This will build with older toolchains, without the upstream support
for -mbranch-protection. Such a toolchain will produce a warning
in such cases,
ld: warning: /tmp/ccyZt0kq.o: unsupported GNU_PROPERTY_TYPE (5) \
type: 0xc000
but the still places the note at the correct location in the binary
for processing by the runtime loader.
Signed-off-by: Richard Henderson
---
tests/tcg/aarch64/bti-1.c | 77 +++
tests/tcg/aarch64/bti-crt.inc.c | 69 +++
tests/tcg/aarch64/Makefile.target | 3 ++
tests/tcg/aarch64/bti.ld | 15 ++
4 files changed, 164 insertions(+)
create mode 100644 tests/tcg/aarch64/bti-1.c
create mode 100644 tests/tcg/aarch64/bti-crt.inc.c
create mode 100644 tests/tcg/aarch64/bti.ld
diff --git a/tests/tcg/aarch64/bti-1.c b/tests/tcg/aarch64/bti-1.c
new file mode 100644
index 00..2aee57ea7a
--- /dev/null
+++ b/tests/tcg/aarch64/bti-1.c
@@ -0,0 +1,77 @@
+/*
+ * Branch target identification, basic notskip cases.
+ */
+
+#include "bti-crt.inc.c"
+
+/*
+ * Work around lack of -mbranch-protection=standard in older toolchains.
+ * The signal handler is invoked by the kernel with PSTATE.BTYPE=2, which
+ * means that the handler must begin with a marker like BTI_C.
+ */
+asm("skip2_sigill1:\n\
+ hint#34\n\
+ b skip2_sigill2\n\
+.type skip2_sigill1,%function\n\
+.size skip2_sigill1,8");
+
+extern void skip2_sigill1(int sig, siginfo_t *info, ucontext_t *uc)
+__attribute__((visibility("hidden")));
+
+static void __attribute__((used))
+skip2_sigill2(int sig, siginfo_t *info, ucontext_t *uc)
+{
+uc->uc_mcontext.pc += 8;
+uc->uc_mcontext.pstate = 1;
+}
+
+#define NOP "nop"
+#define BTI_N "hint #32"
+#define BTI_C "hint #34"
+#define BTI_J "hint #36"
+#define BTI_JC"hint #38"
+
+#define BTYPE_1(DEST) \
+asm("mov %0,#1; adr x16, 1f; br x16; 1: " DEST "; mov %0,#0" \
+: "=r"(skipped) : : "x16")
+
+#define BTYPE_2(DEST) \
+asm("mov %0,#1; adr x16, 1f; blr x16; 1: " DEST "; mov %0,#0" \
+: "=r"(skipped) : : "x16", "x30")
+
+#define BTYPE_3(DEST) \
+asm("mov %0,#1; adr x15, 1f; br x15; 1: " DEST "; mov %0,#0" \
+: "=r"(skipped) : : "x15")
+
+#define TEST(WHICH, DEST, EXPECT) \
+do { WHICH(DEST); fail += skipped ^ EXPECT; } while (0)
+
+
+int main()
+{
+int fail = 0;
+int skipped;
+
+/* Signal-like with SA_SIGINFO. */
+signal_info(SIGILL, skip2_sigill1);
+
+TEST(BTYPE_1, NOP, 1);
+TEST(BTYPE_1, BTI_N, 1);
+TEST(BTYPE_1, BTI_C, 0);
+TEST(BTYPE_1, BTI_J, 0);
+TEST(BTYPE_1, BTI_JC, 0);
+
+TEST(BTYPE_2, NOP, 1);
+TEST(BTYPE_2, BTI_N, 1);
+TEST(BTYPE_2, BTI_C, 0);
+TEST(BTYPE_2, BTI_J, 1);
+TEST(BTYPE_2, BTI_JC, 0);
+
+TEST(BTYPE_3, NOP, 1);
+TEST(BTYPE_3, BTI_N, 1);
+TEST(BTYPE_3, BTI_C, 1);
+TEST(BTYPE_3, BTI_J, 0);
+TEST(BTYPE_3, BTI_JC, 0);
+
+return fail;
+}
diff --git a/tests/tcg/aarch64/bti-crt.inc.c b/tests/tcg/aarch64/bti-crt.inc.c
new file mode 100644
index 00..bb363853de
--- /dev/null
+++ b/tests/tcg/aarch64/bti-crt.inc.c
@@ -0,0 +1,69 @@
+/*
+ * Minimal user-environment for testing BTI.
+ *
+ * Normal libc is not built with BTI support enabled, and so could
+ * generate a BTI TRAP before ever reaching main.
+ */
+
+#include
+#include
+#include
+#include
+
+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") =
+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");
+}
+
+/*
+ * Create the PT_NOTE that will enable BTI in the page tables.
+ * This will be created by the compiler with -mbranch-protection=standard,
+ * but as of 2019-03-29, this is has not been committed to gcc mainline.
+ * This will probably be in GCC10.
+ */
+asm(".section .note.gnu.property,\"a\"\n\
+ .align 3\n\
+ .long 4\n\
+.long 16\n\
+.long 5\n\
+.string\"GNU\"\n\
+ .long 0xc000\n\
+ .long 4\n\
+ .long 1\n\
+
