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| author | Song Liu <songliubraving@fb.com> | 2021-11-06 02:23:29 +0300 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2021-11-07 22:54:51 +0300 |
| commit | 7c7e3d31e7856a8260a254f8c71db416f7f9f5a1 (patch) | |
| tree | d2754fa3a377dd507bfa4e6131e554f3d011d844 /kernel/trace | |
| parent | 5fd79ed9bed1934de0ba0024e62eacaedb3c4c8a (diff) | |
| download | linux-7c7e3d31e7856a8260a254f8c71db416f7f9f5a1.tar.xz | |
bpf: Introduce helper bpf_find_vma
In some profiler use cases, it is necessary to map an address to the
backing file, e.g., a shared library. bpf_find_vma helper provides a
flexible way to achieve this. bpf_find_vma maps an address of a task to
the vma (vm_area_struct) for this address, and feed the vma to an callback
BPF function. The callback function is necessary here, as we need to
ensure mmap_sem is unlocked.
It is necessary to lock mmap_sem for find_vma. To lock and unlock mmap_sem
safely when irqs are disable, we use the same mechanism as stackmap with
build_id. Specifically, when irqs are disabled, the unlocked is postponed
in an irq_work. Refactor stackmap.c so that the irq_work is shared among
bpf_find_vma and stackmap helpers.
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Hengqi Chen <hengqi.chen@gmail.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211105232330.1936330-2-songliubraving@fb.com
Diffstat (limited to 'kernel/trace')
| -rw-r--r-- | kernel/trace/bpf_trace.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 7396488793ff..390176a3031a 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1208,6 +1208,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_get_func_ip_proto_tracing; case BPF_FUNC_get_branch_snapshot: return &bpf_get_branch_snapshot_proto; + case BPF_FUNC_find_vma: + return &bpf_find_vma_proto; case BPF_FUNC_trace_vprintk: return bpf_get_trace_vprintk_proto(); default: |