From: Vasily Gorbik gor@linux.ibm.com
commit 7e756f423af808b6571fed3144747db2ef7fa1c5 upstream.
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 Signed-off-by: Jason A. Donenfeld Jason@zx2c4.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/linux/random.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- 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,