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Message-Id: <20240924-regcache-zero-value-v1-1-8a1224214b52@kernel.org>
Date: Tue, 24 Sep 2024 12:08:53 +0200
From: Mark Brown <broonie@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: Mark Brown <broonie@...nel.org>
Subject: [PATCH] regmap: Specifically test writing 0 as a value to sparse
caches
Since 0 can look a lot like a NULL pointer when used in a cache some clever
data structures might potentially introduce bugs specific to handling it.
Add some explicit testing of storing 0 as a value in a sparse cache, at the
minute there are no issues and this will stop any appearing in the future.
Signed-off-by: Mark Brown <broonie@...nel.org>
---
drivers/base/regmap/regmap-kunit.c | 43 ++++++++++++++++++++++++++++++++++++++
1 file changed, 43 insertions(+)
diff --git a/drivers/base/regmap/regmap-kunit.c b/drivers/base/regmap/regmap-kunit.c
index d790c7df5cac..64df047d9d53 100644
--- a/drivers/base/regmap/regmap-kunit.c
+++ b/drivers/base/regmap/regmap-kunit.c
@@ -1486,6 +1486,48 @@ static void cache_present(struct kunit *test)
KUNIT_ASSERT_TRUE(test, regcache_reg_cached(map, param->from_reg + i));
}
+static void cache_write_zero(struct kunit *test)
+{
+ const struct regmap_test_param *param = test->param_value;
+ struct regmap *map;
+ struct regmap_config config;
+ struct regmap_ram_data *data;
+ unsigned int val;
+ int i;
+
+ config = test_regmap_config;
+
+ map = gen_regmap(test, &config, &data);
+ KUNIT_ASSERT_FALSE(test, IS_ERR(map));
+ if (IS_ERR(map))
+ return;
+
+ for (i = 0; i < BLOCK_TEST_SIZE; i++)
+ data->read[param->from_reg + i] = false;
+
+ /* No defaults so no registers cached. */
+ for (i = 0; i < BLOCK_TEST_SIZE; i++)
+ KUNIT_ASSERT_FALSE(test, regcache_reg_cached(map, param->from_reg + i));
+
+ /* We didn't trigger any reads */
+ for (i = 0; i < BLOCK_TEST_SIZE; i++)
+ KUNIT_ASSERT_FALSE(test, data->read[param->from_reg + i]);
+
+ /* Write a zero value */
+ KUNIT_EXPECT_EQ(test, 0, regmap_write(map, 1, 0));
+
+ /* Read that zero value back */
+ KUNIT_EXPECT_EQ(test, 0, regmap_read(map, 1, &val));
+ KUNIT_EXPECT_EQ(test, 0, val);
+
+ /* From the cache? */
+ KUNIT_ASSERT_TRUE(test, regcache_reg_cached(map, 1));
+
+ /* Try to throw it away */
+ KUNIT_EXPECT_EQ(test, 0, regcache_drop_region(map, 1, 1));
+ KUNIT_ASSERT_FALSE(test, regcache_reg_cached(map, 1));
+}
+
/* Check that caching the window register works with sync */
static void cache_range_window_reg(struct kunit *test)
{
@@ -1999,6 +2041,7 @@ static struct kunit_case regmap_test_cases[] = {
KUNIT_CASE_PARAM(cache_drop_all_and_sync_no_defaults, sparse_cache_types_gen_params),
KUNIT_CASE_PARAM(cache_drop_all_and_sync_has_defaults, sparse_cache_types_gen_params),
KUNIT_CASE_PARAM(cache_present, sparse_cache_types_gen_params),
+ KUNIT_CASE_PARAM(cache_write_zero, sparse_cache_types_gen_params),
KUNIT_CASE_PARAM(cache_range_window_reg, real_cache_types_only_gen_params),
KUNIT_CASE_PARAM(raw_read_defaults_single, raw_test_types_gen_params),
---
base-commit: 98f7e32f20d28ec452afb208f9cffc08448a2652
change-id: 20240923-regcache-zero-value-d95494d1f70e
Best regards,
--
Mark Brown <broonie@...nel.org>
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