[Qemu-devel] [PATCH v3 20/32] target-arm: arrayfying fieldoffset for banking

[Fabian Aggeler <aggelerf@ethz.ch>]

Prepare ARMCPRegInfo to support specifying two fieldoffsets per
register definition. This will allow us to keep one register
definition for banked registers (different offsets for secure/
non-secure world).

Signed-off-by: Fabian Aggeler <aggelerf@ethz.ch>
---
 target-arm/cpu.h    | 16 +++++++++++++---
 target-arm/helper.c | 35 +++++++++++++++++++++++------------
 2 files changed, 36 insertions(+), 15 deletions(-)

diff --git a/target-arm/cpu.h b/target-arm/cpu.h
index d4eab39..7d7782e 100644
--- a/target-arm/cpu.h
+++ b/target-arm/cpu.h
@@ -1086,12 +1086,22 @@ struct ARMCPRegInfo {
      * fieldoffset is non-zero, the reset value of the register.
      */
     uint64_t resetvalue;
-    /* Offset of the field in CPUARMState for this register. This is not
-     * needed if either:
+    /* Offsets of the fields (secure/non-secure) in CPUARMState for this
+     * register. The array will be accessed by the ns bit which means the
+     * secure instance has to be at [0] while the non-secure instance must be
+     * at [1]. If a register is not banked .fieldoffset can be used, which maps
+     * to the non-secure bank.
+     * This is not needed if either:
      *  1. type is ARM_CP_CONST or one of the ARM_CP_SPECIALs
      *  2. both readfn and writefn are specified
      */
-    ptrdiff_t fieldoffset; /* offsetof(CPUARMState, field) */
+    union { /* offsetof(CPUARMState, field) */
+        struct {
+            ptrdiff_t fieldoffset_padding;
+            ptrdiff_t fieldoffset;
+        };
+        ptrdiff_t bank_fieldoffsets[2];
+    };
     /* Function for making any access checks for this register in addition to
      * those specified by the 'access' permissions bits. If NULL, no extra
      * checks required. The access check is performed at runtime, not at
diff --git a/target-arm/helper.c b/target-arm/helper.c
index 610245d..dfaf636 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -2891,20 +2891,31 @@ static void add_cpreg_to_hashtable(ARMCPU *cpu, const ARMCPRegInfo *r,
     uint32_t *key = g_new(uint32_t, 1);
     ARMCPRegInfo *r2 = g_memdup(r, sizeof(ARMCPRegInfo));
     int is64 = (r->type & ARM_CP_64BIT) ? 1 : 0;
-    if (r->state == ARM_CP_STATE_BOTH && state == ARM_CP_STATE_AA32) {
-        /* The AArch32 view of a shared register sees the lower 32 bits
-         * of a 64 bit backing field. It is not migratable as the AArch64
-         * view handles that. AArch64 also handles reset.
-         * We assume it is a cp15 register.
-         */
-        r2->cp = 15;
-        r2->type |= ARM_CP_NO_MIGRATE;
-        r2->resetfn = arm_cp_reset_ignore;
-#ifdef HOST_WORDS_BIGENDIAN
-        if (r2->fieldoffset) {
-            r2->fieldoffset += sizeof(uint32_t);
+
+    if (state == ARM_CP_STATE_AA32) {
+        if (r->bank_fieldoffsets[0] && r->bank_fieldoffsets[1]) {
+            /* Register is banked (using both entries in array).
+             * Overwriting fieldoffset as the array was only used to define
+             * banked registers but later only fieldoffset is used.
+             */
+            r2->fieldoffset = r->bank_fieldoffsets[nsbit];
         }
+
+        if (r->state == ARM_CP_STATE_BOTH) {
+            /* The AArch32 view of a shared register sees the lower 32 bits
+             * of a 64 bit backing field. It is not migratable as the AArch64
+             * view handles that. AArch64 also handles reset.
+             * We assume it is a cp15 register.
+             */
+            r2->cp = 15;
+            r2->type |= ARM_CP_NO_MIGRATE;
+            r2->resetfn = arm_cp_reset_ignore;
+#ifdef HOST_WORDS_BIGENDIAN
+            if (r2->fieldoffset) {
+                r2->fieldoffset += sizeof(uint32_t);
+            }
 #endif
+        }
     }
     if (state == ARM_CP_STATE_AA64) {
         /* To allow abbreviation of ARMCPRegInfo
-- 
1.8.3.2