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Merge changes from topic "pgsize_compat_loader" into main am: 403ea86b2e

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Original change: https://android-review.googlesource.com/c/platform/bionic/+/3006239

Change-Id: I87ae5645545a7a116be0fae34814ea93eafaed54
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
This commit is contained in:
Kalesh Singh 2024-05-02 19:54:54 +00:00 committed by Automerger Merge Worker
commit 472cb3a522
1 changed files with 22 additions and 4 deletions
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26
linker/linker_phdr.cpp
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@ -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);