This is a note to let you know that I've just added the patch titled latent_entropy: avoid build error when plugin cflags are not set to the 4.19-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: latent_entropy-avoid-build-error-when-plugin-cflags-are-not-set.patch and it can be found in the queue-4.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Fri Jun 17 08:58:56 AM CEST 2022 From: Vasily Gorbik <gor@xxxxxxxxxxxxx> Date: Tue, 7 May 2019 16:28:15 +0200 Subject: latent_entropy: avoid build error when plugin cflags are not set From: Vasily Gorbik <gor@xxxxxxxxxxxxx> 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@xxxxxxxxxxxxx> Acked-by: Kees Cook <keescook@xxxxxxxxxxxx> Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx> Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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, Patches currently in stable-queue which might be from gor@xxxxxxxxxxxxx are queue-4.19/latent_entropy-avoid-build-error-when-plugin-cflags-are-not-set.patch queue-4.19/s390-define-get_cycles-macro-for-arch-override.patch