linux/scripts/mksysmap
Pierre-Clément Tosi 71025b8565 scripts/mksysmap: Ignore prefixed KCFI symbols
The (relatively) new KCFI feature in LLVM/Clang encodes type information
for C functions by generating symbols named __kcfi_typeid_<fname>, which
can then be referenced from assembly. However, some custom build rules
(e.g. nVHE or early PIE on arm64) use objcopy to add a prefix to all the
symbols in their object files, making mksysmap's ignore filter miss
those KCFI symbols.

Therefore, explicitly list those twice-prefixed KCFI symbols as ignored.

Alternatively, this could also be achieved in a less verbose way by
ignoring any symbol containing the string "__kcfi_typeid_". However,
listing the combined prefixes explicitly saves us from running the small
risk of ignoring symbols that should be kept.

Signed-off-by: Pierre-Clément Tosi <ptosi@google.com>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-27 08:35:43 +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 [exclude]
#####
# Generate System.map (actual filename passed as second argument)
# The following refers to the symbol type as per nm(1).
# 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'.
#
${NM} -n ${1} | sed >${2} -e "
# ---------------------------------------------------------------------------
# Ignored symbol types
#
# a: local absolute symbols
# N: debugging symbols
# U: undefined global symbols
# w: local weak symbols
/ [aNUw] /d
# ---------------------------------------------------------------------------
# Ignored prefixes
# (do not forget a space before each pattern)
# local symbols for ARM, MIPS, etc.
/ \\$/d
# local labels, .LBB, .Ltmpxxx, .L__unnamed_xx, .LASANPC, etc.
/ \.L/d
# arm64 EFI stub namespace
/ __efistub_/d
# arm64 local symbols in PIE namespace
/ __pi_\\$/d
/ __pi_\.L/d
# arm64 local symbols in non-VHE KVM namespace
/ __kvm_nvhe_\\$/d
/ __kvm_nvhe_\.L/d
# arm64 lld
/ __AArch64ADRPThunk_/d
# arm lld
/ __ARMV5PILongThunk_/d
/ __ARMV7PILongThunk_/d
/ __ThumbV7PILongThunk_/d
# mips lld
/ __LA25Thunk_/d
/ __microLA25Thunk_/d
# CFI type identifiers
/ __kcfi_typeid_/d
/ __kvm_nvhe___kcfi_typeid_/d
/ __pi___kcfi_typeid_/d
# CRC from modversions
/ __crc_/d
# EXPORT_SYMBOL (symbol name)
/ __kstrtab_/d
# EXPORT_SYMBOL (namespace)
/ __kstrtabns_/d
# ---------------------------------------------------------------------------
# Ignored suffixes
# (do not forget '$' after each pattern)
# arm
/_from_arm$/d
/_from_thumb$/d
/_veneer$/d
# ---------------------------------------------------------------------------
# Ignored symbols (exact match)
# (do not forget a space before and '$' after each pattern)
# for LoongArch?
/ L0$/d
# ppc
/ _SDA_BASE_$/d
/ _SDA2_BASE_$/d
# ---------------------------------------------------------------------------
# Ignored patterns
# (symbols that contain the pattern are ignored)
# ppc stub
/\.long_branch\./d
/\.plt_branch\./d
# ---------------------------------------------------------------------------
# Ignored kallsyms symbols
#
# If the 3rd parameter exists, symbols from it will be omitted from the output.
# This makes kallsyms have the identical symbol lists in the step 1 and 2.
# Without this, the step2 would get new symbols generated by scripts/kallsyms.c
# when CONFIG_KALLSYMS_ALL is enabled. That might require one more pass.
$(if [ $# -ge 3 ]; then ${NM} ${3} | sed -n '/ U /!s:.* \([^ ]*\)$:/ \1$/d:p'; fi)
"