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

1 files changed, 19 insertions, 7 deletions

diff --git a/scripts/atomic/gen-atomic-fallback.sh b/scripts/atomic/gen-atomic-fallback.sh
index 86aca4f9f315..2b470d31e353 100755
--- a/scripts/atomic/gen-atomic-fallback.sh
+++ b/scripts/atomic/gen-atomic-fallback.sh
@@ -60,13 +60,23 @@ gen_proto_order_variant()
 	local name="$1"; shift
 	local sfx="$1"; shift
 	local order="$1"; shift
-	local atomic="$1"
+	local atomic="$1"; shift
+	local int="$1"; shift
 
 	local atomicname="${atomic}_${pfx}${name}${sfx}${order}"
 	local basename="${atomic}_${pfx}${name}${sfx}"
 
 	local template="$(find_fallback_template "${pfx}" "${name}" "${sfx}" "${order}")"
 
+	local ret="$(gen_ret_type "${meta}" "${int}")"
+	local retstmt="$(gen_ret_stmt "${meta}")"
+	local params="$(gen_params "${int}" "${atomic}" "$@")"
+	local args="$(gen_args "$@")"
+
+	printf "static __always_inline ${ret}\n"
+	printf "raw_${atomicname}(${params})\n"
+	printf "{\n"
+
 	# Where there is no possible fallback, this order variant is mandatory
 	# and must be provided by arch code. Add a comment to the header to
 	# make this obvious.
@@ -75,33 +85,35 @@ gen_proto_order_variant()
 	# define this order variant as a C function without a preprocessor
 	# symbol.
 	if [ -z ${template} ] && [ -z "${order}" ] && ! meta_has_relaxed "${meta}"; then
-		printf "#define raw_${atomicname} arch_${atomicname}\n\n"
+		printf "\t${retstmt}arch_${atomicname}(${args});\n"
+		printf "}\n\n"
 		return
 	fi
 
 	printf "#if defined(arch_${atomicname})\n"
-	printf "#define raw_${atomicname} arch_${atomicname}\n"
+	printf "\t${retstmt}arch_${atomicname}(${args});\n"
 
 	# Allow FULL/ACQUIRE/RELEASE ops to be defined in terms of RELAXED ops
 	if [ "${order}" != "_relaxed" ] && meta_has_relaxed "${meta}"; then
 		printf "#elif defined(arch_${basename}_relaxed)\n"
-		gen_order_fallback "${meta}" "${pfx}" "${name}" "${sfx}" "${order}" "$@"
+		gen_order_fallback "${meta}" "${pfx}" "${name}" "${sfx}" "${order}" "${atomic}" "${int}" "$@"
 	fi
 
 	# Allow ACQUIRE/RELEASE/RELAXED ops to be defined in terms of FULL ops
 	if [ ! -z "${order}" ]; then
 		printf "#elif defined(arch_${basename})\n"
-		printf "#define raw_${atomicname} arch_${basename}\n"
+		printf "\t${retstmt}arch_${basename}(${args});\n"
 	fi
 
 	printf "#else\n"
 	if [ ! -z "${template}" ]; then
-		gen_proto_fallback "${meta}" "${pfx}" "${name}" "${sfx}" "${order}" "$@"
+		gen_proto_fallback "${meta}" "${pfx}" "${name}" "${sfx}" "${order}" "${atomic}" "${int}" "$@"
 	else
 		printf "#error \"Unable to define raw_${atomicname}\"\n"
 	fi
 
-	printf "#endif\n\n"
+	printf "#endif\n"
+	printf "}\n\n"
 }