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ba39486d2c
[Changes from V1:
- The __compat_break has been abandoned in favor of
a more readable can_loop macro that can be used anywhere, including
loop conditions.]
The macro list_for_each_entry is defined in bpf_arena_list.h as
follows:
#define list_for_each_entry(pos, head, member) \
for (void * ___tmp = (pos = list_entry_safe((head)->first, \
typeof(*(pos)), member), \
(void *)0); \
pos && ({ ___tmp = (void *)pos->member.next; 1; }); \
cond_break, \
pos = list_entry_safe((void __arena *)___tmp, typeof(*(pos)), member))
The macro cond_break, in turn, expands to a statement expression that
contains a `break' statement. Compound statement expressions, and the
subsequent ability of placing statements in the header of a `for'
loop, are GNU extensions.
Unfortunately, clang implements this GNU extension differently than
GCC:
- In GCC the `break' statement is bound to the containing "breakable"
context in which the defining `for' appears. If there is no such
context, GCC emits a warning: break statement without enclosing `for'
o `switch' statement.
- In clang the `break' statement is bound to the defining `for'. If
the defining `for' is itself inside some breakable construct, then
clang emits a -Wgcc-compat warning.
This patch adds a new macro can_loop to bpf_experimental, that
implements the same logic than cond_break but evaluates to a boolean
expression. The patch also changes all the current instances of usage
of cond_break withing the header of loop accordingly.
Tested in bpf-next master.
No regressions.
Signed-off-by: Jose E. Marchesi <jose.marchesi@oracle.com>
Cc: david.faust@oracle.com
Cc: cupertino.miranda@oracle.com
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Link: https://lore.kernel.org/r/20240511212243.23477-1-jose.marchesi@oracle.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
88 lines
1.7 KiB
C
88 lines
1.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */
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#include <vmlinux.h>
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_tracing.h>
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#include <bpf/bpf_core_read.h>
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#include "bpf_experimental.h"
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struct {
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__uint(type, BPF_MAP_TYPE_ARENA);
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__uint(map_flags, BPF_F_MMAPABLE);
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__uint(max_entries, 100); /* number of pages */
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#ifdef __TARGET_ARCH_arm64
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__ulong(map_extra, 0x1ull << 32); /* start of mmap() region */
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#else
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__ulong(map_extra, 0x1ull << 44); /* start of mmap() region */
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#endif
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} arena SEC(".maps");
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#include "bpf_arena_alloc.h"
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#include "bpf_arena_list.h"
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struct elem {
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struct arena_list_node node;
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__u64 value;
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};
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struct arena_list_head __arena *list_head;
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int list_sum;
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int cnt;
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bool skip = false;
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#ifdef __BPF_FEATURE_ADDR_SPACE_CAST
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long __arena arena_sum;
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int __arena test_val = 1;
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struct arena_list_head __arena global_head;
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#else
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long arena_sum SEC(".addr_space.1");
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int test_val SEC(".addr_space.1");
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#endif
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int zero;
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SEC("syscall")
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int arena_list_add(void *ctx)
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{
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#ifdef __BPF_FEATURE_ADDR_SPACE_CAST
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__u64 i;
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list_head = &global_head;
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for (i = zero; i < cnt && can_loop; i++) {
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struct elem __arena *n = bpf_alloc(sizeof(*n));
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test_val++;
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n->value = i;
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arena_sum += i;
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list_add_head(&n->node, list_head);
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}
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#else
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skip = true;
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#endif
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return 0;
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}
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SEC("syscall")
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int arena_list_del(void *ctx)
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{
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#ifdef __BPF_FEATURE_ADDR_SPACE_CAST
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struct elem __arena *n;
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int sum = 0;
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arena_sum = 0;
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list_for_each_entry(n, list_head, node) {
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sum += n->value;
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arena_sum += n->value;
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list_del(&n->node);
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bpf_free(n);
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}
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list_sum = sum;
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#else
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skip = true;
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#endif
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return 0;
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}
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char _license[] SEC("license") = "GPL";
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