From patchwork Wed Apr 2 14:49:04 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 14036112 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 8363023A9BA; Wed, 2 Apr 2025 14:48:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743605330; cv=none; b=bQepXt/MBbKAqovwEfuUff7/bA0JarmDwjFawFo0ZPIep28WM8ttab5z0SeTNhGyP6KWKmQsva5MixTU1wvey83t/RSMs0jNogFRyhRBboDswhdUP4bsZid49+dZL7mRiYBsIQd0+QUR6YQGSux8WyvoDyPrPaKcZCJkOaUtSug= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743605330; c=relaxed/simple; bh=kD1slgJMHB22SQH7ZSUUCP8644JVmC+VECus+O3nWzc=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=GsTTGSyMk/9sZ8aRD08VgIDOFeApTnB4b1ltximkDAfjlATqKDWXd10GtE68zrzYeC8QP+0kO0mw+6UYCD3NxB0KihCixth2hZaECcpb7iuR/if/Gsr+gyxCex117S3HWi9PDyOnW3f9UoPiIBZd7ifKBbZriJJPo+qX9Xyevx4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 01356C4CEDD; Wed, 2 Apr 2025 14:48:50 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.98) (envelope-from ) id 1tzzPd-00000006SOA-2MRv; Wed, 02 Apr 2025 10:49:53 -0400 Message-ID: <20250402144953.412882844@goodmis.org> User-Agent: quilt/0.68 Date: Wed, 02 Apr 2025 10:49:04 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: Linus Torvalds , Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , Vincent Donnefort , Vlastimil Babka , Mike Rapoport , Jann Horn Subject: [PATCH v6 1/4] tracing: Enforce the persistent ring buffer to be page aligned References: <20250402144903.993276623@goodmis.org> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Steven Rostedt Enforce that the address and the size of the memory used by the persistent ring buffer is page aligned. Also update the documentation to reflect this requirement. Link: https://lore.kernel.org/all/CAHk-=whUOfVucfJRt7E0AH+GV41ELmS4wJqxHDnui6Giddfkzw@mail.gmail.com/ Suggested-by: Linus Torvalds Signed-off-by: Steven Rostedt (Google) --- Change since v5: https://lore.kernel.org/linux-trace-kernel/20250401225842.261475465@goodmis.org/ - Use %pa instead of %lx for start and size sizes (Mike Rapoport) Documentation/admin-guide/kernel-parameters.txt | 2 ++ Documentation/trace/debugging.rst | 2 ++ kernel/trace/trace.c | 10 ++++++++++ 3 files changed, 14 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index fb8752b42ec8..71861643ef14 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -7241,6 +7241,8 @@ This is just one of many ways that can clear memory. Make sure your system keeps the content of memory across reboots before relying on this option. + NB: Both the mapped address and size must be page aligned for the architecture. + See also Documentation/trace/debugging.rst diff --git a/Documentation/trace/debugging.rst b/Documentation/trace/debugging.rst index 54fb16239d70..d54bc500af80 100644 --- a/Documentation/trace/debugging.rst +++ b/Documentation/trace/debugging.rst @@ -136,6 +136,8 @@ kernel, so only the same kernel is guaranteed to work if the mapping is preserved. Switching to a different kernel version may find a different layout and mark the buffer as invalid. +NB: Both the mapped address and size must be page aligned for the architecture. + Using trace_printk() in the boot instance ----------------------------------------- By default, the content of trace_printk() goes into the top level tracing diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 14c38fcd6f9e..96129985e81c 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -10774,6 +10774,16 @@ __init static void enable_instances(void) } if (start) { + /* Start and size must be page aligned */ + if (start & ~PAGE_MASK) { + pr_warn("Tracing: mapping start addr %pa is not page aligned\n", &start); + continue; + } + if (size & ~PAGE_MASK) { + pr_warn("Tracing: mapping size %pa is not page aligned\n", &size); + continue; + } + addr = map_pages(start, size); if (addr) { pr_info("Tracing: mapped boot instance %s at physical memory %pa of size 0x%lx\n",