kbuild: create a way to create preprocessor constants from C expressions
The use of enums create constants that are not available to the preprocessor
when building the kernel (f.e. MAX_NR_ZONES).
Arch code already has a way to export constants calculated to the preprocessor
through the asm-offsets.c file. Generate something similar for the core
kernel through kbuild.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Kbuild b/Kbuild
index 1570d24..7136de7 100644
--- a/Kbuild
+++ b/Kbuild
@@ -1,19 +1,54 @@
#
# Kbuild for top-level directory of the kernel
# This file takes care of the following:
-# 1) Generate asm-offsets.h
-# 2) Check for missing system calls
+# 1) Generate bounds.h
+# 2) Generate asm-offsets.h (may need bounds.h)
+# 3) Check for missing system calls
#####
-# 1) Generate asm-offsets.h
+# 1) Generate bounds.h
+
+bounds-file := include/linux/bounds.h
+
+always := $(bounds-file)
+targets := $(bounds-file) kernel/bounds.s
+
+quiet_cmd_bounds = GEN $@
+define cmd_bounds
+ (set -e; \
+ echo "#ifndef __LINUX_BOUNDS_H__"; \
+ echo "#define __LINUX_BOUNDS_H__"; \
+ echo "/*"; \
+ echo " * DO NOT MODIFY."; \
+ echo " *"; \
+ echo " * This file was generated by Kbuild"; \
+ echo " *"; \
+ echo " */"; \
+ echo ""; \
+ sed -ne $(sed-y) $<; \
+ echo ""; \
+ echo "#endif" ) > $@
+endef
+
+# We use internal kbuild rules to avoid the "is up to date" message from make
+kernel/bounds.s: kernel/bounds.c FORCE
+ $(Q)mkdir -p $(dir $@)
+ $(call if_changed_dep,cc_s_c)
+
+$(obj)/$(bounds-file): kernel/bounds.s Kbuild
+ $(Q)mkdir -p $(dir $@)
+ $(call cmd,bounds)
+
+#####
+# 2) Generate asm-offsets.h
#
offsets-file := include/asm-$(SRCARCH)/asm-offsets.h
-always := $(offsets-file)
-targets := $(offsets-file)
+always += $(offsets-file)
+targets += $(offsets-file)
targets += arch/$(SRCARCH)/kernel/asm-offsets.s
-clean-files := $(addprefix $(objtree)/,$(targets))
+
# Default sed regexp - multiline due to syntax constraints
define sed-y
@@ -40,7 +75,8 @@
endef
# We use internal kbuild rules to avoid the "is up to date" message from make
-arch/$(SRCARCH)/kernel/asm-offsets.s: arch/$(SRCARCH)/kernel/asm-offsets.c FORCE
+arch/$(SRCARCH)/kernel/asm-offsets.s: arch/$(SRCARCH)/kernel/asm-offsets.c \
+ $(obj)/$(bounds-file) FORCE
$(Q)mkdir -p $(dir $@)
$(call if_changed_dep,cc_s_c)
@@ -49,7 +85,7 @@
$(call cmd,offsets)
#####
-# 2) Check for missing system calls
+# 3) Check for missing system calls
#
quiet_cmd_syscalls = CALL $<
@@ -58,3 +94,7 @@
PHONY += missing-syscalls
missing-syscalls: scripts/checksyscalls.sh FORCE
$(call cmd,syscalls)
+
+# Delete all targets during make clean
+clean-files := $(addprefix $(objtree)/,$(targets))
+
diff --git a/kernel/bounds.c b/kernel/bounds.c
new file mode 100644
index 0000000..85bb281
--- /dev/null
+++ b/kernel/bounds.c
@@ -0,0 +1,19 @@
+/*
+ * Generate definitions needed by the preprocessor.
+ * This code generates raw asm output which is post-processed
+ * to extract and format the required data.
+ */
+
+#define __GENERATING_BOUNDS_H
+/* Include headers that define the enum constants of interest */
+
+#define DEFINE(sym, val) \
+ asm volatile("\n->" #sym " %0 " #val : : "i" (val))
+
+#define BLANK() asm volatile("\n->" : : )
+
+void foo(void)
+{
+ /* The enum constants to put into include/linux/bounds.h */
+ /* End of constants */
+}