linux/scripts/mksysmap
Masahiro Yamada d32b55f4bb kallsyms: ignore __kstrtab_* and __kstrtabns_* symbols
Every EXPORT_SYMBOL creates __kstrtab_* and __kstrtabns_*, which
consumes 15-20% of the kallsyms entries.

For example, on the system built from the x86_64 defconfig,

  $ cat /proc/kallsyms | wc
     129527    388581   5685465
  $ cat /proc/kallsyms | grep __kstrtab | wc
      23489     70467   1187932

We already ignore __crc_* symbols populated by EXPORT_SYMBOL, so it
should be fine to ignore __kstrtab_* and __kstrtabns_* as well.

This makes vmlinux a bit smaller.

  $ size vmlinux.before vmlinux.after
     text    data     bss     dec     hex filename
  22785374        8559694 1413328 32758396        1f3da7c vmlinux.before
  22785374        8137806 1413328 32336508        1ed6a7c vmlinux.after

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2022-10-03 03:51:58 +09:00

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#!/bin/sh -x
# Based on the vmlinux file create the System.map file
# System.map is used by module-init tools and some debugging
# tools to retrieve the actual addresses of symbols in the kernel.
#
# Usage
# mksysmap vmlinux System.map
#####
# Generate System.map (actual filename passed as second argument)
# $NM produces the following output:
# f0081e80 T alloc_vfsmnt
# The second row specify the type of the symbol:
# A = Absolute
# B = Uninitialised data (.bss)
# C = Common symbol
# D = Initialised data
# G = Initialised data for small objects
# I = Indirect reference to another symbol
# N = Debugging symbol
# R = Read only
# S = Uninitialised data for small objects
# T = Text code symbol
# U = Undefined symbol
# V = Weak symbol
# W = Weak symbol
# Corresponding small letters are local symbols
# For System.map filter away:
# a - local absolute symbols
# U - undefined global symbols
# N - debugging symbols
# w - local weak symbols
# readprofile starts reading symbols when _stext is found, and
# continue until it finds a symbol which is not either of 'T', 't',
# 'W' or 'w'.
#
# Ignored prefixes:
# $ - local symbols for ARM, MIPS, etc.
# .L - local labels, .LBB,.Ltmpxxx,.L__unnamed_xx,.LASANPC, etc.
# __crc_ - modversions
# __kstrtab_ - EXPORT_SYMBOL (symbol name)
# __kstrtabns_ - EXPORT_SYMBOL (namespace)
#
# Ignored symbols:
# L0 - for LoongArch?
$NM -n $1 | grep -v \
-e ' [aNUw] ' \
-e ' \$' \
-e ' \.L' \
-e ' __crc_' \
-e ' __kstrtab_' \
-e ' __kstrtabns_' \
-e ' L0$' \
> $2