tests/tcg/aarch64: Add bti smoke tests

The note test requires gcc 10 for -mbranch-protection=standard.
The mmap test uses PROT_BTI and does not require special compiler support.

Acked-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20201021173749.111103-13-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 51 insertions, 0 deletions

diff --git a/tests/tcg/aarch64/bti-crt.inc.c b/tests/tcg/aarch64/bti-crt.inc.c
new file mode 100644
index 0000000000..47805f4e35
--- /dev/null
+++ b/tests/tcg/aarch64/bti-crt.inc.c
@@ -0,0 +1,51 @@
+/*
+ * Minimal user-environment for testing BTI.
+ *
+ * Normal libc is not (yet) built with BTI support enabled,
+ * and so could generate a BTI TRAP before ever reaching main.
+ */
+
+#include <stdlib.h>
+#include <signal.h>
+#include <ucontext.h>
+#include <asm/unistd.h>
+
+int main(void);
+
+void _start(void)
+{
+    exit(main());
+}
+
+void exit(int ret)
+{
+    register int x0 __asm__("x0") = ret;
+    register int x8 __asm__("x8") = __NR_exit;
+
+    asm volatile("svc #0" : : "r"(x0), "r"(x8));
+    __builtin_unreachable();
+}
+
+/*
+ * Irritatingly, the user API struct sigaction does not match the
+ * kernel API struct sigaction.  So for simplicity, isolate the
+ * kernel ABI here, and make this act like signal.
+ */
+void signal_info(int sig, void (*fn)(int, siginfo_t *, ucontext_t *))
+{
+    struct kernel_sigaction {
+        void (*handler)(int, siginfo_t *, ucontext_t *);
+        unsigned long flags;
+        unsigned long restorer;
+        unsigned long mask;
+    } sa = { fn, SA_SIGINFO, 0, 0 };
+
+    register int x0 __asm__("x0") = sig;
+    register void *x1 __asm__("x1") = &sa;
+    register void *x2 __asm__("x2") = 0;
+    register int x3 __asm__("x3") = sizeof(unsigned long);
+    register int x8 __asm__("x8") = __NR_rt_sigaction;
+
+    asm volatile("svc #0"
+                 : : "r"(x0), "r"(x1), "r"(x2), "r"(x3), "r"(x8) : "memory");
+}