locking/atomics: Add common header generation files
To minimize repetition, to allow for future rework, and to ensure
regularity of the various atomic APIs, we'd like to automatically
generate (the bulk of) a number of headers related to atomics.
This patch adds the infrastructure to do so, leaving actual conversion
of headers to subsequent patches. This infrastructure consists of:
* atomics.tbl - a table describing the functions in the atomics API,
with names, prototypes, and metadata describing the variants that
exist (e.g fetch/return, acquire/release/relaxed). Note that the
return type is dependent on the particular variant.
* atomic-tbl.sh - a library of routines useful for dealing with
atomics.tbl (e.g. querying which variants exist, or generating
argument/parameter lists for a given function variant).
* gen-atomic-fallback.sh - a script which generates a header of
fallbacks, covering cases where architecture omit certain functions
(e.g. omitting relaxed variants).
* gen-atomic-long.sh - a script which generates wrappers providing the
atomic_long API atomic of the relevant atomic or atomic64 API,
ensuring the APIs are consistent.
* gen-atomic-instrumented.sh - a script which generates atomic* wrappers
atop of arch_atomic* functions, with automatically generated KASAN
instrumentation.
* fallbacks/* - a set of fallback implementations for atomics, which
should be used when no implementation of a given atomic is provided.
These are used by gen-atomic-fallback.sh to generate fallbacks, and
these are also used by other scripts to determine the set of optional
atomics (as required to generate preprocessor guards correctly).
Fallbacks may use the following variables:
${atomic} atomic prefix: atomic/atomic64/atomic_long, which can be
used to derive the atomic type, and to prefix functions
${int} integer type: int/s64/long
${pfx} variant prefix, e.g. fetch_
${name} base function name, e.g. add
${sfx} variant suffix, e.g. _return
${order} order suffix, e.g. _relaxed
${atomicname} full name, e.g. atomic64_fetch_add_relaxed
${ret} return type of the function, e.g. void
${retstmt} a return statement (with a trailing space), unless the
variant returns void
${params} parameter list for the function declaration, e.g.
"int i, atomic_t *v"
${args} argument list for invoking the function, e.g. "i, v"
... for clarity, ${ret}, ${retstmt}, ${params}, and ${args} are
open-coded for fallbacks where these do not vary, or are critical to
understanding the logic of the fallback.
The MAINTAINERS entry for the atomic infrastructure is updated to cover
the new scripts.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: catalin.marinas@arm.com
Cc: Will Deacon <will.deacon@arm.com>
Cc: linuxdrivers@attotech.com
Cc: dvyukov@google.com
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: arnd@arndb.de
Cc: aryabinin@virtuozzo.com
Cc: glider@google.com
Link: http://lkml.kernel.org/r/20180904104830.2975-2-mark.rutland@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-09-04 18:48:25 +08:00
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cat <<EOF
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${int} r, o = *old;
|
locking/atomic: scripts: restructure fallback ifdeffery
Currently the various ordering variants of an atomic operation are
defined in groups of full/acquire/release/relaxed ordering variants with
some shared ifdeffery and several potential definitions of each ordering
variant in different branches of the shared ifdeffery.
As an ordering variant can have several potential definitions down
different branches of the shared ifdeffery, it can be painful for a
human to find a relevant definition, and we don't have a good location
to place anything common to all definitions of an ordering variant (e.g.
kerneldoc).
Historically the grouping of full/acquire/release/relaxed ordering
variants was necessary as we filled in the missing atomics in the same
namespace as the architecture used. It would be easy to accidentally
define one ordering fallback in terms of another ordering fallback with
redundant barriers, and avoiding that would otherwise require a lot of
baroque ifdeffery.
With recent changes we no longer need to fill in the missing atomics in
the arch_atomic*_<op>() namespace, and only need to fill in the
raw_atomic*_<op>() namespace. Due to this, there's no risk of a
namespace collision, and we can define each raw_atomic*_<op> ordering
variant with its own ifdeffery checking for the arch_atomic*_<op>
ordering variants.
Restructure the fallbacks in this way, with each ordering variant having
its own ifdeffery of the form:
| #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
Note that where there's no relevant arch_atomic*_<op>() ordering
variant, we'll define the operation in terms of a distinct
raw_atomic*_<otherop>(), as this itself might have been filled in with a
fallback.
As we now generate the raw_atomic*_<op>() implementations directly, we
no longer need the trivial wrappers, so they are removed.
This makes the ifdeffery easier to follow, and will allow for further
improvements in subsequent patches.
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/20230605070124.3741859-21-mark.rutland@arm.com
2023-06-05 15:01:17 +08:00
|
|
|
r = raw_${atomic}_cmpxchg${order}(v, o, new);
|
locking/atomics: Add common header generation files
To minimize repetition, to allow for future rework, and to ensure
regularity of the various atomic APIs, we'd like to automatically
generate (the bulk of) a number of headers related to atomics.
This patch adds the infrastructure to do so, leaving actual conversion
of headers to subsequent patches. This infrastructure consists of:
* atomics.tbl - a table describing the functions in the atomics API,
with names, prototypes, and metadata describing the variants that
exist (e.g fetch/return, acquire/release/relaxed). Note that the
return type is dependent on the particular variant.
* atomic-tbl.sh - a library of routines useful for dealing with
atomics.tbl (e.g. querying which variants exist, or generating
argument/parameter lists for a given function variant).
* gen-atomic-fallback.sh - a script which generates a header of
fallbacks, covering cases where architecture omit certain functions
(e.g. omitting relaxed variants).
* gen-atomic-long.sh - a script which generates wrappers providing the
atomic_long API atomic of the relevant atomic or atomic64 API,
ensuring the APIs are consistent.
* gen-atomic-instrumented.sh - a script which generates atomic* wrappers
atop of arch_atomic* functions, with automatically generated KASAN
instrumentation.
* fallbacks/* - a set of fallback implementations for atomics, which
should be used when no implementation of a given atomic is provided.
These are used by gen-atomic-fallback.sh to generate fallbacks, and
these are also used by other scripts to determine the set of optional
atomics (as required to generate preprocessor guards correctly).
Fallbacks may use the following variables:
${atomic} atomic prefix: atomic/atomic64/atomic_long, which can be
used to derive the atomic type, and to prefix functions
${int} integer type: int/s64/long
${pfx} variant prefix, e.g. fetch_
${name} base function name, e.g. add
${sfx} variant suffix, e.g. _return
${order} order suffix, e.g. _relaxed
${atomicname} full name, e.g. atomic64_fetch_add_relaxed
${ret} return type of the function, e.g. void
${retstmt} a return statement (with a trailing space), unless the
variant returns void
${params} parameter list for the function declaration, e.g.
"int i, atomic_t *v"
${args} argument list for invoking the function, e.g. "i, v"
... for clarity, ${ret}, ${retstmt}, ${params}, and ${args} are
open-coded for fallbacks where these do not vary, or are critical to
understanding the logic of the fallback.
The MAINTAINERS entry for the atomic infrastructure is updated to cover
the new scripts.
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>
Cc: linux-arm-kernel@lists.infradead.org
Cc: catalin.marinas@arm.com
Cc: Will Deacon <will.deacon@arm.com>
Cc: linuxdrivers@attotech.com
Cc: dvyukov@google.com
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: arnd@arndb.de
Cc: aryabinin@virtuozzo.com
Cc: glider@google.com
Link: http://lkml.kernel.org/r/20180904104830.2975-2-mark.rutland@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-09-04 18:48:25 +08:00
|
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if (unlikely(r != o))
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*old = r;
|
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return likely(r == o);
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EOF
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