linux-kernel - [PATCH] tracing/user_events: fix long size check in the ABI selftest

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Message-ID: <20230911160935.10720-1-aleksander.lobakin@intel.com>
Date:   Mon, 11 Sep 2023 18:09:35 +0200
From:   Alexander Lobakin <aleksander.lobakin@...el.com>
To:     Shuah Khan <shuah@...nel.org>,
        "Steven Rostedt (Google)" <rostedt@...dmis.org>
Cc:     Alexander Lobakin <aleksander.lobakin@...el.com>,
        Beau Belgrave <beaub@...ux.microsoft.com>,
        Ira Weiny <ira.weiny@...el.com>,
        linux-kselftest@...r.kernel.org, stable@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] tracing/user_events: fix long size check in the ABI selftest

The current check for 64-bit architecture is double-bugged.
First of all, %BITS_PER_LONG is not available in the userspace,
the underscored version from <asm/bitsperlong.h> must be used.
The following check:

 #if BITS_PER_LONG == 0
 #error
 #endif

triggers the error in this source file -- the macro is undefined and
thus is implicitly evaluated to 0.
Next, %BITS_PER_LONG means "bits", not "bytes". In the Linux kernel,
it can be 32 or 64, never 8. Given that the tests guarded by that check
are meant to be run on a 64-bit system, the correct value would be 64.

Prefix the macro name and fix the value it's compared to.

Fixes: 60b1af8de8c1 ("tracing/user_events: Add ABI self-test")
Cc: stable@...r.kernel.org # 6.4+
Reviewed-by: Ira Weiny <ira.weiny@...el.com>
Signed-off-by: Alexander Lobakin <aleksander.lobakin@...el.com>
---
 tools/testing/selftests/user_events/abi_test.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/user_events/abi_test.c b/tools/testing/selftests/user_events/abi_test.c
index 5125c42efe65..4b30461fc741 100644
--- a/tools/testing/selftests/user_events/abi_test.c
+++ b/tools/testing/selftests/user_events/abi_test.c
@@ -129,7 +129,7 @@ TEST_F(user, bit_sizes) {
 	ASSERT_EQ(0, reg_disable(&self->check, 0));
 	ASSERT_EQ(0, reg_disable(&self->check, 31));
 
-#if BITS_PER_LONG == 8
+#if __BITS_PER_LONG == 64
 	/* Allow 0-64 bits for 64-bit */
 	ASSERT_EQ(0, reg_enable(&self->check, sizeof(long), 63));
 	ASSERT_NE(0, reg_enable(&self->check, sizeof(long), 64));
-- 
2.41.0