linux-kernel - Re: [PATCH 2/3] MODSIGN: Avoid using .incbin in C source

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Date:	Wed, 05 Dec 2012 10:28:48 +1030
From:	Rusty Russell <rusty@...abs.org>
To:	David Howells <dhowells@...hat.com>, Michal Marek <mmarek@...e.cz>
Cc:	dhowells@...hat.com, linux-kernel@...r.kernel.org,
	Takashi Iwai <tiwai@...e.de>,
	James Hogan <james.hogan@...tec.com>
Subject: Re: [PATCH 2/3] MODSIGN: Avoid using .incbin in C source

David Howells <dhowells@...hat.com> writes:

> Michal Marek <mmarek@...e.cz> wrote:
>
>> Using the asm .incbin statement in C sources breaks any gcc wrapper which
>> assumes that preprocessed C source is self-contained. Use a separate .S
>> file to include the siging key and certificate.
>
> I was trying to avoid that as .S files generally don't crop up in generic
> code and the format of the assembly varies with the arch.  However, you don't
> seem to have anything that should cause a problem - so:
>
> Acked-by: David Howells <dhowells@...hat.com>

GLOBAL() is defined in x86 only, AFAICT.

Plus, we now have a patch from James (CC:d) to prepend
CONFIG_SYMBOL_PREFIX to these as requird.

I think this will have to be done more carefully...

Thanks,
Rusty.

From: Takashi Iwai <tiwai@...e.de>

Using the asm .incbin statement in C sources breaks any gcc wrapper which
assumes that preprocessed C source is self-contained. Use a separate .S
file to include the siging key and certificate.

Tested-by: Michal Marek <mmarek@...e.cz>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
---
 kernel/Makefile              |    4 ++--
 kernel/modsign_certificate.S |    9 +++++++++
 kernel/modsign_pubkey.c      |    6 ------
 3 files changed, 11 insertions(+), 8 deletions(-)
 create mode 100644 kernel/modsign_certificate.S

diff --git a/kernel/Makefile b/kernel/Makefile
index 86e3285..0bd9d43 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -54,7 +54,7 @@ obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o
 obj-$(CONFIG_PROVE_LOCKING) += spinlock.o
 obj-$(CONFIG_UID16) += uid16.o
 obj-$(CONFIG_MODULES) += module.o
-obj-$(CONFIG_MODULE_SIG) += module_signing.o modsign_pubkey.o
+obj-$(CONFIG_MODULE_SIG) += module_signing.o modsign_pubkey.o modsign_certificate.o
 obj-$(CONFIG_KALLSYMS) += kallsyms.o
 obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o
 obj-$(CONFIG_KEXEC) += kexec.o
@@ -139,7 +139,7 @@ ifeq ($(CONFIG_MODULE_SIG),y)
 extra_certificates:
 	touch $@
 
-kernel/modsign_pubkey.o: signing_key.x509 extra_certificates
+kernel/modsign_certificate.o: signing_key.x509 extra_certificates
 
 ###############################################################################
 #
diff --git a/kernel/modsign_certificate.S b/kernel/modsign_certificate.S
new file mode 100644
index 0000000..6bde029
--- /dev/null
+++ b/kernel/modsign_certificate.S
@@ -0,0 +1,9 @@
+#include <linux/linkage.h>
+
+	.section ".init.data","aw"
+
+GLOBAL(modsign_certificate_list)
+	.incbin "signing_key.x509"
+	.incbin "extra_certificates"
+END(modsign_certificate_list)
+GLOBAL(modsign_certificate_list_end)
diff --git a/kernel/modsign_pubkey.c b/kernel/modsign_pubkey.c
index 4646eb2..045504f 100644
--- a/kernel/modsign_pubkey.c
+++ b/kernel/modsign_pubkey.c
@@ -20,12 +20,6 @@ struct key *modsign_keyring;
 
 extern __initdata const u8 modsign_certificate_list[];
 extern __initdata const u8 modsign_certificate_list_end[];
-asm(".section .init.data,\"aw\"\n"
-    "modsign_certificate_list:\n"
-    ".incbin \"signing_key.x509\"\n"
-    ".incbin \"extra_certificates\"\n"
-    "modsign_certificate_list_end:"
-    );
 
 /*
  * We need to make sure ccache doesn't cache the .o file as it doesn't notice
-- 
1.7.10.4

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