Set the alignment of the new LOAD segment the same as others

Author: brenoguim

src/patchelf.cc

@@ -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);
 
@@ -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);
@@ -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();

tests/Makefile.am

@@ -55,7 +55,7 @@ build_TESTS = \
 
 TESTS = $(src_TESTS) $(build_TESTS)
 
-EXTRA_DIST = no-rpath-prebuild $(src_TESTS) no-rpath-prebuild.sh invalid-elf endianness empty-note
+EXTRA_DIST = no-rpath-prebuild $(src_TESTS) no-rpath-prebuild.sh invalid-elf endianness empty-note libnon-default-alignment.so.zip
 
 TESTS_ENVIRONMENT = PATCHELF_DEBUG=1 STRIP=$(STRIP) OBJDUMP=$(OBJDUMP) READELF=$(READELF) OBJCOPY=$(OBJCOPY)
 

tests/libnon-default-alignment.so.zip

@@ -10,10 +10,13 @@ rm -rf "${SCRATCH}"
 mkdir -p "${SCRATCH}"
 mkdir -p "${SCRATCH}/libsA"
 mkdir -p "${SCRATCH}/libsB"
+mkdir -p "${SCRATCH}/libnon-default-alignment"
 
 cp main-scoped "${SCRATCH}/"
 cp libfoo-scoped.so "${SCRATCH}/libsA/"
 cp libbar-scoped.so "${SCRATCH}/libsB/"
+cp ../../tests/libnon-default-alignment.so.zip "${SCRATCH}/libnon-default-alignment/"
+(cd "${SCRATCH}/libnon-default-alignment/"; unzip libnon-default-alignment.so.zip)
 
 oldRPath=$(../src/patchelf --print-rpath "${SCRATCH}"/main-scoped)
 if test -z "$oldRPath"; then oldRPath="/oops"; fi
@@ -56,3 +59,12 @@ if test "$exitCode" != 46; then
     echo "bad exit code!"
     exit 1
 fi
+
+# ALL loads should have the same alignment
+lib="${SCRATCH}/libnon-default-alignment/libnon-default-alignment.so"
+../src/patchelf --set-rpath "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" "$lib"
+num_alignments=$(${READELF} -W -l "${lib}"  | grep LOAD | awk '{ print $NF }' | sort -u | wc -l)
+echo "$num_alignments"
+if test "${num_alignments}" -ne "1"; then
+    exit 1
+fi