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latent_entropy: avoid build error when plugin cflags are not set 

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 a80313ff91 ("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>
This commit is contained in:
Vasily Gorbik 2019-05-07 16:28:15 +02:00 committed by Martin Schwidefsky
parent 8db16d1911
commit 7e756f423a
1 changed files with 1 additions and 1 deletions
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2
include/linux/random.h
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@ -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,