[PATCH for v5.15+] powerpc: Export mmu_feature_keys[] as non-GPL

[PATCH for v5.15+] powerpc: Export mmu_feature_keys[] as non-GPL

[Dimitri John Ledkov]

From: Kevin Hao <haokexin@gmail.com>

commit d9e5c3e9e75162f845880535957b7fd0b4637d23 upstream.

When the mmu_feature_keys[] was introduced in the commit c12e6f24d413
("powerpc: Add option to use jump label for mmu_has_feature()"),
it is unlikely that it would be used either directly or indirectly in
the out of tree modules. So we exported it as GPL only.

But with the evolution of the codes, especially the PPC_KUAP support, it
may be indirectly referenced by some primitive macro or inline functions
such as get_user() or __copy_from_user_inatomic(), this will make it
impossible to build many non GPL modules (such as ZFS) on ppc
architecture. Fix this by exposing the mmu_feature_keys[] to the non-GPL
modules too.

Fixes: 7613f5a66bec ("powerpc/64s/kuap: Use mmu_has_feature()")
Reported-by: Nathaniel Filardo <nwfilardo@gmail.com>
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220329085709.4132729-1-haokexin@gmail.com

Signed-off-by: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
---

 Please apply this patch to v5.15+ as it unbreaks zfs-dkms usage on
 powerpc platforms.

 Overall, this patch applies to v5.12+ kernels.

 arch/powerpc/kernel/cputable.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c
index ae0fdef0ac11..3a8cd40b6368 100644
--- a/arch/powerpc/kernel/cputable.c
+++ b/arch/powerpc/kernel/cputable.c
@@ -2119,7 +2119,7 @@ void __init cpu_feature_keys_init(void)
 struct static_key_true mmu_feature_keys[NUM_MMU_FTR_KEYS] = {
 			[0 ... NUM_MMU_FTR_KEYS - 1] = STATIC_KEY_TRUE_INIT
 };
-EXPORT_SYMBOL_GPL(mmu_feature_keys);
+EXPORT_SYMBOL(mmu_feature_keys);
 
 void __init mmu_feature_keys_init(void)
 {
-- 
2.32.0

Re: [PATCH for v5.15+] powerpc: Export mmu_feature_keys[] as non-GPL

[Greg KH]

On Wed, Jun 29, 2022 at 10:37:36AM +0100, Dimitri John Ledkov wrote:
> From: Kevin Hao <haokexin@gmail.com>
> 
> commit d9e5c3e9e75162f845880535957b7fd0b4637d23 upstream.
> 
> When the mmu_feature_keys[] was introduced in the commit c12e6f24d413
> ("powerpc: Add option to use jump label for mmu_has_feature()"),
> it is unlikely that it would be used either directly or indirectly in
> the out of tree modules. So we exported it as GPL only.
> 
> But with the evolution of the codes, especially the PPC_KUAP support, it
> may be indirectly referenced by some primitive macro or inline functions
> such as get_user() or __copy_from_user_inatomic(), this will make it
> impossible to build many non GPL modules (such as ZFS) on ppc
> architecture. Fix this by exposing the mmu_feature_keys[] to the non-GPL
> modules too.
> 
> Fixes: 7613f5a66bec ("powerpc/64s/kuap: Use mmu_has_feature()")
> Reported-by: Nathaniel Filardo <nwfilardo@gmail.com>
> Signed-off-by: Kevin Hao <haokexin@gmail.com>
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
> Link: https://lore.kernel.org/r/20220329085709.4132729-1-haokexin@gmail.com
> 
> Signed-off-by: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
> ---
> 
>  Please apply this patch to v5.15+ as it unbreaks zfs-dkms usage on
>  powerpc platforms.

Sorry, but for obvious reasons, I am not allowed to do anything related
to zfs code.  Please feel free to keep this in your distro kernel if you
need it there.

greg k-h