linux-kernel - Re: [PATCH V7 04/15] kprobes: Add perf ksymbol events for kprobe insn pages

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Message-ID: <20200527161732.GA706495@hirez.programming.kicks-ass.net>
Date:   Wed, 27 May 2020 18:17:32 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Leo Yan <leo.yan@...aro.org>, Jiri Olsa <jolsa@...hat.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V7 04/15] kprobes: Add perf ksymbol events for kprobe
 insn pages

On Tue, May 12, 2020 at 03:19:11PM +0300, Adrian Hunter wrote:
> @@ -202,6 +207,13 @@ static int collect_one_slot(struct kprobe_insn_page *kip, int idx)
>  		 * next time somebody inserts a probe.
>  		 */
>  		if (!list_is_singular(&kip->list)) {
> +			/*
> +			 * Record perf ksymbol unregister event before removing
> +			 * the page.
> +			 */
> +			perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL,
> +					   (u64)kip->insns, PAGE_SIZE, true,
> +					   kip->cache->sym);
>  			list_del_rcu(&kip->list);
>  			synchronize_rcu();
>  			kip->cache->free(kip->insns);

My manual build script haz complaints:

i386-defconfig  ../kernel/kprobes.c: In function ‘__get_insn_slot’:
../kernel/kprobes.c:190:51: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL, (u64)kip->insns,
^
../kernel/kprobes.c: In function ‘collect_one_slot’:
../kernel/kprobes.c:215:9: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
(u64)kip->insns, PAGE_SIZE, true,
^
FAIL


Now, there's a ton of such warnings elsewhere in the tree, but still I
feel we should perhaps strive for a clean build.