[Lldb-commits] [lldb] [lldb] [Mach-O] ProcessMachCore needs to strip TBI data from addrs (PR #84998)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-lldb

Author: Jason Molenda (jasonmolenda)

<details>
<summary>Changes</summary>

Darwin AArch64 application processors are run with Top Byte Ignore mode enabled so metadata may be stored in the top byte, it needs to be ignored when reading/writing memory.  David Spickett handled this already in the base class Process::ReadMemory but ProcessMachCore overrides that method (to avoid the memory cache) and did not pick up the same change.  I add a test case that creates a pointer with metadata in the top byte and dereferences it with a live process and with a corefile.

rdar://123784501

---
Full diff: https://github.com/llvm/llvm-project/pull/84998.diff


4 Files Affected:

- (modified) lldb/source/Plugins/Process/mach-core/ProcessMachCore.cpp (+1-1) 
- (added) lldb/test/API/macosx/tbi-honored/Makefile (+3) 
- (added) lldb/test/API/macosx/tbi-honored/TestTBIHonored.py (+49) 
- (added) lldb/test/API/macosx/tbi-honored/main.c (+13) 


``````````diff
diff --git a/lldb/source/Plugins/Process/mach-core/ProcessMachCore.cpp b/lldb/source/Plugins/Process/mach-core/ProcessMachCore.cpp
index 3961dcf0fbcc0e..7b9938d4f02020 100644
--- a/lldb/source/Plugins/Process/mach-core/ProcessMachCore.cpp
+++ b/lldb/source/Plugins/Process/mach-core/ProcessMachCore.cpp
@@ -652,7 +652,7 @@ size_t ProcessMachCore::ReadMemory(addr_t addr, void *buf, size_t size,
                                    Status &error) {
   // Don't allow the caching that lldb_private::Process::ReadMemory does since
   // in core files we have it all cached our our core file anyway.
-  return DoReadMemory(addr, buf, size, error);
+  return DoReadMemory(FixAnyAddress(addr), buf, size, error);
 }
 
 size_t ProcessMachCore::DoReadMemory(addr_t addr, void *buf, size_t size,
diff --git a/lldb/test/API/macosx/tbi-honored/Makefile b/lldb/test/API/macosx/tbi-honored/Makefile
new file mode 100644
index 00000000000000..10495940055b63
--- /dev/null
+++ b/lldb/test/API/macosx/tbi-honored/Makefile
@@ -0,0 +1,3 @@
+C_SOURCES := main.c
+
+include Makefile.rules
diff --git a/lldb/test/API/macosx/tbi-honored/TestTBIHonored.py b/lldb/test/API/macosx/tbi-honored/TestTBIHonored.py
new file mode 100644
index 00000000000000..d38685359af6d1
--- /dev/null
+++ b/lldb/test/API/macosx/tbi-honored/TestTBIHonored.py
@@ -0,0 +1,49 @@
+"""Test that lldb on Darwin ignores metadata in the top byte of addresses."""
+
+import os
+import re
+import subprocess
+
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class TestTBIHonored(TestBase):
+    @no_debug_info_test
+    @skipUnlessDarwin
+    @skipIf(archs=no_match(["arm64", "arm64e"]))
+    @skipIfRemote
+    def do_variable_access_tests(self, frame):
+        self.assertEqual(
+            frame.variables["pb"][0]
+            .GetChildMemberWithName("p")
+            .Dereference()
+            .GetValueAsUnsigned(),
+            15,
+        )
+        addr = frame.variables["pb"][0].GetChildMemberWithName("p").GetValueAsUnsigned()
+        self.expect("expr -- *pb.p", substrs=["15"])
+        self.expect("frame variable *pb.p", substrs=["15"])
+        self.expect("expr -- *(int*)0x%x" % addr, substrs=["15"])
+
+    def test(self):
+        corefile = self.getBuildArtifact("process.core")
+        self.build()
+        (target, process, thread, bkpt) = lldbutil.run_to_source_breakpoint(
+            self, "// break here", lldb.SBFileSpec("main.c")
+        )
+
+        self.do_variable_access_tests(thread.GetFrameAtIndex(0))
+
+        self.runCmd("process save-core -s stack " + corefile)
+        self.dbg.DeleteTarget(target)
+
+        # Now load the corefile
+        target = self.dbg.CreateTarget("")
+        process = target.LoadCore(corefile)
+        thread = process.GetSelectedThread()
+        self.assertTrue(process.GetSelectedThread().IsValid())
+
+        self.do_variable_access_tests(thread.GetFrameAtIndex(0))
diff --git a/lldb/test/API/macosx/tbi-honored/main.c b/lldb/test/API/macosx/tbi-honored/main.c
new file mode 100644
index 00000000000000..3d7ad0b04cd664
--- /dev/null
+++ b/lldb/test/API/macosx/tbi-honored/main.c
@@ -0,0 +1,13 @@
+#include <stdint.h>
+#include <stdio.h>
+union ptrbytes {
+  int *p;
+  uint8_t bytes[8];
+};
+int main() {
+  int c = 15;
+  union ptrbytes pb;
+  pb.p = &c;
+  pb.bytes[7] = 0xfe;
+  printf("%d\n", *pb.p); // break here
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/84998