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author | Mark Rutland <mark.rutland@arm.com> | 2017-02-23 16:03:17 +0000 |
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committer | Will Deacon <will.deacon@arm.com> | 2017-02-24 11:14:12 +0000 |
commit | 638f863dbbc8da16834ee0acc6ac10754f79c486 (patch) | |
tree | 0cedb24f37dbbd00fd95d55d8ac6f1b0e2f85ed9 /security/keys/user_defined.c | |
parent | d81bbe6d882461dec4b71dbe2aa85565fcca4187 (diff) | |
download | linux-638f863dbbc8da16834ee0acc6ac10754f79c486.tar.gz linux-638f863dbbc8da16834ee0acc6ac10754f79c486.tar.bz2 linux-638f863dbbc8da16834ee0acc6ac10754f79c486.zip |
arm64/cpufeature: check correct field width when updating sys_val
When we're updating a register's sys_val, we use arm64_ftr_value() to
find the new field value. We use cpuid_feature_extract_field() to find
the new value, but this implicitly assumes a 4-bit field, so we may
extract more bits than we mean to for fields like CTR_EL0.L1ip.
This affects update_cpu_ftr_reg(), where we may extract erroneous values
for ftr_cur and ftr_new. Depending on the additional bits extracted in
either case, we may erroneously detect that the value is mismatched, and
we'll try to compute a new safe value.
Dependent on these extra bits and feature type, arm64_ftr_safe_value()
may pessimistically select the always-safe value, or may erroneously
choose either the extracted cur or new value as the safe option. The
extra bits will subsequently be masked out in arm64_ftr_set_value(), so
we may choose a higher value, yet write back a lower one.
Fix this by passing the width down explicitly in arm64_ftr_value(), so
we always extract the correct amount.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'security/keys/user_defined.c')
0 files changed, 0 insertions, 0 deletions