Re: [PATCH 01/13] static_call: Index code text reservation lookups

[Jiri Olsa <olsajiri@gmail.com>]

On Thu, Nov 12, 2026 at 09:34:13AM +0100, Peter Zijlstra wrote:
> On Mon, Nov 09, 2026 at 08:49:04PM +0100, Jiri Olsa wrote:
> 
> > +static int static_call_site_index_cmp(const void *a, const void *b, const void *priv)
> > +{
> > +	const struct static_call_site *base = priv;
> > +	unsigned int ia = *(u32 *)a;
> > +	unsigned int ib = *(u32 *)b;
> > +	unsigned long ca = (unsigned long)static_call_addr(base + ia);
> > +	unsigned long cb = (unsigned long)static_call_addr(base + ib);
> > +
> > +	return cmp_int(ca, cb);
> > +}
> > +
> > +static struct static_call_site_index *
> > +static_call_site_index_alloc(struct static_call_site *start,
> > +			     struct static_call_site *stop)
> > +{
> > +	struct static_call_site_index *index;
> > +	unsigned int nr = stop - start;
> > +	unsigned int i;
> > +
> > +	if (!nr)
> > +		return NULL;
> > +
> > +	index = kvmalloc_flex(*index, entries, nr, GFP_KERNEL);
> > +	if (!index)
> > +		return NULL;
> > +
> > +	index->nr = nr;
> > +	index->base = start;
> > +	for (i = 0; i < nr; i++)
> > +		index->entries[i] = i;
> > +
> > +	sort_r(index->entries, nr, sizeof(index->entries[0]),
> > +	       static_call_site_index_cmp, NULL, start);
> > +
> > +	return index;
> > +}
> > +
> > +static int
> > +static_call_site_index_text_reserved(struct static_call_site_index *index,
> > +				     void *start, void *end, bool init)
> > +{
> > +	unsigned int low = 0, high = index->nr, i;
> > +
> > +	/* Find the first site after @start. */
> > +	while (low < high) {
> > +		unsigned int mid = low + (high - low) / 2;
> > +		void *addr = static_call_addr(index->base + index->entries[mid]);
> > +
> > +		if (addr <= start)
> > +			low = mid + 1;
> > +		else
> > +			high = mid;
> > +	}
> > +
> > +	/* The preceding site may overlap @start. */
> > +	if (low)
> > +		low--;
> > +
> > +	for (i = low; i < index->nr; i++) {
> > +		struct static_call_site *site = index->base + index->entries[i];
> > +		void *addr = static_call_addr(site);
> > +
> > +		/* Later sites cannot overlap once this address is past @end. */
> > +		if (addr > end)
> > +			break;
> > +		if ((init || !static_call_is_init(site)) &&
> > +		    addr_conflict(site, start, end))
> > +			return 1;
> > +	}
> > +
> > +	return 0;
> > +}
> 
> FWIW, we do have bsearch() as well.

yes, but bsearch() returns exact match, but we need to find first entry
after start even when no entry matches it... I'm not sure how to do that
with bsearch

jirka