Re: [Xen-devel] [PATCH v5 11/17] xenctx: Add -d (--dump-as-stack) <daddr> option to dump memory at daddr as a stack.

[Don Slutz <dslutz@xxxxxxxxxxx>]

On 03/21/14 10:57, Ian Campbell wrote:
> On Thu, 2014-03-20 at 15:06 -0400, Don Slutz wrote:
> > @@ -797,14 +796,17 @@ static int print_stack(vcpu_guest_context_any_t *ctx, int 
> > vcpu, int width)
> >           printf("Stack Trace:\n");
> >       else
> >           printf("Call Trace:\n");
> > -    if ( xenctx.tag_call_trace )
> > -        printf(" %*s", width*2, "");
> > -    printf("%c [<", xenctx.stack_trace ? '*' : ' ');
> > -    print_stack_word(instr_pointer(ctx), width);
> > -    printf(">]");
> > -
> > -    print_symbol(instr_pointer(ctx));
> > -    printf(" <--\n");
> > +    if ( !xenctx.do_stack )
> Why not?
This code output's rip (instr_pointer(ctx)) which does not apply
in this case.

> > +    {
> > +        if ( xenctx.tag_call_trace )
> > +            printf(" %*s", width*2, "");
> > +        printf("%c [<", xenctx.stack_trace ? '*' : ' ');
> > +        print_stack_word(instr_pointer(ctx), width);
> > +        printf(">]");
> > +
> > +        print_symbol(instr_pointer(ctx));
> > +        printf(" <--\n");
> > +    }
> >       if (xenctx.frame_ptrs) {
> >           stack = stack_pointer(ctx);
> >           frame = frame_pointer(ctx);
> > @@ -944,13 +946,19 @@ static void dump_ctx(int vcpu)
> >           print_mem(&ctx, vcpu, guest_word_size, xenctx.mem_addr);
> >           return;
> >       }
> > +    if ( xenctx.do_stack )
> > +    {
> > +        print_stack(&ctx, vcpu, guest_word_size, xenctx.stk_addr);
> > +        return;
> > +    }
> It's starting to seem like print_mem and print_stack should be called
> from main instead of here. In other words actually have multiple modes
> instead of tuffing things in as special cases here.
The issue is that ctx (vcpu_guest_context_any_t) does not exist
in main and is needed by map_page() (called from these).

dump_ctx() is the routine that gets this and guest_word_size,
guest_protected_mode, and ctxt_word_size.

And so yes, this part of dump_ctx() could be moved to main
and/or ctx could be made global.

Let me know if I should rework all this.



> > ,
> > @@ -1110,6 +1121,11 @@ int main(int argc, char **argv)
> >               xenctx.do_memory = 1;
> >               do_default = 0;
> >               break;
> > +        case 'd':
> > +            xenctx.stk_addr = strtoull(optarg, NULL, 0);
> You can reuse mem_addr here, can't you?
Nope.  If both -d and -m are specified, then both are done.


   -Don Slutz


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