From 19bd8981dc2ee35fdc81ab1b0104b607c917d470 Mon Sep 17 00:00:00 2001 From: Zhen Lei Date: Wed, 2 Nov 2022 16:49:16 +0800 Subject: 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: Zhen Lei Signed-off-by: Luis Chamberlain --- kernel/kallsyms.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) (limited to 'kernel/kallsyms.c') diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index ba351dfa109b..48f36fd7e10b 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -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); } -- cgit v1.2.3