[lldb] Remove non address bits from memory read arguments

Addresses on AArch64 can have top byte tags, memory tags and pointer
authentication signatures in the upper bits.

While testing memory tagging I found that memory read couldn't
read a range if the two addresses had different tags. The same
could apply to signed pointers given the right circumstance.

(lldb) memory read mte_buf_alt_tag mte_buf+16
error: end address (0x900fffff7ff8010) must be greater than the start
address (0xa00fffff7ff8000).

Or it would try to read a lot more memory than expected.

(lldb) memory read mte_buf mte_buf_alt_tag+16
error: Normally, 'memory read' will not read over 1024 bytes of data.
error: Please use --force to override this restriction just once.
error: or set target.max-memory-read-size if you will often need a
larger limit.

Fix this by removing non address bits before we calculate the read
range. A test is added for AArch64 Linux that confirms this by using
the top byte ignore feature.

This means that if you do read with a tagged pointer the output
does not include those tags. This is potentially confusing but I think
overall it's better that we don't pretend that we're reading memory
from a range that the process is unable to map.

(lldb) p ptr1
(char *) $4 = 0x3400fffffffff140 "\x80\xf1\xff\xff\xff\xff"
(lldb) p ptr2
(char *) $5 = 0x5600fffffffff140 "\x80\xf1\xff\xff\xff\xff"
(lldb) memory read ptr1 ptr2+16
0xfffffffff140: 80 f1 ff ff ff ff 00 00 38 70 bc f7 ff ff 00 00  ........8p......

Reviewed By: omjavaid, danielkiss

Differential Revision: https://reviews.llvm.org/D103626

1 files changed, 8 insertions, 0 deletions

diff --git a/lldb/source/Commands/CommandObjectMemory.cpp b/lldb/source/Commands/CommandObjectMemory.cpp
index 9df42f36fafd..e59cd8028998 100644
--- a/lldb/source/Commands/CommandObjectMemory.cpp
+++ b/lldb/source/Commands/CommandObjectMemory.cpp
@@ -23,6 +23,7 @@
 #include "lldb/Interpreter/Options.h"
 #include "lldb/Symbol/SymbolFile.h"
 #include "lldb/Symbol/TypeList.h"
+#include "lldb/Target/ABI.h"
 #include "lldb/Target/Language.h"
 #include "lldb/Target/MemoryHistory.h"
 #include "lldb/Target/MemoryRegionInfo.h"
@@ -590,9 +591,16 @@ protected:
       return false;
     }
 
+    ABISP abi = m_exe_ctx.GetProcessPtr()->GetABI();
+    if (abi)
+      addr = abi->FixDataAddress(addr);
+
     if (argc == 2) {
       lldb::addr_t end_addr = OptionArgParser::ToAddress(
           &m_exe_ctx, command[1].ref(), LLDB_INVALID_ADDRESS, nullptr);
+      if (end_addr != LLDB_INVALID_ADDRESS && abi)
+        end_addr = abi->FixDataAddress(end_addr);
+
       if (end_addr == LLDB_INVALID_ADDRESS) {
         result.AppendError("invalid end address expression.");
         result.AppendError(error.AsCString());