Re: [PATCH 05/10] kbuild: sort the list of symbols exported by thekernel (__ksymtab)

From: Alan Jenkins
Date: Thu Nov 05 2009 - 09:24:23 EST

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Sam Ravnborg wrote:

On Wed, Nov 04, 2009 at 10:00:50AM +0000, Alan Jenkins wrote:

Rusty Russell wrote:

On Tue, 3 Nov 2009 08:36:17 pm Alan Jenkins wrote:

+/*
+ * We use CPP macros since they are more familiar than assembly macros.
+ * Note that CPP macros eat newlines, so each statement must be terminated
+ * by a semicolon.
+ */
+
+#ifdef CONFIG_HAVE_SYMBOL_PREFIX
+#define __SYM(sym) _##sym
+#else
+#define __SYM(sym) sym
+#endif

Ideally, you would used MODULE_SYMBOL_PREFIX here, but of course it's a
string. I don't think Kconfig can do arbitrary identifiers, so we can't
make CONFIG_SYMBOL_PREFIX empty or _.

Perhaps clarify it to a bool CONFIG_HAVE_MODULE_UNDERSCORE_PREFIX then,
since that's what you're assuming here?

Thanks,
Rusty.

I made the same assumption in patch 4. The arch defines CONFIG_HAVE_SYMBOL_PREFIX, which then causes init/Kconfig to define CONFIG_SYMBOL_PREFIX="_".

Mike suggested that I hack kbuild instead, to do something like

unquote = ...
AFLAGS_.tmp_export-asm.o += -DSYMBOL_PREFIX=$(unquote CONFIG_SYMBOL_PREFIX)

I'm experimenting with the idea, but I haven't managed to get it working

Something like this:
unquote = $(patsubst "%",%,$($1))

AFLAGS_.tmp_export-asm.o += -DSYMBOL_PREFIX=$(call unquote,CONFIG_SYMBOL_PREFIX)

But the readability is low so we could be better off doing it direct:

AFLAGS_.tmp_export-asm.o += -DSYMBOL_PREFIX=$(patsubst "%",",$(CONFIG_SYMBOL_PREFIX))

Sam

Thanks to both of you, I have something that works now.

Unfortunately I had to export the variable AFLAGS_.tmp_export-asm.o, otherwise it had no effect. I assume it's a limitation of the top-level Makefile.

To make SYMBOL_PREFIX available for linker scripts, I also added it to "cpp_flags" in scripts/Makefile.lib. (As far as I can see, cpp_flags is _only_ used for preprocessing linker scripts).

If this is all getting too brittle, I guess I could be less timid and add it to the global KBUILD_CPPFLAGS instead :).

Here's the incremental diff:

diff --git a/Makefile b/Makefile
index d7e4ed9..dfd672b 100644
--- a/Makefile
+++ b/Makefile
@@ -912,6 +912,11 @@ vmlinux.o: $(modpost-init) $(vmlinux-main) FORCE
# when loading modules.
.tmp_exports-asm.S: vmlinux.o

+ifneq ($(CONFIG_SYMBOL_PREFIX),)
+export AFLAGS_.tmp_exports-asm.o += -DSYMBOL_PREFIX=$(patsubst "%",%,$(CONFIG_SYMBOL_PREFIX))
+endif
+
+
# The actual objects are generated when descending, # make sure no implicit rule kicks in
$(sort $(vmlinux-init) $(vmlinux-main)) $(vmlinux-lds): $(vmlinux-dirs) ;
diff --git a/arch/blackfin/Kconfig b/arch/blackfin/Kconfig
index 6c99419..1983662 100644
--- a/arch/blackfin/Kconfig
+++ b/arch/blackfin/Kconfig
@@ -5,6 +5,10 @@

mainmenu "Blackfin Kernel Configuration"

+config SYMBOL_PREFIX
+ string
+ default "_"
+
config MMU
def_bool n

@@ -26,7 +30,6 @@ config BLACKFIN
select HAVE_KERNEL_BZIP2
select HAVE_KERNEL_LZMA
select HAVE_OPROFILE
- select HAVE_SYMBOL_PREFIX
select ARCH_WANT_OPTIONAL_GPIOLIB

config GENERIC_BUG
diff --git a/arch/blackfin/kernel/vmlinux.lds.S b/arch/blackfin/kernel/vmlinux.lds.S
index ffd90fb..1f585e8 100644
--- a/arch/blackfin/kernel/vmlinux.lds.S
+++ b/arch/blackfin/kernel/vmlinux.lds.S
@@ -27,8 +27,6 @@
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/

-#define VMLINUX_SYMBOL(_sym_) _##_sym_
-
#include <asm-generic/vmlinux.lds.h>
#include <asm/mem_map.h>
#include <asm/page.h>
diff --git a/arch/h8300/Kconfig b/arch/h8300/Kconfig
index cc03bbf..53cc669 100644
--- a/arch/h8300/Kconfig
+++ b/arch/h8300/Kconfig
@@ -9,7 +9,10 @@ config H8300
bool
default y
select HAVE_IDE
- select HAVE_SYMBOL_PREFIX
+
+config SYMBOL_PREFIX
+ string
+ default "_"

config MMU
bool
diff --git a/arch/h8300/kernel/vmlinux.lds.S b/arch/h8300/kernel/vmlinux.lds.S
index b9e2490..03d356d 100644
--- a/arch/h8300/kernel/vmlinux.lds.S
+++ b/arch/h8300/kernel/vmlinux.lds.S
@@ -1,4 +1,3 @@
-#define VMLINUX_SYMBOL(_sym_) _##_sym_
#include <asm-generic/vmlinux.lds.h>
#include <asm/page.h>

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 9feb474..4a0e9b2 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -52,10 +52,15 @@
#define LOAD_OFFSET 0
#endif

-#ifndef VMLINUX_SYMBOL
-#define VMLINUX_SYMBOL(_sym_) _sym_
+#ifndef SYMBOL_PREFIX
+#define VMLINUX_SYMBOL(sym) sym
+#else
+#define PASTE2(x,y) x##y
+#define PASTE(x,y) PASTE2(x,y)
+#define VMLINUX_SYMBOL(sym) PASTE(SYMBOL_PREFIX, sym)
#endif

+
/* Align . to a 8 byte boundary equals to maximum function alignment. */
#define ALIGN_FUNCTION() . = ALIGN(8)

diff --git a/include/linux/mod_export.h b/include/linux/mod_export.h
index 3bb14e9..f694ff5 100644
--- a/include/linux/mod_export.h
+++ b/include/linux/mod_export.h
@@ -18,7 +18,11 @@
#endif

/* Some toolchains use a `_' prefix for all user symbols. */
+#ifdef CONFIG_SYMBOL_PREFIX
#define MODULE_SYMBOL_PREFIX CONFIG_SYMBOL_PREFIX
+#else
+#define MODULE_SYMBOL_PREFIX ""
+#endif

#ifndef __GENKSYMS__
@@ -98,14 +102,14 @@ struct kernel_symbol {
* by a semicolon.
*/

-#ifdef CONFIG_HAVE_SYMBOL_PREFIX
-#define __SYM(sym) _##sym
+#ifndef SYMBOL_PREFIX
+#define SYM(sym) sym
#else
-#define __SYM(sym) sym
+#define PASTE2(x,y) x##y
+#define PASTE(x,y) PASTE2(x,y)
+#define SYM(sym) PASTE(SYMBOL_PREFIX, sym)
#endif

-#define SYM(sym) __SYM(sym)
-

#ifdef CONFIG_MODVERSIONS
#define __CRC_SYMBOL(sym, crcsec) \
diff --git a/init/Kconfig b/init/Kconfig
index 7f4ddf6..bb4051c 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1176,17 +1176,6 @@ config MODULE_SRCVERSION_ALL

endif # MODULES

-config HAVE_SYMBOL_PREFIX
- bool
- help
- Some arch toolchains use a `_' prefix for all user symbols.
- This option will be taken into account when loading modules.
-
-config SYMBOL_PREFIX
- string
- default "_" if HAVE_SYMBOL_PREFIX
- default ""
-
config INIT_ALL_POSSIBLE
bool
help
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 7a77787..f9f1f6c 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -127,6 +127,11 @@ _c_flags += $(if $(patsubst n%,, \
$(CFLAGS_GCOV))
endif

+ifdef CONFIG_SYMBOL_PREFIX
+_cpp_flags += -DSYMBOL_PREFIX=$(patsubst "%",%,$(CONFIG_SYMBOL_PREFIX))
+endif
+
+
# If building the kernel in a separate objtree expand all occurrences
# of -Idir to -I$(srctree)/dir except for absolute paths (starting with '/').

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 404b69a..b5a801d 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -19,7 +19,12 @@
#include "../../include/linux/license.h"

/* Some toolchains use a `_' prefix for all user symbols. */
+#ifdef CONFIG_SYMBOL_PREFIX
#define MODULE_SYMBOL_PREFIX CONFIG_SYMBOL_PREFIX
+#else
+#define MODULE_SYMBOL_PREFIX ""
+#endif
+

/* Are we using CONFIG_MODVERSIONS? */
int modversions = 0;

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Next message: Miklos Szeredi: "Re: [PATCH v2 resend] vfs: new O_NODE open flag"
Previous message: Herbert Xu: "Re: [PATCH 1/2] x86, crypto, Generate .byte code for some newinstructions via gas macro"
In reply to: Sam Ravnborg: "Re: [PATCH 05/10] kbuild: sort the list of symbols exported by thekernel (__ksymtab)"
Next in thread: Mike Frysinger: "Re: [PATCH 05/10] kbuild: sort the list of symbols exported by the kernel (__ksymtab)"
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