[lldb] Correct format of qMemTags type field

The type field is a signed integer.
(https://sourceware.org/gdb/current/onlinedocs/gdb/General-Query-Packets.html)

However it's not packed in the packet in the way
you might think. For example the type -1 should be:
qMemTags:<addr>,<len>:ffffffff
Instead of:
qMemTags:<addr>,<len>:-1

This change makes lldb-server's parsing more strict
and adds more tests to check that we handle negative types
correctly in lldb and lldb-server.

We only support one tag type value at this point,
for AArch64 MTE, which is positive. So this doesn't change
any of those interactions. It just brings us in line with GDB.

Also check that the test target has MTE. Previously
we just checked that we were AArch64 with a toolchain
that supports MTE.

Finally, update the tag type check for QMemTags to use
the same conversion steps that qMemTags now does.
Using static_cast can invoke UB and though we do do a limit
check to avoid this, I think it's clearer with the new method.

Reviewed By: omjavaid

Differential Revision: https://reviews.llvm.org/D104914

1 files changed, 29 insertions, 18 deletions

diff --git a/lldb/unittests/Process/gdb-remote/GDBRemoteCommunicationClientTest.cpp b/lldb/unittests/Process/gdb-remote/GDBRemoteCommunicationClientTest.cpp
index 37ed0f7..d15b852 100644
--- a/lldb/unittests/Process/gdb-remote/GDBRemoteCommunicationClientTest.cpp
+++ b/lldb/unittests/Process/gdb-remote/GDBRemoteCommunicationClientTest.cpp
@@ -470,19 +470,18 @@ TEST_F(GDBRemoteCommunicationClientTest, GetQOffsets) {
 
 static void
 check_qmemtags(TestClient &client, MockServer &server, size_t read_len,
-               const char *packet, llvm::StringRef response,
+               int32_t type, const char *packet, llvm::StringRef response,
                llvm::Optional<std::vector<uint8_t>> expected_tag_data) {
-  const auto &ReadMemoryTags = [&](size_t len, const char *packet,
-                                   llvm::StringRef response) {
+  const auto &ReadMemoryTags = [&]() {
     std::future<DataBufferSP> result = std::async(std::launch::async, [&] {
-      return client.ReadMemoryTags(0xDEF0, read_len, 1);
+      return client.ReadMemoryTags(0xDEF0, read_len, type);
     });
 
     HandlePacket(server, packet, response);
     return result.get();
   };
 
-  auto result = ReadMemoryTags(0, packet, response);
+  auto result = ReadMemoryTags();
   if (expected_tag_data) {
     ASSERT_TRUE(result);
     llvm::ArrayRef<uint8_t> expected(*expected_tag_data);
@@ -495,41 +494,53 @@ check_qmemtags(TestClient &client, MockServer &server, size_t read_len,
 
 TEST_F(GDBRemoteCommunicationClientTest, ReadMemoryTags) {
   // Zero length reads are valid
-  check_qmemtags(client, server, 0, "qMemTags:def0,0:1", "m",
+  check_qmemtags(client, server, 0, 1, "qMemTags:def0,0:1", "m",
                  std::vector<uint8_t>{});
 
+  // Type can be negative. Put into the packet as the raw bytes
+  // (as opposed to a literal -1)
+  check_qmemtags(client, server, 0, -1, "qMemTags:def0,0:ffffffff", "m",
+                 std::vector<uint8_t>{});
+  check_qmemtags(client, server, 0, std::numeric_limits<int32_t>::min(),
+                 "qMemTags:def0,0:80000000", "m", std::vector<uint8_t>{});
+  check_qmemtags(client, server, 0, std::numeric_limits<int32_t>::max(),
+                 "qMemTags:def0,0:7fffffff", "m", std::vector<uint8_t>{});
+
   // The client layer does not check the length of the received data.
   // All we need is the "m" and for the decode to use all of the chars
-  check_qmemtags(client, server, 32, "qMemTags:def0,20:1", "m09",
+  check_qmemtags(client, server, 32, 2, "qMemTags:def0,20:2", "m09",
                  std::vector<uint8_t>{0x9});
 
   // Zero length response is fine as long as the "m" is present
-  check_qmemtags(client, server, 0, "qMemTags:def0,0:1", "m",
+  check_qmemtags(client, server, 0, 0x34, "qMemTags:def0,0:34", "m",
                  std::vector<uint8_t>{});
 
   // Normal responses
-  check_qmemtags(client, server, 16, "qMemTags:def0,10:1", "m66",
+  check_qmemtags(client, server, 16, 1, "qMemTags:def0,10:1", "m66",
                  std::vector<uint8_t>{0x66});
-  check_qmemtags(client, server, 32, "qMemTags:def0,20:1", "m0102",
+  check_qmemtags(client, server, 32, 1, "qMemTags:def0,20:1", "m0102",
                  std::vector<uint8_t>{0x1, 0x2});
 
   // Empty response is an error
-  check_qmemtags(client, server, 17, "qMemTags:def0,11:1", "", llvm::None);
+  check_qmemtags(client, server, 17, 1, "qMemTags:def0,11:1", "", llvm::None);
   // Usual error response
-  check_qmemtags(client, server, 17, "qMemTags:def0,11:1", "E01", llvm::None);
+  check_qmemtags(client, server, 17, 1, "qMemTags:def0,11:1", "E01",
+                 llvm::None);
   // Leading m missing
-  check_qmemtags(client, server, 17, "qMemTags:def0,11:1", "01", llvm::None);
+  check_qmemtags(client, server, 17, 1, "qMemTags:def0,11:1", "01", llvm::None);
   // Anything other than m is an error
-  check_qmemtags(client, server, 17, "qMemTags:def0,11:1", "z01", llvm::None);
+  check_qmemtags(client, server, 17, 1, "qMemTags:def0,11:1", "z01",
+                 llvm::None);
   // Decoding tag data doesn't use all the chars in the packet
-  check_qmemtags(client, server, 32, "qMemTags:def0,20:1", "m09zz", llvm::None);
+  check_qmemtags(client, server, 32, 1, "qMemTags:def0,20:1", "m09zz",
+                 llvm::None);
   // Data that is not hex bytes
-  check_qmemtags(client, server, 32, "qMemTags:def0,20:1", "mhello",
+  check_qmemtags(client, server, 32, 1, "qMemTags:def0,20:1", "mhello",
                  llvm::None);
   // Data is not a complete hex char
-  check_qmemtags(client, server, 32, "qMemTags:def0,20:1", "m9", llvm::None);
+  check_qmemtags(client, server, 32, 1, "qMemTags:def0,20:1", "m9", llvm::None);
   // Data has a trailing hex char
-  check_qmemtags(client, server, 32, "qMemTags:def0,20:1", "m01020",
+  check_qmemtags(client, server, 32, 1, "qMemTags:def0,20:1", "m01020",
                  llvm::None);
 }