target/arm: Add v8M stack limit checks on NS function calls

Check the v8M stack limits when pushing the frame for a
non-secure function call via BLXNS.

In order to be able to generate the exception we need to
promote raise_exception() from being local to op_helper.c
so we can call it from helper.c.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20181002163556.10279-8-peter.maydell@linaro.org

1 files changed, 4 insertions, 0 deletions

diff --git a/target/arm/helper.c b/target/arm/helper.c
index 4cc4369255..33c7e2f48e 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -6738,6 +6738,10 @@ void HELPER(v7m_blxns)(CPUARMState *env, uint32_t dest)
                       "BLXNS with misaligned SP is UNPREDICTABLE\n");
     }
 
+    if (sp < v7m_sp_limit(env)) {
+        raise_exception(env, EXCP_STKOF, 0, 1);
+    }
+
     saved_psr = env->v7m.exception;
     if (env->v7m.control[M_REG_S] & R_V7M_CONTROL_SFPA_MASK) {
         saved_psr |= XPSR_SFPA;