atomics: Constify loads

In order to match reality, allow using these functions with pointers on
const objects, and bring us closer to C11.

Remove the '+' modifier in the atomic_load_acq_64_i586()'s

atomics: Constify loads

In order to match reality, allow using these functions with pointers on
const objects, and bring us closer to C11.

Remove the '+' modifier in the atomic_load_acq_64_i586()'s inline asm
statement's constraint for '*p' (the value to load). CMPXCHG8B always
writes back some value, even when the value exchange does not happen in
which case what was read is written back. atomic_load_acq_64_i586()
further takes care of the operation atomically writing back the same
value that was read in any case. All in all, this makes the inline
asm's write back undetectable by any other code, whether executing on
other CPUs or code on the same CPU before and after the call to
atomic_load_acq_64_i586(), except for the fact that CMPXCHG8B will
trigger a #GP(0) if the memory address is part of a read-only mapping.
This unfortunate property is however out of scope of the C abstract
machine, and in particular independent of whether the 'uint64_t' pointed
to is declared 'const' or not.

Approved by: markj (mentor)
MFC after: 5 days
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D46887

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sys: Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

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atomic: Remove cdefs.h includes from atomic_*.h

Avoid including cdefs.h in system headers. Both headers now include
types.h, and we can assume that that pulls in cdefs.h (required for
__typeof usag

atomic: Remove cdefs.h includes from atomic_*.h

Avoid including cdefs.h in system headers. Both headers now include
types.h, and we can assume that that pulls in cdefs.h (required for
__typeof usage in some of the atomic macro expansions).

No functional change intended.

Reviewed by: imp, kib
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D38039

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atomic: Style

Fixes: 30253da1a982 ("atomic: Add some type checking to plain atomic_load/store helpers")
MFC after: 1 week

atomic: Add plain atomic_load/store_bool()

Reviewed by: kib
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D36078

atomic: Add some type checking to plain atomic_load/store helpers

Reviewed by: rpokala, mjg, imp, kib
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.f

atomic: Add some type checking to plain atomic_load/store helpers

Reviewed by: rpokala, mjg, imp, kib
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D35828

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Remove "All Rights Reserved" from FreeBSD Foundation sys/ copyrights

These ones were unambiguous cases where the Foundation was the only
listed copyright holder (in the associated license block).

S

Remove "All Rights Reserved" from FreeBSD Foundation sys/ copyrights

These ones were unambiguous cases where the Foundation was the only
listed copyright holder (in the associated license block).

Sponsored by: The FreeBSD Foundation

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atomic: add atomic_interrupt_fence()

with the semantic following C11 signal_fence, that is, it establishes
ordering between its place and any interrupt handler executing on the
same CPU.

Reviewed b

atomic: add atomic_interrupt_fence()

with the semantic following C11 signal_fence, that is, it establishes
ordering between its place and any interrupt handler executing on the
same CPU.

Reviewed by: markj, mjg, rlibby
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D28909

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atomic: add stub atomic_load_consume_ptr

atomic: make atomic_store_ptr type-aware

atomic_common.h: Fix the volatile qualifier placement in atomic_load_ptr

This was broken in r357940 which introduced the __typeof use. We need
the volatile qualifier to be on the pointee not the poi

atomic_common.h: Fix the volatile qualifier placement in atomic_load_ptr

This was broken in r357940 which introduced the __typeof use. We need
the volatile qualifier to be on the pointee not the pointer otherwise it
does nothing. This was found by mhorne in D26498, noticing there was a
problem (a spin loop condition was hoisted for RISC-V boot code) but not
the root cause of it.

Reported by: mhorne
Reviewed by: mhorne, mjg
Approved by: mhorne, mjg
Differential Revision: https://reviews.freebsd.org/D26500

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Merge ^/head r357931 through r357965.

Make atomic_load_ptr type-aware

Returned value has type based on the argument, meaning consumers no longer
have to cast in the commmon case.

This commit keeps the kernel compilable without patching

Make atomic_load_ptr type-aware

Returned value has type based on the argument, meaning consumers no longer
have to cast in the commmon case.

This commit keeps the kernel compilable without patching the rest.

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Add the missing volatile qualifier in atomic_store_ptr

MFC after: 1 week
Sponsored by: DARPA, AFRL

Merge ^/head r326936 through r327149.

Add atomic_load(9) and atomic_store(9) operations.

They provide relaxed-ordered atomic access semantic. Due to the
FreeBSD memory model, the operations are syntaxical wrappers around
the volatile a

Add atomic_load(9) and atomic_store(9) operations.

They provide relaxed-ordered atomic access semantic. Due to the
FreeBSD memory model, the operations are syntaxical wrappers around
the volatile accesses. The volatile qualifier is used to ensure that
the access not optimized out and in turn depends on the volatile
semantic as implemented by supported compilers.

The motivation for adding the operation is to help people coming from
other systems or knowing the C11/C++ standards where atomics have
special type and require use of the special access operations. It is
still the case that FreeBSD requires plain load and stores of aligned
integer types to be atomic.

Suggested by: jhb
Reviewed by: alc, jhb
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D13534

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