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-rw-r--r--include/linux/export.h13
-rw-r--r--scripts/Kbuild.include27
-rw-r--r--scripts/basic/fixdep.c1
3 files changed, 40 insertions, 1 deletions
diff --git a/include/linux/export.h b/include/linux/export.h
index 77afdb2a2506..2f9ccbe6a639 100644
--- a/include/linux/export.h
+++ b/include/linux/export.h
@@ -65,7 +65,18 @@ extern struct module __this_module;
__attribute__((section("___ksymtab" sec "+" #sym), unused)) \
= { (unsigned long)&sym, __kstrtab_##sym }
-#ifdef CONFIG_TRIM_UNUSED_KSYMS
+#if defined(__KSYM_DEPS__)
+
+/*
+ * For fine grained build dependencies, we want to tell the build system
+ * about each possible exported symbol even if they're not actually exported.
+ * We use a string pattern that is unlikely to be valid code that the build
+ * system filters out from the preprocessor output (see ksym_dep_filter
+ * in scripts/Kbuild.include).
+ */
+#define __EXPORT_SYMBOL(sym, sec) === __KSYM_##sym ===
+
+#elif defined(CONFIG_TRIM_UNUSED_KSYMS)
#include <linux/kconfig.h>
#include <generated/autoksyms.h>
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index 80ca538bfba9..a09927e02713 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -258,12 +258,39 @@ if_changed_dep = $(if $(strip $(any-prereq) $(arg-check) ), \
@set -e; \
$(cmd_and_fixdep), @:)
+ifndef CONFIG_TRIM_UNUSED_KSYMS
+
cmd_and_fixdep = \
$(echo-cmd) $(cmd_$(1)); \
scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).tmp;\
rm -f $(depfile); \
mv -f $(dot-target).tmp $(dot-target).cmd;
+else
+
+# Filter out exported kernel symbol names from the preprocessor output.
+# See also __KSYM_DEPS__ in include/linux/export.h.
+# We disable the depfile generation here, so as not to overwrite the existing
+# depfile while fixdep is parsing it.
+flags_nodeps = $(filter-out -Wp$(comma)-M%, $($(1)))
+ksym_dep_filter = \
+ case "$(1)" in \
+ cc_*_c) $(CPP) $(call flags_nodeps,c_flags) -D__KSYM_DEPS__ $< ;; \
+ as_*_S) $(CPP) $(call flags_nodeps,a_flags) -D__KSYM_DEPS__ $< ;; \
+ boot*|build*|*cpp_lds_S|dtc|host*|vdso*) : ;; \
+ *) echo "Don't know how to preprocess $(1)" >&2; false ;; \
+ esac | sed -rn 's/^.*=== __KSYM_(.*) ===.*$$/KSYM_\1/p'
+
+cmd_and_fixdep = \
+ $(echo-cmd) $(cmd_$(1)); \
+ $(ksym_dep_filter) | \
+ scripts/basic/fixdep -e $(depfile) $@ '$(make-cmd)' \
+ > $(dot-target).tmp; \
+ rm -f $(depfile); \
+ mv -f $(dot-target).tmp $(dot-target).cmd;
+
+endif
+
# Usage: $(call if_changed_rule,foo)
# Will check if $(cmd_foo) or any of the prerequisites changed,
# and if so will execute $(rule_foo).
diff --git a/scripts/basic/fixdep.c b/scripts/basic/fixdep.c
index 7e90a1f7de0f..746ec1ece614 100644
--- a/scripts/basic/fixdep.c
+++ b/scripts/basic/fixdep.c
@@ -358,6 +358,7 @@ static void parse_dep_file(void *map, size_t len)
/* Ignore certain dependencies */
if (strrcmp(s, "include/generated/autoconf.h") &&
+ strrcmp(s, "include/generated/autoksyms.h") &&
strrcmp(s, "arch/um/include/uml-config.h") &&
strrcmp(s, "include/linux/kconfig.h") &&
strrcmp(s, ".ver")) {
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