[MTE] split heap and stack MTE initialization
Bug: 315182011
Test: On both an MTE-enabled and non-MTE-enabled device:
Test: atest libprocinfo_test bionic-unit-tests bionic-unit-tests-static CtsGwpAsanTestCases gwp_asan_unittest debuggerd_test memtag_stack_dlopen_test
Change-Id: Idaacce32eb7c569237714171e96dc7392c565983
diff --git a/libc/bionic/libc_init_static.cpp b/libc/bionic/libc_init_static.cpp
index 7c46113..b54ef85 100644
--- a/libc/bionic/libc_init_static.cpp
+++ b/libc/bionic/libc_init_static.cpp
@@ -344,19 +344,12 @@
// This function is called from the linker before the main executable is relocated.
__attribute__((no_sanitize("hwaddress", "memtag"))) void __libc_init_mte(
const memtag_dynamic_entries_t* memtag_dynamic_entries, const void* phdr_start, size_t phdr_ct,
- uintptr_t load_bias, void* stack_top) {
+ uintptr_t load_bias) {
bool memtag_stack = false;
HeapTaggingLevel level =
__get_tagging_level(memtag_dynamic_entries, phdr_start, phdr_ct, load_bias, &memtag_stack);
- // initial_memtag_stack is used by the linker (in linker.cpp) to communicate than any library
- // linked by this executable enables memtag-stack.
- // memtag_stack is also set for static executables if they request memtag stack via the note,
- // in which case it will differ from initial_memtag_stack.
- if (__libc_shared_globals()->initial_memtag_stack || memtag_stack) {
- memtag_stack = true;
- __libc_shared_globals()->initial_memtag_stack_abi = true;
- __get_bionic_tcb()->tls_slot(TLS_SLOT_STACK_MTE) = __allocate_stack_mte_ringbuffer(0, nullptr);
- }
+ if (memtag_stack) __libc_shared_globals()->initial_memtag_stack_abi = true;
+
if (int64_t timed_upgrade = __get_memtag_upgrade_secs()) {
if (level == M_HEAP_TAGGING_LEVEL_ASYNC) {
async_safe_format_log(ANDROID_LOG_INFO, "libc",
@@ -380,15 +373,7 @@
if (prctl(PR_SET_TAGGED_ADDR_CTRL, prctl_arg | PR_MTE_TCF_SYNC, 0, 0, 0) == 0 ||
prctl(PR_SET_TAGGED_ADDR_CTRL, prctl_arg, 0, 0, 0) == 0) {
__libc_shared_globals()->initial_heap_tagging_level = level;
- __libc_shared_globals()->initial_memtag_stack = memtag_stack;
- if (memtag_stack) {
- void* pg_start =
- reinterpret_cast<void*>(page_start(reinterpret_cast<uintptr_t>(stack_top)));
- if (mprotect(pg_start, page_size(), PROT_READ | PROT_WRITE | PROT_MTE | PROT_GROWSDOWN)) {
- async_safe_fatal("error: failed to set PROT_MTE on main thread stack: %m");
- }
- }
struct sigaction action = {};
action.sa_flags = SA_SIGINFO | SA_RESTART;
action.sa_sigaction = __enable_mte_signal_handler;
@@ -404,11 +389,34 @@
}
// We did not enable MTE, so we do not need to arm the upgrade timer.
__libc_shared_globals()->heap_tagging_upgrade_timer_sec = 0;
- // We also didn't enable memtag_stack.
- __libc_shared_globals()->initial_memtag_stack = false;
}
+
+// Figure out whether we need to map the stack as PROT_MTE.
+// For dynamic executables, this has to be called after loading all
+// DT_NEEDED libraries, in case one of them needs stack MTE.
+__attribute__((no_sanitize("hwaddress", "memtag"))) void __libc_init_mte_stack(void* stack_top) {
+ if (!__libc_shared_globals()->initial_memtag_stack_abi) {
+ return;
+ }
+
+ // Even if the device doesn't support MTE, we have to allocate stack
+ // history buffers for code compiled for stack MTE. That is because the
+ // codegen expects a buffer to be present in TLS_SLOT_STACK_MTE either
+ // way.
+ __get_bionic_tcb()->tls_slot(TLS_SLOT_STACK_MTE) = __allocate_stack_mte_ringbuffer(0, nullptr);
+
+ if (__libc_mte_enabled()) {
+ __libc_shared_globals()->initial_memtag_stack = true;
+ void* pg_start = reinterpret_cast<void*>(page_start(reinterpret_cast<uintptr_t>(stack_top)));
+ if (mprotect(pg_start, page_size(), PROT_READ | PROT_WRITE | PROT_MTE | PROT_GROWSDOWN)) {
+ async_safe_fatal("error: failed to set PROT_MTE on main thread stack: %m");
+ }
+ }
+}
+
#else // __aarch64__
-void __libc_init_mte(const memtag_dynamic_entries_t*, const void*, size_t, uintptr_t, void*) {}
+void __libc_init_mte(const memtag_dynamic_entries_t*, const void*, size_t, uintptr_t) {}
+void __libc_init_mte_stack(void*) {}
#endif // __aarch64__
void __libc_init_profiling_handlers() {
@@ -436,7 +444,8 @@
__libc_init_common();
__libc_init_mte(/*memtag_dynamic_entries=*/nullptr,
reinterpret_cast<ElfW(Phdr)*>(getauxval(AT_PHDR)), getauxval(AT_PHNUM),
- /*load_bias = */ 0, /*stack_top = */ raw_args);
+ /*load_bias = */ 0);
+ __libc_init_mte_stack(/*stack_top = */ raw_args);
__libc_init_scudo();
__libc_init_profiling_handlers();
__libc_init_fork_handler();
@@ -511,3 +520,8 @@
static libc_shared_globals globals;
return &globals;
}
+
+__LIBC_HIDDEN__ bool __libc_mte_enabled() {
+ HeapTaggingLevel lvl = __libc_shared_globals()->initial_heap_tagging_level;
+ return lvl == M_HEAP_TAGGING_LEVEL_SYNC || lvl == M_HEAP_TAGGING_LEVEL_ASYNC;
+}