Re: [PATCH 3/3] Make jprobes a little safer for users

On Tue, 2007-06-26 at 07:53 +0200, Christoph Hellwig wrote:

On Tue, Jun 26, 2007 at 11:48:51AM +1000, Michael Ellerman wrote:

quoted

I realise jprobes are a razor-blades-included type of interface, but
that doesn't mean we can't try and make them safer to use. This guy I
know once wrote code like this:

struct jprobe jp = { .kp.symbol_name = "foo", .entry = "jprobe_foo" };

And then his kernel exploded. Oops.

This patch adds an arch hook, arch_deref_entry_point() (I don't like it either)
which takes the void * in a struct jprobe, and gives back the text address
that it represents.

We can then use that in register_jprobe() to check that the entry point
we're passed is actually in the kernel text, rather than just some random
value.

Please don't add more weak functions, they're utterly horrible for
anyone trying to understand the code.  Otherwise this looks fine to me.

What do you recommend instead? #define ARCH_HAS_FOO_BAR ?

I don't see what's utterly horrible about them. The fact that they're
weak is fairly reasonable documentation that they're overridden
somewhere else. And grep/cscope/ctags will find both the weak and
non-weak versions for you?

cheers

-- 
Michael Ellerman
OzLabs, IBM Australia Development Lab

wwweb: http://michael.ellerman.id.au
phone: +61 2 6212 1183 (tie line 70 21183)

We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person