| 1 | // SPDX-License-Identifier: GPL-2.0 |
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| 2 | /* Copyright (c) 2020 Facebook */ |
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| 3 | |
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| 4 | #include "vmlinux.h" |
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| 5 | |
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| 6 | #include <bpf/bpf_helpers.h> |
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| 7 | |
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| 8 | extern const struct rq runqueues __ksym; /* struct type global var. */ |
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| 9 | extern const int bpf_prog_active __ksym; /* int type global var. */ |
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| 10 | |
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| 11 | SEC("raw_tp/sys_enter" ) |
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| 12 | int handler(const void *ctx) |
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| 13 | { |
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| 14 | struct rq *rq; |
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| 15 | int *active; |
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| 16 | __u32 cpu; |
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| 17 | |
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| 18 | cpu = bpf_get_smp_processor_id(); |
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| 19 | rq = (struct rq *)bpf_per_cpu_ptr(&runqueues, cpu); |
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| 20 | active = (int *)bpf_per_cpu_ptr(&bpf_prog_active, cpu); |
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| 21 | if (active) { |
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| 22 | /* READ_ONCE */ |
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| 23 | *(volatile int *)active; |
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| 24 | /* !rq has not been tested, so verifier should reject. */ |
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| 25 | *(volatile int *)(&rq->cpu); |
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| 26 | } |
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| 27 | |
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| 28 | return 0; |
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| 29 | } |
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| 30 | |
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| 31 | char _license[] SEC("license" ) = "GPL" ; |
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| 32 | |
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