kernel: add a config option for keeping the kallsyms table uncompressed, saving ~9kb kernel size after lzma on ar71xx

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@35154 3c298f89-4303-0410-b956-a3cf2f4a3e73

target/linux/generic/config-3.7

@@ -1343,6 +1343,7 @@ CONFIG_JOLIET=y
 # CONFIG_JUMP_LABEL is not set
 # CONFIG_KALLSYMS is not set
 # CONFIG_KALLSYMS_ALL is not set
+CONFIG_KALLSYMS_UNCOMPRESSED=y
 # CONFIG_KARMA_PARTITION is not set
 # CONFIG_KERNEL_BZIP2 is not set
 # CONFIG_KERNEL_GZIP is not set

target/linux/generic/patches-3.7/203-kallsyms_uncompressed.patch

@@ -0,0 +1,108 @@
+--- a/scripts/kallsyms.c
++++ b/scripts/kallsyms.c
+@@ -83,6 +83,7 @@ static struct text_range text_ranges[] =
+ static struct sym_entry *table;
+ static unsigned int table_size, table_cnt;
+ static int all_symbols = 0;
++static int uncompressed = 0;
+ static char symbol_prefix_char = '\0';
+ 
+ int token_profit[0x10000];
+@@ -389,6 +390,9 @@ static void write_src(void)
+ 
+ 	free(markers);
+ 
++	if (uncompressed)
++		return;
++
+ 	output_label("kallsyms_token_table");
+ 	off = 0;
+ 	for (i = 0; i < 256; i++) {
+@@ -447,6 +451,9 @@ 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];
+@@ -519,6 +526,9 @@ 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--) {
+@@ -675,7 +685,9 @@ int main(int argc, char **argv)
+ 				if ((*p == '"' && *(p+2) == '"') || (*p == '\'' && *(p+2) == '\''))
+ 					p++;
+ 				symbol_prefix_char = *p;
+-			} else
++			} else if (strcmp(argv[i], "--uncompressed") == 0)
++				uncompressed = 1;
++			else
+ 				usage();
+ 		}
+ 	} else if (argc != 1)
+--- a/init/Kconfig
++++ b/init/Kconfig
+@@ -1198,6 +1198,17 @@ config KALLSYMS_ALL
+ 
+ 	   Say N unless you really need all symbols.
+ 
++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 HOTPLUG
+ 	def_bool y
+ 
+--- a/scripts/link-vmlinux.sh
++++ b/scripts/link-vmlinux.sh
+@@ -83,6 +83,10 @@ kallsyms()
+ 		kallsymopt="${kallsymopt} --all-symbols"
+ 	fi
+ 
++	if [ -n "${CONFIG_KALLSYMS_UNCOMPRESSED}" ]; then
++		kallsymopt="${kallsymopt} --uncompressed"
++	fi
++
+ 	local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL}               \
+ 		      ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}"
+ 
+--- a/kernel/kallsyms.c
++++ b/kernel/kallsyms.c
+@@ -106,6 +106,11 @@ 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++;
+@@ -133,6 +138,9 @@ static unsigned int kallsyms_expand_symb
+  */
+ 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.