diff options
Diffstat (limited to 'linker/linker_phdr.cpp')
| -rw-r--r-- | linker/linker_phdr.cpp | 26 |
1 files changed, 22 insertions, 4 deletions
diff --git a/linker/linker_phdr.cpp b/linker/linker_phdr.cpp index 80f1ad9d4..fa712a10a 100644 --- a/linker/linker_phdr.cpp +++ b/linker/linker_phdr.cpp @@ -918,10 +918,28 @@ bool ElfReader::LoadSegments() { // 2) Break the COW backing, faulting in new anon pages for a region // that will not be used. - // _seg_file_end = unextended seg_file_end - uint64_t _seg_file_end = seg_start + phdr->p_filesz; - if ((phdr->p_flags & PF_W) != 0 && page_offset(_seg_file_end) > 0) { - memset(reinterpret_cast<void*>(_seg_file_end), 0, kPageSize - page_offset(_seg_file_end)); + uint64_t unextended_seg_file_end = seg_start + phdr->p_filesz; + if ((phdr->p_flags & PF_W) != 0 && page_offset(unextended_seg_file_end) > 0) { + memset(reinterpret_cast<void*>(unextended_seg_file_end), 0, + kPageSize - page_offset(unextended_seg_file_end)); + } + + // Pages may be brought in due to readahead. + // Drop the padding (zero) pages, to avoid reclaim work later. + // + // NOTE: The madvise() here is special, as it also serves to hint to the + // kernel the portion of the LOAD segment that is padding. + // + // See: [1] https://android-review.googlesource.com/c/kernel/common/+/3032411 + // [2] https://android-review.googlesource.com/c/kernel/common/+/3048835 + uint64_t pad_start = page_end(unextended_seg_file_end); + uint64_t pad_end = page_end(seg_file_end); + CHECK(pad_start <= pad_end); + uint64_t pad_len = pad_end - pad_start; + if (page_size_migration_supported() && pad_len > 0 && + madvise(reinterpret_cast<void*>(pad_start), pad_len, MADV_DONTNEED)) { + DL_WARN("\"%s\": madvise(0x%" PRIx64 ", 0x%" PRIx64 ", MADV_DONTNEED) failed: %m", + name_.c_str(), pad_start, pad_len); } seg_file_end = page_end(seg_file_end); |