From patchwork Thu Oct 10 14:31:38 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Adrian Hunter X-Patchwork-Id: 13830331 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.18]) (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 0A2C61CBEA0; Thu, 10 Oct 2024 14:32:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728570751; cv=none; b=cdRT6e/TaY7iMzGKgi8FAZEiEqjeFXkHbjrVIYicUxl2I+P6TctJK8clJj8kdh0A7h47ndedxJ+jtWQeUngOacK95onTjmSG+/wQdarxWIBcvKsroMY8KLrXEWmrAuC7B9p80iWliJFvBKJx+kZkbJbgjM4BadMzSgObJFKSiIg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728570751; c=relaxed/simple; bh=RIkzm8s+UqO9ZE+38HTFnfVOxc5zFK1dr9ab+2KoDs8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=c5RA2r8cIJjkImdJstOKkV8Xq0Zx9QqhJWJ29QiSKQb5z9w9Kc0VAm8N6wkXqm4JEkxZbeTbeZJab8eOHe5G8GeLgyH7IJ2IOlgqd5pg2PKQFc2VF2ONzghjFYU/6slaivQyjBO4Szvf0HNVVblGfAmyNJar2JwPjIuUfwzawqc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=lurMV7uk; arc=none smtp.client-ip=198.175.65.18 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="lurMV7uk" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1728570749; x=1760106749; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=RIkzm8s+UqO9ZE+38HTFnfVOxc5zFK1dr9ab+2KoDs8=; b=lurMV7uklchIaFTK7S6LxFnoyG2UGp1Yuo6oEQbuSHtFkR5UlT9kqs2e 6kizXZXSRdQ6q4Qe0gdP7DQrfI0fJlNKZaUexbgqjghbAdE4EDn67W4Vz HUgaaP1jGN2IANpOVzhdvFIjRmKkBVfi5RBl1PidJ299exigKbXKGgLq1 FL9TaVD9X/130Wpruh67x6Ij3WZYygcXBbZSx0R7H5E/KqI51h7BEHIBW I69B5tV6x3fbWRun4REW6LXLvbD14ohFqRzhvpWDCeuTViDfR1VKXu/cb cxnJTQi4OSvfYHC4r5BDc2+qsf64c6VVpK4CuCDyILS3Nxe9VQrNv1emy A==; X-CSE-ConnectionGUID: tVk66enbRVKMbwseClOOzw== X-CSE-MsgGUID: E9ORp1r1QwKQAsphItGlDQ== X-IronPort-AV: E=McAfee;i="6700,10204,11220"; a="28064057" X-IronPort-AV: E=Sophos;i="6.11,193,1725346800"; d="scan'208";a="28064057" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by orvoesa110.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Oct 2024 07:32:26 -0700 X-CSE-ConnectionGUID: DqQhQVeXTci6O6wKVy113g== X-CSE-MsgGUID: Xu6bnZqOSUSOMbU8Qdg5/Q== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.11,193,1725346800"; d="scan'208";a="81188970" Received: from ahunter6-mobl1.ger.corp.intel.com (HELO localhost.localdomain) ([10.246.16.81]) by fmviesa004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Oct 2024 07:32:15 -0700 From: Adrian Hunter To: Peter Zijlstra , Sean Christopherson , Paolo Bonzini Cc: Ingo Molnar , Mark Rutland , Alexander Shishkin , Heiko Carstens , Thomas Richter , Hendrik Brueckner , Suzuki K Poulose , Mike Leach , James Clark , coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, Yicong Yang , Jonathan Cameron , Will Deacon , Arnaldo Carvalho de Melo , Jiri Olsa , Namhyung Kim , Ian Rogers , Andi Kleen , Thomas Gleixner , Borislav Petkov , Dave Hansen , x86@kernel.org, H Peter Anvin , Kan Liang , Zhenyu Wang , kvm@vger.kernel.org, Shuah Khan , linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: [PATCH V12 01/14] perf/x86/intel/pt: Fix buffer full but size is 0 case Date: Thu, 10 Oct 2024 17:31:38 +0300 Message-ID: <20241010143152.19071-2-adrian.hunter@intel.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241010143152.19071-1-adrian.hunter@intel.com> References: <20241010143152.19071-1-adrian.hunter@intel.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki If the trace data buffer becomes full, a truncated flag [T] is reported in PERF_RECORD_AUX. In some cases, the size reported is 0, even though data must have been added to make the buffer full. That happens when the buffer fills up from empty to full before the Intel PT driver has updated the buffer position. Then the driver calculates the new buffer position before calculating the data size. If the old and new positions are the same, the data size is reported as 0, even though it is really the whole buffer size. Fix by detecting when the buffer position is wrapped, and adjust the data size calculation accordingly. Example Use a very small buffer size (8K) and observe the size of truncated [T] data. Before the fix, it is possible to see records of 0 size. Before: $ perf record -m,8K -e intel_pt// uname Linux [ perf record: Woken up 2 times to write data ] [ perf record: Captured and wrote 0.105 MB perf.data ] $ perf script -D --no-itrace | grep AUX | grep -F '[T]' Warning: AUX data lost 2 times out of 3! 5 19462712368111 0x19710 [0x40]: PERF_RECORD_AUX offset: 0 size: 0 flags: 0x1 [T] 5 19462712700046 0x19ba8 [0x40]: PERF_RECORD_AUX offset: 0x170 size: 0xe90 flags: 0x1 [T] After: $ perf record -m,8K -e intel_pt// uname Linux [ perf record: Woken up 3 times to write data ] [ perf record: Captured and wrote 0.040 MB perf.data ] $ perf script -D --no-itrace | grep AUX | grep -F '[T]' Warning: AUX data lost 2 times out of 3! 1 113720802995 0x4948 [0x40]: PERF_RECORD_AUX offset: 0 size: 0x2000 flags: 0x1 [T] 1 113720979812 0x6b10 [0x40]: PERF_RECORD_AUX offset: 0x2000 size: 0x2000 flags: 0x1 [T] Fixes: 52ca9ced3f70 ("perf/x86/intel/pt: Add Intel PT PMU driver") Cc: stable@vger.kernel.org Signed-off-by: Adrian Hunter --- arch/x86/events/intel/pt.c | 11 ++++++++--- arch/x86/events/intel/pt.h | 2 ++ 2 files changed, 10 insertions(+), 3 deletions(-) diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c index fd4670a6694e..a087bc0c5498 100644 --- a/arch/x86/events/intel/pt.c +++ b/arch/x86/events/intel/pt.c @@ -828,11 +828,13 @@ static void pt_buffer_advance(struct pt_buffer *buf) buf->cur_idx++; if (buf->cur_idx == buf->cur->last) { - if (buf->cur == buf->last) + if (buf->cur == buf->last) { buf->cur = buf->first; - else + buf->wrapped = true; + } else { buf->cur = list_entry(buf->cur->list.next, struct topa, list); + } buf->cur_idx = 0; } } @@ -846,8 +848,11 @@ static void pt_buffer_advance(struct pt_buffer *buf) static void pt_update_head(struct pt *pt) { struct pt_buffer *buf = perf_get_aux(&pt->handle); + bool wrapped = buf->wrapped; u64 topa_idx, base, old; + buf->wrapped = false; + if (buf->single) { local_set(&buf->data_size, buf->output_off); return; @@ -865,7 +870,7 @@ static void pt_update_head(struct pt *pt) } else { old = (local64_xchg(&buf->head, base) & ((buf->nr_pages << PAGE_SHIFT) - 1)); - if (base < old) + if (base < old || (base == old && wrapped)) base += buf->nr_pages << PAGE_SHIFT; local_add(base - old, &buf->data_size); diff --git a/arch/x86/events/intel/pt.h b/arch/x86/events/intel/pt.h index f5e46c04c145..a1b6c04b7f68 100644 --- a/arch/x86/events/intel/pt.h +++ b/arch/x86/events/intel/pt.h @@ -65,6 +65,7 @@ struct pt_pmu { * @head: logical write offset inside the buffer * @snapshot: if this is for a snapshot/overwrite counter * @single: use Single Range Output instead of ToPA + * @wrapped: buffer advance wrapped back to the first topa table * @stop_pos: STOP topa entry index * @intr_pos: INT topa entry index * @stop_te: STOP topa entry pointer @@ -82,6 +83,7 @@ struct pt_buffer { local64_t head; bool snapshot; bool single; + bool wrapped; long stop_pos, intr_pos; struct topa_entry *stop_te, *intr_te; void **data_pages;