From: Vasily Gorbik <gor@linux.ibm.com>

Date: Tue, 7 May 2019 16:28:15 +0200

Subject: latent_entropy: avoid build error when plugin cflags are not set

Git-commit: 7e756f423af808b6571fed3144747db2ef7fa1c5

Patch-mainline: v5.2-rc1

References: git-fixes

Some architectures set up CFLAGS for linux decompressor phase from

scratch and do not include GCC_PLUGINS_CFLAGS. Since "latent_entropy"

variable declaration is generated by the plugin code itself including

linux/random.h in decompressor code then would cause a build

error. E.g. on s390:

In file included from ./include/linux/net.h:22,

                 from ./include/linux/skbuff.h:29,

                 from ./include/linux/if_ether.h:23,

                 from ./arch/s390/include/asm/diag.h:12,

                 from arch/s390/boot/startup.c:8:

./include/linux/random.h: In function 'add_latent_entropy':

./include/linux/random.h:26:39: error: 'latent_entropy' undeclared

(first use in this function); did you mean 'add_latent_entropy'?

   26 |  add_device_randomness((const void *)&latent_entropy,

      |                                       ^~~~~~~~~~~~~~

      |                                       add_latent_entropy

./include/linux/random.h:26:39: note: each undeclared identifier is

reported only once for each function it appears in

The build error is triggered by commit a80313ff91ab ("s390/kernel:

introduce .dma sections") which made it into 5.2 merge window.

To address that avoid using CONFIG_GCC_PLUGIN_LATENT_ENTROPY in

favour of LATENT_ENTROPY_PLUGIN definition which is defined as a

part of gcc plugins cflags and hence reflect more accurately when gcc

plugin is active. Besides that it is also used for similar purpose in

linux/compiler-gcc.h for latent_entropy attribute definition.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

Acked-by: Kees Cook <keescook@chromium.org>

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

Acked-by: Lee Duncan <lduncan@suse.com>

---

 include/linux/random.h | 2 +-

 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/random.h b/include/linux/random.h

index 445a0ea4ff49..d4eb9b3789ad 100644

--- a/include/linux/random.h

+++ b/include/linux/random.h

@@ -20,7 +20,7 @@ struct random_ready_callback {

 extern void add_device_randomness(const void *, unsigned int);

-#if defined(CONFIG_GCC_PLUGIN_LATENT_ENTROPY) && !defined(__CHECKER__)

+#if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__)

 static inline void add_latent_entropy(void)

 {

 	add_device_randomness((const void *)&latent_entropy,