Merge remote-tracking branch 'remotes/pmaydell/tags/pull-target-arm-20190704-1' into staging

target-arm queue:
 * more code-movement to separate TCG-only functions into their own files
 * Correct VMOV_imm_dp handling of short vectors
 * Execute Thumb instructions when their condbits are 0xf
 * armv7m_systick: Forbid non-privileged accesses
 * Use _ra versions of cpu_stl_data() in v7M helpers
 * v8M: Check state of exception being returned from
 * v8M: Forcibly clear negative-priority exceptions on deactivate

# gpg: Signature made Thu 04 Jul 2019 17:31:22 BST
# gpg:                using RSA key E1A5C593CD419DE28E8315CF3C2525ED14360CDE
# gpg:                issuer "peter.maydell@linaro.org"
# gpg: Good signature from "Peter Maydell <peter.maydell@linaro.org>" [ultimate]
# gpg:                 aka "Peter Maydell <pmaydell@gmail.com>" [ultimate]
# gpg:                 aka "Peter Maydell <pmaydell@chiark.greenend.org.uk>" [ultimate]
# Primary key fingerprint: E1A5 C593 CD41 9DE2 8E83  15CF 3C25 25ED 1436 0CDE

* remotes/pmaydell/tags/pull-target-arm-20190704-1:
  target/arm: Correct VMOV_imm_dp handling of short vectors
  target/arm: Execute Thumb instructions when their condbits are 0xf
  hw/timer/armv7m_systick: Forbid non-privileged accesses
  target/arm: Use _ra versions of cpu_stl_data() in v7M helpers
  target/arm: v8M: Check state of exception being returned from
  arm v8M: Forcibly clear negative-priority exceptions on deactivate
  target/arm/helper: Move M profile routines to m_helper.c
  target/arm: Restrict semi-hosting to TCG
  target/arm: Move debug routines to debug_helper.c

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

2 files changed, 68 insertions, 12 deletions

diff --git a/hw/intc/armv7m_nvic.c b/hw/intc/armv7m_nvic.c
index b8ede30b3c..9f8f0d3ff5 100644
--- a/hw/intc/armv7m_nvic.c
+++ b/hw/intc/armv7m_nvic.c
@@ -812,15 +812,45 @@ void armv7m_nvic_get_pending_irq_info(void *opaque,
 int armv7m_nvic_complete_irq(void *opaque, int irq, bool secure)
 {
     NVICState *s = (NVICState *)opaque;
-    VecInfo *vec;
+    VecInfo *vec = NULL;
     int ret;
 
     assert(irq > ARMV7M_EXCP_RESET && irq < s->num_irq);
 
-    if (secure && exc_is_banked(irq)) {
-        vec = &s->sec_vectors[irq];
-    } else {
-        vec = &s->vectors[irq];
+    /*
+     * For negative priorities, v8M will forcibly deactivate the appropriate
+     * NMI or HardFault regardless of what interrupt we're being asked to
+     * deactivate (compare the DeActivate() pseudocode). This is a guard
+     * against software returning from NMI or HardFault with a corrupted
+     * IPSR and leaving the CPU in a negative-priority state.
+     * v7M does not do this, but simply deactivates the requested interrupt.
+     */
+    if (arm_feature(&s->cpu->env, ARM_FEATURE_V8)) {
+        switch (armv7m_nvic_raw_execution_priority(s)) {
+        case -1:
+            if (s->cpu->env.v7m.aircr & R_V7M_AIRCR_BFHFNMINS_MASK) {
+                vec = &s->vectors[ARMV7M_EXCP_HARD];
+            } else {
+                vec = &s->sec_vectors[ARMV7M_EXCP_HARD];
+            }
+            break;
+        case -2:
+            vec = &s->vectors[ARMV7M_EXCP_NMI];
+            break;
+        case -3:
+            vec = &s->sec_vectors[ARMV7M_EXCP_HARD];
+            break;
+        default:
+            break;
+        }
+    }
+
+    if (!vec) {
+        if (secure && exc_is_banked(irq)) {
+            vec = &s->sec_vectors[irq];
+        } else {
+            vec = &s->vectors[irq];
+        }
     }
 
     trace_nvic_complete_irq(irq, secure);
@@ -830,7 +860,19 @@ int armv7m_nvic_complete_irq(void *opaque, int irq, bool secure)
         return -1;
     }
 
-    ret = nvic_rettobase(s);
+    /*
+     * If this is a configurable exception and it is currently
+     * targeting the opposite security state from the one we're trying
+     * to complete it for, this counts as an illegal exception return.
+     * We still need to deactivate whatever vector the logic above has
+     * selected, though, as it might not be the same as the one for the
+     * requested exception number.
+     */
+    if (!exc_is_banked(irq) && exc_targets_secure(s, irq) != secure) {
+        ret = -1;
+    } else {
+        ret = nvic_rettobase(s);
+    }
 
     vec->active = 0;
     if (vec->level) {
diff --git a/hw/timer/armv7m_systick.c b/hw/timer/armv7m_systick.c
index a17317ce2f..94640743b5 100644
--- a/hw/timer/armv7m_systick.c
+++ b/hw/timer/armv7m_systick.c
@@ -75,11 +75,17 @@ static void systick_timer_tick(void *opaque)
     }
 }
 
-static uint64_t systick_read(void *opaque, hwaddr addr, unsigned size)
+static MemTxResult systick_read(void *opaque, hwaddr addr, uint64_t *data,
+                                unsigned size, MemTxAttrs attrs)
 {
     SysTickState *s = opaque;
     uint32_t val;
 
+    if (attrs.user) {
+        /* Generate BusFault for unprivileged accesses */
+        return MEMTX_ERROR;
+    }
+
     switch (addr) {
     case 0x0: /* SysTick Control and Status.  */
         val = s->control;
@@ -121,14 +127,21 @@ static uint64_t systick_read(void *opaque, hwaddr addr, unsigned size)
     }
 
     trace_systick_read(addr, val, size);
-    return val;
+    *data = val;
+    return MEMTX_OK;
 }
 
-static void systick_write(void *opaque, hwaddr addr,
-                          uint64_t value, unsigned size)
+static MemTxResult systick_write(void *opaque, hwaddr addr,
+                                 uint64_t value, unsigned size,
+                                 MemTxAttrs attrs)
 {
     SysTickState *s = opaque;
 
+    if (attrs.user) {
+        /* Generate BusFault for unprivileged accesses */
+        return MEMTX_ERROR;
+    }
+
     trace_systick_write(addr, value, size);
 
     switch (addr) {
@@ -172,11 +185,12 @@ static void systick_write(void *opaque, hwaddr addr,
         qemu_log_mask(LOG_GUEST_ERROR,
                       "SysTick: Bad write offset 0x%" HWADDR_PRIx "\n", addr);
     }
+    return MEMTX_OK;
 }
 
 static const MemoryRegionOps systick_ops = {
-    .read = systick_read,
-    .write = systick_write,
+    .read_with_attrs = systick_read,
+    .write_with_attrs = systick_write,
     .endianness = DEVICE_NATIVE_ENDIAN,
     .valid.min_access_size = 4,
     .valid.max_access_size = 4,