linux-kernel - [PATCH v3 02/24] powerpc/secvar: WARN_ON_ONCE() if multiple secvar ops are set

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Message-Id: <20230118061049.1006141-3-ajd@linux.ibm.com>
Date:   Wed, 18 Jan 2023 17:10:27 +1100
From:   Andrew Donnellan <ajd@...ux.ibm.com>
To:     linuxppc-dev@...ts.ozlabs.org, linux-integrity@...r.kernel.org
Cc:     gregkh@...uxfoundation.org, gcwilson@...ux.ibm.com,
        linux-kernel@...r.kernel.org, nayna@...ux.ibm.com,
        ruscur@...sell.cc, zohar@...ux.ibm.com, mpe@...erman.id.au,
        gjoyce@...ux.ibm.com, sudhakar@...ux.ibm.com, bgray@...ux.ibm.com,
        erichte@...ux.ibm.com
Subject: [PATCH v3 02/24] powerpc/secvar: WARN_ON_ONCE() if multiple secvar ops are set

From: Russell Currey <ruscur@...sell.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@...sell.cc>
Signed-off-by: Andrew Donnellan <ajd@...ux.ibm.com>
---
 arch/powerpc/kernel/secvar-ops.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/secvar-ops.c b/arch/powerpc/kernel/secvar-ops.c
index 6a29777d6a2d..aa1b2adc2710 100644
--- a/arch/powerpc/kernel/secvar-ops.c
+++ b/arch/powerpc/kernel/secvar-ops.c
@@ -8,10 +8,12 @@
 
 #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)
 {
+	WARN_ON_ONCE(secvar_ops);
 	secvar_ops = ops;
 }
-- 
2.39.0