Stephen Rothwell reported a build error on ppc64 when
CONFIG_TRIM_UNUSED_KSYMS is enabled.
Jessica Yu pointed out the cause of the error with the reference to the
ppc64 elf ABI:
"Symbol names with a dot (.) prefix are reserved for holding entry
point addresses. The value of a symbol named ".FN", if it exists,
is the entry point of the function "FN".
As it turned out, CONFIG_TRIM_UNUSED_KSYMS has never worked for ppc64,
which has been unnoticed until recently because this option depends on
!UNUSED_SYMBOLS hence is disabled by all{mod,yes}config. (Then, it was
uncovered by another patch removing UNUSED_SYMBOLS.)
Removing the dot prefix in scripts/gen_autoksyms.sh fixes the issue.
Please note it must be done before 'sort -u', because modules have
both ._mcount and _mcount undefined when CONFIG_FUNCTION_TRACER=y.
Link: https://lore.kernel.org/lkml/20210209210843.3af66662@xxxxxxxxxxxxxxxx/
Reported-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
---
scripts/gen_autoksyms.sh | 3 +++
1 file changed, 3 insertions(+)
diff --git a/scripts/gen_autoksyms.sh b/scripts/gen_autoksyms.sh
index 16c0b2ddaa4c..d54dfba15bf2 100755
--- a/scripts/gen_autoksyms.sh
+++ b/scripts/gen_autoksyms.sh
@@ -43,6 +43,9 @@ EOT
sed 's/ko$/mod/' $modlist |
xargs -n1 sed -n -e '2{s/ /\n/g;/^$/!p;}' -- |
cat - "$ksym_wl" |
+# Remove the dot prefix for ppc64; symbol names with a dot (.) hold entry
+# point addresses.
+sed -e 's/^\.//' |
sort -u |
sed -e 's/\(.*\)/#define __KSYM_\1 1/' >> "$output_file"
--
2.27.0
