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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:27:49 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:27:49 +0000 |
commit | ace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch) | |
tree | b2d64bc10158fdd5497876388cd68142ca374ed3 /samples/bpf/lathist_kern.c | |
parent | Initial commit. (diff) | |
download | linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip |
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'samples/bpf/lathist_kern.c')
-rw-r--r-- | samples/bpf/lathist_kern.c | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/samples/bpf/lathist_kern.c b/samples/bpf/lathist_kern.c new file mode 100644 index 0000000000..4adfcbbe6e --- /dev/null +++ b/samples/bpf/lathist_kern.c @@ -0,0 +1,99 @@ +/* Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com + * Copyright (c) 2015 BMW Car IT GmbH + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of version 2 of the GNU General Public + * License as published by the Free Software Foundation. + */ +#include <linux/version.h> +#include <linux/ptrace.h> +#include <uapi/linux/bpf.h> +#include <bpf/bpf_helpers.h> + +#define MAX_ENTRIES 20 +#define MAX_CPU 4 + +/* We need to stick to static allocated memory (an array instead of + * hash table) because managing dynamic memory from the + * trace_preempt_[on|off] tracepoints hooks is not supported. + */ + +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __type(key, int); + __type(value, u64); + __uint(max_entries, MAX_CPU); +} my_map SEC(".maps"); + +SEC("kprobe/trace_preempt_off") +int bpf_prog1(struct pt_regs *ctx) +{ + int cpu = bpf_get_smp_processor_id(); + u64 *ts = bpf_map_lookup_elem(&my_map, &cpu); + + if (ts) + *ts = bpf_ktime_get_ns(); + + return 0; +} + +static unsigned int log2(unsigned int v) +{ + unsigned int r; + unsigned int shift; + + r = (v > 0xFFFF) << 4; v >>= r; + shift = (v > 0xFF) << 3; v >>= shift; r |= shift; + shift = (v > 0xF) << 2; v >>= shift; r |= shift; + shift = (v > 0x3) << 1; v >>= shift; r |= shift; + r |= (v >> 1); + + return r; +} + +static unsigned int log2l(unsigned long v) +{ + unsigned int hi = v >> 32; + + if (hi) + return log2(hi) + 32; + else + return log2(v); +} + +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __type(key, int); + __type(value, long); + __uint(max_entries, MAX_CPU * MAX_ENTRIES); +} my_lat SEC(".maps"); + +SEC("kprobe/trace_preempt_on") +int bpf_prog2(struct pt_regs *ctx) +{ + u64 *ts, cur_ts, delta; + int key, cpu; + long *val; + + cpu = bpf_get_smp_processor_id(); + ts = bpf_map_lookup_elem(&my_map, &cpu); + if (!ts) + return 0; + + cur_ts = bpf_ktime_get_ns(); + delta = log2l(cur_ts - *ts); + + if (delta > MAX_ENTRIES - 1) + delta = MAX_ENTRIES - 1; + + key = cpu * MAX_ENTRIES + delta; + val = bpf_map_lookup_elem(&my_lat, &key); + if (val) + __sync_fetch_and_add((long *)val, 1); + + return 0; + +} + +char _license[] SEC("license") = "GPL"; +u32 _version SEC("version") = LINUX_VERSION_CODE; |