Read fault address on arm64 using proposed kernel API.
On aarch64, the top 8 bits of the address (i.e. the tag bits) of
the fault address in si_addr are always clear. This isn't ideal for
MTE which will require these bits in order to correctly diagnose
tag mismatches.
A proposed kernel patch [1] exposes the full fault address including
the tag bits as part of the ucontext. Change debuggerd to read this
fault address if available.
[1] https://patchwork.kernel.org/patch/11435077/
Bug: 135772972
Change-Id: Ia05be574113860f4e9ecc36a310c4b740e0c4afb
diff --git a/debuggerd/debuggerd_test.cpp b/debuggerd/debuggerd_test.cpp
index 6a8cc56..054f836 100644
--- a/debuggerd/debuggerd_test.cpp
+++ b/debuggerd/debuggerd_test.cpp
@@ -305,6 +305,32 @@
ASSERT_MATCH(result, R"(signal 11 \(SIGSEGV\), code 1 \(SEGV_MAPERR\), fault addr 0xdead)");
}
+TEST_F(CrasherTest, tagged_fault_addr) {
+#if !defined(__aarch64__)
+ GTEST_SKIP() << "Requires aarch64";
+#endif
+ int intercept_result;
+ unique_fd output_fd;
+ StartProcess([]() {
+ *reinterpret_cast<volatile char*>(0x100000000000dead) = '1';
+ });
+
+ StartIntercept(&output_fd);
+ FinishCrasher();
+ AssertDeath(SIGSEGV);
+ FinishIntercept(&intercept_result);
+
+ ASSERT_EQ(1, intercept_result) << "tombstoned reported failure";
+
+ std::string result;
+ ConsumeFd(std::move(output_fd), &result);
+
+ // The address can either be tagged (new kernels) or untagged (old kernels).
+ ASSERT_MATCH(
+ result,
+ R"(signal 11 \(SIGSEGV\), code 1 \(SEGV_MAPERR\), fault addr (0x100000000000dead|0xdead))");
+}
+
TEST_F(CrasherTest, LD_PRELOAD) {
int intercept_result;
unique_fd output_fd;