Messages in this thread | | | Date | Thu, 28 Jun 2018 10:50:03 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 2/5] kernel/jump_label: implement generic support for relative references |
| |
On Wed, Jun 27, 2018 at 06:06:01PM +0200, Ard Biesheuvel wrote: > diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h > index 86ec0652d3b1..aa203dffe72c 100644 > --- a/include/linux/jump_label.h > +++ b/include/linux/jump_label.h > @@ -121,6 +121,32 @@ struct static_key { > #include <asm/jump_label.h> > > #ifndef __ASSEMBLY__ > +#ifdef CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE > + > +struct jump_entry { > + int code; > + int target; > + int key; > +};
I much prefer you use 'u32' there.
> +static void jump_label_swap(void *a, void *b, int size) > +{ > + long delta = (unsigned long)a - (unsigned long)b; > + struct jump_entry *jea = a; > + struct jump_entry *jeb = b; > + struct jump_entry tmp = *jea; > + > + jea->code = jeb->code - delta; > + jea->target = jeb->target - delta; > + jea->key = jeb->key - delta; > + > + jeb->code = tmp.code + delta; > + jeb->target = tmp.target + delta; > + jeb->key = tmp.key + delta; > +} > + > static void > jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop) > { > @@ -56,7 +72,9 @@ jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop) > > size = (((unsigned long)stop - (unsigned long)start) > / sizeof(struct jump_entry)); > - sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL); > + sort(start, size, sizeof(struct jump_entry), jump_label_cmp, > + IS_ENABLED(CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE) ? jump_label_swap > + : NULL); > }
That will result in jump_label_swap being an unused symbol for some compile options.
Would it not be much nicer to write that like:
static void jump_label_swap(void *a, void *b, int size) { struct jump_entry *jea = a, *jeb = b;
#ifdef CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE long delta = a - b;
jea->code += delta; jea->target += delta; jea->key += delta;
jeb->code -= delta; jeb->target -= delta; jeb->key -= delta; #else
swap(*jea, *jeb); }
And then unconditionally use jump_label_swap().
| |