target/linux/generic/pending-4.9/203-kallsyms_uncompressed.patch

   1 From: Felix Fietkau <nbd@nbd.name>
   2 Subject: kernel: add a config option for keeping the kallsyms table uncompressed, saving ~9kb kernel size after lzma on ar71xx
   3
   4 [john@phrozen.org: added to my upstream queue 30.12.2016]
   5 lede-commit: e0e3509b5ce2ccf93d4d67ea907613f5f7ec2eed
   6 Signed-off-by: Felix Fietkau <nbd@nbd.name>
   7 ---
   8  init/Kconfig            | 11 +++++++++++
   9  kernel/kallsyms.c       |  8 ++++++++
  10  scripts/kallsyms.c      | 12 ++++++++++++
  11  scripts/link-vmlinux.sh |  4 ++++
  12  4 files changed, 35 insertions(+)
  13
  14 diff --git a/init/Kconfig b/init/Kconfig
  15 index 34407f15e6d3..9063c81b9665 100644
  16 --- a/init/Kconfig
  17 +++ b/init/Kconfig
  18 @@ -1370,6 +1370,17 @@ config SYSCTL_ARCH_UNALIGN_ALLOW
  19           the unaligned access emulation.
  20           see arch/parisc/kernel/unaligned.c for reference
  21
  22 +config KALLSYMS_UNCOMPRESSED
  23 +       bool "Keep kallsyms uncompressed"
  24 +       depends on KALLSYMS
  25 +       help
  26 +               Normally kallsyms contains compressed symbols (using a token table),
  27 +               reducing the uncompressed kernel image size. Keeping the symbol table
  28 +               uncompressed significantly improves the size of this part in compressed
  29 +               kernel images.
  30 +
  31 +               Say N unless you need compressed kernel images to be small.
  32 +
  33  config HAVE_PCSPKR_PLATFORM
  34         bool
  35
  36 diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
  37 index fafd1a3ef0da..abe49579212f 100644
  38 --- a/kernel/kallsyms.c
  39 +++ b/kernel/kallsyms.c
  40 @@ -113,6 +113,11 @@ static unsigned int kallsyms_expand_symbol(unsigned int off,
  41          * For every byte on the compressed symbol data, copy the table
  42          * entry for that byte.
  43          */
  44 +#ifdef CONFIG_KALLSYMS_UNCOMPRESSED
  45 +       memcpy(result, data + 1, len - 1);
  46 +       result += len - 1;
  47 +       len = 0;
  48 +#endif
  49         while (len) {
  50                 tptr = &kallsyms_token_table[kallsyms_token_index[*data]];
  51                 data++;
  52 @@ -145,6 +150,9 @@ static unsigned int kallsyms_expand_symbol(unsigned int off,
  53   */
  54  static char kallsyms_get_symbol_type(unsigned int off)
  55  {
  56 +#ifdef CONFIG_KALLSYMS_UNCOMPRESSED
  57 +       return kallsyms_names[off + 1];
  58 +#endif
  59         /*
  60          * Get just the first code, look it up in the token table,
  61          * and return the first char from this token.
  62 diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
  63 index 1f22a186c18c..e7f0f19e39a9 100644
  64 --- a/scripts/kallsyms.c
  65 +++ b/scripts/kallsyms.c
  66 @@ -61,6 +61,7 @@ static struct addr_range percpu_range = {
  67  static struct sym_entry *table;
  68  static unsigned int table_size, table_cnt;
  69  static int all_symbols = 0;
  70 +static int uncompressed = 0;
  71  static int absolute_percpu = 0;
  72  static char symbol_prefix_char = '\0';
  73  static int base_relative = 0;
  74 @@ -446,6 +447,9 @@ static void write_src(void)
  75
  76         free(markers);
  77
  78 +       if (uncompressed)
  79 +               return;
  80 +
  81         output_label("kallsyms_token_table");
  82         off = 0;
  83         for (i = 0; i < 256; i++) {
  84 @@ -504,6 +508,9 @@ static void *find_token(unsigned char *str, int len, unsigned char *token)
  85  {
  86         int i;
  87
  88 +       if (uncompressed)
  89 +               return NULL;
  90 +
  91         for (i = 0; i < len - 1; i++) {
  92                 if (str[i] == token[0] && str[i+1] == token[1])
  93                         return &str[i];
  94 @@ -576,6 +583,9 @@ static void optimize_result(void)
  95  {
  96         int i, best;
  97
  98 +       if (uncompressed)
  99 +               return;
 100 +
 101         /* using the '\0' symbol last allows compress_symbols to use standard
 102          * fast string functions */
 103         for (i = 255; i >= 0; i--) {
 104 @@ -764,6 +774,8 @@ int main(int argc, char **argv)
 105                                 symbol_prefix_char = *p;
 106                         } else if (strcmp(argv[i], "--base-relative") == 0)
 107                                 base_relative = 1;
 108 +                       else if (strcmp(argv[i], "--uncompressed") == 0)
 109 +                               uncompressed = 1;
 110                         else
 111                                 usage();
 112                 }
 113 diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
 114 index f742c65108b9..6aabf1d71bb6 100755
 115 --- a/scripts/link-vmlinux.sh
 116 +++ b/scripts/link-vmlinux.sh
 117 @@ -136,6 +136,10 @@ kallsyms()
 118                 kallsymopt="${kallsymopt} --base-relative"
 119         fi
 120
 121 +       if [ -n "${CONFIG_KALLSYMS_UNCOMPRESSED}" ]; then
 122 +               kallsymopt="${kallsymopt} --uncompressed"
 123 +       fi
 124 +
 125         local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL}               \
 126                       ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}"
 127
 128 --
 129 2.11.0
 130