db_backtrace
db_backtrace(curthread, NULL, frame, callpc, 0, -1);
return (db_backtrace(thr, tf, ctx->pcb_rbp, ctx->pcb_rip, ctx->pcb_rsp,
db_backtrace(curthread, NULL, frame, callpc, 0, -1);
return (db_backtrace(thr, tf, (struct i386_frame *)ctx->pcb_ebp,
db_backtrace(curthread, *(db_addr_t *)addr, -1);
return (db_backtrace(td, (db_addr_t)ctx->pcb_sp, count));