[Qemu-arm] [PATCH 05/10] armv7m: honour CCR.STACKALIGN on exception entry

[Peter Maydell]

From: Michael Davidsaver <address@hidden>

The CCR.STACKALIGN bit controls whether the CPU is supposed to force
8-alignment of the stack pointer on entry to the exception handler.

Signed-off-by: Michael Davidsaver <address@hidden>
[PMM: commit message and comment tweaks]
Signed-off-by: Peter Maydell <address@hidden>
---
 target/arm/helper.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/target/arm/helper.c b/target/arm/helper.c
index ce7e43b..7dc30f5 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -6110,10 +6110,8 @@ void arm_v7m_cpu_do_interrupt(CPUState *cs)
         return; /* Never happens.  Keep compiler happy.  */
     }
 
-    /* Align stack pointer.  */
-    /* ??? Should only do this if Configuration Control Register
-       STACKALIGN bit is set.  */
-    if (env->regs[13] & 4) {
+    /* Align stack pointer if the guest wants that */
+    if ((env->regs[13] & 4) && (env->v7m.ccr & R_V7M_CCR_STKALIGN_MASK)) {
         env->regs[13] -= 4;
         xpsr |= 0x200;
     }
-- 
2.7.4