core: Allow sizing the loader hash table

For now this will only apply to the dwarf loader, for experimenting as
time passes and kernels grow bigger or with more symbols.

Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: acmel

dwarf_loader.c

@@ -3042,6 +3042,21 @@ static int dwarf__load_file(struct cus *cus, struct conf_load *conf,
 {
 	int fd, err;
 
+	if (conf->max_hashtable_bits != 0) {
+		if (conf->max_hashtable_bits > 31)
+			return -E2BIG;
+
+		max_hashtags__bits = conf->max_hashtable_bits;
+	}
+
+	if (conf->hashtable_bits != 0) {
+		if (conf->hashtable_bits > max_hashtags__bits)
+			return -E2BIG;
+
+		hashtags__bits = conf->hashtable_bits;
+	} else if (hashtags__bits > max_hashtags__bits)
+		return -EINVAL;
+
 	elf_version(EV_CURRENT);
 
 	fd = open(filename, O_RDONLY);

dwarves.h

@@ -56,6 +56,8 @@ struct conf_load {
 	bool			ignore_alignment_attr;
 	bool			ignore_inline_expansions;
 	bool			ignore_labels;
+	uint8_t			hashtable_bits;
+	uint8_t			max_hashtable_bits;
 	uint16_t		kabi_prefix_len;
 	const char		*kabi_prefix;
 	struct btf		*base_btf;