All xchg() and cmpxchg() ops are atomic RMWs, but currently we
instrument these with instrument_atomic_write() rather than
instrument_atomic_read_write(), missing the read aspect.
Similarly, all try_cmpxchg() ops are non-atomic RMWs on *oldp, but we
instrument these accesses with instrument_atomic_write() rather than
instrument_read_write(), missing the read aspect and erroneously marking
these as atomic.
Fix the instrumentation for both points.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20230413160644.490976-1-mark.rutland@arm.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Add generic support for try_cmpxchg{,64}_local() and their falbacks.
These provides the generic try_cmpxchg_local family of functions
from the arch_ prefixed version, also adding explicit instrumentation.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20230405141710.3551-2-ubizjak@gmail.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Add generic support for try_cmpxchg64{,_acquire,_release,_relaxed}
and their falbacks involving cmpxchg64.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220515184205.103089-2-ubizjak@gmail.com
Adds the required KCSAN instrumentation for barriers of atomics.
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Now that all architectures provide arch_{atomic,atomic64}_*(), we can
build arch_atomic_long_*() atop these, which can be safely used in
noinstr code. The regular atomic_long_*() wrappers are built atop these,
as we do for {atomic,atomic64}_*() atop arch_{atomic,atomic64}_*().
We don't provide arch_* versions of the cond_read*() variants, as we
don't have arch_* versions of the underlying atomic/atomic64 functions
(nor the smp_cond_load*() helpers these are typically based on).
Note that the headers in this patch under include/linux/atomic/ are
generated by the scripts in scripts/atomic/.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210713105253.7615-5-mark.rutland@arm.com
The generated atomic headers are only intended to be included directly
by <linux/atomic.h>, but are spread across include/linux/ and
include/asm-generic/, where people mnay be encouraged to include them.
This patch centralizes them under include/linux/atomic/.
Other than the header guards and hashes, there is no change to any of
the generated headers as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210713105253.7615-4-mark.rutland@arm.com
Now that all architectures implement ARCH_ATOMIC, the fallbacks are
generated before the instrumented wrappers are generated. Due to this,
in atomic-instrumented.h we can assume that the whole set of atomic
functions has been generated. Likewise, atomic-instrumented.h doesn't
need to provide a preprocessor definition for every atomic it wraps.
This patch removes the redundant ifdeffery.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210525140232.53872-34-mark.rutland@arm.com
Conflicts:
include/asm-generic/atomic-instrumented.h
kernel/kprobes.c
Use the upstream atomic-instrumented.h checksum, and pick
the kprobes version of kernel/kprobes.c, which effectively
reverts this upstream workaround:
645f224e7b: ("kprobes: Tell lockdep about kprobe nesting")
Since the new code *should* be fine without nesting.
Knock on wood ...
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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
Use instrument_atomic_read_write() for atomic RMW ops.
Cc: Will Deacon <will@kernel.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: <linux-arch@vger.kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This switches atomic-instrumented.h to use the generic instrumentation
wrappers provided by instrumented.h.
No functional change intended.
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Prefer __always_inline for atomic 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.
By using __always_inline, we let the real implementation and not the
wrapper determine the final inlining preference.
For x86 tinyconfig we observe:
- vmlinux baseline: 1316204
- vmlinux with patch: 1315988 (-216 bytes)
This came up when addressing UACCESS warnings with CC_OPTIMIZE_FOR_SIZE
in the KCSAN runtime:
http://lkml.kernel.org/r/58708908-84a0-0a81-a836-ad97e33dbb62@infradead.org
Reported-by: Randy Dunlap <rdunlap@infradead.org>
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>
This adds KCSAN instrumentation to atomic-instrumented.h.
Signed-off-by: Marco Elver <elver@google.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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>
