[15/19] nvic: Handle v8M changes in nvic_exec_prio()

Message ID 1505240046-11454-16-git-send-email-peter.maydell@linaro.org
State Superseded
Headers show
Series
  • ARMv8M: support security extn in the NVIC
Related show

Commit Message

Peter Maydell Sept. 12, 2017, 6:14 p.m.
Update nvic_exec_prio() to support the v8M changes:
 * BASEPRI, FAULTMASK and PRIMASK are all banked
 * AIRCR.PRIS can affect NS priorities
 * AIRCR.BFHFNMINS affects FAULTMASK behaviour

These changes mean that it's no longer possible to
definitely say that if FAULTMASK is set it overrides
PRIMASK, and if PRIMASK is set it overrides BASEPRI
(since if PRIMASK_NS is set and AIRCR.PRIS is set then
whether that 0x80 priority should take effect or the
priority in BASEPRI_S depends on the value of BASEPRI_S,
for instance). So we switch to the same approach used
by the pseudocode of working through BASEPRI, PRIMASK
and FAULTMASK and overriding the previous values if
needed.

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

---
 hw/intc/armv7m_nvic.c | 51 ++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 42 insertions(+), 9 deletions(-)

-- 
2.7.4

Comments

Richard Henderson Sept. 20, 2017, 5:21 p.m. | #1
On 09/12/2017 01:14 PM, Peter Maydell wrote:
> Update nvic_exec_prio() to support the v8M changes:

>  * BASEPRI, FAULTMASK and PRIMASK are all banked

>  * AIRCR.PRIS can affect NS priorities

>  * AIRCR.BFHFNMINS affects FAULTMASK behaviour

> 

> These changes mean that it's no longer possible to

> definitely say that if FAULTMASK is set it overrides

> PRIMASK, and if PRIMASK is set it overrides BASEPRI

> (since if PRIMASK_NS is set and AIRCR.PRIS is set then

> whether that 0x80 priority should take effect or the

> priority in BASEPRI_S depends on the value of BASEPRI_S,

> for instance). So we switch to the same approach used

> by the pseudocode of working through BASEPRI, PRIMASK

> and FAULTMASK and overriding the previous values if

> needed.

> 

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

> ---

>  hw/intc/armv7m_nvic.c | 51 ++++++++++++++++++++++++++++++++++++++++++---------

>  1 file changed, 42 insertions(+), 9 deletions(-)


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


r~

Patch

diff --git a/hw/intc/armv7m_nvic.c b/hw/intc/armv7m_nvic.c
index 91d2f33..b13327d 100644
--- a/hw/intc/armv7m_nvic.c
+++ b/hw/intc/armv7m_nvic.c
@@ -319,18 +319,51 @@  static void nvic_recompute_state(NVICState *s)
 static inline int nvic_exec_prio(NVICState *s)
 {
     CPUARMState *env = &s->cpu->env;
-    int running;
+    int running = NVIC_NOEXC_PRIO;
 
-    if (env->v7m.faultmask[env->v7m.secure]) {
-        running = -1;
-    } else if (env->v7m.primask[env->v7m.secure]) {
+    if (env->v7m.basepri[M_REG_NS] > 0) {
+        running = exc_group_prio(s, env->v7m.basepri[M_REG_NS], M_REG_NS);
+    }
+
+    if (env->v7m.basepri[M_REG_S] > 0) {
+        int basepri = exc_group_prio(s, env->v7m.basepri[M_REG_S], M_REG_S);
+        if (running > basepri) {
+            running = basepri;
+        }
+    }
+
+    if (env->v7m.primask[M_REG_NS]) {
+        if (env->v7m.aircr & R_V7M_AIRCR_PRIS_MASK) {
+            if (running > NVIC_NS_PRIO_LIMIT) {
+                running = NVIC_NS_PRIO_LIMIT;
+            }
+        } else {
+            running = 0;
+        }
+    }
+
+    if (env->v7m.primask[M_REG_S]) {
         running = 0;
-    } else if (env->v7m.basepri[env->v7m.secure] > 0) {
-        running = env->v7m.basepri[env->v7m.secure] &
-            nvic_gprio_mask(s, env->v7m.secure);
-    } else {
-        running = NVIC_NOEXC_PRIO; /* lower than any possible priority */
     }
+
+    if (env->v7m.faultmask[M_REG_NS]) {
+        if (env->v7m.aircr & R_V7M_AIRCR_BFHFNMINS_MASK) {
+            running = -1;
+        } else {
+            if (env->v7m.aircr & R_V7M_AIRCR_PRIS_MASK) {
+                if (running > NVIC_NS_PRIO_LIMIT) {
+                    running = NVIC_NS_PRIO_LIMIT;
+                }
+            } else {
+                running = 0;
+            }
+        }
+    }
+
+    if (env->v7m.faultmask[M_REG_S]) {
+        running = (env->v7m.aircr & R_V7M_AIRCR_BFHFNMINS_MASK) ? -3 : -1;
+    }
+
     /* consider priority of active handler */
     return MIN(running, s->exception_prio);
 }