locking/refcount: Consolidate implementations of refcount_t

[ Upstream commit fb041bb7c0a918b95c6889fc965cdc4a75b4c0ca ]

The generic implementation of refcount_t should be good enough for
everybody, so remove ARCH_HAS_REFCOUNT and REFCOUNT_FULL entirely,
leaving the generic implementation enabled unconditionally.

Signed-off-by: Will Deacon <[email protected]>
Reviewed-by: Ard Biesheuvel <[email protected]>
Acked-by: Kees Cook <[email protected]>
Tested-by: Hanjun Guo <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Elena Reshetova <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
This commit is contained in:
Will Deacon 2019-11-21 11:59:00 +00:00 • committed by Greg Kroah-Hartman
commit d0d583484d
11 changed files with 59 additions and 308 deletions

View file

@ -915,27 +915,6 @@ config STRICT_MODULE_RWX
config ARCH_HAS_PHYS_TO_DMA
bool
config ARCH_HAS_REFCOUNT
bool
help
An architecture selects this when it has implemented refcount_t
using open coded assembly primitives that provide an optimized
refcount_t implementation, possibly at the expense of some full
refcount state checks of CONFIG_REFCOUNT_FULL=y.
The refcount overflow check behavior, however, must be retained.
Catching overflows is the primary security concern for protecting
against bugs in reference counts.
config REFCOUNT_FULL
bool "Perform full reference count validation at the expense of speed"
help
Enabling this switches the refcounting infrastructure from a fast
unchecked atomic_t implementation to a fully state checked
implementation, which can be (slightly) slower but provides protections
against various use-after-free conditions that can be used in
security flaw exploits.
config HAVE_ARCH_COMPILER_H
bool
help