Re: [PATCH 2/2] perf tools: Fix hybrid config terms list corruption
From: Jiri Olsa
Date: Fri Sep 10 2021 - 15:33:10 EST
On Thu, Sep 09, 2021 at 03:55:08PM +0300, Adrian Hunter wrote:
> A config terms list was spliced twice, resulting in a never-ending loop
> when the list was traversed. Fix by using list_splice_init() and copying
> and freeing the lists as necessary.
>
> This patch also depends on patch "perf tools: Factor out
> copy_config_terms() and free_config_terms()"
>
> Example on ADL:
>
> Before:
>
> # perf record -e '{intel_pt//,cycles/aux-sample-size=4096/pp}' uname &
> # jobs
> [1]+ Running perf record -e "{intel_pt//,cycles/aux-sample-size=4096/pp}" uname
> # perf top -E 10
> PerfTop: 4071 irqs/sec kernel: 6.9% exact: 100.0% lost: 0/0 drop: 0/0 [4000Hz cycles], (all, 24 CPUs)
> ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> 97.60% perf [.] __evsel__get_config_term
> 0.25% [kernel] [k] kallsyms_expand_symbol.constprop.13
> 0.24% perf [.] kallsyms__parse
> 0.15% [kernel] [k] _raw_spin_lock
> 0.14% [kernel] [k] number
> 0.13% [kernel] [k] advance_transaction
> 0.08% [kernel] [k] format_decode
> 0.08% perf [.] map__process_kallsym_symbol
> 0.08% perf [.] rb_insert_color
> 0.08% [kernel] [k] vsnprintf
> exiting.
> # kill %1
>
> After:
>
> # perf record -e '{intel_pt//,cycles/aux-sample-size=4096/pp}' uname &
> Linux
> [ perf record: Woken up 1 times to write data ]
> [ perf record: Captured and wrote 0.060 MB perf.data ]
> # perf script | head
> perf-exec 604 [001] 1827.312293: psb: psb offs: 0 ffffffffb8415e87 pt_config_start+0x37 ([kernel.kallsyms])
> perf-exec 604 1827.312293: 1 branches: ffffffffb856a3bd event_sched_in.isra.133+0xfd ([kernel.kallsyms]) => ffffffffb856a9a0 perf_pmu_nop_void+0x0 ([kernel.kallsyms])
> perf-exec 604 1827.312293: 1 branches: ffffffffb856b10e merge_sched_in+0x26e ([kernel.kallsyms]) => ffffffffb856a2c0 event_sched_in.isra.133+0x0 ([kernel.kallsyms])
> perf-exec 604 1827.312293: 1 branches: ffffffffb856a45d event_sched_in.isra.133+0x19d ([kernel.kallsyms]) => ffffffffb8568b80 perf_event_set_state.part.61+0x0 ([kernel.kallsyms])
> perf-exec 604 1827.312293: 1 branches: ffffffffb8568b86 perf_event_set_state.part.61+0x6 ([kernel.kallsyms]) => ffffffffb85662a0 perf_event_update_time+0x0 ([kernel.kallsyms])
> perf-exec 604 1827.312293: 1 branches: ffffffffb856a35c event_sched_in.isra.133+0x9c ([kernel.kallsyms]) => ffffffffb8567610 perf_log_itrace_start+0x0 ([kernel.kallsyms])
> perf-exec 604 1827.312293: 1 branches: ffffffffb856a377 event_sched_in.isra.133+0xb7 ([kernel.kallsyms]) => ffffffffb8403b40 x86_pmu_add+0x0 ([kernel.kallsyms])
> perf-exec 604 1827.312293: 1 branches: ffffffffb8403b86 x86_pmu_add+0x46 ([kernel.kallsyms]) => ffffffffb8403940 collect_events+0x0 ([kernel.kallsyms])
> perf-exec 604 1827.312293: 1 branches: ffffffffb8403a7b collect_events+0x13b ([kernel.kallsyms]) => ffffffffb8402cd0 collect_event+0x0 ([kernel.kallsyms])
>
> Fixes: 94da591b1c7913 ("perf parse-events: Create two hybrid raw events")
> Fixes: 9cbfa2f64c04d9 ("perf parse-events: Create two hybrid hardware events")
> Fixes: 30def61f64bac5 ("perf parse-events: Create two hybrid cache events")
> Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> ---
> tools/perf/util/parse-events-hybrid.c | 18 +++++++++++++++---
> tools/perf/util/parse-events.c | 18 ++++++++++++------
> 2 files changed, 27 insertions(+), 9 deletions(-)
>
> diff --git a/tools/perf/util/parse-events-hybrid.c b/tools/perf/util/parse-events-hybrid.c
> index 10160ab126f9..b234d95fb10a 100644
> --- a/tools/perf/util/parse-events-hybrid.c
> +++ b/tools/perf/util/parse-events-hybrid.c
> @@ -76,12 +76,16 @@ static int add_hw_hybrid(struct parse_events_state *parse_state,
> int ret;
>
> perf_pmu__for_each_hybrid_pmu(pmu) {
> + LIST_HEAD(terms);
> +
> if (pmu_cmp(parse_state, pmu))
> continue;
>
> + copy_config_terms(&terms, config_terms);
> ret = create_event_hybrid(PERF_TYPE_HARDWARE,
> &parse_state->idx, list, attr, name,
> - config_terms, pmu);
> + &terms, pmu);
> + free_config_terms(&terms);
hm, why is this needed.. there's now list_splice_init &terms within
create_event_hybrid call right? so there should be nothing nothing
to clean
same below
> if (ret)
> return ret;
> }
> @@ -115,11 +119,15 @@ static int add_raw_hybrid(struct parse_events_state *parse_state,
> int ret;
>
> perf_pmu__for_each_hybrid_pmu(pmu) {
> + LIST_HEAD(terms);
> +
> if (pmu_cmp(parse_state, pmu))
> continue;
>
> + copy_config_terms(&terms, config_terms);
> ret = create_raw_event_hybrid(&parse_state->idx, list, attr,
> - name, config_terms, pmu);
> + name, &terms, pmu);
> + free_config_terms(&terms);
> if (ret)
> return ret;
> }
> @@ -165,11 +173,15 @@ int parse_events__add_cache_hybrid(struct list_head *list, int *idx,
>
> *hybrid = true;
> perf_pmu__for_each_hybrid_pmu(pmu) {
> + LIST_HEAD(terms);
> +
> if (pmu_cmp(parse_state, pmu))
> continue;
>
> + copy_config_terms(&terms, config_terms);
> ret = create_event_hybrid(PERF_TYPE_HW_CACHE, idx, list,
> - attr, name, config_terms, pmu);
> + attr, name, &terms, pmu);
> + free_config_terms(&terms);
> if (ret)
> return ret;
> }
> diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
> index ded5808798f9..51a2219df601 100644
> --- a/tools/perf/util/parse-events.c
> +++ b/tools/perf/util/parse-events.c
> @@ -387,7 +387,7 @@ __add_event(struct list_head *list, int *idx,
> evsel->name = strdup(name);
>
> if (config_terms)
> - list_splice(config_terms, &evsel->config_terms);
> + list_splice_init(config_terms, &evsel->config_terms);
>
> if (list)
> list_add_tail(&evsel->core.node, list);
> @@ -535,9 +535,12 @@ int parse_events_add_cache(struct list_head *list, int *idx,
> config_name ? : name, &config_terms,
> &hybrid, parse_state);
> if (hybrid)
> - return ret;
> + goto out_free_terms;
>
> - return add_event(list, idx, &attr, config_name ? : name, &config_terms);
> + ret = add_event(list, idx, &attr, config_name ? : name, &config_terms);
> +out_free_terms:
> + free_config_terms(&config_terms);
.. apart from this one and below, when coming from 'goto out_free_terms'
we should call free_config_terms
jirka
> + return ret;
> }
>
> static void tracepoint_error(struct parse_events_error *e, int err,
> @@ -1457,10 +1460,13 @@ int parse_events_add_numeric(struct parse_events_state *parse_state,
> get_config_name(head_config),
> &config_terms, &hybrid);
> if (hybrid)
> - return ret;
> + goto out_free_terms;
>
> - return add_event(list, &parse_state->idx, &attr,
> - get_config_name(head_config), &config_terms);
> + ret = add_event(list, &parse_state->idx, &attr,
> + get_config_name(head_config), &config_terms);
> +out_free_terms:
> + free_config_terms(&config_terms);
> + return ret;
> }
>
> int parse_events_add_tool(struct parse_events_state *parse_state,
> --
> 2.17.1
>