Reduce p_align for program header to page size.
Having p_align > page_size leads to the situation when striping
packed executables results in unnecessary p_vaddr adjustments.
And it also may result (with probability 1 - 1/sizeof(uintptr_t)) in
misaligned segments following .dynstr
Bug: http://b/20629834
Bug: http://b/18051137
Change-Id: I1c5da4911e4409d63cb09f6b6b0a16ef54f6501b
diff --git a/tools/relocation_packer/src/elf_file.cc b/tools/relocation_packer/src/elf_file.cc
index c8ddde6..6ac9deb 100644
--- a/tools/relocation_packer/src/elf_file.cc
+++ b/tools/relocation_packer/src/elf_file.cc
@@ -37,11 +37,13 @@
static constexpr uint32_t SHT_ANDROID_REL = SHT_LOOS + 1;
static constexpr uint32_t SHT_ANDROID_RELA = SHT_LOOS + 2;
+static const size_t kPageSize = 4096;
+
// Alignment to preserve, in bytes. This must be at least as large as the
// largest d_align and sh_addralign values found in the loaded file.
// Out of caution for RELRO page alignment, we preserve to a complete target
// page. See http://www.airs.com/blog/archives/189.
-static constexpr size_t kPreserveAlignment = 4096;
+static const size_t kPreserveAlignment = kPageSize;
// Get section data. Checks that the section has exactly one data entry,
// so that the section size and the data size are the same. True in
@@ -318,9 +320,13 @@
} else {
program_header->p_vaddr -= hole_size;
program_header->p_paddr -= hole_size;
+ if (program_header->p_align > kPageSize) {
+ program_header->p_align = kPageSize;
+ }
VLOG(1) << "phdr[" << i
<< "] p_vaddr adjusted to "<< program_header->p_vaddr
- << "; p_paddr adjusted to "<< program_header->p_paddr;
+ << "; p_paddr adjusted to "<< program_header->p_paddr
+ << "; p_align adjusted to "<< program_header->p_align;
}
}
}
diff --git a/tools/relocation_packer/test_data/elf_file_unittest_relocs_arm64_packed.so b/tools/relocation_packer/test_data/elf_file_unittest_relocs_arm64_packed.so
index a2b0039..ed85ce1 100755
--- a/tools/relocation_packer/test_data/elf_file_unittest_relocs_arm64_packed.so
+++ b/tools/relocation_packer/test_data/elf_file_unittest_relocs_arm64_packed.so
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