Revert "RELAND: bionic: loader: Extend LOAD segment VMAs"
Revert submission 2966884
Reason for revert: b/328266487
Reverted changes: /q/submissionid:2966884
Bug: 328266487
Change-Id: I45a2c5888eefab36c069f992de00ec8c87105288
diff --git a/linker/linker_phdr.cpp b/linker/linker_phdr.cpp
index 07b54c5..82b37a4 100644
--- a/linker/linker_phdr.cpp
+++ b/linker/linker_phdr.cpp
@@ -46,8 +46,6 @@
#include "private/CFIShadow.h" // For kLibraryAlignment
#include "private/elf_note.h"
-#include <procinfo/process_map.h>
-
static int GetTargetElfMachine() {
#if defined(__arm__)
return EM_ARM;
@@ -198,7 +196,7 @@
// For Armv8.5-A loaded executable segments may require PROT_BTI.
if (note_gnu_property_.IsBTICompatible()) {
did_load_ = (phdr_table_protect_segments(phdr_table_, phdr_num_, load_bias_,
- should_pad_segments_, ¬e_gnu_property_) == 0);
+ ¬e_gnu_property_) == 0);
}
#endif
}
@@ -758,41 +756,6 @@
return true;
}
-static inline void _extend_load_segment_vma(const ElfW(Phdr)* phdr_table, size_t phdr_count,
- size_t phdr_idx, ElfW(Addr)* p_memsz,
- ElfW(Addr)* p_filesz, bool should_pad_segments) {
- const ElfW(Phdr)* phdr = &phdr_table[phdr_idx];
- const ElfW(Phdr)* next = nullptr;
- size_t next_idx = phdr_idx + 1;
-
- if (phdr->p_align == kPageSize || !should_pad_segments) {
- return;
- }
-
- if (next_idx < phdr_count && phdr_table[next_idx].p_type == PT_LOAD) {
- next = &phdr_table[next_idx];
- }
-
- // If this is the last LOAD segment, no extension is needed
- if (!next || *p_memsz != *p_filesz) {
- return;
- }
-
- ElfW(Addr) next_start = page_start(next->p_vaddr);
- ElfW(Addr) curr_end = page_end(phdr->p_vaddr + *p_memsz);
-
- // If adjacent segment mappings overlap, no extension is needed.
- if (curr_end >= next_start) {
- return;
- }
-
- // Extend the LOAD segment mapping to be contiguous with that of
- // the next LOAD segment.
- ElfW(Addr) extend = next_start - curr_end;
- *p_memsz += extend;
- *p_filesz += extend;
-}
-
bool ElfReader::LoadSegments() {
for (size_t i = 0; i < phdr_num_; ++i) {
const ElfW(Phdr)* phdr = &phdr_table_[i];
@@ -801,22 +764,18 @@
continue;
}
- ElfW(Addr) p_memsz = phdr->p_memsz;
- ElfW(Addr) p_filesz = phdr->p_filesz;
- _extend_load_segment_vma(phdr_table_, phdr_num_, i, &p_memsz, &p_filesz, should_pad_segments_);
-
// Segment addresses in memory.
ElfW(Addr) seg_start = phdr->p_vaddr + load_bias_;
- ElfW(Addr) seg_end = seg_start + p_memsz;
+ ElfW(Addr) seg_end = seg_start + phdr->p_memsz;
ElfW(Addr) seg_page_start = page_start(seg_start);
ElfW(Addr) seg_page_end = page_end(seg_end);
- ElfW(Addr) seg_file_end = seg_start + p_filesz;
+ ElfW(Addr) seg_file_end = seg_start + phdr->p_filesz;
// File offsets.
ElfW(Addr) file_start = phdr->p_offset;
- ElfW(Addr) file_end = file_start + p_filesz;
+ ElfW(Addr) file_end = file_start + phdr->p_filesz;
ElfW(Addr) file_page_start = page_start(file_start);
ElfW(Addr) file_length = file_end - file_page_start;
@@ -826,12 +785,12 @@
return false;
}
- if (file_start + phdr->p_filesz > static_cast<size_t>(file_size_)) {
+ if (file_end > static_cast<size_t>(file_size_)) {
DL_ERR("invalid ELF file \"%s\" load segment[%zd]:"
" p_offset (%p) + p_filesz (%p) ( = %p) past end of file (0x%" PRIx64 ")",
name_.c_str(), i, reinterpret_cast<void*>(phdr->p_offset),
reinterpret_cast<void*>(phdr->p_filesz),
- reinterpret_cast<void*>(file_start + phdr->p_filesz), file_size_);
+ reinterpret_cast<void*>(file_end), file_size_);
return false;
}
@@ -869,25 +828,10 @@
}
}
- // if the segment is writable, and its memory map extends beyond
- // the segment contents on file (p_filesz); zero-fill it until the
- // end of the mapping backed by the file, rounded to the next
- // page boundary; as this portion of the mapping corresponds to either
- // garbage (partial page at the end) or data from other segments.
- //
- // If any part of the mapping extends beyond the file size there is
- // no need to zero it since that region is not touchable by userspace
- // and attempting to do so will causes the kernel to throw a SIGBUS.
- //
- // See: system/libprocinfo/include/procinfo/process_map_size.h
- uint64_t file_backed_size = ::android::procinfo::MappedFileSize(seg_page_start,
- page_end(seg_page_start + file_length),
- file_offset_ + file_page_start, file_size_);
- // _seg_file_end = unextended seg_file_end
- uint64_t _seg_file_end = seg_start + phdr->p_filesz;
- uint64_t zero_fill_len = file_backed_size - (_seg_file_end - seg_page_start);
- if ((phdr->p_flags & PF_W) != 0 && zero_fill_len > 0) {
- memset(reinterpret_cast<void*>(_seg_file_end), 0, zero_fill_len);
+ // if the segment is writable, and does not end on a page boundary,
+ // zero-fill it until the page limit.
+ if ((phdr->p_flags & PF_W) != 0 && page_offset(seg_file_end) > 0) {
+ memset(reinterpret_cast<void*>(seg_file_end), 0, page_size() - page_offset(seg_file_end));
}
seg_file_end = page_end(seg_file_end);
@@ -920,21 +864,17 @@
* phdr_table_protect_segments and phdr_table_unprotect_segments.
*/
static int _phdr_table_set_load_prot(const ElfW(Phdr)* phdr_table, size_t phdr_count,
- ElfW(Addr) load_bias, int extra_prot_flags,
- bool should_pad_segments) {
- for (size_t i = 0; i < phdr_count; ++i) {
- const ElfW(Phdr)* phdr = &phdr_table[i];
+ ElfW(Addr) load_bias, int extra_prot_flags) {
+ const ElfW(Phdr)* phdr = phdr_table;
+ const ElfW(Phdr)* phdr_limit = phdr + phdr_count;
+ for (; phdr < phdr_limit; phdr++) {
if (phdr->p_type != PT_LOAD || (phdr->p_flags & PF_W) != 0) {
continue;
}
- ElfW(Addr) p_memsz = phdr->p_memsz;
- ElfW(Addr) p_filesz = phdr->p_filesz;
- _extend_load_segment_vma(phdr_table, phdr_count, i, &p_memsz, &p_filesz, should_pad_segments);
-
- ElfW(Addr) seg_page_start = page_start(phdr->p_vaddr + load_bias);
- ElfW(Addr) seg_page_end = page_end(phdr->p_vaddr + p_memsz + load_bias);
+ ElfW(Addr) seg_page_start = page_start(phdr->p_vaddr) + load_bias;
+ ElfW(Addr) seg_page_end = page_end(phdr->p_vaddr + phdr->p_memsz) + load_bias;
int prot = PFLAGS_TO_PROT(phdr->p_flags) | extra_prot_flags;
if ((prot & PROT_WRITE) != 0) {
@@ -969,21 +909,19 @@
* phdr_table -> program header table
* phdr_count -> number of entries in tables
* load_bias -> load bias
- * should_pad_segments -> Are segments extended to avoid gaps in the memory map
* prop -> GnuPropertySection or nullptr
* Return:
* 0 on success, -1 on failure (error code in errno).
*/
int phdr_table_protect_segments(const ElfW(Phdr)* phdr_table, size_t phdr_count,
- ElfW(Addr) load_bias, bool should_pad_segments,
- const GnuPropertySection* prop __unused) {
+ ElfW(Addr) load_bias, const GnuPropertySection* prop __unused) {
int prot = 0;
#if defined(__aarch64__)
if ((prop != nullptr) && prop->IsBTICompatible()) {
prot |= PROT_BTI;
}
#endif
- return _phdr_table_set_load_prot(phdr_table, phdr_count, load_bias, prot, should_pad_segments);
+ return _phdr_table_set_load_prot(phdr_table, phdr_count, load_bias, prot);
}
/* Change the protection of all loaded segments in memory to writable.
@@ -999,15 +937,12 @@
* phdr_table -> program header table
* phdr_count -> number of entries in tables
* load_bias -> load bias
- * should_pad_segments -> Are segments extended to avoid gaps in the memory map
* Return:
* 0 on success, -1 on failure (error code in errno).
*/
int phdr_table_unprotect_segments(const ElfW(Phdr)* phdr_table,
- size_t phdr_count, ElfW(Addr) load_bias,
- bool should_pad_segments) {
- return _phdr_table_set_load_prot(phdr_table, phdr_count, load_bias, PROT_WRITE,
- should_pad_segments);
+ size_t phdr_count, ElfW(Addr) load_bias) {
+ return _phdr_table_set_load_prot(phdr_table, phdr_count, load_bias, PROT_WRITE);
}
/* Used internally by phdr_table_protect_gnu_relro and