hi/low addr space bits can be sent in stop-rely packet

Add support for the `low_mem_addressing_bits` and
`high_mem_addressing_bits` keys in the stop reply packet,
in addition to the existing `addressing_bits`.  Same
behavior as in the qHostInfo packet.

Clean up AddressableBits so we don't need to check if
any values have been set in the object before using it
to potentially update the Process address masks.

Differential Revision: https://reviews.llvm.org/D158041

(cherry picked from commit 6f4a0c7)

Author: jasonmolenda

lldb/docs/lldb-gdb-remote.txt

@@ -1621,6 +1621,18 @@ for this region.
 //                                       start code that may be changing the
 //                                       page table setup, a dynamically set
 //                                       value may be needed.
+//  "low_mem_addressing_bits" unsigned optional, specifies how many bits in 
+//                                       addresses in low memory are significant 
+//                                       for addressing, base 10.  AArch64 can 
+//                                       have different page table setups for low 
+//                                       and high memory, and therefore a different 
+//                                       number of bits used for addressing.
+//  "high_mem_addressing_bits" unsigned optional, specifies how many bits in 
+//                                       addresses in high memory are significant 
+//                                       for addressing, base 10.  AArch64 can have 
+//                                       different page table setups for low and 
+//                                       high memory, and therefore a different 
+//                                       number of bits used for addressing.
 //
 // BEST PRACTICES:
 //  Since register values can be supplied with this packet, it is often useful

lldb/include/lldb/Symbol/ObjectFile.h

@@ -521,15 +521,10 @@ class ObjectFile : public std::enable_shared_from_this<ObjectFile>,
   /// object files can return an AddressableBits object that can can be
   /// used to set the address masks in the Process.
   ///
-  /// \param[out] address_bits
-  ///     Can be used to set the Process address masks.
-  ///
   /// \return
-  ///     Returns true if addressable bits metadata was found.
-  virtual bool GetAddressableBits(lldb_private::AddressableBits &address_bits) {
-    address_bits.Clear();
-    return false;
-  }
+  ///     Returns an AddressableBits object which can be used to set
+  ///     the address masks in the Process.
+  virtual lldb_private::AddressableBits GetAddressableBits() { return {}; }
 
   /// When the ObjectFile is a core file, lldb needs to locate the "binary" in
   /// the core file.  lldb can iterate over the pages looking for a valid

lldb/include/lldb/Utility/AddressableBits.h

@@ -29,9 +29,11 @@ class AddressableBits {
   void SetAddressableBits(uint32_t lowmem_addressing_bits,
                           uint32_t highmem_addressing_bits);
 
-  void SetProcessMasks(lldb_private::Process &process);
+  void SetLowmemAddressableBits(uint32_t lowmem_addressing_bits);
+
+  void SetHighmemAddressableBits(uint32_t highmem_addressing_bits);
 
-  void Clear();
+  void SetProcessMasks(lldb_private::Process &process);
 
 private:
   uint32_t m_low_memory_addr_bits;

lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp

@@ -5533,8 +5533,8 @@ std::string ObjectFileMachO::GetIdentifierString() {
   return result;
 }
 
-bool ObjectFileMachO::GetAddressableBits(AddressableBits &address_bits) {
-  address_bits.Clear();
+AddressableBits ObjectFileMachO::GetAddressableBits() {
+  AddressableBits addressable_bits;
 
   Log *log(GetLog(LLDBLog::Process));
   ModuleSP module_sp(GetModule());
@@ -5562,32 +5562,32 @@ bool ObjectFileMachO::GetAddressableBits(AddressableBits &address_bits) {
             if (version == 3) {
               uint32_t num_addr_bits = m_data.GetU32_unchecked(&offset);
               if (num_addr_bits != 0) {
-                address_bits.SetAddressableBits(num_addr_bits);
+                addressable_bits.SetAddressableBits(num_addr_bits);
               }
               LLDB_LOGF(log,
                         "LC_NOTE 'addrable bits' v3 found, value %d "
                         "bits",
                         num_addr_bits);
-              return true;
+              break;
             }
             if (version == 4) {
               uint32_t lo_addr_bits = m_data.GetU32_unchecked(&offset);
               uint32_t hi_addr_bits = m_data.GetU32_unchecked(&offset);
 
-              address_bits.SetAddressableBits(lo_addr_bits, hi_addr_bits);
+              addressable_bits.SetAddressableBits(lo_addr_bits, hi_addr_bits);
               LLDB_LOGF(log,
                         "LC_NOTE 'addrable bits' v4 found, value %d & %d bits",
                         lo_addr_bits, hi_addr_bits);
 
-              return true;
+              break;
             }
           }
         }
       }
       offset = cmd_offset + lc.cmdsize;
     }
   }
-  return false;
+  return addressable_bits;
 }
 
 bool ObjectFileMachO::GetCorefileMainBinaryInfo(addr_t &value,

lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.h

@@ -121,7 +121,7 @@ class ObjectFileMachO : public lldb_private::ObjectFile {
 
   std::string GetIdentifierString() override;
 
-  bool GetAddressableBits(lldb_private::AddressableBits &address_bits) override;
+  lldb_private::AddressableBits GetAddressableBits() override;
 
   bool GetCorefileMainBinaryInfo(lldb::addr_t &value, bool &value_is_offset,
                                  lldb_private::UUID &uuid,

lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp

@@ -1412,17 +1412,17 @@ GDBRemoteCommunicationClient::GetHostArchitecture() {
   return m_host_arch;
 }
 
-bool GDBRemoteCommunicationClient::GetAddressableBits(
-    lldb_private::AddressableBits &addressable_bits) {
-  addressable_bits.Clear();
+AddressableBits GDBRemoteCommunicationClient::GetAddressableBits() {
+  AddressableBits addressable_bits;
   if (m_qHostInfo_is_valid == eLazyBoolCalculate)
     GetHostInfo();
-  if (m_low_mem_addressing_bits != 0 || m_high_mem_addressing_bits != 0) {
-    addressable_bits.SetAddressableBits(m_low_mem_addressing_bits,
-                                        m_high_mem_addressing_bits);
-    return true;
-  }
-  return false;
+
+  // m_low_mem_addressing_bits and m_high_mem_addressing_bits
+  // will be 0 if we did not receive values; AddressableBits
+  // treats 0 as "unspecified".
+  addressable_bits.SetAddressableBits(m_low_mem_addressing_bits,
+                                      m_high_mem_addressing_bits);
+  return addressable_bits;
 }
 
 seconds GDBRemoteCommunicationClient::GetHostDefaultPacketTimeout() {

lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.h

@@ -238,7 +238,7 @@ class GDBRemoteCommunicationClient : public GDBRemoteClientBase {
 
   ArchSpec GetSystemArchitecture();
 
-  bool GetAddressableBits(lldb_private::AddressableBits &addressable_bits);
+  lldb_private::AddressableBits GetAddressableBits();
 
   bool GetHostname(std::string &s);
 

lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp

@@ -892,10 +892,8 @@ void ProcessGDBRemote::DidLaunchOrAttach(ArchSpec &process_arch) {
              process_arch.GetTriple().getTriple());
   }
 
-  AddressableBits addressable_bits;
-  if (m_gdb_comm.GetAddressableBits(addressable_bits)) {
-    addressable_bits.SetProcessMasks(*this);
-  }
+  AddressableBits addressable_bits = m_gdb_comm.GetAddressableBits();
+  addressable_bits.SetProcessMasks(*this);
 
   if (process_arch.IsValid()) {
     const ArchSpec &target_arch = GetTarget().GetArchitecture();
@@ -2103,6 +2101,7 @@ StateType ProcessGDBRemote::SetThreadStopInfo(StringExtractor &stop_packet) {
     QueueKind queue_kind = eQueueKindUnknown;
     uint64_t queue_serial_number = 0;
     ExpeditedRegisterMap expedited_register_map;
+    AddressableBits addressable_bits;
     while (stop_packet.GetNameColonValue(key, value)) {
       if (key.compare("metype") == 0) {
         // exception type in big endian hex
@@ -2247,9 +2246,17 @@ StateType ProcessGDBRemote::SetThreadStopInfo(StringExtractor &stop_packet) {
       } else if (key.compare("addressing_bits") == 0) {
         uint64_t addressing_bits;
         if (!value.getAsInteger(0, addressing_bits)) {
-          addr_t address_mask = ~((1ULL << addressing_bits) - 1);
-          SetCodeAddressMask(address_mask);
-          SetDataAddressMask(address_mask);
+          addressable_bits.SetAddressableBits(addressing_bits);
+        }
+      } else if (key.compare("low_mem_addressing_bits") == 0) {
+        uint64_t addressing_bits;
+        if (!value.getAsInteger(0, addressing_bits)) {
+          addressable_bits.SetLowmemAddressableBits(addressing_bits);
+        }
+      } else if (key.compare("high_mem_addressing_bits") == 0) {
+        uint64_t addressing_bits;
+        if (!value.getAsInteger(0, addressing_bits)) {
+          addressable_bits.SetHighmemAddressableBits(addressing_bits);
         }
       } else if (key.size() == 2 && ::isxdigit(key[0]) && ::isxdigit(key[1])) {
         uint32_t reg = UINT32_MAX;
@@ -2278,6 +2285,8 @@ StateType ProcessGDBRemote::SetThreadStopInfo(StringExtractor &stop_packet) {
       }
     }
 
+    addressable_bits.SetProcessMasks(*this);
+
     ThreadSP thread_sp = SetThreadStopInfo(
         tid, expedited_register_map, signo, thread_name, reason, description,
         exc_type, exc_data, thread_dispatch_qaddr, queue_vars_valid,

lldb/source/Plugins/Process/mach-core/ProcessMachCore.cpp

@@ -574,10 +574,9 @@ Status ProcessMachCore::DoLoadCore() {
 
   CleanupMemoryRegionPermissions();
 
-  AddressableBits addressable_bits;
-  if (core_objfile->GetAddressableBits(addressable_bits)) {
-    addressable_bits.SetProcessMasks(*this);
-  }
+  AddressableBits addressable_bits = core_objfile->GetAddressableBits();
+  addressable_bits.SetProcessMasks(*this);
+
   return error;
 }
 

lldb/source/Utility/AddressableBits.cpp

@@ -23,28 +23,57 @@ void AddressableBits::SetAddressableBits(uint32_t lowmem_addressing_bits,
   m_high_memory_addr_bits = highmem_addressing_bits;
 }
 
-void AddressableBits::Clear() {
-  m_low_memory_addr_bits = m_high_memory_addr_bits = 0;
+void AddressableBits::SetLowmemAddressableBits(
+    uint32_t lowmem_addressing_bits) {
+  m_low_memory_addr_bits = lowmem_addressing_bits;
+}
+
+void AddressableBits::SetHighmemAddressableBits(
+    uint32_t highmem_addressing_bits) {
+  m_high_memory_addr_bits = highmem_addressing_bits;
 }
 
 void AddressableBits::SetProcessMasks(Process &process) {
-  // In case either value is set to 0, indicating it was not set, use the
-  // other value.
-  if (m_low_memory_addr_bits == 0)
-    m_low_memory_addr_bits = m_high_memory_addr_bits;
-  if (m_high_memory_addr_bits == 0)
-    m_high_memory_addr_bits = m_low_memory_addr_bits;
-
-  if (m_low_memory_addr_bits == 0)
+  if (m_low_memory_addr_bits == 0 && m_high_memory_addr_bits == 0)
     return;
 
-  addr_t address_mask = ~((1ULL << m_low_memory_addr_bits) - 1);
-  process.SetCodeAddressMask(address_mask);
-  process.SetDataAddressMask(address_mask);
+  // If we don't have an addressable bits value for low memory,
+  // see if we have a Code/Data mask already, and use that.
+  // Or use the high memory addressable bits value as a last
+  // resort.
+  addr_t low_addr_mask;
+  if (m_low_memory_addr_bits == 0) {
+    if (process.GetCodeAddressMask() != UINT64_MAX)
+      low_addr_mask = process.GetCodeAddressMask();
+    else if (process.GetDataAddressMask() != UINT64_MAX)
+      low_addr_mask = process.GetDataAddressMask();
+    else
+      low_addr_mask = ~((1ULL << m_high_memory_addr_bits) - 1);
+  } else {
+    low_addr_mask = ~((1ULL << m_low_memory_addr_bits) - 1);
+  }
+
+  // If we don't have an addressable bits value for high memory,
+  // see if we have a Code/Data mask already, and use that.
+  // Or use the low memory addressable bits value as a last
+  // resort.
+  addr_t hi_addr_mask;
+  if (m_high_memory_addr_bits == 0) {
+    if (process.GetHighmemCodeAddressMask() != UINT64_MAX)
+      hi_addr_mask = process.GetHighmemCodeAddressMask();
+    else if (process.GetHighmemDataAddressMask() != UINT64_MAX)
+      hi_addr_mask = process.GetHighmemDataAddressMask();
+    else
+      hi_addr_mask = ~((1ULL << m_low_memory_addr_bits) - 1);
+  } else {
+    hi_addr_mask = ~((1ULL << m_high_memory_addr_bits) - 1);
+  }
+
+  process.SetCodeAddressMask(low_addr_mask);
+  process.SetDataAddressMask(low_addr_mask);
 
-  if (m_low_memory_addr_bits != m_high_memory_addr_bits) {
-    lldb::addr_t hi_address_mask = ~((1ULL << m_high_memory_addr_bits) - 1);
-    process.SetHighmemCodeAddressMask(hi_address_mask);
-    process.SetHighmemDataAddressMask(hi_address_mask);
+  if (low_addr_mask != hi_addr_mask) {
+    process.SetHighmemCodeAddressMask(hi_addr_mask);
+    process.SetHighmemDataAddressMask(hi_addr_mask);
   }
 }