[PATCH] powerpc/signal: Fix possible build failure with unsafe_copy_fpr_{to/from}_user

[PATCH] powerpc/signal: Fix possible build failure with unsafe_copy_fpr_{to/from}_user

[Christophe Leroy]

When neither CONFIG_VSX nor CONFIG_PPC_FPU_REGS are selected,
unsafe_copy_fpr_to_user() and unsafe_copy_fpr_from_user() are
doing nothing.

Then, unless the 'label' operand is used elsewhere, GCC complains
about it being defined but not used.

To fix that, add an impossible 'goto label'.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/kernel/signal.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/signal.h b/arch/powerpc/kernel/signal.h
index f4aafa337c2e..1f07317964e4 100644
--- a/arch/powerpc/kernel/signal.h
+++ b/arch/powerpc/kernel/signal.h
@@ -166,9 +166,9 @@ copy_ckfpr_from_user(struct task_struct *task, void __user *from)
 }
 #endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
 #else
-#define unsafe_copy_fpr_to_user(to, task, label) do { } while (0)
+#define unsafe_copy_fpr_to_user(to, task, label) do { if (0) goto label;} while (0)
 
-#define unsafe_copy_fpr_from_user(task, from, label) do { } while (0)
+#define unsafe_copy_fpr_from_user(task, from, label) do { if (0) goto label;} while (0)
 
 static inline unsigned long
 copy_fpr_to_user(void __user *to, struct task_struct *task)
-- 
2.25.0

Re: [PATCH] powerpc/signal: Fix possible build failure with unsafe_copy_fpr_{to/from}_user

[Michael Ellerman]

On Sat, 8 May 2021 09:25:44 +0000 (UTC), Christophe Leroy wrote:
> When neither CONFIG_VSX nor CONFIG_PPC_FPU_REGS are selected,
> unsafe_copy_fpr_to_user() and unsafe_copy_fpr_from_user() are
> doing nothing.
> 
> Then, unless the 'label' operand is used elsewhere, GCC complains
> about it being defined but not used.
> 
> [...]

Applied to powerpc/fixes.

[1/1] powerpc/signal: Fix possible build failure with unsafe_copy_fpr_{to/from}_user
      https://git.kernel.org/powerpc/c/bc581dbab26edf0b6acc98c76943b4a0c7d672a2

cheers