target/linux/generic/pending-6.1/203-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 --- a/init/Kconfig
  15 +++ b/init/Kconfig
  16 @@ -1481,6 +1481,17 @@ config SYSCTL_ARCH_UNALIGN_ALLOW
  17           the unaligned access emulation.
  18           see arch/parisc/kernel/unaligned.c for reference
  19
  20 +config KALLSYMS_UNCOMPRESSED
  21 +       bool "Keep kallsyms uncompressed"
  22 +       depends on KALLSYMS
  23 +       help
  24 +               Normally kallsyms contains compressed symbols (using a token table),
  25 +               reducing the uncompressed kernel image size. Keeping the symbol table
  26 +               uncompressed significantly improves the size of this part in compressed
  27 +               kernel images.
  28 +
  29 +               Say N unless you need compressed kernel images to be small.
  30 +
  31  config HAVE_PCSPKR_PLATFORM
  32         bool
  33
  34 --- a/kernel/kallsyms.c
  35 +++ b/kernel/kallsyms.c
  36 @@ -69,6 +69,11 @@ static unsigned int kallsyms_expand_symb
  37          * For every byte on the compressed symbol data, copy the table
  38          * entry for that byte.
  39          */
  40 +#ifdef CONFIG_KALLSYMS_UNCOMPRESSED
  41 +       memcpy(result, data + 1, len - 1);
  42 +       result += len - 1;
  43 +       len = 0;
  44 +#endif
  45         while (len) {
  46                 tptr = &kallsyms_token_table[kallsyms_token_index[*data]];
  47                 data++;
  48 @@ -101,6 +106,9 @@ tail:
  49   */
  50  static char kallsyms_get_symbol_type(unsigned int off)
  51  {
  52 +#ifdef CONFIG_KALLSYMS_UNCOMPRESSED
  53 +       return kallsyms_names[off + 1];
  54 +#endif
  55         /*
  56          * Get just the first code, look it up in the token table,
  57          * and return the first char from this token.
  58 --- a/scripts/kallsyms.c
  59 +++ b/scripts/kallsyms.c
  60 @@ -77,6 +77,7 @@ static struct addr_range percpu_range =
  61  static struct sym_entry **table;
  62  static unsigned int table_size, table_cnt;
  63  static int all_symbols;
  64 +static int uncompressed;
  65  static int absolute_percpu;
  66  static int base_relative;
  67  static int lto_clang;
  68 @@ -605,6 +606,9 @@ static void write_src(void)
  69                 printf("\t.long\t%u\n", table[i]->seq);
  70         printf("\n");
  71
  72 +       if (uncompressed)
  73 +               return;
  74 +
  75         output_label("kallsyms_token_table");
  76         off = 0;
  77         for (i = 0; i < 256; i++) {
  78 @@ -656,6 +660,9 @@ static unsigned char *find_token(unsigne
  79  {
  80         int i;
  81
  82 +       if (uncompressed)
  83 +               return NULL;
  84 +
  85         for (i = 0; i < len - 1; i++) {
  86                 if (str[i] == token[0] && str[i+1] == token[1])
  87                         return &str[i];
  88 @@ -728,6 +735,9 @@ static void optimize_result(void)
  89  {
  90         int i, best;
  91
  92 +       if (uncompressed)
  93 +               return;
  94 +
  95         /* using the '\0' symbol last allows compress_symbols to use standard
  96          * fast string functions */
  97         for (i = 255; i >= 0; i--) {
  98 @@ -889,6 +899,7 @@ int main(int argc, char **argv)
  99                         {"absolute-percpu", no_argument, &absolute_percpu, 1},
 100                         {"base-relative",   no_argument, &base_relative,   1},
 101                         {"lto-clang",       no_argument, &lto_clang,       1},
 102 +                       {"uncompressed",   no_argument, &uncompressed,   1},
 103                         {},
 104                 };
 105
 106 --- a/scripts/link-vmlinux.sh
 107 +++ b/scripts/link-vmlinux.sh
 108 @@ -160,6 +160,10 @@ kallsyms()
 109                 kallsymopt="${kallsymopt} --lto-clang"
 110         fi
 111
 112 +       if is_enabled CONFIG_KALLSYMS_UNCOMPRESSED; then
 113 +               kallsymopt="${kallsymopt} --uncompressed"
 114 +       fi
 115 +
 116         info KSYMS ${2}
 117         scripts/kallsyms ${kallsymopt} ${1} > ${2}
 118  }