[PATCH v5 05/25] powerpc/secvar: Warn and error if multiple secvar ops are set

Andrew Donnellan
2023-01-31T06:41:59Z

From: Russell Currey <ruscur@russell.cc>

The secvar code only supports one consumer at a time.

Multiple consumers aren't possible at this point in time, but we'd want
it to be obvious if it ever could happen.

Signed-off-by: Russell Currey <ruscur@russell.cc>
Co-developed-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>

---

v4: Return an error and don't actually try to set secvar_operations if the
warning is triggered (npiggin)

v5: Drop "extern" to fix a checkpatch check (snowpatch)
---
arch/powerpc/include/asm/secvar.h | 4 ++--
arch/powerpc/kernel/secvar-ops.c | 8 ++++++--
arch/powerpc/platforms/powernv/opal-secvar.c | 4 +---
3 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/include/asm/secvar.h b/arch/powerpc/include/asm/secvar.h
index 07ba36f868a7..a2b5f2203dc5 100644
--- a/arch/powerpc/include/asm/secvar.h
+++ b/arch/powerpc/include/asm/secvar.h
@@ -21,11 +21,11 @@ struct secvar_operations {

#ifdef CONFIG_PPC_SECURE_BOOT

-extern void set_secvar_ops(const struct secvar_operations *ops);
+int set_secvar_ops(const struct secvar_operations *ops);

#else

-static inline void set_secvar_ops(const struct secvar_operations *ops) { }
+static inline int set_secvar_ops(const struct secvar_operations *ops) { return 0; }

#endif

diff --git a/arch/powerpc/kernel/secvar-ops.c b/arch/powerpc/kernel/secvar-ops.c
index 6a29777d6a2d..9c8dd4e7c270 100644
--- a/arch/powerpc/kernel/secvar-ops.c
+++ b/arch/powerpc/kernel/secvar-ops.c
@@ -8,10 +8,14 @@

#include <linux/cache.h>
#include <asm/secvar.h>
+#include <asm/bug.h>

-const struct secvar_operations *secvar_ops __ro_after_init;
+const struct secvar_operations *secvar_ops __ro_after_init = NULL;

-void set_secvar_ops(const struct secvar_operations *ops)
+int set_secvar_ops(const struct secvar_operations *ops)
{
+ if (WARN_ON_ONCE(secvar_ops))
+ return -1;
secvar_ops = ops;
+ return 0;
}
diff --git a/arch/powerpc/platforms/powernv/opal-secvar.c b/arch/powerpc/platforms/powernv/opal-secvar.c
index ef89861569e0..4c0a3b030fe0 100644
--- a/arch/powerpc/platforms/powernv/opal-secvar.c
+++ b/arch/powerpc/platforms/powernv/opal-secvar.c
@@ -113,9 +113,7 @@ static int opal_secvar_probe(struct platform_device *pdev)
return -ENODEV;
}

- set_secvar_ops(&opal_secvar_ops);
-
- return 0;
+ return set_secvar_ops(&opal_secvar_ops);
}

static const struct of_device_id opal_secvar_match[] = {
--
2.39.1