[Qemu-devel] [patch] Arm BKPT instruction

[Paul Brook]

The attached patch implements the Arm bkpt instruction.

In full system emulation it causes a prefect abort (as defined by the 
architecture). For usermode emulation we capture it the same as SWI.

Paul

Index: linux-user/main.c
===================================================================
RCS file: /sources/qemu/qemu/linux-user/main.c,v
retrieving revision 1.76
diff -u -p -r1.76 main.c
--- linux-user/main.c   5 Dec 2005 21:04:24 -0000       1.76
+++ linux-user/main.c   2 Feb 2006 20:41:06 -0000
@@ -358,14 +358,27 @@ void cpu_loop(CPUARMState *env)
             }
             break;
         case EXCP_SWI:
+        case EXCP_BKPT:
             {
                 /* system call */
-                if (env->thumb) {
-                    insn = lduw((void *)(env->regs[15] - 2));
-                    n = insn & 0xff;
+                if (trapnr == EXCP_BKPT) {
+                    if (env->thumb) {
+                        insn = lduw((void *)(env->regs[15]));
+                        n = insn & 0xff;
+                        env->regs[15] += 2;
+                    } else {
+                        insn = ldl((void *)(env->regs[15]));
+                        n = (insn & 0xf) | ((insn >> 4) & 0xff0);
+                        env->regs[15] += 4;
+                    }
                 } else {
-                    insn = ldl((void *)(env->regs[15] - 4));
-                    n = insn & 0xffffff;
+                    if (env->thumb) {
+                        insn = lduw((void *)(env->regs[15] - 2));
+                        n = insn & 0xff;
+                    } else {
+                        insn = ldl((void *)(env->regs[15] - 4));
+                        n = insn & 0xffffff;
+                    }
                 }
 
                 if (n == ARM_NR_cacheflush) {
Index: target-arm/cpu.h
===================================================================
RCS file: /sources/qemu/qemu/target-arm/cpu.h,v
retrieving revision 1.13
diff -u -p -r1.13 cpu.h
--- target-arm/cpu.h    26 Nov 2005 10:46:39 -0000      1.13
+++ target-arm/cpu.h    2 Feb 2006 20:41:06 -0000
@@ -34,6 +34,7 @@
 #define EXCP_DATA_ABORT      4
 #define EXCP_IRQ             5
 #define EXCP_FIQ             6
+#define EXCP_BKPT            7
 
 /* We currently assume float and double are IEEE single and double
    precision respectively.
Index: target-arm/helper.c
===================================================================
RCS file: /sources/qemu/qemu/target-arm/helper.c,v
retrieving revision 1.2
diff -u -p -r1.2 helper.c
--- target-arm/helper.c 18 Dec 2005 16:54:08 -0000      1.2
+++ target-arm/helper.c 2 Feb 2006 20:41:06 -0000
@@ -127,6 +127,7 @@ void do_interrupt(CPUARMState *env)
         offset = 0;
         break;
     case EXCP_PREFETCH_ABORT:
+    case EXCP_BKPT:
         new_mode = ARM_CPU_MODE_ABT;
         addr = 0x0c;
         mask = CPSR_A | CPSR_I;
Index: target-arm/op.c
===================================================================
RCS file: /sources/qemu/qemu/target-arm/op.c,v
retrieving revision 1.17
diff -u -p -r1.17 op.c
--- target-arm/op.c     26 Nov 2005 10:46:39 -0000      1.17
+++ target-arm/op.c     2 Feb 2006 20:41:06 -0000
@@ -885,6 +885,12 @@ void OPPROTO op_wfi(void)
     cpu_loop_exit();
 }
 
+void OPPROTO op_bkpt(void)
+{
+    env->exception_index = EXCP_BKPT;
+    cpu_loop_exit();
+}
+
 /* VFP support.  We follow the convention used for VFP instrunctions:
    Single precition routines have a "s" suffix, double precision a
    "d" suffix.  */
Index: target-arm/translate.c
===================================================================
RCS file: /sources/qemu/qemu/target-arm/translate.c,v
retrieving revision 1.35
diff -u -p -r1.35 translate.c
--- target-arm/translate.c      18 Dec 2005 16:55:25 -0000      1.35
+++ target-arm/translate.c      2 Feb 2006 20:41:07 -0000
@@ -1217,6 +1217,12 @@ static void disas_arm_insn(CPUState * en
                 gen_op_addl_T0_T1_saturate();
             gen_movl_reg_T0(s, rd);
             break;
+        case 7: /* bkpt */
+            gen_op_movl_T0_im((long)s->pc - 4);
+            gen_op_movl_reg_TN[0][15]();
+            gen_op_bkpt();
+            s->is_jmp = DISAS_JUMP;
+            break;
         case 0x8: /* signed multiply */
         case 0xa:
         case 0xc:
@@ -2183,6 +2197,13 @@ static void disas_thumb_insn(DisasContex
                 gen_bx(s);
             break;
 
+        case 0xe: /* bkpt */
+            gen_op_movl_T0_im((long)s->pc - 2);
+            gen_op_movl_reg_TN[0][15]();
+            gen_op_bkpt();
+            s->is_jmp = DISAS_JUMP;
+            break;
+
         default:
             goto undef;
         }