64 lines
2.3 KiB
Diff
64 lines
2.3 KiB
Diff
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From 6acb32f72618dbaa9d4938fc3007b0ff7ca151c4 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 00:38:45 +0000
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Subject: [PATCH] bpftool: use a local copy of perf_event to fix accessing
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::bpf_cookie
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When CONFIG_PERF_EVENTS is not set, struct perf_event remains empty.
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However, the structure is being used by bpftool indirectly via BTF.
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This leads to:
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skeleton/pid_iter.bpf.c:49:30: error: no member named 'bpf_cookie' in 'struct perf_event'
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return BPF_CORE_READ(event, bpf_cookie);
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~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~
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...
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skeleton/pid_iter.bpf.c:49:9: error: returning 'void' from a function with incompatible result type '__u64' (aka 'unsigned long long')
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return BPF_CORE_READ(event, bpf_cookie);
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^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Tools and samples can't use any CONFIG_ definitions, so the fields
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used there should always be present.
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Define struct perf_event___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 perf_event
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accesses later on.
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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 | 6 +++++-
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1 file changed, 5 insertions(+), 1 deletion(-)
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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 eb05ea53afb1..e2af8e5fb29e 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 +15,10 @@ enum bpf_obj_type {
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BPF_OBJ_BTF,
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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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+
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extern const void bpf_link_fops __ksym;
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extern const void bpf_map_fops __ksym;
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extern const void bpf_prog_fops __ksym;
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@@ -41,8 +45,8 @@ 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 perf_event___local *event;
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struct bpf_perf_link *perf_link;
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- struct perf_event *event;
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perf_link = container_of(link, struct bpf_perf_link, link);
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event = BPF_CORE_READ(perf_link, perf_file, private_data);
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--
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2.40.0
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