[Lldb-commits] [lldb] f88eadd - [lldb] Call FixUpPointer in WritePointerToMemory (try 2) (#153585)
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Thu Sep 4 13:05:14 PDT 2025
Author: Felipe de Azevedo Piovezan
Date: 2025-09-04T13:05:10-07:00
New Revision: f88eadda357b0429b390ec0bcf64c361ad1a8f28
URL: https://github.com/llvm/llvm-project/commit/f88eadda357b0429b390ec0bcf64c361ad1a8f28
DIFF: https://github.com/llvm/llvm-project/commit/f88eadda357b0429b390ec0bcf64c361ad1a8f28.diff
LOG: [lldb] Call FixUpPointer in WritePointerToMemory (try 2) (#153585)
In architectures where pointers may contain metadata, such as arm64e,
the metadata may need to be cleaned prior to sending this pointer to be
used in expression evaluation generated code.
This patch is a step towards allowing consumers of pointers to decide
whether they want to keep or remove metadata, as opposed to discarding
metadata at the moment pointers are created. See #150537.
This was tested running the LLDB test suite on arm64e.
(The first attempt at this patch caused a failure in
TestScriptedProcessEmptyMemoryRegion.py. This test exercises a case
where IRMemoryMap uses host memory in its allocations; pointers to such
allocations should not be fixed, which is what the original patch failed
to account for).
Added:
lldb/test/API/macosx/arm-pointer-metadata-stripping/Makefile
lldb/test/API/macosx/arm-pointer-metadata-stripping/TestArmPointerMetadataStripping.py
lldb/test/API/macosx/arm-pointer-metadata-stripping/extra_symbols.json
lldb/test/API/macosx/arm-pointer-metadata-stripping/main.c
Modified:
lldb/source/Expression/IRMemoryMap.cpp
Removed:
################################################################################
diff --git a/lldb/source/Expression/IRMemoryMap.cpp b/lldb/source/Expression/IRMemoryMap.cpp
index 150699352a2e3..26e59b76a4dac 100644
--- a/lldb/source/Expression/IRMemoryMap.cpp
+++ b/lldb/source/Expression/IRMemoryMap.cpp
@@ -640,6 +640,15 @@ void IRMemoryMap::WritePointerToMemory(lldb::addr_t process_address,
lldb::addr_t address, Status &error) {
error.Clear();
+ /// Only ask the Process to fix the address if this address belongs to the
+ /// process. An address belongs to the process if the Allocation policy is not
+ /// eAllocationPolicyHostOnly.
+ auto it = FindAllocation(address, 1);
+ if (it == m_allocations.end() ||
+ it->second.m_policy != AllocationPolicy::eAllocationPolicyHostOnly)
+ if (auto process_sp = GetProcessWP().lock())
+ address = process_sp->FixAnyAddress(address);
+
Scalar scalar(address);
WriteScalarToMemory(process_address, scalar, GetAddressByteSize(), error);
diff --git a/lldb/test/API/macosx/arm-pointer-metadata-stripping/Makefile b/lldb/test/API/macosx/arm-pointer-metadata-stripping/Makefile
new file mode 100644
index 0000000000000..c9319d6e6888a
--- /dev/null
+++ b/lldb/test/API/macosx/arm-pointer-metadata-stripping/Makefile
@@ -0,0 +1,2 @@
+C_SOURCES := main.c
+include Makefile.rules
diff --git a/lldb/test/API/macosx/arm-pointer-metadata-stripping/TestArmPointerMetadataStripping.py b/lldb/test/API/macosx/arm-pointer-metadata-stripping/TestArmPointerMetadataStripping.py
new file mode 100644
index 0000000000000..f61945b3eb4c9
--- /dev/null
+++ b/lldb/test/API/macosx/arm-pointer-metadata-stripping/TestArmPointerMetadataStripping.py
@@ -0,0 +1,48 @@
+import lldb
+import json
+import os
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+ at skipUnlessDarwin
+ at skipIf(archs=no_match(["arm64", "arm64e"]))
+class TestArmPointerMetadataStripping(TestBase):
+ # Use extra_symbols.json as a template to add a new symbol whose address
+ # contains non-zero high order bits set.
+ def create_symbols_file(self):
+ template_path = os.path.join(self.getSourceDir(), "extra_symbols.json")
+ with open(template_path, "r") as f:
+ symbols_data = json.load(f)
+
+ target = self.dbg.GetSelectedTarget()
+ symbols_data["triple"] = target.GetTriple()
+
+ module = target.GetModuleAtIndex(0)
+ symbols_data["uuid"] = module.GetUUIDString()
+
+ json_filename = self.getBuildArtifact("extra_symbols.json")
+ with open(json_filename, "w") as file:
+ json.dump(symbols_data, file, indent=4)
+
+ return json_filename
+
+ def test(self):
+ self.build()
+ src = lldb.SBFileSpec("main.c")
+ target, process, thread, bkpt = lldbutil.run_to_source_breakpoint(
+ self, "break here", src
+ )
+
+ symbols_file = self.create_symbols_file()
+ self.runCmd(f"target module add {symbols_file}")
+
+ # The high order bits should be stripped.
+ self.expect_expr("get_high_bits(&myglobal_json)", result_value="0")
+
+ # Mark all bits as used for addresses and ensure bits are no longer stripped.
+ self.runCmd("settings set target.process.virtual-addressable-bits 64")
+ self.expect_expr(
+ "get_high_bits(&myglobal_json)", result_value=str(0x1200000000000000)
+ )
diff --git a/lldb/test/API/macosx/arm-pointer-metadata-stripping/extra_symbols.json b/lldb/test/API/macosx/arm-pointer-metadata-stripping/extra_symbols.json
new file mode 100644
index 0000000000000..5c2503d508b42
--- /dev/null
+++ b/lldb/test/API/macosx/arm-pointer-metadata-stripping/extra_symbols.json
@@ -0,0 +1,21 @@
+{
+ "triple": "replace me",
+ "uuid": "replace me",
+ "type": "executable",
+ "sections": [
+ {
+ "name": "__DATA",
+ "type": "data",
+ "address": 1297224342667202580,
+ "size": 16
+ }
+ ],
+ "symbols": [
+ {
+ "name": "myglobal_json",
+ "size": 8,
+ "type": "data",
+ "address": 1297224342667202580
+ }
+ ]
+}
diff --git a/lldb/test/API/macosx/arm-pointer-metadata-stripping/main.c b/lldb/test/API/macosx/arm-pointer-metadata-stripping/main.c
new file mode 100644
index 0000000000000..05a85133caf72
--- /dev/null
+++ b/lldb/test/API/macosx/arm-pointer-metadata-stripping/main.c
@@ -0,0 +1,13 @@
+#include <stdint.h>
+
+uintptr_t get_high_bits(void *ptr) {
+ uintptr_t address_bits = 56;
+ uintptr_t mask = ~((1ULL << address_bits) - 1);
+ uintptr_t ptrtoint = (uintptr_t)ptr;
+ uintptr_t high_bits = ptrtoint & mask;
+ return high_bits;
+}
+
+int main() {
+ return 0; // break here
+}
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