target-arm: Add 32/64-bit register sync

Add AArch32 to AArch64 register sychronization functions.
Replace manual register synchronization with new functions in
aarch64_cpu_do_interrupt() and HELPER(exception_return)().

Signed-off-by: Greg Bellows <greg.bellows@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

---

v6 -> v7
-Fix comment issues

v5 -> v6
- Add r14 set in 32_to_64
- Reorder conditionals in 64_to_32 fomr reg order to xreg order

v4 -> v5
- Rework sync routines a bit more.

v3 -> v4
- Rework sync routines to cover various exception levels
- Move sync routines to helper.c

v2 -> v3
- Conditionalize interrupt handler update of aarch64.

4 files changed, 216 insertions, 8 deletions

diff --git a/target-arm/cpu.h b/target-arm/cpu.h
index 1830a12d4..11845a664 100644
--- a/target-arm/cpu.h
+++ b/target-arm/cpu.h
@@ -495,6 +495,8 @@ typedef struct CPUARMState {
 ARMCPU *cpu_arm_init(const char *cpu_model);
 int cpu_arm_exec(CPUARMState *s);
 uint32_t do_arm_semihosting(CPUARMState *env);
+void aarch64_sync_32_to_64(CPUARMState *env);
+void aarch64_sync_64_to_32(CPUARMState *env);
 
 static inline bool is_a64(CPUARMState *env)
 {
diff --git a/target-arm/helper-a64.c b/target-arm/helper-a64.c
index 8aa40e976..7e0d03856 100644
--- a/target-arm/helper-a64.c
+++ b/target-arm/helper-a64.c
@@ -466,7 +466,6 @@ void aarch64_cpu_do_interrupt(CPUState *cs)
     unsigned int new_el = arm_excp_target_el(cs, cs->exception_index);
     target_ulong addr = env->cp15.vbar_el[new_el];
     unsigned int new_mode = aarch64_pstate_mode(new_el, true);
-    int i;
 
     if (arm_current_el(env) < new_el) {
         if (env->aarch64) {
@@ -530,9 +529,7 @@ void aarch64_cpu_do_interrupt(CPUState *cs)
         }
         env->elr_el[new_el] = env->regs[15];
 
-        for (i = 0; i < 15; i++) {
-            env->xregs[i] = env->regs[i];
-        }
+        aarch64_sync_32_to_64(env);
 
         env->condexec_bits = 0;
     }
diff --git a/target-arm/helper.c b/target-arm/helper.c
index 1a1a00577..3bc20af04 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -4096,6 +4096,11 @@ unsigned int arm_excp_target_el(CPUState *cs, unsigned int excp_idx)
     return 1;
 }
 
+void aarch64_sync_64_to_32(CPUARMState *env)
+{
+    g_assert_not_reached();
+}
+
 #else
 
 /* Map CPU modes onto saved register banks.  */
@@ -4425,6 +4430,212 @@ void arm_v7m_cpu_do_interrupt(CPUState *cs)
     env->thumb = addr & 1;
 }
 
+/* Function used to synchronize QEMU's AArch64 register set with AArch32
+ * register set.  This is necessary when switching between AArch32 and AArch64
+ * execution state.
+ */
+void aarch64_sync_32_to_64(CPUARMState *env)
+{
+    int i;
+    uint32_t mode = env->uncached_cpsr & CPSR_M;
+
+    /* We can blanket copy R[0:7] to X[0:7] */
+    for (i = 0; i < 8; i++) {
+        env->xregs[i] = env->regs[i];
+    }
+
+    /* Unless we are in FIQ mode, x8-x12 come from the user registers r8-r12.
+     * Otherwise, they come from the banked user regs.
+     */
+    if (mode == ARM_CPU_MODE_FIQ) {
+        for (i = 8; i < 13; i++) {
+            env->xregs[i] = env->usr_regs[i - 8];
+        }
+    } else {
+        for (i = 8; i < 13; i++) {
+            env->xregs[i] = env->regs[i];
+        }
+    }
+
+    /* Registers x13-x23 are the various mode SP and FP registers. Registers
+     * r13 and r14 are only copied if we are in that mode, otherwise we copy
+     * from the mode banked register.
+     */
+    if (mode == ARM_CPU_MODE_USR || mode == ARM_CPU_MODE_SYS) {
+        env->xregs[13] = env->regs[13];
+        env->xregs[14] = env->regs[14];
+    } else {
+        env->xregs[13] = env->banked_r13[bank_number(ARM_CPU_MODE_USR)];
+        /* HYP is an exception in that it is copied from r14 */
+        if (mode == ARM_CPU_MODE_HYP) {
+            env->xregs[14] = env->regs[14];
+        } else {
+            env->xregs[14] = env->banked_r14[bank_number(ARM_CPU_MODE_USR)];
+        }
+    }
+
+    if (mode == ARM_CPU_MODE_HYP) {
+        env->xregs[15] = env->regs[13];
+    } else {
+        env->xregs[15] = env->banked_r13[bank_number(ARM_CPU_MODE_HYP)];
+    }
+
+    if (mode == ARM_CPU_MODE_IRQ) {
+        env->xregs[16] = env->regs[13];
+        env->xregs[17] = env->regs[14];
+    } else {
+        env->xregs[16] = env->banked_r13[bank_number(ARM_CPU_MODE_IRQ)];
+        env->xregs[17] = env->banked_r14[bank_number(ARM_CPU_MODE_IRQ)];
+    }
+
+    if (mode == ARM_CPU_MODE_SVC) {
+        env->xregs[18] = env->regs[13];
+        env->xregs[19] = env->regs[14];
+    } else {
+        env->xregs[18] = env->banked_r13[bank_number(ARM_CPU_MODE_SVC)];
+        env->xregs[19] = env->banked_r14[bank_number(ARM_CPU_MODE_SVC)];
+    }
+
+    if (mode == ARM_CPU_MODE_ABT) {
+        env->xregs[20] = env->regs[13];
+        env->xregs[21] = env->regs[14];
+    } else {
+        env->xregs[20] = env->banked_r13[bank_number(ARM_CPU_MODE_ABT)];
+        env->xregs[21] = env->banked_r14[bank_number(ARM_CPU_MODE_ABT)];
+    }
+
+    if (mode == ARM_CPU_MODE_UND) {
+        env->xregs[22] = env->regs[13];
+        env->xregs[23] = env->regs[14];
+    } else {
+        env->xregs[22] = env->banked_r13[bank_number(ARM_CPU_MODE_UND)];
+        env->xregs[23] = env->banked_r14[bank_number(ARM_CPU_MODE_UND)];
+    }
+
+    /* Registers x24-x30 are mapped to r8-r14 in FIQ mode.  If we are in FIQ
+     * mode, then we can copy from r8-r14.  Otherwise, we copy from the
+     * FIQ bank for r8-r14.
+     */
+    if (mode == ARM_CPU_MODE_FIQ) {
+        for (i = 24; i < 31; i++) {
+            env->xregs[i] = env->regs[i - 16];   /* X[24:30] <- R[8:14] */
+        }
+    } else {
+        for (i = 24; i < 29; i++) {
+            env->xregs[i] = env->fiq_regs[i - 24];
+        }
+        env->xregs[29] = env->banked_r13[bank_number(ARM_CPU_MODE_FIQ)];
+        env->xregs[30] = env->banked_r14[bank_number(ARM_CPU_MODE_FIQ)];
+    }
+
+    env->pc = env->regs[15];
+}
+
+/* Function used to synchronize QEMU's AArch32 register set with AArch64
+ * register set.  This is necessary when switching between AArch32 and AArch64
+ * execution state.
+ */
+void aarch64_sync_64_to_32(CPUARMState *env)
+{
+    int i;
+    uint32_t mode = env->uncached_cpsr & CPSR_M;
+
+    /* We can blanket copy X[0:7] to R[0:7] */
+    for (i = 0; i < 8; i++) {
+        env->regs[i] = env->xregs[i];
+    }
+
+    /* Unless we are in FIQ mode, r8-r12 come from the user registers x8-x12.
+     * Otherwise, we copy x8-x12 into the banked user regs.
+     */
+    if (mode == ARM_CPU_MODE_FIQ) {
+        for (i = 8; i < 13; i++) {
+            env->usr_regs[i - 8] = env->xregs[i];
+        }
+    } else {
+        for (i = 8; i < 13; i++) {
+            env->regs[i] = env->xregs[i];
+        }
+    }
+
+    /* Registers r13 & r14 depend on the current mode.
+     * If we are in a given mode, we copy the corresponding x registers to r13
+     * and r14.  Otherwise, we copy the x register to the banked r13 and r14
+     * for the mode.
+     */
+    if (mode == ARM_CPU_MODE_USR || mode == ARM_CPU_MODE_SYS) {
+        env->regs[13] = env->xregs[13];
+        env->regs[14] = env->xregs[14];
+    } else {
+        env->banked_r13[bank_number(ARM_CPU_MODE_USR)] = env->xregs[13];
+
+        /* HYP is an exception in that it does not have its own banked r14 but
+         * shares the USR r14
+         */
+        if (mode == ARM_CPU_MODE_HYP) {
+            env->regs[14] = env->xregs[14];
+        } else {
+            env->banked_r14[bank_number(ARM_CPU_MODE_USR)] = env->xregs[14];
+        }
+    }
+
+    if (mode == ARM_CPU_MODE_HYP) {
+        env->regs[13] = env->xregs[15];
+    } else {
+        env->banked_r13[bank_number(ARM_CPU_MODE_HYP)] = env->xregs[15];
+    }
+
+    if (mode == ARM_CPU_MODE_IRQ) {
+        env->regs[13] = env->xregs[16];
+        env->regs[14] = env->xregs[17];
+    } else {
+        env->banked_r13[bank_number(ARM_CPU_MODE_IRQ)] = env->xregs[16];
+        env->banked_r14[bank_number(ARM_CPU_MODE_IRQ)] = env->xregs[17];
+    }
+
+    if (mode == ARM_CPU_MODE_SVC) {
+        env->regs[13] = env->xregs[18];
+        env->regs[14] = env->xregs[19];
+    } else {
+        env->banked_r13[bank_number(ARM_CPU_MODE_SVC)] = env->xregs[18];
+        env->banked_r14[bank_number(ARM_CPU_MODE_SVC)] = env->xregs[19];
+    }
+
+    if (mode == ARM_CPU_MODE_ABT) {
+        env->regs[13] = env->xregs[20];
+        env->regs[14] = env->xregs[21];
+    } else {
+        env->banked_r13[bank_number(ARM_CPU_MODE_ABT)] = env->xregs[20];
+        env->banked_r14[bank_number(ARM_CPU_MODE_ABT)] = env->xregs[21];
+    }
+
+    if (mode == ARM_CPU_MODE_UND) {
+        env->regs[13] = env->xregs[22];
+        env->regs[14] = env->xregs[23];
+    } else {
+        env->banked_r13[bank_number(ARM_CPU_MODE_UND)] = env->xregs[22];
+        env->banked_r14[bank_number(ARM_CPU_MODE_UND)] = env->xregs[23];
+    }
+
+    /* Registers x24-x30 are mapped to r8-r14 in FIQ mode.  If we are in FIQ
+     * mode, then we can copy to r8-r14.  Otherwise, we copy to the
+     * FIQ bank for r8-r14.
+     */
+    if (mode == ARM_CPU_MODE_FIQ) {
+        for (i = 24; i < 31; i++) {
+            env->regs[i - 16] = env->xregs[i];   /* X[24:30] -> R[8:14] */
+        }
+    } else {
+        for (i = 24; i < 29; i++) {
+            env->fiq_regs[i - 24] = env->xregs[i];
+        }
+        env->banked_r13[bank_number(ARM_CPU_MODE_FIQ)] = env->xregs[29];
+        env->banked_r14[bank_number(ARM_CPU_MODE_FIQ)] = env->xregs[30];
+    }
+
+    env->regs[15] = env->pc;
+}
+
 /* Handle a CPU exception.  */
 void arm_cpu_do_interrupt(CPUState *cs)
 {
diff --git a/target-arm/op_helper.c b/target-arm/op_helper.c
index 2bed91477..771302275 100644
--- a/target-arm/op_helper.c
+++ b/target-arm/op_helper.c
@@ -465,7 +465,7 @@ void HELPER(exception_return)(CPUARMState *env)
     int cur_el = arm_current_el(env);
     unsigned int spsr_idx = aarch64_banked_spsr_index(cur_el);
     uint32_t spsr = env->banked_spsr[spsr_idx];
-    int new_el, i;
+    int new_el;
 
     aarch64_save_sp(env, cur_el);
 
@@ -491,9 +491,7 @@ void HELPER(exception_return)(CPUARMState *env)
         if (!arm_singlestep_active(env)) {
             env->uncached_cpsr &= ~PSTATE_SS;
         }
-        for (i = 0; i < 15; i++) {
-            env->regs[i] = env->xregs[i];
-        }
+        aarch64_sync_64_to_32(env);
 
         env->regs[15] = env->elr_el[1] & ~0x1;
     } else {