Only x86 provides try_cmpxchg() outside of the atomic_t interfaces,
provide generic fallbacks to create this interface from the widely
available cmpxchg() function.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/159870621515.1229682.15506193091065001742.stgit@devnote2
Architectures with instrumented (KASAN/KCSAN) atomic operations
natively provide arch_atomic_ variants that are not instrumented.
It turns out that some generic code also requires arch_atomic_ in
order to avoid instrumentation, so provide the arch_atomic_ interface
as a direct map into the regular atomic_ interface for
non-instrumented architectures.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Currently instrumentation of atomic primitives is done at the architecture
level, while composites or fallbacks are provided at the generic level.
The result is that there are no uninstrumented variants of the
fallbacks. Since there is now need of such variants to isolate text poke
from any form of instrumentation invert this ordering.
Doing this means moving the instrumentation into the generic code as
well as having (for now) two variants of the fallbacks.
Notes:
- the various *cond_read* primitives are not proper fallbacks
and got moved into linux/atomic.c. No arch_ variants are
generated because the base primitives smp_cond_load*()
are instrumented.
- once all architectures are moved over to arch_atomic_ one of the
fallback variants can be removed and some 2300 lines reclaimed.
- atomic_{read,set}*() are no longer double-instrumented
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lkml.kernel.org/r/20200505134058.769149955@linutronix.de
Use __always_inline for atomic fallback wrappers. When building for size
(CC_OPTIMIZE_FOR_SIZE), some compilers appear to be less inclined to
inline even relatively small static inline functions that are assumed to
be inlinable such as atomic ops. This can cause problems, for example in
UACCESS regions.
While the fallback wrappers aren't pure wrappers, they are trivial
nonetheless, and the function they wrap should determine the final
inlining policy.
For x86 tinyconfig we observe:
- vmlinux baseline: 1315988
- vmlinux with patch: 1315928 (-60 bytes)
[ tglx: Cherry-picked from KCSAN ]
Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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>
Peter Zijlstra