Re: [PATCH v4 0/3] Compile-time stack frame pointer validation

[Josh Poimboeuf]

On Fri, May 22, 2015 at 11:18:57PM +0200, Jiri Kosina wrote:
> On Fri, 22 May 2015, Josh Poimboeuf wrote:
> 
> > Hm, alternatives do complicate things a bit.  It *is* a false positive,
> > but not necessarily because its part of an alternative instruction
> > block.
> > 
> > The above code would be patched into memmove(), which is a leaf function
> > because it doesn't call any other functions.  Leaf functions don't need
> > frame pointer logic, so we can ignore them.
> > 
> > If instead the above code were patched into a non-leaf function, we'd
> > have to change it to restore the frame pointer before returning.
> 
> Is this really only a problem of alternatives? How about 
> dynamically-enabled tracepoints?

I think tracepoints are only in C code, right?  stackvalidate only
analyzes asm code, so it's not a concern for this patch set.

And I think tracepoints rely on normal call instructions, so they
shouldn't cause any problems with frame pointers as far as I can tell.

-- 
Josh
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/