Dump the per-thread TAGGED_ADDR_CTRL value if available.

This value indicates whether memory tagging is enabled on a thread,
the mode (sync or async) and the set of excluded tags. This information
can sometimes be important for understanding an MTE related crash,
so include it in the per-thread tombstone output.

Bug: 135772972
Change-Id: I25a16e10ac7fbb2b1ab2a961a5279f787039000b

debuggerd/Android.bp

@@ -343,6 +343,12 @@ cc_binary {
     apex_available: [
         "com.android.runtime",
     ],
+
+    product_variables: {
+        experimental_mte: {
+            cflags: ["-DANDROID_EXPERIMENTAL_MTE"],
+        },
+    },
 }
 
 cc_binary {

debuggerd/crash_dump.cpp

@@ -40,6 +40,7 @@
 #include <android-base/stringprintf.h>
 #include <android-base/strings.h>
 #include <android-base/unique_fd.h>
+#include <bionic/mte_kernel.h>
 #include <bionic/reserved_signals.h>
 #include <cutils/sockets.h>
 #include <log/log.h>
@@ -486,6 +487,17 @@ int main(int argc, char** argv) {
         continue;
       }
 
+#ifdef ANDROID_EXPERIMENTAL_MTE
+      struct iovec iov = {
+          &info.tagged_addr_ctrl,
+          sizeof(info.tagged_addr_ctrl),
+      };
+      if (ptrace(PTRACE_GETREGSET, thread, NT_ARM_TAGGED_ADDR_CTRL,
+                 reinterpret_cast<void*>(&iov)) == -1) {
+        info.tagged_addr_ctrl = -1;
+      }
+#endif
+
       if (thread == g_target_thread) {
         // Read the thread's registers along with the rest of the crash info out of the pipe.
         ReadCrashInfo(input_pipe, &siginfo, &info.registers, &process_info);

debuggerd/debuggerd_test.cpp

@@ -309,6 +309,11 @@ TEST_F(CrasherTest, smoke) {
   std::string result;
   ConsumeFd(std::move(output_fd), &result);
   ASSERT_MATCH(result, R"(signal 11 \(SIGSEGV\), code 1 \(SEGV_MAPERR\), fault addr 0xdead)");
+
+  if (mte_supported()) {
+    // Test that the default TAGGED_ADDR_CTRL value is set.
+    ASSERT_MATCH(result, R"(tagged_addr_ctrl: 000000000007fff3)");
+  }
 }
 
 TEST_F(CrasherTest, tagged_fault_addr) {

debuggerd/libdebuggerd/include/libdebuggerd/types.h

@@ -23,6 +23,7 @@
 
 struct ThreadInfo {
   std::unique_ptr<unwindstack::Regs> registers;
+  long tagged_addr_ctrl = -1;
 
   pid_t uid;
 

debuggerd/libdebuggerd/tombstone.cpp

@@ -180,6 +180,9 @@ static void dump_thread_info(log_t* log, const ThreadInfo& thread_info) {
   _LOG(log, logtype::HEADER, "pid: %d, tid: %d, name: %s  >>> %s <<<\n", thread_info.pid,
        thread_info.tid, thread_info.thread_name.c_str(), thread_info.process_name.c_str());
   _LOG(log, logtype::HEADER, "uid: %d\n", thread_info.uid);
+  if (thread_info.tagged_addr_ctrl != -1) {
+    _LOG(log, logtype::HEADER, "tagged_addr_ctrl: %016lx\n", thread_info.tagged_addr_ctrl);
+  }
 }
 
 static std::string get_addr_string(uint64_t addr) {