[lldb] Recognize MTE faults with EXC_GUARD exception type #172579
+23
−10
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Member
|
@llvm/pr-subscribers-lldb Author: Julian Lettner (yln) Changes5a5a315 [lldb][NFC] Extract StopInfoMachException::GetTagFaultAddress() helper function 9a91ded [lldb] Recognize MTE faults with EXC_GUARD exception type rdar://166415268 Full diff: https://github.com/llvm/llvm-project/pull/172579.diff 2 Files Affected:
diff --git a/lldb/source/Plugins/Process/Utility/StopInfoMachException.cpp b/lldb/source/Plugins/Process/Utility/StopInfoMachException.cpp
index 601cfdcb4e9f7..826807e47ce96 100644
--- a/lldb/source/Plugins/Process/Utility/StopInfoMachException.cpp
+++ b/lldb/source/Plugins/Process/Utility/StopInfoMachException.cpp
@@ -77,19 +77,27 @@ static void DescribeAddressBriefly(Stream &strm, const Address &addr,
strm.Printf(".\n");
}
+std::optional<addr_t> StopInfoMachException::GetTagFaultAddress() const {
+ bool bad_access =
+ (m_value == 1 || m_value == 12); // EXC_BAD_ACCESS or EXC_GUARD
+ bool tag_fault = (m_exc_code == 0x106); // EXC_ARM_MTE_TAG_FAULT
+ bool has_fault_addr = (m_exc_data_count >= 2); // m_exc_subcode -> fault addr
+
+ if (bad_access && tag_fault && has_fault_addr)
+ return m_exc_subcode; // Fault address
+
+ return std::nullopt;
+}
+
static constexpr uint8_t g_mte_tag_shift = 64 - 8;
static constexpr addr_t g_mte_tag_mask = (addr_t)0x0f << g_mte_tag_shift;
-bool StopInfoMachException::DetermineTagMismatch(ExecutionContext &exe_ctx) {
- const bool IsBadAccess = m_value == 1; // EXC_BAD_ACCESS
- const bool IsMTETagFault = (m_exc_code == 0x106); // EXC_ARM_MTE_TAG_FAULT
- if (!IsBadAccess || !IsMTETagFault)
- return false;
-
- if (m_exc_data_count < 2)
- return false;
+bool StopInfoMachException::DetermineTagMismatch() {
+ auto fault_address = GetTagFaultAddress();
+ if (!fault_address)
+ return false;
- const uint64_t bad_address = m_exc_subcode;
+ const uint64_t bad_address = *fault_address;
StreamString strm;
strm.Printf("EXC_ARM_MTE_TAG_FAULT (code=%" PRIu64 ", address=0x%" PRIx64
@@ -295,7 +303,7 @@ const char *StopInfoMachException::GetDescription() {
case llvm::Triple::aarch64:
if (DeterminePtrauthFailure(exe_ctx))
return m_description.c_str();
- if (DetermineTagMismatch(exe_ctx))
+ if (DetermineTagMismatch())
return m_description.c_str();
break;
@@ -490,6 +498,8 @@ const char *StopInfoMachException::GetDescription() {
#endif
break;
case 12:
+ if (DetermineTagMismatch())
+ return m_description.c_str();
exc_desc = "EXC_GUARD";
break;
}
diff --git a/lldb/source/Plugins/Process/Utility/StopInfoMachException.h b/lldb/source/Plugins/Process/Utility/StopInfoMachException.h
index c02389e5b3642..26f93e0bb348f 100644
--- a/lldb/source/Plugins/Process/Utility/StopInfoMachException.h
+++ b/lldb/source/Plugins/Process/Utility/StopInfoMachException.h
@@ -27,7 +27,7 @@ class StopInfoMachException : public StopInfo {
/// is auth-related failure, and returns false otherwise.
bool DeterminePtrauthFailure(ExecutionContext &exe_ctx);
- bool DetermineTagMismatch(ExecutionContext &exe_ctx);
+ bool DetermineTagMismatch();
public:
// Constructors and Destructors
@@ -48,6 +48,9 @@ class StopInfoMachException : public StopInfo {
const char *GetDescription() override;
+ // Returns the fault address, iff this is a EXC_ARM_MTE_TAG_FAULT.
+ std::optional<lldb::addr_t> GetTagFaultAddress() const;
+
#if defined(__APPLE__)
struct MachException {
static const char *Name(exception_type_t exc_type);
|
This comment was marked as resolved.
This comment was marked as resolved.
Recognize the new `EXC_GUARD` mach exception type for MTE faults. We also keep supporting the old `EXC_BAD_ACCESS` exception type for backward compatibility (newer LLDB on older OS). rdar://166415268
yln
force-pushed
the
users/yln/lldb-mte-fault-EXC_GUARD
branch
from
9a91ded to
1f7ddff
Compare
Comment on lines
+81
to
+84
| bool bad_access = | ||
| (m_value == 1 || m_value == 12); // EXC_BAD_ACCESS or EXC_GUARD | ||
| bool tag_fault = (m_exc_code == 0x106); // EXC_ARM_MTE_TAG_FAULT | ||
| bool has_fault_addr = (m_exc_data_count >= 2); // m_exc_subcode -> fault addr |
Member
There was a problem hiding this comment.
Suggested change
| bool bad_access = | |
| (m_value == 1 || m_value == 12); // EXC_BAD_ACCESS or EXC_GUARD | |
| bool tag_fault = (m_exc_code == 0x106); // EXC_ARM_MTE_TAG_FAULT | |
| bool has_fault_addr = (m_exc_data_count >= 2); // m_exc_subcode -> fault addr | |
| const bool bad_access = | |
| (m_value == 1 || m_value == 12); // EXC_BAD_ACCESS or EXC_GUARD | |
| const bool tag_fault = (m_exc_code == 0x106); // EXC_ARM_MTE_TAG_FAULT | |
| // Whether the subcode (m_exc_subcode) holds the fault address. | |
| const bool has_fault_addr = (m_exc_data_count >= 2); |
Comment on lines
+86
to
+87
| if (bad_access && tag_fault && has_fault_addr) | ||
| return m_exc_subcode; // Fault address |
Member
There was a problem hiding this comment.
Comments should be english prose with capitalization and periods.
Suggested change
| if (bad_access && tag_fault && has_fault_addr) | |
| return m_exc_subcode; // Fault address | |
| if (bad_access && tag_fault && has_fault_addr) | |
| return m_exc_subcode; // The subcode is the fault address. |
|
|
||
| if (m_exc_data_count < 2) | ||
| bool StopInfoMachException::DetermineTagMismatch() { | ||
| auto fault_address = GetTagFaultAddress(); |
Member
There was a problem hiding this comment.
The type isn't obvious from the RHS.
Suggested change
| auto fault_address = GetTagFaultAddress(); | |
| std::optional<addr_t> fault_address = GetTagFaultAddress(); |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
5a5a315 [lldb][NFC] Extract StopInfoMachException::GetTagFaultAddress() helper function
9a91ded [lldb] Recognize MTE faults with EXC_GUARD exception type
Recognize the new
EXC_GUARDmach exception typefor MTE faults. We also keep supporting the old
EXC_BAD_ACCESSexception type for backwardcompatibility (newer LLDB on older OS).
rdar://166415268