linux-kernel - [PATCH 4/8] scripts/kallsyms: exclude symbols generated by itself dynamically

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Message-Id: <20230308115243.82592-4-masahiroy@kernel.org>
Date:   Wed,  8 Mar 2023 20:52:39 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     linux-kbuild@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Zhen Lei <thunder.leizhen@...wei.com>,
        Arnd Bergmann <arnd@...db.de>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nicolas Schier <nicolas@...sle.eu>
Subject: [PATCH 4/8] scripts/kallsyms: exclude symbols generated by itself dynamically

Drop the symbols generated by scripts/kallsyms itself automatically
instead of maintaining the symbol list manually.

Pass the kallsyms object from the previous kallsyms step (if it exists)
as the third parameter of scripts/mksysmap, which will weed out the
generated symbols from the input to the next kallsyms step.

Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
---

 scripts/kallsyms.c      | 17 -----------------
 scripts/link-vmlinux.sh |  6 +++---
 scripts/mksysmap        | 11 ++++++++++-
 3 files changed, 13 insertions(+), 21 deletions(-)

diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
index 8148e880f78e..e572fda6fe42 100644
--- a/scripts/kallsyms.c
+++ b/scripts/kallsyms.c
@@ -104,23 +104,6 @@ static bool is_ignored_symbol(const char *name, char type)
 {
 	/* Symbol names that exactly match to the following are ignored.*/
 	static const char * const ignored_symbols[] = {
-		/*
-		 * Symbols which vary between passes. Passes 1 and 2 must have
-		 * identical symbol lists. The kallsyms_* symbols below are
-		 * only added after pass 1, they would be included in pass 2
-		 * when --all-symbols is specified so exclude them to get a
-		 * stable symbol list.
-		 */
-		"kallsyms_addresses",
-		"kallsyms_offsets",
-		"kallsyms_relative_base",
-		"kallsyms_num_syms",
-		"kallsyms_names",
-		"kallsyms_markers",
-		"kallsyms_token_table",
-		"kallsyms_token_index",
-		"kallsyms_seqs_of_names",
-		/* Exclude linker generated symbols which vary between passes */
 		"_SDA_BASE_",		/* ppc */
 		"_SDA2_BASE_",		/* ppc */
 		NULL
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 32e573943cf0..679eb4653b16 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -174,7 +174,7 @@ kallsyms_step()
 	kallsyms_S=${kallsyms_vmlinux}.S
 
 	vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
-	mksysmap ${kallsyms_vmlinux} ${kallsyms_vmlinux}.syms
+	mksysmap ${kallsyms_vmlinux} ${kallsyms_vmlinux}.syms ${kallsymso_prev}
 	kallsyms ${kallsyms_vmlinux}.syms ${kallsyms_S}
 
 	info AS ${kallsyms_S}
@@ -188,7 +188,7 @@ kallsyms_step()
 mksysmap()
 {
 	info NM ${2}
-	${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
+	${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2} ${3}
 }
 
 sorttable()
@@ -277,7 +277,7 @@ if is_enabled CONFIG_DEBUG_INFO_BTF && is_enabled CONFIG_BPF; then
 	${RESOLVE_BTFIDS} vmlinux
 fi
 
-mksysmap vmlinux System.map
+mksysmap vmlinux System.map ${kallsymso}
 
 if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then
 	info SORTTAB vmlinux
diff --git a/scripts/mksysmap b/scripts/mksysmap
index 8ea1955e03c6..1efd61ee0bac 100755
--- a/scripts/mksysmap
+++ b/scripts/mksysmap
@@ -4,7 +4,7 @@
 # tools to retrieve the actual addresses of symbols in the kernel.
 #
 # Usage
-# mksysmap vmlinux System.map
+# mksysmap vmlinux System.map [exclude]
 
 
 #####
@@ -51,4 +51,13 @@ ${NM} -n ${1} | sed >${2} -e "
 
 # for LoongArch?
 / L0$/d
+
+# ---------------------------------------------------------------------------
+# Ignored kallsyms symbols
+#
+# If the 3rd parameter exists, symbols from it will be omitted from the output.
+# This makes kallsyms have the identical symbol lists in the step 1 and 2.
+# Without this, the step2 would get new symbols generated by scripts/kallsyms.c
+# when CONFIG_KALLSYMS_ALL is enabled. That might require one more pass.
+$(if [ $# -ge 3 ]; then ${NM} ${3} | sed -n '/ U /!s:.* \([^ ]*\)$:/ \1$/d:p'; fi)
 "
-- 
2.34.1