[PATCH v1 11/15] tests/tcg/aarch64: Add bti smoke test

["Alex Bennée" <alex.bennee@linaro.org>]

From: Richard Henderson <richard.henderson@linaro.org>

Requires gcc 10 for -mbranch-protection=standard.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20200520023139.9812-3-richard.henderson@linaro.org>
[AJB: add CROSS_CC_HAS_ARMV8_BTI check]
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
---
 tests/tcg/aarch64/bti-1.c         | 62 +++++++++++++++++++++++++++++++
 tests/tcg/aarch64/bti-crt.inc.c   | 51 +++++++++++++++++++++++++
 tests/tcg/aarch64/Makefile.target |  9 +++++
 tests/tcg/configure.sh            |  4 ++
 4 files changed, 126 insertions(+)
 create mode 100644 tests/tcg/aarch64/bti-1.c
 create mode 100644 tests/tcg/aarch64/bti-crt.inc.c

diff --git a/tests/tcg/aarch64/bti-1.c b/tests/tcg/aarch64/bti-1.c
new file mode 100644
index 00000000000..61924f0d7a4
--- /dev/null
+++ b/tests/tcg/aarch64/bti-1.c
@@ -0,0 +1,62 @@
+/*
+ * Branch target identification, basic notskip cases.
+ */
+
+#include "bti-crt.inc.c"
+
+static void skip2_sigill(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_sigill);
+
+    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 00000000000..ef7831ad76a
--- /dev/null
+++ b/tests/tcg/aarch64/bti-crt.inc.c
@@ -0,0 +1,51 @@
+/*
+ * 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 <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");
+}
diff --git a/tests/tcg/aarch64/Makefile.target b/tests/tcg/aarch64/Makefile.target
index 312f36cde5f..8d39f4b2f45 100644
--- a/tests/tcg/aarch64/Makefile.target
+++ b/tests/tcg/aarch64/Makefile.target
@@ -24,6 +24,15 @@ run-pauth-%: QEMU_OPTS += -cpu max
 pauth-%: CFLAGS += -march=armv8.3-a
 endif
 
+# We need binutils-2.32 to link this test case without warnings.
+# And if we know that we have 2.32, we also don't need the linker script.
+# In the meantime, disable the test by default.
+ifneq ($(DOCKER_IMAGE)$(CROSS_CC_HAS_ARMV8_BTI),)
+AARCH64_TESTS += bti-1
+bti-%: CFLAGS += -mbranch-protection=standard
+bti-1: LDFLAGS += -nostdlib
+endif
+
 # Semihosting smoke test for linux-user
 AARCH64_TESTS += semihosting
 run-semihosting: semihosting
diff --git a/tests/tcg/configure.sh b/tests/tcg/configure.sh
index 2326f978562..ebfe3e2ce5a 100755
--- a/tests/tcg/configure.sh
+++ b/tests/tcg/configure.sh
@@ -231,6 +231,10 @@ for target in $target_list; do
                -march=armv8.3-a -o $TMPE $TMPC; then
                 echo "CROSS_CC_HAS_ARMV8_3=y" >> $config_target_mak
             fi
+            if do_compiler "$target_compiler" $target_compiler_cflags \
+               -mbranch-protection=standard -o $TMPE $TMPC; then
+                echo "CROSS_CC_HAS_ARMV8_BTI=y" >> $config_target_mak
+            fi
         ;;
     esac
 
-- 
2.20.1