From patchwork Thu Jun 6 21:17:41 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 13688994 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 E7EF7196DAB; Thu, 6 Jun 2024 21:21:31 +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=1717708892; cv=none; b=CNk4/1w0m2lSr+4xjwx9Vl2VrjGsa0oOt8Cm7Z8gdRdQ1VTTU+OBz/9RhgV8GHZ8mg4WesPuu9ve+e06IcLUcCj+CylQxqPEr6n2WiNzBKxsXhlFdRRAPfJ4L926JEMjo04A8ZSf0SXJAshBiuLn6rM2bjzXZd6bmsoA3gVUa88= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717708892; c=relaxed/simple; bh=jN0UJbZ1ieOpK2a7AmK6Zn7zT7sw+AyyRVp/MP8Ex34=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=KKOV0b/JeuOwx0URV6uNBqtVv1gaLEPcqUwOtSfWOY4H0fJdA189/EHAoDMEwOApFBvDrxuaMWVBFDOzC0j7v3Cl3MeoUbQqJO6LISkVlMIAH9pOEbq2vreDh78zRHKVbRWbx8uSF1rY7gStQRgnjS+admeIyslADWhzs+puvfw= 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 B18A3C4AF1C; Thu, 6 Jun 2024 21:21:31 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.97) (envelope-from ) id 1sFKYD-00000000qKD-0btQ; Thu, 06 Jun 2024 17:21:37 -0400 Message-ID: <20240606212137.006600684@goodmis.org> User-Agent: quilt/0.68 Date: Thu, 06 Jun 2024 17:17:41 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , Vincent Donnefort , Joel Fernandes , Daniel Bristot de Oliveira , Ingo Molnar , Peter Zijlstra , suleiman@google.com, Thomas Gleixner , Vineeth Pillai , Youssef Esmat , Beau Belgrave , Alexander Graf , Baoquan He , Borislav Petkov , "Paul E. McKenney" , David Howells , Mike Rapoport , Dave Hansen , Tony Luck , Guenter Roeck , Ross Zwisler , Kees Cook Subject: [PATCH v3 06/13] ring-buffer: Add test if range of boot buffer is valid References: <20240606211735.684785459@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 (Google)" Add a test against the ring buffer memory range to see if it has valid data. The ring_buffer_meta structure is given a new field called "first_buffer" which holds the address of the first sub-buffer. This is used to both determine if the other fields are valid as well as finding the offset between the old addresses of the sub-buffer from the previous boot to the new addresses of the current boot. Since the values for nr_subbufs and subbuf_size is to be the same, check if the values in the meta page match the values calculated. Take the range of the first_buffer and the total size of all the buffers and make sure the saved head_buffer and commit_buffer fall in the range. Iterate through all the sub-buffers to make sure that the values in the sub-buffer "commit" field (the field that holds the amount of data on the sub-buffer) is within the end of the sub-buffer. Also check the index array to make sure that all the indexes are within nr_subbufs. Signed-off-by: Steven Rostedt (Google) --- kernel/trace/ring_buffer.c | 143 ++++++++++++++++++++++++++++++++++--- 1 file changed, 135 insertions(+), 8 deletions(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 093c73c617cc..aecd4a7d62be 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -45,6 +45,7 @@ static void update_pages_handler(struct work_struct *work); struct ring_buffer_meta { + unsigned long first_buffer; unsigned long head_buffer; unsigned long commit_buffer; __u32 subbuf_size; @@ -1617,21 +1618,103 @@ static void *rb_range_buffer(struct ring_buffer_per_cpu *cpu_buffer, int idx) return (void *)ptr; } +/* + * See if the existing memory contains valid ring buffer data. + * As the previous kernel must be the same as this kernel, all + * the calculations (size of buffers and number of buffers) + * must be the same. + */ +static bool rb_meta_valid(struct ring_buffer_meta *meta, int cpu, + struct trace_buffer *buffer, int nr_pages) +{ + int subbuf_size = PAGE_SIZE; + struct buffer_data_page *subbuf; + unsigned long buffers_start; + unsigned long buffers_end; + int i; + + /* The subbuffer's size and number of subbuffers must match */ + if (meta->subbuf_size != subbuf_size || + meta->nr_subbufs != nr_pages + 1) { + pr_info("Ring buffer boot meta [%d] mismatch of subbuf_size/nr_pages\n", cpu); + return false; + } + + buffers_start = meta->first_buffer; + buffers_end = meta->first_buffer + (subbuf_size * meta->nr_subbufs); + + /* Is the head and commit buffers within the range of buffers? */ + if (meta->head_buffer < buffers_start || + meta->head_buffer >= buffers_end) { + pr_info("Ring buffer boot meta [%d] head buffer out of range\n", cpu); + return false; + } + + if (meta->commit_buffer < buffers_start || + meta->commit_buffer >= buffers_end) { + pr_info("Ring buffer boot meta [%d] commit buffer out of range\n", cpu); + return false; + } + + subbuf = rb_subbufs_from_meta(meta); + + /* Is the meta buffers and the subbufs themselves have correct data? */ + for (i = 0; i < meta->nr_subbufs; i++) { + if (meta->buffers[i] < 0 || + meta->buffers[i] >= meta->nr_subbufs) { + pr_info("Ring buffer boot meta [%d] array out of range\n", cpu); + return false; + } + + if ((unsigned)local_read(&subbuf->commit) > subbuf_size) { + pr_info("Ring buffer boot meta [%d] buffer invalid commit\n", cpu); + return false; + } + + subbuf = (void *)subbuf + subbuf_size; + } + + pr_info("Ring buffer meta is from previous boot!\n"); + return true; +} + static void rb_range_meta_init(struct trace_buffer *buffer, int nr_pages) { struct ring_buffer_meta *meta; + unsigned long delta; void *subbuf; int cpu; int i; for (cpu = 0; cpu < nr_cpu_ids; cpu++) { + void *next_meta; + meta = rb_range_meta(buffer, nr_pages, cpu); + if (rb_meta_valid(meta, cpu, buffer, nr_pages)) { + /* Make the mappings match the current address */ + subbuf = rb_subbufs_from_meta(meta); + delta = (unsigned long)subbuf - meta->first_buffer; + meta->first_buffer += delta; + meta->head_buffer += delta; + meta->commit_buffer += delta; + continue; + } + + if (cpu < nr_cpu_ids - 1) + next_meta = rb_range_meta(buffer, nr_pages, cpu + 1); + else + next_meta = (void *)buffer->range_addr_end; + + memset(meta, 0, next_meta - (void *)meta); + meta->nr_subbufs = nr_pages + 1; meta->subbuf_size = PAGE_SIZE; subbuf = rb_subbufs_from_meta(meta); + meta->first_buffer = (unsigned long)subbuf; + /* * The buffers[] array holds the order of the sub-buffers * that are after the meta data. The sub-buffers may @@ -1723,10 +1806,26 @@ int ring_buffer_meta_seq_init(struct file *file, struct trace_buffer *buffer, in return 0; } +/* Map the buffer_pages to the previous head and commit pages */ +static void rb_meta_buffer_update(struct ring_buffer_per_cpu *cpu_buffer, + struct buffer_page *bpage) +{ + struct ring_buffer_meta *meta = cpu_buffer->ring_meta; + + if (meta->head_buffer == (unsigned long)bpage->page) + cpu_buffer->head_page = bpage; + + if (meta->commit_buffer == (unsigned long)bpage->page) { + cpu_buffer->commit_page = bpage; + cpu_buffer->tail_page = bpage; + } +} + static int __rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, long nr_pages, struct list_head *pages) { struct trace_buffer *buffer = cpu_buffer->buffer; + struct ring_buffer_meta *meta = NULL; struct buffer_page *bpage, *tmp; bool user_thread = current->mm != NULL; gfp_t mflags; @@ -1761,6 +1860,10 @@ static int __rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, */ if (user_thread) set_current_oom_origin(); + + if (buffer->range_addr_start) + meta = rb_range_meta(buffer, nr_pages, cpu_buffer->cpu); + for (i = 0; i < nr_pages; i++) { struct page *page; @@ -1777,11 +1880,14 @@ static int __rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, */ list_add_tail(&bpage->list, pages); - if (buffer->range_addr_start) { + if (meta) { /* A range was given. Use that for the buffer page */ bpage->page = rb_range_buffer(cpu_buffer, i + 1); if (!bpage->page) goto free_pages; + /* If this is valid from a previous boot */ + if (meta->head_buffer) + rb_meta_buffer_update(cpu_buffer, bpage); bpage->range = 1; bpage->id = i + 1; } else { @@ -1843,6 +1949,7 @@ static struct ring_buffer_per_cpu * rb_allocate_cpu_buffer(struct trace_buffer *buffer, long nr_pages, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; + struct ring_buffer_meta *meta; struct buffer_page *bpage; struct page *page; int ret; @@ -1883,6 +1990,8 @@ rb_allocate_cpu_buffer(struct trace_buffer *buffer, long nr_pages, int cpu) bpage->page = rb_range_buffer(cpu_buffer, 0); if (!bpage->page) goto fail_free_reader; + if (cpu_buffer->ring_meta->head_buffer) + rb_meta_buffer_update(cpu_buffer, bpage); bpage->range = 1; } else { page = alloc_pages_node(cpu_to_node(cpu), @@ -1901,14 +2010,32 @@ rb_allocate_cpu_buffer(struct trace_buffer *buffer, long nr_pages, int cpu) if (ret < 0) goto fail_free_reader; - cpu_buffer->head_page - = list_entry(cpu_buffer->pages, struct buffer_page, list); - cpu_buffer->tail_page = cpu_buffer->commit_page = cpu_buffer->head_page; + /* If the boot meta was valid then this has already been updated */ + meta = cpu_buffer->ring_meta; + if (!meta || !meta->head_buffer || + !cpu_buffer->head_page || !cpu_buffer->commit_page || !cpu_buffer->tail_page) { + if (meta && meta->head_buffer && + (cpu_buffer->head_page || cpu_buffer->commit_page || cpu_buffer->tail_page)) { + pr_warn("Ring buffer meta buffers not all mapped\n"); + if (!cpu_buffer->head_page) + pr_warn(" Missing head_page\n"); + if (!cpu_buffer->commit_page) + pr_warn(" Missing commit_page\n"); + if (!cpu_buffer->tail_page) + pr_warn(" Missing tail_page\n"); + } - rb_head_page_activate(cpu_buffer); - if (cpu_buffer->ring_meta) { - struct ring_buffer_meta *meta = cpu_buffer->ring_meta; - meta->commit_buffer = meta->head_buffer; + cpu_buffer->head_page + = list_entry(cpu_buffer->pages, struct buffer_page, list); + cpu_buffer->tail_page = cpu_buffer->commit_page = cpu_buffer->head_page; + + rb_head_page_activate(cpu_buffer); + + if (cpu_buffer->ring_meta) + meta->commit_buffer = meta->head_buffer; + } else { + /* The valid meta buffer still needs to activate the head page */ + rb_head_page_activate(cpu_buffer); } return cpu_buffer;