For M-profile exception returns, the mmu index to use for exception
return unstacking is supposed to be that of wherever we are returning to:
* if returning to handler mode, privileged
* if returning to thread mode, privileged or unprivileged depending on
CONTROL.nPRIV for the destination security state
We were passing the wrong thing as the 'priv' argument to
arm_v7m_mmu_idx_for_secstate_and_priv(). The effect was that guests
which programmed the MPU to behave differently for privileged and
unprivileged code could get spurious MemManage Unstack exceptions.
Reported-by: Adithya Baglody <adithya.nagaraj.bagl...@intel.com>
Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
---
target/arm/helper.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/target/arm/helper.c b/target/arm/helper.c
index a2ac96084e7..0604a0efbe2 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -7171,9 +7171,11 @@ static void do_v7m_exception_exit(ARMCPU *cpu)
uint32_t frameptr = *frame_sp_p;
bool pop_ok = true;
ARMMMUIdx mmu_idx;
+ bool return_to_priv = return_to_handler ||
+ !(env->v7m.control[return_to_secure] & R_V7M_CONTROL_NPRIV_MASK);
mmu_idx = arm_v7m_mmu_idx_for_secstate_and_priv(env, return_to_secure,
- !return_to_handler);
+ return_to_priv);
if (!QEMU_IS_ALIGNED(frameptr, 8) &&
arm_feature(env, ARM_FEATURE_V8)) {
--
2.17.1
