71 lines
2.8 KiB
Diff
71 lines
2.8 KiB
Diff
From cf4dcbae4799415fc5a85f9bb9f31bbf036f2994 Mon Sep 17 00:00:00 2001
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From: Alexander Lobakin <alobakin@pm.me>
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Date: Thu, 21 Apr 2022 00:38:58 +0000
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Subject: [PATCH] bpftool: define a local bpf_perf_link to fix accessing its
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fields
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When building bpftool with !CONFIG_PERF_EVENTS:
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skeleton/pid_iter.bpf.c:47:14: error: incomplete definition of type 'struct bpf_perf_link'
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perf_link = container_of(link, struct bpf_perf_link, link);
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^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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tools/bpf/bpftool/bootstrap/libbpf/include/bpf/bpf_helpers.h:74:22: note: expanded from macro 'container_of'
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((type *)(__mptr - offsetof(type, member))); \
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^~~~~~~~~~~~~~~~~~~~~~
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tools/bpf/bpftool/bootstrap/libbpf/include/bpf/bpf_helpers.h:68:60: note: expanded from macro 'offsetof'
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#define offsetof(TYPE, MEMBER) ((unsigned long)&((TYPE *)0)->MEMBER)
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~~~~~~~~~~~^
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skeleton/pid_iter.bpf.c:44:9: note: forward declaration of 'struct bpf_perf_link'
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struct bpf_perf_link *perf_link;
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^
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&bpf_perf_link is being defined and used only under the ifdef.
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Define struct bpf_perf_link___local with the `preserve_access_index`
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attribute inside the pid_iter BPF prog to allow compiling on any
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configs. CO-RE will substitute it with the real struct bpf_perf_link
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accesses later on.
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container_of() is not CO-REd, but it is a noop for
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bpf_perf_link <-> bpf_link and the local copy is a full mirror of
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the original structure.
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Fixes: cbdaf71f7e65 ("bpftool: Add bpf_cookie to link output")
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Suggested-by: Andrii Nakryiko <andrii@kernel.org>
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Signed-off-by: Alexander Lobakin <alobakin@pm.me>
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Signed-off-by: Quentin Monnet <quentin@isovalent.com>
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---
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tools/bpf/bpftool/skeleton/pid_iter.bpf.c | 9 +++++++--
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1 file changed, 7 insertions(+), 2 deletions(-)
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diff --git a/src/skeleton/pid_iter.bpf.c b/src/skeleton/pid_iter.bpf.c
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index e2af8e5fb29e..3a4c4f7d83d8 100644
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--- a/src/skeleton/pid_iter.bpf.c
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+++ b/src/skeleton/pid_iter.bpf.c
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@@ -15,6 +15,11 @@ enum bpf_obj_type {
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BPF_OBJ_BTF,
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};
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+struct bpf_perf_link___local {
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+ struct bpf_link link;
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+ struct file *perf_file;
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+} __attribute__((preserve_access_index));
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+
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struct perf_event___local {
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u64 bpf_cookie;
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} __attribute__((preserve_access_index));
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@@ -45,10 +50,10 @@ static __always_inline __u32 get_obj_id(void *ent, enum bpf_obj_type type)
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/* could be used only with BPF_LINK_TYPE_PERF_EVENT links */
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static __u64 get_bpf_cookie(struct bpf_link *link)
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{
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+ struct bpf_perf_link___local *perf_link;
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struct perf_event___local *event;
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- struct bpf_perf_link *perf_link;
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- perf_link = container_of(link, struct bpf_perf_link, link);
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+ perf_link = container_of(link, struct bpf_perf_link___local, link);
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event = BPF_CORE_READ(perf_link, perf_file, private_data);
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return BPF_CORE_READ(event, bpf_cookie);
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}
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--
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2.40.0
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