[Lldb-commits] [lldb] [lldb] Recognize MTE fault Mach exceptions (PR #159117)

[David Spickett via lldb-commits]

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@@ -77,6 +77,35 @@ static void DescribeAddressBriefly(Stream &strm, const Address &addr,
   strm.Printf(".\n");
 }
 
+static constexpr uint8_t g_mte_tag_shift = 64 - 8;
+static constexpr uintptr_t g_mte_tag_mask = (uintptr_t)0x0f << g_mte_tag_shift;
+
+bool StopInfoMachException::DetermineTagMismatch(ExecutionContext &exe_ctx) {
+  const bool IsBadAccess = m_value == 1;            // EXC_BAD_ACCESS
+  const bool IsMTETagFault = (m_exc_code == 0x106); // EXC_ARM_MTE_TAG_FAULT
+  if (!IsBadAccess || !IsMTETagFault)
+    return false;
+
+  if (m_exc_data_count < 2)
+    return false;
+
+  const uint64_t bad_address = m_exc_subcode;
+
+  StreamString strm;
+  strm.Printf("EXC_ARM_MTE_TAG_FAULT (code=%" PRIu64 ", address=0x%" PRIx64
+              ")\n",
+              m_exc_code, bad_address);
+
+  const uint8_t tag = (bad_address & g_mte_tag_mask) >> g_mte_tag_shift;
+  const uint64_t canonical_addr = bad_address & ~g_mte_tag_mask;
+  strm.Printf(
+      "Note: MTE tag mismatch detected: pointer tag=%d, address=0x%" PRIx64,
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DavidSpickett wrote:

The Linux version will go and fetch the allocation tag, but I am not sure whether you have access to process here to do that.

https://github.com/llvm/llvm-project/pull/159117