From 118c5ee6e6d7517ca2a4b0723bd0e8b0d56e7b05 Mon Sep 17 00:00:00 2001
From: Peter Collingbourne <pcc@google.com>
Date: Fri, 24 Apr 2020 17:33:37 -0700
Subject: [PATCH] Switch to new kernel ptrace interface for reading tags.

Bug: 135772972
Change-Id: I506429d7bff79f83828e1f0d5c0ea0468ee1580b
---
 libunwindstack/MemoryMte.cpp | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/libunwindstack/MemoryMte.cpp b/libunwindstack/MemoryMte.cpp
index d1d0ebc29..46a546e1c 100644
--- a/libunwindstack/MemoryMte.cpp
+++ b/libunwindstack/MemoryMte.cpp
@@ -17,6 +17,7 @@
 #if defined(ANDROID_EXPERIMENTAL_MTE)
 
 #include <sys/ptrace.h>
+#include <sys/uio.h>
 
 #include <bionic/mte.h>
 #include <bionic/mte_kernel.h>
@@ -28,7 +29,13 @@ namespace unwindstack {
 
 long MemoryRemote::ReadTag(uint64_t addr) {
 #if defined(__aarch64__)
-  return ptrace(PTRACE_PEEKTAG, pid_, (void*)addr, nullptr);
+  char tag;
+  iovec iov = {&tag, 1};
+  if (ptrace(PTRACE_PEEKMTETAGS, pid_, reinterpret_cast<void*>(addr), &iov) != 0 ||
+      iov.iov_len != 1) {
+    return -1;
+  }
+  return tag;
 #else
   (void)addr;
   return -1;