Add bpf_atomic.h including atomic read/write macros like READ_ONCE() and try_cmpxchg(). This version is a stripped down copy of the one currently present in selftests/bpf/libarena.
Signed-off-by: Gabriele Monaco <[email protected]> --- .../verification/rv/bpf_monitors/bpf_atomic.h | 105 ++++++++++++++++++ 1 file changed, 105 insertions(+) create mode 100644 tools/verification/rv/bpf_monitors/bpf_atomic.h diff --git a/tools/verification/rv/bpf_monitors/bpf_atomic.h b/tools/verification/rv/bpf_monitors/bpf_atomic.h new file mode 100644 index 000000000000..f834ea91c9d3 --- /dev/null +++ b/tools/verification/rv/bpf_monitors/bpf_atomic.h @@ -0,0 +1,105 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */ +#ifndef BPF_ATOMIC_H +#define BPF_ATOMIC_H + +#include <vmlinux.h> +#include <bpf/bpf_helpers.h> + +extern bool CONFIG_X86_64 __kconfig __weak; + +/* + * __unqual_typeof(x) - Declare an unqualified scalar type, leaving + * non-scalar types unchanged, + * + * Prefer C11 _Generic for better compile-times and simpler code. Note: 'char' + * is not type-compatible with 'signed char', and we define a separate case. + * + * This is copied verbatim from kernel's include/linux/compiler_types.h, but + * with default expression (for pointers) changed from (x) to (typeof(x)0). + * + * This is because LLVM has a bug where for lvalue (x), it does not get rid of + * an extra address_space qualifier, but does in case of rvalue (typeof(x)0). + * Hence, for pointers, we need to create an rvalue expression to get the + * desired type. See https://github.com/llvm/llvm-project/issues/53400. + */ +#define __scalar_type_to_expr_cases(type) \ + unsigned type : (unsigned type)0, signed type : (signed type)0 + +#define __unqual_typeof(x) \ + typeof(_Generic((x), \ + char: (char)0, \ + __scalar_type_to_expr_cases(char), \ + __scalar_type_to_expr_cases(short), \ + __scalar_type_to_expr_cases(int), \ + __scalar_type_to_expr_cases(long), \ + __scalar_type_to_expr_cases(long long), \ + default: (typeof(x))0)) + +/* No-op for BPF */ +#define cpu_relax() ({}) + +#define READ_ONCE(x) (*(volatile typeof(x) *)&(x)) + +#ifndef WRITE_ONCE +#define WRITE_ONCE(x, val) ((*(volatile typeof(x) *)&(x)) = (val)) +#endif + +#define cmpxchg(p, old, new) __sync_val_compare_and_swap((p), old, new) + +#define try_cmpxchg(p, pold, new) \ + ({ \ + __unqual_typeof(*(pold)) __o = *(pold); \ + __unqual_typeof(*(p)) __r = cmpxchg(p, __o, new); \ + if (__r != __o) \ + *(pold) = __r; \ + __r == __o; \ + }) + +#define try_cmpxchg_relaxed(p, pold, new) try_cmpxchg(p, pold, new) + +#define try_cmpxchg_acquire(p, pold, new) try_cmpxchg(p, pold, new) + +#define smp_mb() \ + ({ \ + volatile unsigned long __val; \ + __sync_fetch_and_add(&__val, 0); \ + }) + +#define smp_rmb() \ + ({ \ + if (!CONFIG_X86_64) \ + smp_mb(); \ + else \ + barrier(); \ + }) + +#define smp_wmb() \ + ({ \ + if (!CONFIG_X86_64) \ + smp_mb(); \ + else \ + barrier(); \ + }) + +/* Control dependency provides LOAD->STORE, provide LOAD->LOAD */ +#define smp_acquire__after_ctrl_dep() ({ smp_rmb(); }) + +#define smp_load_acquire(p) \ + ({ \ + __unqual_typeof(*(p)) __v = READ_ONCE(*(p)); \ + if (!CONFIG_X86_64) \ + smp_mb(); \ + barrier(); \ + __v; \ + }) + +#define smp_store_release(p, val) \ + ({ \ + if (!CONFIG_X86_64) \ + smp_mb(); \ + barrier(); \ + WRITE_ONCE(*(p), val); \ + }) + +#endif /* BPF_ATOMIC_H */ -- 2.55.0
