Re: [Qemu-devel] [PATCH] PPC32 Trace Exception and Trap instruction

[Ely Soto]

Excellent, I had encountered that bug
earlier on when trying to debug using workbench.

Are you guys developing a BSP for qemu?
I have a partially working one.

Ely Soto

Jason Wessel <address@hidden>
Sent by: address@hidden

12/27/2006 11:05 AM

Please respond to
address@hidden

To	address@hidden
cc
Subject	[Qemu-devel] [PATCH] PPC32 Trace Exception and Trap instruction

Please add this patch to CVS. 

The patch has two purposes:

1) The NIP needs to be updated for a tw instruction. 
    I found that when executing protected mode traps
    the PC was always set to the begining of the code
    generation block instead of the instruction the trap
    occurred on.

    The usual PPC breakpoint instruction is:
    7d 82 10 08 twge    r2,r2  (Trap when rA >=
rB)

2) Single stepping was fixed up earlier in the year
    for using a debugger connected to the QEMU
    gdb stub.  Now it is enabled for connecting a
    runtime single stepping with the trace trap so you
    can use ptrace() or even debug KGDB.

signed-off-by: address@hidden

Thanks,
Jason.
Index: qemu/target-ppc/helper.c
===================================================================
--- qemu.orig/target-ppc/helper.c
+++ qemu/target-ppc/helper.c
@@ -1113,8 +1113,6 @@ void do_interrupt (CPUState *env)
         }
         goto store_next;
     case EXCP_TRACE: /* 0x0D00 */
-        /* XXX: TODO */
-        cpu_abort(env, "Trace exception is not
implemented yet !\n");
         goto store_next;
     case EXCP_PERF: /* 0x0F00 */
         /* XXX: TODO */
Index: qemu/target-ppc/translate.c
===================================================================
--- qemu.orig/target-ppc/translate.c
+++ qemu/target-ppc/translate.c
@@ -1956,6 +1956,8 @@ GEN_HANDLER(tw, 0x1F, 0x04, 0xFF, 0x0000
 {
     gen_op_load_gpr_T0(rA(ctx->opcode));
     gen_op_load_gpr_T1(rB(ctx->opcode));
+    /* Update the nip since this might generate a trap exception
*/
+    gen_op_update_nip(ctx->nip);
     gen_op_tw(TO(ctx->opcode));
 }
 
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