diff options
| author | Mark Brown | 2022-03-09 13:12:00 +0000 |
|---|---|---|
| committer | Will Deacon | 2022-03-09 18:14:56 +0000 |
| commit | cf220ad6749b8305ba11bdf601c55a17ad2a715d (patch) | |
| tree | 9b59d05da4a20ad31cc38dda19bb8535568436d1 /include | |
| parent | d8fd5a1e78db375f2246d43df7833fec07a221cd (diff) | |
arm64/mte: Remove asymmetric mode from the prctl() interface
As pointed out by Evgenii Stepanov one potential issue with the new ABI for
enabling asymmetric is that if there are multiple places where MTE is
configured in a process, some of which were compiled with the old prctl.h
and some of which were compiled with the new prctl.h, there may be problems
keeping track of which MTE modes are requested. For example some code may
disable only sync and async modes leaving asymmetric mode enabled when it
intended to fully disable MTE.
In order to avoid such mishaps remove asymmetric mode from the prctl(),
instead implicitly allowing it if both sync and async modes are requested.
This should not disrupt userspace since a process requesting both may
already see a mix of sync and async modes due to differing defaults between
CPUs or changes in default while the process is running but it does mean
that userspace is unable to explicitly request asymmetric mode without
changing the system default for CPUs.
Reported-by: Evgenii Stepanov <eugenis@google.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Evgenii Stepanov <eugenis@google.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Branislav Rankov <branislav.rankov@arm.com>
Link: https://lore.kernel.org/r/20220309131200.112637-1-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/uapi/linux/prctl.h | 4 |
1 files changed, 1 insertions, 3 deletions
diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h index 4ae2b21e4066..e998764f0262 100644 --- a/include/uapi/linux/prctl.h +++ b/include/uapi/linux/prctl.h @@ -238,9 +238,7 @@ struct prctl_mm_map { # define PR_MTE_TCF_NONE 0UL # define PR_MTE_TCF_SYNC (1UL << 1) # define PR_MTE_TCF_ASYNC (1UL << 2) -# define PR_MTE_TCF_ASYMM (1UL << 19) -# define PR_MTE_TCF_MASK (PR_MTE_TCF_SYNC | PR_MTE_TCF_ASYNC | \ - PR_MTE_TCF_ASYMM) +# define PR_MTE_TCF_MASK (PR_MTE_TCF_SYNC | PR_MTE_TCF_ASYNC) /* MTE tag inclusion mask */ # define PR_MTE_TAG_SHIFT 3 # define PR_MTE_TAG_MASK (0xffffUL << PR_MTE_TAG_SHIFT) |