linux/scripts/atomic/gen-atomic-fallback.sh
Uros Bizjak e01cc1e8c2 locking/atomic: Add generic support for sync_try_cmpxchg() and its fallback
Provide the generic sync_try_cmpxchg() function from the
raw_ prefixed version, also adding explicit instrumentation.

The patch amends existing scripts to generate sync_try_cmpxchg()
locking primitive and its raw_sync_try_cmpxchg() fallback, while
leaving existing macros from the try_cmpxchg() family unchanged.

The target can define its own arch_sync_try_cmpxchg() to override the
generic version of raw_sync_try_cmpxchg(). This allows the target
to generate more optimal assembly than the generic version.

Additionally, the patch renames two scripts to better reflect
whet they really do.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
2023-10-09 18:14:15 +02:00

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#!/bin/sh
# SPDX-License-Identifier: GPL-2.0
ATOMICDIR=$(dirname $0)
. ${ATOMICDIR}/atomic-tbl.sh
#gen_template_fallback(template, meta, pfx, name, sfx, order, atomic, int, args...)
gen_template_fallback()
{
local template="$1"; shift
local meta="$1"; shift
local pfx="$1"; shift
local name="$1"; shift
local sfx="$1"; shift
local order="$1"; shift
local atomic="$1"; shift
local int="$1"; shift
local ret="$(gen_ret_type "${meta}" "${int}")"
local retstmt="$(gen_ret_stmt "${meta}")"
local params="$(gen_params "${int}" "${atomic}" "$@")"
local args="$(gen_args "$@")"
. ${template}
}
#gen_order_fallback(meta, pfx, name, sfx, order, atomic, int, args...)
gen_order_fallback()
{
local meta="$1"; shift
local pfx="$1"; shift
local name="$1"; shift
local sfx="$1"; shift
local order="$1"; shift
local tmpl_order=${order#_}
local tmpl="${ATOMICDIR}/fallbacks/${tmpl_order:-fence}"
gen_template_fallback "${tmpl}" "${meta}" "${pfx}" "${name}" "${sfx}" "${order}" "$@"
}
#gen_proto_fallback(meta, pfx, name, sfx, order, atomic, int, args...)
gen_proto_fallback()
{
local meta="$1"; shift
local pfx="$1"; shift
local name="$1"; shift
local sfx="$1"; shift
local order="$1"; shift
local tmpl="$(find_fallback_template "${pfx}" "${name}" "${sfx}" "${order}")"
gen_template_fallback "${tmpl}" "${meta}" "${pfx}" "${name}" "${sfx}" "${order}" "$@"
}
#gen_proto_order_variant(meta, pfx, name, sfx, order, atomic, int, args...)
gen_proto_order_variant()
{
local meta="$1"; shift
local pfx="$1"; shift
local name="$1"; shift
local sfx="$1"; shift
local order="$1"; shift
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="$(gen_args "$@")"
gen_kerneldoc "raw_" "${meta}" "${pfx}" "${name}" "${sfx}" "${order}" "${atomic}" "${int}" "$@"
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.
#
# Ideally we'd error on a missing definition, but arch code might
# define this order variant as a C function without a preprocessor
# symbol.
if [ -z ${template} ] && [ -z "${order}" ] && ! meta_has_relaxed "${meta}"; then
printf "\t${retstmt}arch_${atomicname}(${args});\n"
printf "}\n\n"
return
fi
printf "#if defined(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}" "${atomic}" "${int}" "$@"
fi
# Allow ACQUIRE/RELEASE/RELAXED ops to be defined in terms of FULL ops
if [ ! -z "${order}" ] && ! meta_is_implicitly_relaxed "${meta}"; then
printf "#elif defined(arch_${basename})\n"
printf "\t${retstmt}arch_${basename}(${args});\n"
fi
printf "#else\n"
if [ ! -z "${template}" ]; then
gen_proto_fallback "${meta}" "${pfx}" "${name}" "${sfx}" "${order}" "${atomic}" "${int}" "$@"
else
printf "#error \"Unable to define raw_${atomicname}\"\n"
fi
printf "#endif\n"
printf "}\n\n"
}
#gen_proto_order_variants(meta, pfx, name, sfx, atomic, int, args...)
gen_proto_order_variants()
{
local meta="$1"; shift
local pfx="$1"; shift
local name="$1"; shift
local sfx="$1"; shift
local atomic="$1"
gen_proto_order_variant "${meta}" "${pfx}" "${name}" "${sfx}" "" "$@"
if meta_has_acquire "${meta}"; then
gen_proto_order_variant "${meta}" "${pfx}" "${name}" "${sfx}" "_acquire" "$@"
fi
if meta_has_release "${meta}"; then
gen_proto_order_variant "${meta}" "${pfx}" "${name}" "${sfx}" "_release" "$@"
fi
if meta_has_relaxed "${meta}"; then
gen_proto_order_variant "${meta}" "${pfx}" "${name}" "${sfx}" "_relaxed" "$@"
fi
}
#gen_basic_fallbacks(basename)
gen_basic_fallbacks()
{
local basename="$1"; shift
cat << EOF
#define raw_${basename}_acquire arch_${basename}
#define raw_${basename}_release arch_${basename}
#define raw_${basename}_relaxed arch_${basename}
EOF
}
gen_order_fallbacks()
{
local xchg="$1"; shift
cat <<EOF
#define raw_${xchg}_relaxed arch_${xchg}_relaxed
#ifdef arch_${xchg}_acquire
#define raw_${xchg}_acquire arch_${xchg}_acquire
#else
#define raw_${xchg}_acquire(...) \\
__atomic_op_acquire(arch_${xchg}, __VA_ARGS__)
#endif
#ifdef arch_${xchg}_release
#define raw_${xchg}_release arch_${xchg}_release
#else
#define raw_${xchg}_release(...) \\
__atomic_op_release(arch_${xchg}, __VA_ARGS__)
#endif
#ifdef arch_${xchg}
#define raw_${xchg} arch_${xchg}
#else
#define raw_${xchg}(...) \\
__atomic_op_fence(arch_${xchg}, __VA_ARGS__)
#endif
EOF
}
gen_xchg_order_fallback()
{
local xchg="$1"; shift
local order="$1"; shift
local forder="${order:-_fence}"
printf "#if defined(arch_${xchg}${order})\n"
printf "#define raw_${xchg}${order} arch_${xchg}${order}\n"
if [ "${order}" != "_relaxed" ]; then
printf "#elif defined(arch_${xchg}_relaxed)\n"
printf "#define raw_${xchg}${order}(...) \\\\\n"
printf " __atomic_op${forder}(arch_${xchg}, __VA_ARGS__)\n"
fi
if [ ! -z "${order}" ]; then
printf "#elif defined(arch_${xchg})\n"
printf "#define raw_${xchg}${order} arch_${xchg}\n"
fi
printf "#else\n"
printf "extern void raw_${xchg}${order}_not_implemented(void);\n"
printf "#define raw_${xchg}${order}(...) raw_${xchg}${order}_not_implemented()\n"
printf "#endif\n\n"
}
gen_xchg_fallbacks()
{
local xchg="$1"; shift
for order in "" "_acquire" "_release" "_relaxed"; do
gen_xchg_order_fallback "${xchg}" "${order}"
done
}
gen_try_cmpxchg_fallback()
{
local prefix="$1"; shift
local cmpxchg="$1"; shift;
local suffix="$1"; shift;
cat <<EOF
#define raw_${prefix}try_${cmpxchg}${suffix}(_ptr, _oldp, _new) \\
({ \\
typeof(*(_ptr)) *___op = (_oldp), ___o = *___op, ___r; \\
___r = raw_${prefix}${cmpxchg}${suffix}((_ptr), ___o, (_new)); \\
if (unlikely(___r != ___o)) \\
*___op = ___r; \\
likely(___r == ___o); \\
})
EOF
}
gen_try_cmpxchg_order_fallback()
{
local cmpxchg="$1"; shift
local order="$1"; shift
local forder="${order:-_fence}"
printf "#if defined(arch_try_${cmpxchg}${order})\n"
printf "#define raw_try_${cmpxchg}${order} arch_try_${cmpxchg}${order}\n"
if [ "${order}" != "_relaxed" ]; then
printf "#elif defined(arch_try_${cmpxchg}_relaxed)\n"
printf "#define raw_try_${cmpxchg}${order}(...) \\\\\n"
printf " __atomic_op${forder}(arch_try_${cmpxchg}, __VA_ARGS__)\n"
fi
if [ ! -z "${order}" ]; then
printf "#elif defined(arch_try_${cmpxchg})\n"
printf "#define raw_try_${cmpxchg}${order} arch_try_${cmpxchg}\n"
fi
printf "#else\n"
gen_try_cmpxchg_fallback "" "${cmpxchg}" "${order}"
printf "#endif\n\n"
}
gen_try_cmpxchg_order_fallbacks()
{
local cmpxchg="$1"; shift;
for order in "" "_acquire" "_release" "_relaxed"; do
gen_try_cmpxchg_order_fallback "${cmpxchg}" "${order}"
done
}
gen_def_and_try_cmpxchg_fallback()
{
local prefix="$1"; shift
local cmpxchg="$1"; shift
local suffix="$1"; shift
printf "#define raw_${prefix}${cmpxchg}${suffix} arch_${prefix}${cmpxchg}${suffix}\n\n"
printf "#ifdef arch_${prefix}try_${cmpxchg}${suffix}\n"
printf "#define raw_${prefix}try_${cmpxchg}${suffix} arch_${prefix}try_${cmpxchg}${suffix}\n"
printf "#else\n"
gen_try_cmpxchg_fallback "${prefix}" "${cmpxchg}" "${suffix}"
printf "#endif\n\n"
}
cat << EOF
// SPDX-License-Identifier: GPL-2.0
// Generated by $0
// DO NOT MODIFY THIS FILE DIRECTLY
#ifndef _LINUX_ATOMIC_FALLBACK_H
#define _LINUX_ATOMIC_FALLBACK_H
#include <linux/compiler.h>
EOF
for xchg in "xchg" "cmpxchg" "cmpxchg64" "cmpxchg128"; do
gen_xchg_fallbacks "${xchg}"
done
for cmpxchg in "cmpxchg" "cmpxchg64" "cmpxchg128"; do
gen_try_cmpxchg_order_fallbacks "${cmpxchg}"
done
for cmpxchg in "cmpxchg" "cmpxchg64" "cmpxchg128"; do
gen_def_and_try_cmpxchg_fallback "" "${cmpxchg}" "_local"
done
for cmpxchg in "cmpxchg"; do
gen_def_and_try_cmpxchg_fallback "sync_" "${cmpxchg}" ""
done
grep '^[a-z]' "$1" | while read name meta args; do
gen_proto "${meta}" "${name}" "atomic" "int" ${args}
done
cat <<EOF
#ifdef CONFIG_GENERIC_ATOMIC64
#include <asm-generic/atomic64.h>
#endif
EOF
grep '^[a-z]' "$1" | while read name meta args; do
gen_proto "${meta}" "${name}" "atomic64" "s64" ${args}
done
cat <<EOF
#endif /* _LINUX_ATOMIC_FALLBACK_H */
EOF