Commit 19bd8981 authored by Zhen Lei's avatar Zhen Lei Committed by Luis Chamberlain
Browse files

kallsyms: Reduce the memory occupied by kallsyms_seqs_of_names[] 



kallsyms_seqs_of_names[] records the symbol index sorted by address, the
maximum value in kallsyms_seqs_of_names[] is the number of symbols. And
2^24 = 16777216, which means that three bytes are enough to store the
index. This can help us save (1 * kallsyms_num_syms) bytes of memory.

Signed-off-by: default avatarZhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
parent 010a0aad

kernel/kallsyms.c

+14 −4
Original line number Diff line number Diff line
@@ -201,6 +201,16 @@ static int compare_symbol_name(const char *name, char *namebuf) 
	return ret;

}



static unsigned int get_symbol_seq(int index)

{

	unsigned int i, seq = 0;



	for (i = 0; i < 3; i++)

		seq = (seq << 8) | kallsyms_seqs_of_names[3 * index + i];



	return seq;

}



static int kallsyms_lookup_names(const char *name,

				 unsigned int *start,

				 unsigned int *end)
@@ -215,7 +225,7 @@ static int kallsyms_lookup_names(const char *name, 


	while (low <= high) {

		mid = low + (high - low) / 2;

		seq = kallsyms_seqs_of_names[mid];

		seq = get_symbol_seq(mid);

		off = get_symbol_offset(seq);

		kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));

		ret = compare_symbol_name(name, namebuf);
@@ -232,7 +242,7 @@ static int kallsyms_lookup_names(const char *name, 


	low = mid;

	while (low) {

		seq = kallsyms_seqs_of_names[low - 1];

		seq = get_symbol_seq(low - 1);

		off = get_symbol_offset(seq);

		kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));

		if (compare_symbol_name(name, namebuf))
@@ -244,7 +254,7 @@ static int kallsyms_lookup_names(const char *name, 
	if (end) {

		high = mid;

		while (high < kallsyms_num_syms - 1) {

			seq = kallsyms_seqs_of_names[high + 1];

			seq = get_symbol_seq(high + 1);

			off = get_symbol_offset(seq);

			kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));

			if (compare_symbol_name(name, namebuf))
@@ -269,7 +279,7 @@ unsigned long kallsyms_lookup_name(const char *name) 


	ret = kallsyms_lookup_names(name, &i, NULL);

	if (!ret)

		return kallsyms_sym_address(kallsyms_seqs_of_names[i]);

		return kallsyms_sym_address(get_symbol_seq(i));



	return module_kallsyms_lookup_name(name);

}

kernel/kallsyms_internal.h

+1 −1
Original line number Diff line number Diff line
@@ -26,6 +26,6 @@ extern const char kallsyms_token_table[] __weak; 
extern const u16 kallsyms_token_index[] __weak;



extern const unsigned int kallsyms_markers[] __weak;

extern const unsigned int kallsyms_seqs_of_names[] __weak;

extern const u8 kallsyms_seqs_of_names[] __weak;



#endif // LINUX_KALLSYMS_INTERNAL_H_

scripts/kallsyms.c

+4 −1
Original line number Diff line number Diff line
@@ -600,7 +600,10 @@ static void write_src(void) 
	sort_symbols_by_name();

	output_label("kallsyms_seqs_of_names");

	for (i = 0; i < table_cnt; i++)

		printf("\t.long\t%u\n", table[i]->seq);

		printf("\t.byte 0x%02x, 0x%02x, 0x%02x\n",

			(unsigned char)(table[i]->seq >> 16),

			(unsigned char)(table[i]->seq >> 8),

			(unsigned char)(table[i]->seq >> 0));

	printf("\n");



	output_label("kallsyms_token_table");