The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 012e8d2034f1bda8863435cd589636e618d6a659 Mon Sep 17 00:00:00 2001 From: Andrew Donnellan ajd@linux.ibm.com Date: Tue, 16 Aug 2022 15:17:20 +1000 Subject: [PATCH] gcc-plugins: Undefine LATENT_ENTROPY_PLUGIN when plugin disabled for a file

Commit 36d4b36b6959 ("lib/nodemask: inline next_node_in() and node_random()") refactored some code by moving node_random() from lib/nodemask.c to include/linux/nodemask.h, thus requiring nodemask.h to include random.h, which conditionally defines add_latent_entropy() depending on whether the macro LATENT_ENTROPY_PLUGIN is defined.

This broke the build on powerpc, where nodemask.h is indirectly included in arch/powerpc/kernel/prom_init.c, part of the early boot machinery that is excluded from the latent entropy plugin using DISABLE_LATENT_ENTROPY_PLUGIN. It turns out that while we add a gcc flag to disable the actual plugin, we don't undefine LATENT_ENTROPY_PLUGIN.

This leads to the following:

CC arch/powerpc/kernel/prom_init.o In file included from ./include/linux/nodemask.h:97, from ./include/linux/mmzone.h:17, from ./include/linux/gfp.h:7, from ./include/linux/xarray.h:15, from ./include/linux/radix-tree.h:21, from ./include/linux/idr.h:15, from ./include/linux/kernfs.h:12, from ./include/linux/sysfs.h:16, from ./include/linux/kobject.h:20, from ./include/linux/pci.h:35, from arch/powerpc/kernel/prom_init.c:24: ./include/linux/random.h: In function 'add_latent_entropy': ./include/linux/random.h:25:46: error: 'latent_entropy' undeclared (first use in this function); did you mean 'add_latent_entropy'? 25 | add_device_randomness((const void *)&latent_entropy, sizeof(latent_entropy)); | ^~~~~~~~~~~~~~ | add_latent_entropy ./include/linux/random.h:25:46: note: each undeclared identifier is reported only once for each function it appears in make[2]: *** [scripts/Makefile.build:249: arch/powerpc/kernel/prom_init.o] Fehler 1 make[1]: *** [scripts/Makefile.build:465: arch/powerpc/kernel] Fehler 2 make: *** [Makefile:1855: arch/powerpc] Error 2

Change the DISABLE_LATENT_ENTROPY_PLUGIN flags to undefine LATENT_ENTROPY_PLUGIN for files where the plugin is disabled.

Cc: Yury Norov yury.norov@gmail.com Fixes: 38addce8b600 ("gcc-plugins: Add latent_entropy plugin") Link: https://bugzilla.kernel.org/show_bug.cgi?id=216367 Link: https://lore.kernel.org/linuxppc-dev/alpine.DEB.2.22.394.2208152006320.28932... Reported-by: Erhard Furtner erhard_f@mailbox.org Signed-off-by: Andrew Donnellan ajd@linux.ibm.com Reviewed-by: Yury Norov yury.norov@gmail.com Signed-off-by: Kees Cook keescook@chromium.org Link: https://lore.kernel.org/r/20220816051720.44108-1-ajd@linux.ibm.com

diff --git a/scripts/Makefile.gcc-plugins b/scripts/Makefile.gcc-plugins index 692d64a70542..e4deaf5fa571 100644 --- a/scripts/Makefile.gcc-plugins +++ b/scripts/Makefile.gcc-plugins @@ -4,7 +4,7 @@ gcc-plugin-$(CONFIG_GCC_PLUGIN_LATENT_ENTROPY) += latent_entropy_plugin.so gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_LATENT_ENTROPY) \ += -DLATENT_ENTROPY_PLUGIN ifdef CONFIG_GCC_PLUGIN_LATENT_ENTROPY - DISABLE_LATENT_ENTROPY_PLUGIN += -fplugin-arg-latent_entropy_plugin-disable + DISABLE_LATENT_ENTROPY_PLUGIN += -fplugin-arg-latent_entropy_plugin-disable -ULATENT_ENTROPY_PLUGIN endif export DISABLE_LATENT_ENTROPY_PLUGIN