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linux/scripts/atomic/atomics.tbl
Mark Rutland 1d78814d41 locking/atomic: scripts: simplify raw_atomic*() definitions
Currently each ordering variant has several potential definitions,
with a mixture of preprocessor and C definitions, including several
copies of its C prototype, e.g.

| #if defined(arch_atomic_fetch_andnot_acquire)
| #define raw_atomic_fetch_andnot_acquire arch_atomic_fetch_andnot_acquire
| #elif defined(arch_atomic_fetch_andnot_relaxed)
| static __always_inline int
| raw_atomic_fetch_andnot_acquire(int i, atomic_t *v)
| {
|       int ret = arch_atomic_fetch_andnot_relaxed(i, v);
|       __atomic_acquire_fence();
|       return ret;
| }
| #elif defined(arch_atomic_fetch_andnot)
| #define raw_atomic_fetch_andnot_acquire arch_atomic_fetch_andnot
| #else
| static __always_inline int
| raw_atomic_fetch_andnot_acquire(int i, atomic_t *v)
| {
|       return raw_atomic_fetch_and_acquire(~i, v);
| }
| #endif

Make this a bit simpler by defining the C prototype once, and writing
the various potential definitions as plain C code guarded by ifdeffery.
For example, the above becomes:

| static __always_inline int
| raw_atomic_fetch_andnot_acquire(int i, atomic_t *v)
| {
| #if defined(arch_atomic_fetch_andnot_acquire)
|         return arch_atomic_fetch_andnot_acquire(i, v);
| #elif defined(arch_atomic_fetch_andnot_relaxed)
|         int ret = arch_atomic_fetch_andnot_relaxed(i, v);
|         __atomic_acquire_fence();
|         return ret;
| #elif defined(arch_atomic_fetch_andnot)
|         return arch_atomic_fetch_andnot(i, v);
| #else
|         return raw_atomic_fetch_and_acquire(~i, v);
| #endif
| }

Which is far easier to read. As we now always have a single copy of the
C prototype wrapping all the potential definitions, we now have an
obvious single location for kerneldoc comments.

At the same time, the fallbacks for raw_atomic*_xhcg() are made to use
'new' rather than 'i' as the name of the new value. This is what the
existing fallback template used, and is more consistent with the
raw_atomic{_try,}cmpxchg() fallbacks.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230605070124.3741859-24-mark.rutland@arm.com
2023-06-05 09:57:22 +02:00

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# name meta args...
#
# Where meta contains a string of variants to generate.
# Upper-case implies _{acquire,release,relaxed} variants.
# Valid meta values are:
# * B/b - bool: returns bool
# * v - void: returns void
# * I/i - int: returns base type
# * R - return: returns base type (has _return variants)
# * F/f - fetch: returns base type (has fetch_ variants)
# * l - load: returns base type (has _acquire order variant)
# * s - store: returns void (has _release order variant)
#
# Where args contains list of type[:name], where type is:
# * cv - const pointer to atomic base type (atomic_t/atomic64_t/atomic_long_t)
# * v - pointer to atomic base type (atomic_t/atomic64_t/atomic_long_t)
# * i - base type (int/s64/long)
# * p - pointer to base type (int/s64/long)
#
read l cv
set s v i
add vRF i v
sub vRF i v
inc vRF v
dec vRF v
and vF i v
andnot vF i v
or vF i v
xor vF i v
xchg I v i:new
cmpxchg I v i:old i:new
try_cmpxchg B v p:old i:new
sub_and_test b i v
dec_and_test b v
inc_and_test b v
add_negative B i v
add_unless fb v i:a i:u
inc_not_zero b v
inc_unless_negative b v
dec_unless_positive b v
dec_if_positive i v