diff mbox series

[05/20] target/arm: Restore SPSEL to correct CONTROL register on exception return

Message ID 1506092407-26985-6-git-send-email-peter.maydell@linaro.org
State Superseded
Headers show
Series ARM v8M: exception entry, exit and security | expand

Commit Message

Peter Maydell Sept. 22, 2017, 2:59 p.m. UTC 
On exception return for v8M, the SPSEL bit in the EXC_RETURN magic
value should be restored to the SPSEL bit in the CONTROL register
banked specified by the EXC_RETURN.ES bit.

Add write_v7m_control_spsel_for_secstate() which behaves like
write_v7m_control_spsel() but allows the caller to specify which
CONTROL bank to use, reimplement write_v7m_control_spsel() in
terms of it, and use it in exception return.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

---
 target/arm/helper.c | 40 +++++++++++++++++++++++++++-------------
 1 file changed, 27 insertions(+), 13 deletions(-)

-- 
2.7.4

Comments

Richard Henderson Oct. 5, 2017, 4:18 p.m. UTC | #1 
On 09/22/2017 10:59 AM, Peter Maydell wrote:
> On exception return for v8M, the SPSEL bit in the EXC_RETURN magic

> value should be restored to the SPSEL bit in the CONTROL register

> banked specified by the EXC_RETURN.ES bit.

> 

> Add write_v7m_control_spsel_for_secstate() which behaves like

> write_v7m_control_spsel() but allows the caller to specify which

> CONTROL bank to use, reimplement write_v7m_control_spsel() in

> terms of it, and use it in exception return.

> 

> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

> ---

>  target/arm/helper.c | 40 +++++++++++++++++++++++++++-------------

>  1 file changed, 27 insertions(+), 13 deletions(-)


Reviewed-by: Richard Henderson <richard.henderson@linaro.org>



r~
diff mbox series

Patch

diff --git a/target/arm/helper.c b/target/arm/helper.c
index a3c63c3..4444d04 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -6052,28 +6052,42 @@  static bool v7m_using_psp(CPUARMState *env)
         env->v7m.control[env->v7m.secure] & R_V7M_CONTROL_SPSEL_MASK;
 }
 
-/* Write to v7M CONTROL.SPSEL bit. This may change the current
- * stack pointer between Main and Process stack pointers.
+/* Write to v7M CONTROL.SPSEL bit for the specified security bank.
+ * This may change the current stack pointer between Main and Process
+ * stack pointers if it is done for the CONTROL register for the current
+ * security state.
  */
-static void write_v7m_control_spsel(CPUARMState *env, bool new_spsel)
+static void write_v7m_control_spsel_for_secstate(CPUARMState *env,
+                                                 bool new_spsel,
+                                                 bool secstate)
 {
-    uint32_t tmp;
-    bool new_is_psp, old_is_psp = v7m_using_psp(env);
+    bool old_is_psp = v7m_using_psp(env);
 
-    env->v7m.control[env->v7m.secure] =
-        deposit32(env->v7m.control[env->v7m.secure],
+    env->v7m.control[secstate] =
+        deposit32(env->v7m.control[secstate],
                   R_V7M_CONTROL_SPSEL_SHIFT,
                   R_V7M_CONTROL_SPSEL_LENGTH, new_spsel);
 
-    new_is_psp = v7m_using_psp(env);
+    if (secstate == env->v7m.secure) {
+        bool new_is_psp = v7m_using_psp(env);
+        uint32_t tmp;
 
-    if (old_is_psp != new_is_psp) {
-        tmp = env->v7m.other_sp;
-        env->v7m.other_sp = env->regs[13];
-        env->regs[13] = tmp;
+        if (old_is_psp != new_is_psp) {
+            tmp = env->v7m.other_sp;
+            env->v7m.other_sp = env->regs[13];
+            env->regs[13] = tmp;
+        }
     }
 }
 
+/* Write to v7M CONTROL.SPSEL bit. This may change the current
+ * stack pointer between Main and Process stack pointers.
+ */
+static void write_v7m_control_spsel(CPUARMState *env, bool new_spsel)
+{
+    write_v7m_control_spsel_for_secstate(env, new_spsel, env->v7m.secure);
+}
+
 void write_v7m_exception(CPUARMState *env, uint32_t new_exc)
 {
     /* Write a new value to v7m.exception, thus transitioning into or out
@@ -6369,7 +6383,7 @@  static void do_v7m_exception_exit(ARMCPU *cpu)
      * Handler mode (and will be until we write the new XPSR.Interrupt
      * field) this does not switch around the current stack pointer.
      */
-    write_v7m_control_spsel(env, return_to_sp_process);
+    write_v7m_control_spsel_for_secstate(env, return_to_sp_process, exc_secure);
 
     switch_v7m_security_state(env, return_to_secure);