target-arm: Add CP15 VBAR support

Added Vector Base Address remapping on ARM v7.

Signed-off-by: Nathan Rossi <nathan.rossi@xilinx.com>
Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
[PMM: removed spurious mask of value with 1<<31]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

2 files changed, 22 insertions, 0 deletions

diff --git a/target-arm/cpu.h b/target-arm/cpu.h
index 2c56740bf6..9f110f15b6 100644
--- a/target-arm/cpu.h
+++ b/target-arm/cpu.h
@@ -176,6 +176,7 @@ typedef struct CPUARMState {
         uint32_t c9_pmxevtyper; /* perf monitor event type */
         uint32_t c9_pmuserenr; /* perf monitor user enable */
         uint32_t c9_pminten; /* perf monitor interrupt enables */
+        uint32_t c12_vbar; /* vector base address register */
         uint32_t c13_fcse; /* FCSE PID.  */
         uint32_t c13_context; /* Context ID.  */
         uint32_t c13_tls1; /* User RW Thread register.  */
diff --git a/target-arm/helper.c b/target-arm/helper.c
index c63bbd7fc1..73476ed5b1 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -537,6 +537,13 @@ static int pmintenclr_write(CPUARMState *env, const ARMCPRegInfo *ri,
     return 0;
 }
 
+static int vbar_write(CPUARMState *env, const ARMCPRegInfo *ri,
+                      uint64_t value)
+{
+    env->cp15.c12_vbar = value & ~0x1Ful;
+    return 0;
+}
+
 static int ccsidr_read(CPUARMState *env, const ARMCPRegInfo *ri,
                        uint64_t *value)
 {
@@ -622,6 +629,10 @@ static const ARMCPRegInfo v7_cp_reginfo[] = {
       .access = PL1_RW, .type = ARM_CP_NO_MIGRATE,
       .fieldoffset = offsetof(CPUARMState, cp15.c9_pminten),
       .resetvalue = 0, .writefn = pmintenclr_write, },
+    { .name = "VBAR", .cp = 15, .crn = 12, .crm = 0, .opc1 = 0, .opc2 = 0,
+      .access = PL1_RW, .writefn = vbar_write,
+      .fieldoffset = offsetof(CPUARMState, cp15.c12_vbar),
+      .resetvalue = 0 },
     { .name = "SCR", .cp = 15, .crn = 1, .crm = 1, .opc1 = 0, .opc2 = 0,
       .access = PL1_RW, .fieldoffset = offsetof(CPUARMState, cp15.c1_scr),
       .resetvalue = 0, },
@@ -2470,7 +2481,17 @@ void arm_cpu_do_interrupt(CPUState *cs)
     }
     /* High vectors.  */
     if (env->cp15.c1_sys & (1 << 13)) {
+        /* when enabled, base address cannot be remapped.  */
         addr += 0xffff0000;
+    } else {
+        /* ARM v7 architectures provide a vector base address register to remap
+         * the interrupt vector table.
+         * This register is only followed in non-monitor mode, and has a secure
+         * and un-secure copy. Since the cpu is always in a un-secure operation
+         * and is never in monitor mode this feature is always active.
+         * Note: only bits 31:5 are valid.
+         */
+        addr += env->cp15.c12_vbar;
     }
     switch_mode (env, new_mode);
     env->spsr = cpsr_read(env);