[PATCH 2/3] powerpc: Fix undefined static key

[Joel Stanley]

When CONFIG_PPC_BARRIER_NOSPEC=n, security.c is not built leading to a
missing definition of uaccess_flush_key.

  LD      vmlinux.o
  MODPOST vmlinux.symvers
  MODINFO modules.builtin.modinfo
  GEN     modules.builtin
  LD      .tmp_vmlinux.kallsyms1
powerpc64le-linux-gnu-ld: arch/powerpc/kernel/align.o:(.toc+0x0): undefined reference to `uaccess_flush_key'
powerpc64le-linux-gnu-ld: arch/powerpc/kernel/signal_64.o:(.toc+0x0): undefined reference to `uaccess_flush_key'
powerpc64le-linux-gnu-ld: arch/powerpc/kernel/process.o:(.toc+0x0): undefined reference to `uaccess_flush_key'
powerpc64le-linux-gnu-ld: arch/powerpc/kernel/traps.o:(.toc+0x0): undefined reference to `uaccess_flush_key'
powerpc64le-linux-gnu-ld: arch/powerpc/kernel/hw_breakpoint_constraints.o:(.toc+0x0): undefined reference to `uaccess_flush_key'
powerpc64le-linux-gnu-ld: arch/powerpc/kernel/ptrace/ptrace.o:(.toc+0x0): more undefined references to `uaccess_flush_key' follow
make[1]: *** [Makefile:1176: vmlinux] Error 1

Hack one in to fix the build.

Signed-off-by: Joel Stanley <joel at jms.id.au>
---
 arch/powerpc/include/asm/security_features.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/powerpc/include/asm/security_features.h b/arch/powerpc/include/asm/security_features.h
index 792eefaf230b..46ade7927a4c 100644
--- a/arch/powerpc/include/asm/security_features.h
+++ b/arch/powerpc/include/asm/security_features.h
@@ -39,6 +39,9 @@ static inline bool security_ftr_enabled(u64 feature)
 	return !!(powerpc_security_features & feature);
 }
 
+#ifndef CONFIG_PPC_BARRIER_NOSPEC
+DEFINE_STATIC_KEY_FALSE(uaccess_flush_key);
+#endif
 
 // Features indicating support for Spectre/Meltdown mitigations
 
-- 
2.32.0