Bionic: Mark PMD aligned text segments huge page eligible
To take advantage of file-backed huge pages for the text segments of key
shared libraries (go/android-hugepages), the dynamic linker must load
candidate ELF files at an appropriately aligned address and mark
executable segments with MADV_HUGEPAGE.
This patches uses segments' p_align values to determine when a file is
PMD aligned (2MB alignment), and performs load operations accordingly.
Bug: 158135888
Test: Verified PMD aligned libraries are backed with huge pages on
supporting kernel versions.
Change-Id: Ia2367fd5652f663d50103e18f7695c59dc31c7b9
diff --git a/linker/linker_phdr.h b/linker/linker_phdr.h
index 548dc51..98bf020 100644
--- a/linker/linker_phdr.h
+++ b/linker/linker_phdr.h
@@ -120,6 +120,8 @@
size_t phdr_table_get_load_size(const ElfW(Phdr)* phdr_table, size_t phdr_count,
ElfW(Addr)* min_vaddr = nullptr, ElfW(Addr)* max_vaddr = nullptr);
+size_t phdr_table_get_maximum_alignment(const ElfW(Phdr)* phdr_table, size_t phdr_count);
+
int phdr_table_protect_segments(const ElfW(Phdr)* phdr_table, size_t phdr_count,
ElfW(Addr) load_bias, const GnuPropertySection* prop = nullptr);