[lldb] Add SBProcess methods for get/set/use address masks

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/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/Target/Process.cpp

@@ -5682,29 +5682,31 @@ void Process::Flush() {
 
 lldb::addr_t Process::GetCodeAddressMask() {
   if (uint32_t num_bits_setting = GetVirtualAddressableBits())
-    return ~((1ULL << num_bits_setting) - 1);
+    return AddressableBits::AddressableBitToMask(num_bits_setting);
 
   return m_code_address_mask;
 }
 
 lldb::addr_t Process::GetDataAddressMask() {
   if (uint32_t num_bits_setting = GetVirtualAddressableBits())
-    return ~((1ULL << num_bits_setting) - 1);
+    return AddressableBits::AddressableBitToMask(num_bits_setting);
 
   return m_data_address_mask;
 }
 
 lldb::addr_t Process::GetHighmemCodeAddressMask() {
   if (uint32_t num_bits_setting = GetHighmemVirtualAddressableBits())
-    return ~((1ULL << num_bits_setting) - 1);
+    return AddressableBits::AddressableBitToMask(num_bits_setting);
+
   if (m_highmem_code_address_mask)
     return m_highmem_code_address_mask;
   return GetCodeAddressMask();
 }
 
 lldb::addr_t Process::GetHighmemDataAddressMask() {
   if (uint32_t num_bits_setting = GetHighmemVirtualAddressableBits())
-    return ~((1ULL << num_bits_setting) - 1);
+    return AddressableBits::AddressableBitToMask(num_bits_setting);
+
   if (m_highmem_data_address_mask)
     return m_highmem_data_address_mask;
   return GetDataAddressMask();

lldb/source/Utility/AddressableBits.cpp

@@ -33,18 +33,26 @@ void AddressableBits::SetHighmemAddressableBits(
   m_high_memory_addr_bits = highmem_addressing_bits;
 }
 
+addr_t AddressableBits::AddressableBitToMask(uint32_t addressable_bits) {
+  assert(addressable_bits <= sizeof(addr_t) * 8);
+  if (addressable_bits == 64)
+    return 0; // all bits used for addressing
+  else
+    return ~((1ULL << addressable_bits) - 1);
+}
+
 void AddressableBits::SetProcessMasks(Process &process) {
   if (m_low_memory_addr_bits == 0 && m_high_memory_addr_bits == 0)
     return;
 
   if (m_low_memory_addr_bits != 0) {
-    addr_t low_addr_mask = ~((1ULL << m_low_memory_addr_bits) - 1);
+    addr_t low_addr_mask = AddressableBitToMask(m_low_memory_addr_bits);
     process.SetCodeAddressMask(low_addr_mask);
     process.SetDataAddressMask(low_addr_mask);
   }
 
   if (m_high_memory_addr_bits != 0) {
-    addr_t hi_addr_mask = ~((1ULL << m_high_memory_addr_bits) - 1);
+    addr_t hi_addr_mask = AddressableBitToMask(m_high_memory_addr_bits);
     process.SetHighmemCodeAddressMask(hi_addr_mask);
     process.SetHighmemDataAddressMask(hi_addr_mask);
   }

lldb/test/API/python_api/process/address-masks/Makefile

@@ -0,0 +1,3 @@
+C_SOURCES := main.c
+
+include Makefile.rules