From: Felix Fietkau Subject: kernel: add a config option for keeping the kallsyms table uncompressed, saving ~9kb kernel size after lzma on ar71xx [john@phrozen.org: added to my upstream queue 30.12.2016] lede-commit: e0e3509b5ce2ccf93d4d67ea907613f5f7ec2eed Signed-off-by: Felix Fietkau --- init/Kconfig | 11 +++++++++++ kernel/kallsyms.c | 8 ++++++++ scripts/kallsyms.c | 12 ++++++++++++ scripts/link-vmlinux.sh | 4 ++++ 4 files changed, 35 insertions(+) --- a/init/Kconfig +++ b/init/Kconfig @@ -1370,6 +1370,17 @@ config SYSCTL_ARCH_UNALIGN_ALLOW the unaligned access emulation. see arch/parisc/kernel/unaligned.c for reference +config KALLSYMS_UNCOMPRESSED + bool "Keep kallsyms uncompressed" + depends on KALLSYMS + help + Normally kallsyms contains compressed symbols (using a token table), + reducing the uncompressed kernel image size. Keeping the symbol table + uncompressed significantly improves the size of this part in compressed + kernel images. + + Say N unless you need compressed kernel images to be small. + config HAVE_PCSPKR_PLATFORM bool --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -113,6 +113,11 @@ static unsigned int kallsyms_expand_symb * For every byte on the compressed symbol data, copy the table * entry for that byte. */ +#ifdef CONFIG_KALLSYMS_UNCOMPRESSED + memcpy(result, data + 1, len - 1); + result += len - 1; + len = 0; +#endif while (len) { tptr = &kallsyms_token_table[kallsyms_token_index[*data]]; data++; @@ -145,6 +150,9 @@ tail: */ static char kallsyms_get_symbol_type(unsigned int off) { +#ifdef CONFIG_KALLSYMS_UNCOMPRESSED + return kallsyms_names[off + 1]; +#endif /* * Get just the first code, look it up in the token table, * and return the first char from this token. --- a/scripts/kallsyms.c +++ b/scripts/kallsyms.c @@ -61,6 +61,7 @@ static struct addr_range percpu_range = static struct sym_entry *table; static unsigned int table_size, table_cnt; static int all_symbols = 0; +static int uncompressed = 0; static int absolute_percpu = 0; static char symbol_prefix_char = '\0'; static int base_relative = 0; @@ -446,6 +447,9 @@ static void write_src(void) free(markers); + if (uncompressed) + return; + output_label("kallsyms_token_table"); off = 0; for (i = 0; i < 256; i++) { @@ -504,6 +508,9 @@ static void *find_token(unsigned char *s { int i; + if (uncompressed) + return NULL; + for (i = 0; i < len - 1; i++) { if (str[i] == token[0] && str[i+1] == token[1]) return &str[i]; @@ -576,6 +583,9 @@ static void optimize_result(void) { int i, best; + if (uncompressed) + return; + /* using the '\0' symbol last allows compress_symbols to use standard * fast string functions */ for (i = 255; i >= 0; i--) { @@ -764,6 +774,8 @@ int main(int argc, char **argv) symbol_prefix_char = *p; } else if (strcmp(argv[i], "--base-relative") == 0) base_relative = 1; + else if (strcmp(argv[i], "--uncompressed") == 0) + uncompressed = 1; else usage(); } --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -136,6 +136,10 @@ kallsyms() kallsymopt="${kallsymopt} --base-relative" fi + if [ -n "${CONFIG_KALLSYMS_UNCOMPRESSED}" ]; then + kallsymopt="${kallsymopt} --uncompressed" + fi + local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \ ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}"