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authorAndrew Donnellan <ajd@linux.ibm.com>2022-08-16 15:17:20 +1000
committerKees Cook <keescook@chromium.org>2022-08-16 12:25:53 -0700
commit012e8d2034f1bda8863435cd589636e618d6a659 (patch)
treeeb5e72ec085cb8f0907bddf94e881af42a81d2c0
parent6a3981af3fd97fec57f2c5eeca213cbf5216a3c0 (diff)
downloadlinux-012e8d2034f1bda8863435cd589636e618d6a659.tar.bz2
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.2.22.394.2208152006320.289321@ramsan.of.borg/ 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
-rw-r--r--scripts/Makefile.gcc-plugins2
1 files changed, 1 insertions, 1 deletions
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