[PATCH] gcc-plugins: Undefine LATENT_ENTROPY_PLUGIN when plugin disabled for a file
Yury Norov
yury.norov at gmail.com
Tue Aug 16 22:14:34 AEST 2022
On Tue, Aug 16, 2022 at 03:17:20PM +1000, Andrew Donnellan wrote:
> 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,
As a side note, xarray can go with gfp_types.h instead of gfp.h
> 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 at gmail.com>
> Cc: Emese Revfy <re.emese at gmail.com>
> Fixes: 36d4b36b6959 ("lib/nodemask: inline next_node_in() and node_random()")
I think it rather fixes 38addce8b600ca33 ("gcc-plugins: Add
latent_entropy plugin").
For the rest,
Reviewed-by: Yury Norov <yury.norov at gmail.com>
> 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 at mailbox.org>
> Signed-off-by: Andrew Donnellan <ajd at linux.ibm.com>
> ---
> scripts/Makefile.gcc-plugins | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> 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
>
> --
> 2.30.2
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