Merge remote-tracking branch 'remotes/pmaydell/tags/pull-target-arm-20170228' into staging

target-arm queue:
 * raspi2: implement RNG module
 * raspi2: implement new SD card controller (but don't wire it up)
 * sdhci: bugfixes for block transfers
 * virt: fix cpu object reference leak
 * Add missing fp_access_check() to aarch64 crypto instructions
 * cputlb: Don't assume do_unassigned_access() never returns
 * virt: Add a user option to disallow ITS instantiation
 * i.MX timers: fix reset handling
 * ARMv7M NVIC: rewrite to fix broken priority handling and masking
 * exynos: Fix proper mapping of CPUs by providing real cluster ID
 * exynos: Fix Linux kernel division by zero for PLLs

# gpg: Signature made Tue 28 Feb 2017 12:40:51 GMT
# gpg:                using RSA key 0x3C2525ED14360CDE
# gpg: Good signature from "Peter Maydell <peter.maydell@linaro.org>"
# gpg:                 aka "Peter Maydell <pmaydell@gmail.com>"
# gpg:                 aka "Peter Maydell <pmaydell@chiark.greenend.org.uk>"
# Primary key fingerprint: E1A5 C593 CD41 9DE2 8E83  15CF 3C25 25ED 1436 0CDE

* remotes/pmaydell/tags/pull-target-arm-20170228: (27 commits)
  hw/arm/exynos: Fix proper mapping of CPUs by providing real cluster ID
  hw/arm/exynos: Fix Linux kernel division by zero for PLLs
  bcm2835_sdhost: add bcm2835 sdhost controller
  armv7m: Allow SHCSR writes to change pending and active bits
  armv7m: Raise correct kind of UsageFault for attempts to execute ARM code
  armv7m: Check exception return consistency
  armv7m: Extract "exception taken" code into functions
  armv7m: VECTCLRACTIVE and VECTRESET are UNPREDICTABLE
  armv7m: Simpler and faster exception start
  armv7m: Remove unused armv7m_nvic_acknowledge_irq() return value
  armv7m: Escalate exceptions to HardFault if necessary
  arm: gic: Remove references to NVIC
  armv7m: Fix condition check for taking exceptions
  armv7m: Rewrite NVIC to not use any GIC code
  armv7m: Implement reading and writing of PRIGROUP
  armv7m: Rename nvic_state to NVICState
  ARM i.MX timers: fix reset handling
  hw/arm/virt: Add a user option to disallow ITS instantiation
  cputlb: Don't assume do_unassigned_access() never returns
  Add missing fp_access_check() to aarch64 crypto instructions
  ...

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

1 files changed, 179 insertions, 66 deletions

diff --git a/target/arm/helper.c b/target/arm/helper.c
index bcedb4a808..3f4211b572 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -6002,22 +6002,165 @@ static void switch_v7m_sp(CPUARMState *env, bool new_spsel)
     }
 }
 
-static void do_v7m_exception_exit(CPUARMState *env)
+static uint32_t arm_v7m_load_vector(ARMCPU *cpu)
 {
+    CPUState *cs = CPU(cpu);
+    CPUARMState *env = &cpu->env;
+    MemTxResult result;
+    hwaddr vec = env->v7m.vecbase + env->v7m.exception * 4;
+    uint32_t addr;
+
+    addr = address_space_ldl(cs->as, vec,
+                             MEMTXATTRS_UNSPECIFIED, &result);
+    if (result != MEMTX_OK) {
+        /* Architecturally this should cause a HardFault setting HSFR.VECTTBL,
+         * which would then be immediately followed by our failing to load
+         * the entry vector for that HardFault, which is a Lockup case.
+         * Since we don't model Lockup, we just report this guest error
+         * via cpu_abort().
+         */
+        cpu_abort(cs, "Failed to read from exception vector table "
+                  "entry %08x\n", (unsigned)vec);
+    }
+    return addr;
+}
+
+static void v7m_exception_taken(ARMCPU *cpu, uint32_t lr)
+{
+    /* Do the "take the exception" parts of exception entry,
+     * but not the pushing of state to the stack. This is
+     * similar to the pseudocode ExceptionTaken() function.
+     */
+    CPUARMState *env = &cpu->env;
+    uint32_t addr;
+
+    armv7m_nvic_acknowledge_irq(env->nvic);
+    switch_v7m_sp(env, 0);
+    /* Clear IT bits */
+    env->condexec_bits = 0;
+    env->regs[14] = lr;
+    addr = arm_v7m_load_vector(cpu);
+    env->regs[15] = addr & 0xfffffffe;
+    env->thumb = addr & 1;
+}
+
+static void v7m_push_stack(ARMCPU *cpu)
+{
+    /* Do the "set up stack frame" part of exception entry,
+     * similar to pseudocode PushStack().
+     */
+    CPUARMState *env = &cpu->env;
+    uint32_t xpsr = xpsr_read(env);
+
+    /* 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;
+    }
+    /* Switch to the handler mode.  */
+    v7m_push(env, xpsr);
+    v7m_push(env, env->regs[15]);
+    v7m_push(env, env->regs[14]);
+    v7m_push(env, env->regs[12]);
+    v7m_push(env, env->regs[3]);
+    v7m_push(env, env->regs[2]);
+    v7m_push(env, env->regs[1]);
+    v7m_push(env, env->regs[0]);
+}
+
+static void do_v7m_exception_exit(ARMCPU *cpu)
+{
+    CPUARMState *env = &cpu->env;
     uint32_t type;
     uint32_t xpsr;
-
+    bool ufault = false;
+    bool return_to_sp_process = false;
+    bool return_to_handler = false;
+    bool rettobase = false;
+
+    /* We can only get here from an EXCP_EXCEPTION_EXIT, and
+     * arm_v7m_do_unassigned_access() enforces the architectural rule
+     * that jumps to magic addresses don't have magic behaviour unless
+     * we're in Handler mode (compare pseudocode BXWritePC()).
+     */
+    assert(env->v7m.exception != 0);
+
+    /* In the spec pseudocode ExceptionReturn() is called directly
+     * from BXWritePC() and gets the full target PC value including
+     * bit zero. In QEMU's implementation we treat it as a normal
+     * jump-to-register (which is then caught later on), and so split
+     * the target value up between env->regs[15] and env->thumb in
+     * gen_bx(). Reconstitute it.
+     */
     type = env->regs[15];
+    if (env->thumb) {
+        type |= 1;
+    }
+
+    qemu_log_mask(CPU_LOG_INT, "Exception return: magic PC %" PRIx32
+                  " previous exception %d\n",
+                  type, env->v7m.exception);
+
+    if (extract32(type, 5, 23) != extract32(-1, 5, 23)) {
+        qemu_log_mask(LOG_GUEST_ERROR, "M profile: zero high bits in exception "
+                      "exit PC value 0x%" PRIx32 " are UNPREDICTABLE\n", type);
+    }
+
     if (env->v7m.exception != ARMV7M_EXCP_NMI) {
         /* Auto-clear FAULTMASK on return from other than NMI */
         env->daif &= ~PSTATE_F;
     }
-    if (env->v7m.exception != 0) {
-        armv7m_nvic_complete_irq(env->nvic, env->v7m.exception);
+
+    switch (armv7m_nvic_complete_irq(env->nvic, env->v7m.exception)) {
+    case -1:
+        /* attempt to exit an exception that isn't active */
+        ufault = true;
+        break;
+    case 0:
+        /* still an irq active now */
+        break;
+    case 1:
+        /* we returned to base exception level, no nesting.
+         * (In the pseudocode this is written using "NestedActivation != 1"
+         * where we have 'rettobase == false'.)
+         */
+        rettobase = true;
+        break;
+    default:
+        g_assert_not_reached();
+    }
+
+    switch (type & 0xf) {
+    case 1: /* Return to Handler */
+        return_to_handler = true;
+        break;
+    case 13: /* Return to Thread using Process stack */
+        return_to_sp_process = true;
+        /* fall through */
+    case 9: /* Return to Thread using Main stack */
+        if (!rettobase &&
+            !(env->v7m.ccr & R_V7M_CCR_NONBASETHRDENA_MASK)) {
+            ufault = true;
+        }
+        break;
+    default:
+        ufault = true;
+    }
+
+    if (ufault) {
+        /* Bad exception return: instead of popping the exception
+         * stack, directly take a usage fault on the current stack.
+         */
+        env->v7m.cfsr |= R_V7M_CFSR_INVPC_MASK;
+        armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE);
+        v7m_exception_taken(cpu, type | 0xf0000000);
+        qemu_log_mask(CPU_LOG_INT, "...taking UsageFault on existing "
+                      "stackframe: failed exception return integrity check\n");
+        return;
     }
 
     /* Switch to the target stack.  */
-    switch_v7m_sp(env, (type & 4) != 0);
+    switch_v7m_sp(env, return_to_sp_process);
     /* Pop registers.  */
     env->regs[0] = v7m_pop(env);
     env->regs[1] = v7m_pop(env);
@@ -6041,11 +6184,24 @@ static void do_v7m_exception_exit(CPUARMState *env)
     /* Undo stack alignment.  */
     if (xpsr & 0x200)
         env->regs[13] |= 4;
-    /* ??? The exception return type specifies Thread/Handler mode.  However
-       this is also implied by the xPSR value. Not sure what to do
-       if there is a mismatch.  */
-    /* ??? Likewise for mismatches between the CONTROL register and the stack
-       pointer.  */
+
+    /* The restored xPSR exception field will be zero if we're
+     * resuming in Thread mode. If that doesn't match what the
+     * exception return type specified then this is a UsageFault.
+     */
+    if (return_to_handler == (env->v7m.exception == 0)) {
+        /* Take an INVPC UsageFault by pushing the stack again. */
+        armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE);
+        env->v7m.cfsr |= R_V7M_CFSR_INVPC_MASK;
+        v7m_push_stack(cpu);
+        v7m_exception_taken(cpu, type | 0xf0000000);
+        qemu_log_mask(CPU_LOG_INT, "...taking UsageFault on new stackframe: "
+                      "failed exception return integrity check\n");
+        return;
+    }
+
+    /* Otherwise, we have a successful exception exit. */
+    qemu_log_mask(CPU_LOG_INT, "...successful exception return\n");
 }
 
 static void arm_log_exception(int idx)
@@ -6063,37 +6219,11 @@ static void arm_log_exception(int idx)
     }
 }
 
-static uint32_t arm_v7m_load_vector(ARMCPU *cpu)
-
-{
-    CPUState *cs = CPU(cpu);
-    CPUARMState *env = &cpu->env;
-    MemTxResult result;
-    hwaddr vec = env->v7m.vecbase + env->v7m.exception * 4;
-    uint32_t addr;
-
-    addr = address_space_ldl(cs->as, vec,
-                             MEMTXATTRS_UNSPECIFIED, &result);
-    if (result != MEMTX_OK) {
-        /* Architecturally this should cause a HardFault setting HSFR.VECTTBL,
-         * which would then be immediately followed by our failing to load
-         * the entry vector for that HardFault, which is a Lockup case.
-         * Since we don't model Lockup, we just report this guest error
-         * via cpu_abort().
-         */
-        cpu_abort(cs, "Failed to read from exception vector table "
-                  "entry %08x\n", (unsigned)vec);
-    }
-    return addr;
-}
-
 void arm_v7m_cpu_do_interrupt(CPUState *cs)
 {
     ARMCPU *cpu = ARM_CPU(cs);
     CPUARMState *env = &cpu->env;
-    uint32_t xpsr = xpsr_read(env);
     uint32_t lr;
-    uint32_t addr;
 
     arm_log_exception(cs->exception_index);
 
@@ -6106,28 +6236,30 @@ void arm_v7m_cpu_do_interrupt(CPUState *cs)
 
     /* For exceptions we just mark as pending on the NVIC, and let that
        handle it.  */
-    /* TODO: Need to escalate if the current priority is higher than the
-       one we're raising.  */
     switch (cs->exception_index) {
     case EXCP_UDEF:
         armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE);
         env->v7m.cfsr |= R_V7M_CFSR_UNDEFINSTR_MASK;
-        return;
+        break;
     case EXCP_NOCP:
         armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE);
         env->v7m.cfsr |= R_V7M_CFSR_NOCP_MASK;
-        return;
+        break;
+    case EXCP_INVSTATE:
+        armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE);
+        env->v7m.cfsr |= R_V7M_CFSR_INVSTATE_MASK;
+        break;
     case EXCP_SWI:
         /* The PC already points to the next instruction.  */
         armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_SVC);
-        return;
+        break;
     case EXCP_PREFETCH_ABORT:
     case EXCP_DATA_ABORT:
         /* TODO: if we implemented the MPU registers, this is where we
          * should set the MMFAR, etc from exception.fsr and exception.vaddress.
          */
         armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_MEM);
-        return;
+        break;
     case EXCP_BKPT:
         if (semihosting_enabled()) {
             int nr;
@@ -6142,39 +6274,20 @@ void arm_v7m_cpu_do_interrupt(CPUState *cs)
             }
         }
         armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_DEBUG);
-        return;
+        break;
     case EXCP_IRQ:
-        env->v7m.exception = armv7m_nvic_acknowledge_irq(env->nvic);
         break;
     case EXCP_EXCEPTION_EXIT:
-        do_v7m_exception_exit(env);
+        do_v7m_exception_exit(cpu);
         return;
     default:
         cpu_abort(cs, "Unhandled exception 0x%x\n", cs->exception_index);
         return; /* Never happens.  Keep compiler happy.  */
     }
 
-    /* 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;
-    }
-    /* Switch to the handler mode.  */
-    v7m_push(env, xpsr);
-    v7m_push(env, env->regs[15]);
-    v7m_push(env, env->regs[14]);
-    v7m_push(env, env->regs[12]);
-    v7m_push(env, env->regs[3]);
-    v7m_push(env, env->regs[2]);
-    v7m_push(env, env->regs[1]);
-    v7m_push(env, env->regs[0]);
-    switch_v7m_sp(env, 0);
-    /* Clear IT bits */
-    env->condexec_bits = 0;
-    env->regs[14] = lr;
-    addr = arm_v7m_load_vector(cpu);
-    env->regs[15] = addr & 0xfffffffe;
-    env->thumb = addr & 1;
+    v7m_push_stack(cpu);
+    v7m_exception_taken(cpu, lr);
+    qemu_log_mask(CPU_LOG_INT, "... as %d\n", env->v7m.exception);
 }
 
 /* Function used to synchronize QEMU's AArch64 register set with AArch32