target-arm: Implement minimal DBGVCR, OSDLR_EL1, MDCCSR_EL0

Implement debug registers DBGVCR, OSDLR_EL1 and MDCCSR_EL0
(as dummy or limited-functionality). 32 bit Linux kernels will
access these at startup so they are required for breakpoints
and watchpoints to be supported.

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

1 files changed, 19 insertions, 0 deletions

diff --git a/target-arm/helper.c b/target-arm/helper.c
index fc6a6f8..d2e741a 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -2250,10 +2250,29 @@ static const ARMCPRegInfo debug_cp_reginfo[] = {
       .access = PL1_RW,
       .fieldoffset = offsetof(CPUARMState, cp15.mdscr_el1),
       .resetvalue = 0 },
+    /* MDCCSR_EL0, aka DBGDSCRint. This is a read-only mirror of MDSCR_EL1.
+     * We don't implement the configurable EL0 access.
+     */
+    { .name = "MDCCSR_EL0", .state = ARM_CP_STATE_BOTH,
+      .cp = 14, .opc0 = 2, .opc1 = 0, .crn = 0, .crm = 1, .opc2 = 0,
+      .type = ARM_CP_NO_MIGRATE,
+      .access = PL1_R,
+      .fieldoffset = offsetof(CPUARMState, cp15.mdscr_el1),
+      .resetfn = arm_cp_reset_ignore },
     /* We define a dummy WI OSLAR_EL1, because Linux writes to it. */
     { .name = "OSLAR_EL1", .state = ARM_CP_STATE_BOTH,
       .cp = 14, .opc0 = 2, .opc1 = 0, .crn = 1, .crm = 0, .opc2 = 4,
       .access = PL1_W, .type = ARM_CP_NOP },
+    /* Dummy OSDLR_EL1: 32-bit Linux will read this */
+    { .name = "OSDLR_EL1", .state = ARM_CP_STATE_BOTH,
+      .cp = 14, .opc0 = 2, .opc1 = 0, .crn = 1, .crm = 3, .opc2 = 4,
+      .access = PL1_RW, .type = ARM_CP_NOP },
+    /* Dummy DBGVCR: Linux wants to clear this on startup, but we don't
+     * implement vector catch debug events yet.
+     */
+    { .name = "DBGVCR",
+      .cp = 14, .opc1 = 0, .crn = 0, .crm = 7, .opc2 = 0,
+      .access = PL1_RW, .type = ARM_CP_NOP },
     REGINFO_SENTINEL
 };