arm64: Use correct ll/sc atomic constraints
The A64 ISA accepts distinct (but overlapping) ranges of immediates for:
* add arithmetic instructions ('I' machine constraint)
* sub arithmetic instructions ('J' machine constraint)
* 32-bit logical instructions ('K' machine constraint)
* 64-bit logical instructions ('L' machine constraint)
... but we currently use the 'I' constraint for many atomic operations
using sub or logical instructions, which is not always valid.
When CONFIG_ARM64_LSE_ATOMICS is not set, this allows invalid immediates
to be passed to instructions, potentially resulting in a build failure.
When CONFIG_ARM64_LSE_ATOMICS is selected the out-of-line ll/sc atomics
always use a register as they have no visibility of the value passed by
the caller.
This patch adds a constraint parameter to the ATOMIC_xx and
__CMPXCHG_CASE macros so that we can pass appropriate constraints for
each case, with uses updated accordingly.
Unfortunately prior to GCC 8.1.0 the 'K' constraint erroneously accepted
'
4294967295', so we must instead force the use of a register.
Signed-off-by: Andrew Murray <andrew.murray@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>