kselftest/arm64: mte: ksm_options: Fix fscanf warning

Out of the box Ubuntu's 20.04 compiler warns about missing return value
checks for fscanf() calls.

Make GCC happy by checking whether we actually parsed one integer.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Mark Brown <broone@kernel.org>
Link: https://lore.kernel.org/r/20210319165334.29213-4-andre.przywara@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

kselftest/arm64: Fix check_ksm_options test

The check_ksm_options test reports the error below because the test
plan is not declared correctly:

# Planned tests != run tests (0 != 4)

Fix the test adding the correct test plan declaration.

Fixes: f981d8fa2646 ("kselftest/arm64: Verify KSM page merge for MTE pages")
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Gabor Kertesz <gabor.kertesz@arm.com>
Cc: Amit Daniel Kachhap <amit.kachhap@arm.com>
Link: https://lore.kernel.org/r/20201026121248.2340-6-vincenzo.frascino@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

kselftest/arm64: Verify KSM page merge for MTE pages

Add a testcase to check that KSM should not merge pages containing
same data with same/different MTE tag values.

This testcase has one positive tests and passes if page merging
happens according to the above rule. It also saves and restores
any modified ksm sysfs entries.

Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Tested-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20201002115630.24683-6-amit.kachhap@arm.com
Signed-off-by: Will Deacon <will@kernel.org>