mirror of
https://github.com/netdata/libbpf.git
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1d483b45fc
Now that the AF_XDP rings have load-acquire/store-release semantics,
move libbpf to that as well.
The library-internal libbpf_smp_{load_acquire,store_release} are only
valid for 32-bit words on ARM64.
Also, remove the barriers that are no longer in use.
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210305094113.413544-3-bjorn.topel@gmail.com
76 lines
1.8 KiB
C
76 lines
1.8 KiB
C
/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
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/* Copyright (c) 2019 Facebook */
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#ifndef __LIBBPF_LIBBPF_UTIL_H
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#define __LIBBPF_LIBBPF_UTIL_H
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#include <stdbool.h>
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#include <linux/compiler.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* Use these barrier functions instead of smp_[rw]mb() when they are
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* used in a libbpf header file. That way they can be built into the
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* application that uses libbpf.
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*/
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#if defined(__i386__) || defined(__x86_64__)
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# define libbpf_smp_store_release(p, v) \
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do { \
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asm volatile("" : : : "memory"); \
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WRITE_ONCE(*p, v); \
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} while (0)
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# define libbpf_smp_load_acquire(p) \
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({ \
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typeof(*p) ___p1 = READ_ONCE(*p); \
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asm volatile("" : : : "memory"); \
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___p1; \
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})
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#elif defined(__aarch64__)
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# define libbpf_smp_store_release(p, v) \
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asm volatile ("stlr %w1, %0" : "=Q" (*p) : "r" (v) : "memory")
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# define libbpf_smp_load_acquire(p) \
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({ \
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typeof(*p) ___p1; \
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asm volatile ("ldar %w0, %1" \
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: "=r" (___p1) : "Q" (*p) : "memory"); \
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__p1; \
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})
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#elif defined(__riscv)
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# define libbpf_smp_store_release(p, v) \
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do { \
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asm volatile ("fence rw,w" : : : "memory"); \
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WRITE_ONCE(*p, v); \
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} while (0)
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# define libbpf_smp_load_acquire(p) \
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({ \
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typeof(*p) ___p1 = READ_ONCE(*p); \
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asm volatile ("fence r,rw" : : : "memory"); \
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___p1; \
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})
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#endif
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#ifndef libbpf_smp_store_release
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#define libbpf_smp_store_release(p, v) \
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do { \
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__sync_synchronize(); \
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WRITE_ONCE(*p, v); \
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} while (0)
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#endif
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#ifndef libbpf_smp_load_acquire
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#define libbpf_smp_load_acquire(p) \
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({ \
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typeof(*p) ___p1 = READ_ONCE(*p); \
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__sync_synchronize(); \
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___p1; \
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})
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#endif
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#ifdef __cplusplus
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} /* extern "C" */
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#endif
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#endif
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