From nobody Sun Feb 8 16:12:26 2026 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1CF061095C; Wed, 10 Apr 2024 04:57:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712725070; cv=none; b=eLMBfpx6BKwduRYjBPl8oTjUcjJOYJCReTmxZwJvy0IJWqqql4EHTyxU7j2Uc9U9r+gHwnAbtgys8Kcd+IRMSTyEHUyWXN9lxZL5saK1mPRt7JUpSbJ/4srJtBd4gn13Qaz4vGcb1I8PoJjzP/kS4e2mhZrVB72nP0jyaw7Q/fw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712725070; c=relaxed/simple; bh=S312C+gavUYz8h3A2GcgRimqY7cpLQKh9KZOsaixUAU=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=PFBMKaop06N1MQXd1fT4iMa0C6zDRjMVjTJeqjZQkk1grb/vTT9el3D+eCK83oYTsxLMW+uvYAizk/Gce86GkteSAvXsqKB2M66AqmdVNl7Y4Aih3yupvRJ0y2wVqwB1cwyrJq5HnSED2QaIUdcyxIDwNfNk0lwVIDJY5mp5jCo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=XvMZH0y3; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=DF79d8tP; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="XvMZH0y3"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="DF79d8tP" Date: Wed, 10 Apr 2024 04:57:46 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1712725067; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=wDT1P1cWGh7lNYe8T33JKPfDBX0TWzCN2az5ox4/RaY=; b=XvMZH0y3cA5pod7CUg+EWQ8reIULmyMxyAKn8X3EFPokSjGsS8oQ9XvtUgx+0Uoe/kxqvy hvUNkjSBGOh7ysReM9scteBhpErEb7V9ADZEtHzjS0905sNiDvmZ2aHYR5b63Ts1r2EGOk NFYZl1HypebCPWnfwHPbWhveAyfhtFutlROC3YWFp3P/EHccGhRqMXWc/NT6vpa9J8Mbrn GubNHKCxTDie6i0LNua80LwpsdPo9DK/Ol7x/ZbLiOWWFcyZ1foQXCxYQzRE24Prj3XmAV OCiNPn/ZTP0Ic8w6qdiL4hPgNi9CTgq3+ZIrajNsgGP29CTVULGYqDrFE19aUQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1712725067; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=wDT1P1cWGh7lNYe8T33JKPfDBX0TWzCN2az5ox4/RaY=; b=DF79d8tPg7AyZt9YNEEnf6uW3oQQCI6mM4W7lLYbm1FI2BeYJ18GQNGyhDYjbhKsOkXdJK f+y1rOnc4kOdKJAA== From: "tip-bot2 for Namhyung Kim" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: perf/urgent] perf/x86: Fix out of range data Cc: Namhyung Kim , Ingo Molnar , Kan Liang , stable@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20240306061003.1894224-1-namhyung@kernel.org> References: <20240306061003.1894224-1-namhyung@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <171272506661.10875.17620123228073910318.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the perf/urgent branch of tip: Commit-ID: dec8ced871e17eea46f097542dd074d022be4bd1 Gitweb: https://git.kernel.org/tip/dec8ced871e17eea46f097542dd074d02= 2be4bd1 Author: Namhyung Kim AuthorDate: Tue, 05 Mar 2024 22:10:03 -08:00 Committer: Ingo Molnar CommitterDate: Wed, 10 Apr 2024 06:12:01 +02:00 perf/x86: Fix out of range data On x86 each struct cpu_hw_events maintains a table for counter assignment b= ut it missed to update one for the deleted event in x86_pmu_del(). This can make perf_clear_dirty_counters() reset used counter if it's called before event scheduling or enabling. Then it would return out of range data which doesn't make sense. The following code can reproduce the problem. $ cat repro.c #include #include #include #include #include #include #include #include struct perf_event_attr attr =3D { .type =3D PERF_TYPE_HARDWARE, .config =3D PERF_COUNT_HW_CPU_CYCLES, .disabled =3D 1, }; void *worker(void *arg) { int cpu =3D (long)arg; int fd1 =3D syscall(SYS_perf_event_open, &attr, -1, cpu, -1, 0); int fd2 =3D syscall(SYS_perf_event_open, &attr, -1, cpu, -1, 0); void *p; do { ioctl(fd1, PERF_EVENT_IOC_ENABLE, 0); p =3D mmap(NULL, 4096, PROT_READ, MAP_SHARED, fd1, 0); ioctl(fd2, PERF_EVENT_IOC_ENABLE, 0); ioctl(fd2, PERF_EVENT_IOC_DISABLE, 0); munmap(p, 4096); ioctl(fd1, PERF_EVENT_IOC_DISABLE, 0); } while (1); return NULL; } int main(void) { int i; int n =3D sysconf(_SC_NPROCESSORS_ONLN); pthread_t *th =3D calloc(n, sizeof(*th)); for (i =3D 0; i < n; i++) pthread_create(&th[i], NULL, worker, (void *)(long)i); for (i =3D 0; i < n; i++) pthread_join(th[i], NULL); free(th); return 0; } And you can see the out of range data using perf stat like this. Probably it'd be easier to see on a large machine. $ gcc -o repro repro.c -pthread $ ./repro & $ sudo perf stat -A -I 1000 2>&1 | awk '{ if (length($3) > 15) print }' 1.001028462 CPU6 196,719,295,683,763 cycles = # 194290.996 GHz (71.54%) 1.001028462 CPU3 396,077,485,787,730 branch-misses = # 15804359784.80% of all branches (71.07%) 1.001028462 CPU17 197,608,350,727,877 branch-misses = # 14594186554.56% of all branches (71.22%) 2.020064073 CPU4 198,372,472,612,140 cycles = # 194681.113 GHz (70.95%) 2.020064073 CPU6 199,419,277,896,696 cycles = # 195720.007 GHz (70.57%) 2.020064073 CPU20 198,147,174,025,639 cycles = # 194474.654 GHz (71.03%) 2.020064073 CPU20 198,421,240,580,145 stalled-cycles-frontend = # 100.14% frontend cycles idle (70.93%) 3.037443155 CPU4 197,382,689,923,416 cycles = # 194043.065 GHz (71.30%) 3.037443155 CPU20 196,324,797,879,414 cycles = # 193003.773 GHz (71.69%) 3.037443155 CPU5 197,679,956,608,205 stalled-cycles-backend = # 1315606428.66% backend cycles idle (71.19%) 3.037443155 CPU5 198,571,860,474,851 instructions = # 13215422.58 insn per cycle It should move the contents in the cpuc->assign as well. Fixes: 5471eea5d3bf ("perf/x86: Reset the dirty counter to prevent the leak= for an RDPMC task") Signed-off-by: Namhyung Kim Signed-off-by: Ingo Molnar Reviewed-by: Kan Liang Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20240306061003.1894224-1-namhyung@kernel.org --- arch/x86/events/core.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index 0905064..5b0dd07 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -1644,6 +1644,7 @@ static void x86_pmu_del(struct perf_event *event, int= flags) while (++i < cpuc->n_events) { cpuc->event_list[i-1] =3D cpuc->event_list[i]; cpuc->event_constraint[i-1] =3D cpuc->event_constraint[i]; + cpuc->assign[i-1] =3D cpuc->assign[i]; } cpuc->event_constraint[i-1] =3D NULL; --cpuc->n_events;