Support loading libraries to a reserved address.
Add flags and parameters to android_dlopen_ext() to allow loading a
library at an already-reserved fixed address. If the library to be
loaded will not fit within the space reserved, then the linker will
either fail, or allocate its own address space as usual, according to
which flag has been specified. This behaviour only applies to the
specific library requested; any other libraries loaded as dependencies
will be loaded in the normal fashion.
There is a new gtest included to cover the functionality added.
Bug: 13005501
Change-Id: I5d1810375b20fc51ba6a9b3191a25f9792c687f1
diff --git a/linker/linker_phdr.cpp b/linker/linker_phdr.cpp
index 7c5d3f6..7e97aa9 100644
--- a/linker/linker_phdr.cpp
+++ b/linker/linker_phdr.cpp
@@ -132,11 +132,11 @@
}
}
-bool ElfReader::Load() {
+bool ElfReader::Load(const android_dlextinfo* extinfo) {
return ReadElfHeader() &&
VerifyElfHeader() &&
ReadProgramHeader() &&
- ReserveAddressSpace() &&
+ ReserveAddressSpace(extinfo) &&
LoadSegments() &&
FindPhdr();
}
@@ -291,7 +291,7 @@
// Reserve a virtual address range big enough to hold all loadable
// segments of a program header table. This is done by creating a
// private anonymous mmap() with PROT_NONE.
-bool ElfReader::ReserveAddressSpace() {
+bool ElfReader::ReserveAddressSpace(const android_dlextinfo* extinfo) {
ElfW(Addr) min_vaddr;
load_size_ = phdr_table_get_load_size(phdr_table_, phdr_num_, &min_vaddr);
if (load_size_ == 0) {
@@ -300,11 +300,33 @@
}
uint8_t* addr = reinterpret_cast<uint8_t*>(min_vaddr);
- int mmap_flags = MAP_PRIVATE | MAP_ANONYMOUS;
- void* start = mmap(addr, load_size_, PROT_NONE, mmap_flags, -1, 0);
- if (start == MAP_FAILED) {
- DL_ERR("couldn't reserve %zd bytes of address space for \"%s\"", load_size_, name_);
- return false;
+ void* start;
+ size_t reserved_size = 0;
+ bool reserved_hint = true;
+
+ if (extinfo != NULL) {
+ if (extinfo->flags & ANDROID_DLEXT_RESERVED_ADDRESS) {
+ reserved_size = extinfo->reserved_size;
+ reserved_hint = false;
+ } else if (extinfo->flags & ANDROID_DLEXT_RESERVED_ADDRESS_HINT) {
+ reserved_size = extinfo->reserved_size;
+ }
+ }
+
+ if (load_size_ > reserved_size) {
+ if (!reserved_hint) {
+ DL_ERR("reserved address space %zd smaller than %zd bytes needed for \"%s\"",
+ reserved_size - load_size_, load_size_, name_);
+ return false;
+ }
+ int mmap_flags = MAP_PRIVATE | MAP_ANONYMOUS;
+ start = mmap(addr, load_size_, PROT_NONE, mmap_flags, -1, 0);
+ if (start == MAP_FAILED) {
+ DL_ERR("couldn't reserve %zd bytes of address space for \"%s\"", load_size_, name_);
+ return false;
+ }
+ } else {
+ start = extinfo->reserved_addr;
}
load_start_ = start;