);
debug("first page is 0x%llx\n", (unsigned long long) firstPage);

Expand Down Expand Up @@ -873,7 +878,7 @@ void ElfFile<ElfFileParamNames>::rewriteSectionsLibrary()
if (!phdrs.empty() &&
rdi(lastSeg.p_type) == PT_LOAD &&
rdi(lastSeg.p_flags) == (PF_R | PF_W) &&
rdi(lastSeg.p_align) == getPageSize()) {
rdi(lastSeg.p_align) == alignStartPage) {
auto segEnd = roundUp(rdi(lastSeg.p_offset) + rdi(lastSeg.p_memsz), getPageSize());
if (segEnd == startOffset) {
auto newSz = startOffset + neededSpace - rdi(lastSeg.p_offset);
Expand All @@ -892,7 +897,7 @@ void ElfFile<ElfFileParamNames>::rewriteSectionsLibrary()
wri(phdr.p_vaddr, wri(phdr.p_paddr, startPage));
wri(phdr.p_filesz, wri(phdr.p_memsz, neededSpace));
wri(phdr.p_flags, PF_R | PF_W);
wri(phdr.p_align, getPageSize());
wri(phdr.p_align, alignStartPage);
}

normalizeNoteSegments();
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5 changes: 4 additions & 1 deletion tests/Makefile.am
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Expand Up @@ -119,7 +119,7 @@ check_DATA = libbig-dynstr.debug
# - with libtool, it is difficult to control options
# - with libtool, it is not possible to compile convenience *dynamic* libraries :-(
check_PROGRAMS += libfoo.so libfoo-scoped.so libbar.so libbar-scoped.so libsimple.so libsimple-execstack.so libbuildid.so libtoomanystrtab.so \
phdr-corruption.so many-syms-main libmany-syms.so
phdr-corruption.so many-syms-main libmany-syms.so liboveralign.so

libbuildid_so_SOURCES = simple.c
libbuildid_so_LDFLAGS = $(LDFLAGS_sharedlib) -Wl,--build-id
Expand All @@ -143,6 +143,9 @@ libbar_scoped_so_LDFLAGS = $(LDFLAGS_sharedlib)
libsimple_so_SOURCES = simple.c
libsimple_so_LDFLAGS = $(LDFLAGS_sharedlib) -Wl,-z,noexecstack

liboveralign_so_SOURCES = simple.c
liboveralign_so_LDFLAGS = $(LDFLAGS_sharedlib) -Wl,-z,max-page-size=0x10000

libsimple_execstack_so_SOURCES = simple.c
libsimple_execstack_so_LDFLAGS = $(LDFLAGS_sharedlib) -Wl,-z,execstack

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10 changes: 10 additions & 0 deletions tests/set-rpath-library.sh
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Expand Up @@ -14,6 +14,7 @@ mkdir -p "${SCRATCH}/libsB"
cp main-scoped "${SCRATCH}/"
cp libfoo-scoped.so "${SCRATCH}/libsA/"
cp libbar-scoped.so "${SCRATCH}/libsB/"
cp liboveralign.so "${SCRATCH}/"

oldRPath=$(../src/patchelf --print-rpath "${SCRATCH}"/main-scoped)
if test -z "$oldRPath"; then oldRPath="/oops"; fi
Expand Down Expand Up @@ -56,3 +57,12 @@ if test "$exitCode" != 46; then
echo "bad exit code!"
exit 1
fi

# ALL loads should have the same alignment
lib="${SCRATCH}/liboveralign.so"
../src/patchelf --set-rpath "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" "$lib"
num_alignments=$(${READELF} -W -l "${lib}" | awk '/LOAD/ { print $NF }' | sort -u | wc -l)
echo "$num_alignments"
if test "${num_alignments}" -ne "1"; then
exit 1
fi