target/arm: Set FPCCR.S when executing M-profile floating point insns

The M-profile FPCCR.S bit indicates the security status of
the floating point context. In the pseudocode ExecuteFPCheck()
function it is unconditionally set to match the current
security state whenever a floating point instruction is
executed.

Implement this by adding a new TB flag which tracks whether
FPCCR.S is different from the current security state, so
that we only need to emit the code to update it in the
less-common case when it is not already set correctly.

Note that we will add the handling for the other work done
by ExecuteFPCheck() in later commits.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20190416125744.27770-19-peter.maydell@linaro.org

1 files changed, 1 insertions, 0 deletions

diff --git a/target/arm/translate.h b/target/arm/translate.h
index 9846177..93abff6 100644
--- a/target/arm/translate.h
+++ b/target/arm/translate.h
@@ -40,6 +40,7 @@ typedef struct DisasContext {
     bool v7m_handler_mode;
     bool v8m_secure; /* true if v8M and we're in Secure mode */
     bool v8m_stackcheck; /* true if we need to perform v8M stack limit checks */
+    bool v8m_fpccr_s_wrong; /* true if v8M FPCCR.S != v8m_secure */
     /* Immediate value in AArch32 SVC insn; must be set if is_jmp == DISAS_SWI
      * so that top level loop can generate correct syndrome information.
      */