[lldb] Address mask sbprocess apis and new mask invalid const (llvm#83663)

[lldb] Add SBProcess methods for get/set/use address masks (llvm#83095)

I'm reviving a patch from phabracator, https://reviews.llvm.org/D155905
which was approved but I wasn't thrilled with all the API I was adding
to SBProcess for all of the address mask types / memory regions. In this
update, I added enums to control type address mask type (code, data,
any) and address space specifiers (low, high, all) with defaulted
arguments for the most common case.  I originally landed this via
llvm#83095 but it failed on CIs
outside of arm64 Darwin so I had to debug it on more environments
and update the patch.

This patch is also fixing a bug in the "addressable bits to address
mask" calculation I added in AddressableBits::SetProcessMasks. If lldb
were told that 64 bits are valid for addressing, this method would
overflow the calculation and set an invalid mask. Added tests to check
this specific bug while I was adding these APIs.

This patch changes the value of "no mask set" from 0 to
LLDB_INVALID_ADDRESS_MASK, which is UINT64_MAX. A mask of all 1's
means "no bits are used for addressing" which is an impossible mask,
whereas a mask of 0 means "all bits are used for addressing" which
is possible.

I added a base class implementation of ABI::FixCodeAddress and
ABI::FixDataAddress that will apply the Process mask values if they
are set to a value other than LLDB_INVALID_ADDRESS_MASK.

I updated all the callers/users of the Mask methods which were
handling a value of 0 to mean invalid mask to use
LLDB_INVALID_ADDRESS_MASK.

I added code to the all AArch64 ABI Fix* methods to apply the
Highmem masks if they have been set.  These will not be set on a
Linux environment, but in TestAddressMasks.py I test the highmem
masks feature for any AArch64 target, so all AArch64 ABI  plugins 
must handle it.

rdar://123530562

Author: jasonmolenda

lldb/include/lldb/API/SBProcess.h

@@ -407,6 +407,120 @@ class LLDB_API SBProcess {
   ///     the process isn't loaded from a core file.
   lldb::SBFileSpec GetCoreFile();
 
+  /// \{
+  /// \group Mask Address Methods
+  ///
+  /// \a type
+  /// All of the methods in this group take \a type argument
+  /// which is an AddressMaskType enum value.
+  /// There can be different address masks for code addresses and
+  /// data addresses, this argument can select which to get/set,
+  /// or to use when clearing non-addressable bits from an address.
+  /// This choice of mask can be important for example on AArch32
+  /// systems. Where instructions where instructions start on even addresses,
+  /// the 0th bit may be used to indicate that a function is thumb code.  On
+  /// such a target, the eAddressMaskTypeCode may clear the 0th bit from an
+  /// address to get the actual address Whereas eAddressMaskTypeData would not.
+  ///
+  /// \a addr_range
+  /// Many of the methods in this group take an \a addr_range argument
+  /// which is an AddressMaskRange enum value.
+  /// Needing to specify the address range is highly unusual, and the
+  /// default argument can be used in nearly all circumstances.
+  /// On some architectures (e.g., AArch64), it is possible to have
+  /// different page table setups for low and high memory, so different
+  /// numbers of bits relevant to addressing. It is possible to have
+  /// a program running in one half of memory and accessing the other
+  /// as heap, so we need to maintain two different sets of address masks
+  /// to debug this correctly.
+
+  /// Get the current address mask that will be applied to addresses
+  /// before reading from memory.
+  ///
+  /// \param[in] type
+  ///     See \ref Mask Address Methods description of this argument.
+  ///     eAddressMaskTypeAny is often a suitable value when code and
+  ///     data masks are the same on a given target.
+  ///
+  /// \param[in] addr_range
+  ///     See \ref Mask Address Methods description of this argument.
+  ///     This will default to eAddressMaskRangeLow which is the
+  ///     only set of masks used normally.
+  ///
+  /// \return
+  ///     The address mask currently in use.  Bits which are not used
+  ///     for addressing will be set to 1 in the mask.
+  lldb::addr_t GetAddressMask(
+      lldb::AddressMaskType type,
+      lldb::AddressMaskRange addr_range = lldb::eAddressMaskRangeLow);
+
+  /// Set the current address mask that can be applied to addresses
+  /// before reading from memory.
+  ///
+  /// \param[in] type
+  ///     See \ref Mask Address Methods description of this argument.
+  ///     eAddressMaskTypeAll is often a suitable value when the
+  ///     same mask is being set for both code and data.
+  ///
+  /// \param[in] mask
+  ///     The address mask to set.  Bits which are not used for addressing
+  ///     should be set to 1 in the mask.
+  ///
+  /// \param[in] addr_range
+  ///     See \ref Mask Address Methods description of this argument.
+  ///     This will default to eAddressMaskRangeLow which is the
+  ///     only set of masks used normally.
+  void SetAddressMask(
+      lldb::AddressMaskType type, lldb::addr_t mask,
+      lldb::AddressMaskRange addr_range = lldb::eAddressMaskRangeLow);
+
+  /// Set the number of bits used for addressing in this Process.
+  ///
+  /// On Darwin and similar systems, the addressable bits are expressed
+  /// as the number of low order bits that are relevant to addressing,
+  /// instead of a more general address mask.
+  /// This method calculates the correct mask value for a given number
+  /// of low order addressable bits.
+  ///
+  /// \param[in] type
+  ///     See \ref Mask Address Methods description of this argument.
+  ///     eAddressMaskTypeAll is often a suitable value when the
+  ///     same mask is being set for both code and data.
+  ///
+  /// \param[in] num_bits
+  ///     Number of bits that are used for addressing.
+  ///     For example, a value of 42 indicates that the low 42 bits
+  ///     are relevant for addressing, and that higher-order bits may
+  ///     be used for various metadata like pointer authentication,
+  ///     Type Byte Ignore, etc.
+  ///
+  /// \param[in] addr_range
+  ///     See \ref Mask Address Methods description of this argument.
+  ///     This will default to eAddressMaskRangeLow which is the
+  ///     only set of masks used normally.
+  void
+  SetAddressableBits(AddressMaskType type, uint32_t num_bits,
+                     AddressMaskRange addr_range = lldb::eAddressMaskRangeLow);
+
+  /// Clear the non-address bits of an \a addr value and return a
+  /// virtual address in memory.
+  ///
+  /// Bits that are not used in addressing may be used for other purposes;
+  /// pointer authentication, or metadata in the top byte, or the 0th bit
+  /// of armv7 code addresses to indicate arm/thumb are common examples.
+  ///
+  /// \param[in] addr
+  ///     The address that should be cleared of non-address bits.
+  ///
+  /// \param[in] type
+  ///     See \ref Mask Address Methods description of this argument.
+  ///     eAddressMaskTypeAny is the default value, correct when it
+  ///     is unknown if the address is a code or data address.
+  lldb::addr_t
+  FixAddress(lldb::addr_t addr,
+             lldb::AddressMaskType type = lldb::eAddressMaskTypeAny);
+  /// \}
+
   /// Allocate memory within the process.
   ///
   /// This function will allocate memory in the process's address space.

lldb/include/lldb/Target/ABI.h

@@ -122,8 +122,8 @@ class ABI : public PluginInterface {
   /// ARM uses bit zero to signify a code address is thumb, so any ARM ABI
   /// plug-ins would strip those bits.
   /// @{
-  virtual lldb::addr_t FixCodeAddress(lldb::addr_t pc) { return pc; }
-  virtual lldb::addr_t FixDataAddress(lldb::addr_t pc) { return pc; }
+  virtual lldb::addr_t FixCodeAddress(lldb::addr_t pc);
+  virtual lldb::addr_t FixDataAddress(lldb::addr_t pc);
   /// @}
 
   /// Use this method when you do not know, or do not care what kind of address
@@ -166,10 +166,6 @@ class ABI : public PluginInterface {
   lldb::ProcessWP m_process_wp;
   std::unique_ptr<llvm::MCRegisterInfo> m_mc_register_info_up;
 
-  virtual lldb::addr_t FixCodeAddress(lldb::addr_t pc, lldb::addr_t mask) {
-    return pc;
-  }
-
 private:
   ABI(const ABI &) = delete;
   const ABI &operator=(const ABI &) = delete;

lldb/include/lldb/Target/Process.h

@@ -1422,9 +1422,23 @@ class Process : public std::enable_shared_from_this<Process>,
 
   virtual void DidExit() {}
 
+  /// Get the current address mask in the Process
+  ///
+  /// This mask can used to set/clear non-address bits in an addr_t.
+  ///
+  /// \return
+  ///   The current address mask.
+  ///   Bits which are set to 1 are not used for addressing.
+  ///   An address mask of 0 means all bits are used for addressing.
+  ///   An address mask of LLDB_INVALID_ADDRESS_MASK (all 1's) means
+  ///   that no mask has been set.
   lldb::addr_t GetCodeAddressMask();
   lldb::addr_t GetDataAddressMask();
 
+  /// The highmem masks are for targets where we may have different masks
+  /// for low memory versus high memory addresses, and they will be left
+  /// as LLDB_INVALID_ADDRESS_MASK normally, meaning the base masks
+  /// should be applied to all addresses.
   lldb::addr_t GetHighmemCodeAddressMask();
   lldb::addr_t GetHighmemDataAddressMask();
 
@@ -3096,16 +3110,20 @@ void PruneThreadPlans();
   // if run while destructing.  We use this flag to determine that.
   std::atomic<bool> m_destructing;
 
-  /// Mask for code an data addresses. The default value (0) means no mask is
-  /// set.  The bits set to 1 indicate bits that are NOT significant for
-  /// addressing.
-  /// The highmem versions are for targets where we may have different masks
-  /// for low memory versus high memory addresses.
+  /// Mask for code an data addresses.
+  /// The default value LLDB_INVALID_ADDRESS_MASK means no mask has been set,
+  /// and addresses values should not be modified.
+  /// In these masks, the bits are set to 1 indicate bits that are not
+  /// significant for addressing.
+  /// The highmem masks are for targets where we may have different masks
+  /// for low memory versus high memory addresses, and they will be left
+  /// as LLDB_INVALID_ADDRESS_MASK normally, meaning the base masks
+  /// should be applied to all addresses.
   /// @{
-  lldb::addr_t m_code_address_mask = 0;
-  lldb::addr_t m_data_address_mask = 0;
-  lldb::addr_t m_highmem_code_address_mask = 0;
-  lldb::addr_t m_highmem_data_address_mask = 0;
+  lldb::addr_t m_code_address_mask = LLDB_INVALID_ADDRESS_MASK;
+  lldb::addr_t m_data_address_mask = LLDB_INVALID_ADDRESS_MASK;
+  lldb::addr_t m_highmem_code_address_mask = LLDB_INVALID_ADDRESS_MASK;
+  lldb::addr_t m_highmem_data_address_mask = LLDB_INVALID_ADDRESS_MASK;
   /// @}
 
   bool m_clear_thread_plans_on_stop;

lldb/include/lldb/Utility/AddressableBits.h

@@ -10,6 +10,7 @@
 #define LLDB_UTILITY_ADDRESSABLEBITS_H
 
 #include "lldb/lldb-forward.h"
+#include "lldb/lldb-public.h"
 
 namespace lldb_private {
 
@@ -33,6 +34,8 @@ class AddressableBits {
 
   void SetHighmemAddressableBits(uint32_t highmem_addressing_bits);
 
+  static lldb::addr_t AddressableBitToMask(uint32_t addressable_bits);
+
   void SetProcessMasks(lldb_private::Process &process);
 
 private:

lldb/include/lldb/lldb-defines.h

@@ -127,6 +127,11 @@
 #define MAX_PATH 260
 #endif
 
+/// Address Mask
+/// Bits not used for addressing are set to 1 in the mask;
+/// all mask bits set is an invalid value.
+#define LLDB_INVALID_ADDRESS_MASK UINT64_MAX
+
 // ignore GCC function attributes
 #if defined(_MSC_VER) && !defined(__clang__)
 #define __attribute__(X)

lldb/include/lldb/lldb-enumerations.h

@@ -1323,6 +1323,22 @@ enum SymbolDownload {
   eSymbolDownloadForeground = 2,
 };
 
+/// Used in the SBProcess AddressMask/FixAddress methods.
+enum AddressMaskType {
+  eAddressMaskTypeCode = 0,
+  eAddressMaskTypeData,
+  eAddressMaskTypeAny,
+  eAddressMaskTypeAll = eAddressMaskTypeAny
+};
+
+/// Used in the SBProcess AddressMask/FixAddress methods.
+enum AddressMaskRange {
+  eAddressMaskRangeLow = 0,
+  eAddressMaskRangeHigh,
+  eAddressMaskRangeAny,
+  eAddressMaskRangeAll = eAddressMaskRangeAny,
+};
+
 } // namespace lldb
 
 #endif // LLDB_LLDB_ENUMERATIONS_H

lldb/source/API/SBProcess.cpp

@@ -1255,6 +1255,98 @@ lldb::SBFileSpec SBProcess::GetCoreFile() {
   return SBFileSpec(core_file);
 }
 
+addr_t SBProcess::GetAddressMask(AddressMaskType type,
+                                 AddressMaskRange addr_range) {
+  LLDB_INSTRUMENT_VA(this, type, addr_range);
+
+  if (ProcessSP process_sp = GetSP()) {
+    switch (type) {
+    case eAddressMaskTypeCode:
+      if (addr_range == eAddressMaskRangeHigh)
+        return process_sp->GetHighmemCodeAddressMask();
+      else
+        return process_sp->GetCodeAddressMask();
+    case eAddressMaskTypeData:
+      if (addr_range == eAddressMaskRangeHigh)
+        return process_sp->GetHighmemDataAddressMask();
+      else
+        return process_sp->GetDataAddressMask();
+    case eAddressMaskTypeAny:
+      if (addr_range == eAddressMaskRangeHigh)
+        return process_sp->GetHighmemDataAddressMask();
+      else
+        return process_sp->GetDataAddressMask();
+    }
+  }
+  return LLDB_INVALID_ADDRESS_MASK;
+}
+
+void SBProcess::SetAddressMask(AddressMaskType type, addr_t mask,
+                               AddressMaskRange addr_range) {
+  LLDB_INSTRUMENT_VA(this, type, mask, addr_range);
+
+  if (ProcessSP process_sp = GetSP()) {
+    switch (type) {
+    case eAddressMaskTypeCode:
+      if (addr_range == eAddressMaskRangeAll) {
+        process_sp->SetCodeAddressMask(mask);
+        process_sp->SetHighmemCodeAddressMask(mask);
+      } else if (addr_range == eAddressMaskRangeHigh) {
+        process_sp->SetHighmemCodeAddressMask(mask);
+      } else {
+        process_sp->SetCodeAddressMask(mask);
+      }
+      break;
+    case eAddressMaskTypeData:
+      if (addr_range == eAddressMaskRangeAll) {
+        process_sp->SetDataAddressMask(mask);
+        process_sp->SetHighmemDataAddressMask(mask);
+      } else if (addr_range == eAddressMaskRangeHigh) {
+        process_sp->SetHighmemDataAddressMask(mask);
+      } else {
+        process_sp->SetDataAddressMask(mask);
+      }
+      break;
+    case eAddressMaskTypeAll:
+      if (addr_range == eAddressMaskRangeAll) {
+        process_sp->SetCodeAddressMask(mask);
+        process_sp->SetDataAddressMask(mask);
+        process_sp->SetHighmemCodeAddressMask(mask);
+        process_sp->SetHighmemDataAddressMask(mask);
+      } else if (addr_range == eAddressMaskRangeHigh) {
+        process_sp->SetHighmemCodeAddressMask(mask);
+        process_sp->SetHighmemDataAddressMask(mask);
+      } else {
+        process_sp->SetCodeAddressMask(mask);
+        process_sp->SetDataAddressMask(mask);
+      }
+      break;
+    }
+  }
+}
+
+void SBProcess::SetAddressableBits(AddressMaskType type, uint32_t num_bits,
+                                   AddressMaskRange addr_range) {
+  LLDB_INSTRUMENT_VA(this, type, num_bits, addr_range);
+
+  SetAddressMask(type, AddressableBits::AddressableBitToMask(num_bits),
+                 addr_range);
+}
+
+addr_t SBProcess::FixAddress(addr_t addr, AddressMaskType type) {
+  LLDB_INSTRUMENT_VA(this, addr, type);
+
+  if (ProcessSP process_sp = GetSP()) {
+    if (type == eAddressMaskTypeAny)
+      return process_sp->FixAnyAddress(addr);
+    else if (type == eAddressMaskTypeData)
+      return process_sp->FixDataAddress(addr);
+    else if (type == eAddressMaskTypeCode)
+      return process_sp->FixCodeAddress(addr);
+  }
+  return addr;
+}
+
 lldb::addr_t SBProcess::AllocateMemory(size_t size, uint32_t permissions,
                                        lldb::SBError &sb_error) {
   LLDB_INSTRUMENT_VA(this, size, permissions, sb_error);

lldb/source/Commands/CommandObjectProcess.cpp

@@ -1408,7 +1408,7 @@ class CommandObjectProcessStatus : public CommandObjectParsed {
     if (m_options.m_verbose) {
       addr_t code_mask = process->GetCodeAddressMask();
       addr_t data_mask = process->GetDataAddressMask();
-      if (code_mask != 0) {
+      if (code_mask != LLDB_INVALID_ADDRESS_MASK) {
         int bits = std::bitset<64>(~code_mask).count();
         result.AppendMessageWithFormat(
             "Addressable code address mask: 0x%" PRIx64 "\n", code_mask);