From patchwork Wed Jun 12 23:19:35 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 13695649 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 A296685628; Wed, 12 Jun 2024 23:20:06 +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=1718234406; cv=none; b=fsjEzANQa/Cbf0Mb7H6HHuWzGA4WCNT5sKnqpFhqodHv22g13lIwBRNOBcKOl4nYTtyF+kBtZF6ocXsjIpKzkQz4cQbZOqASrQUpkn9VQHvqVo4QKDrYQM/cmnxePOtloe6K4uu45ihdvXO4nDgUwMItiIYaG8Hq/mCXwAZDoE0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718234406; c=relaxed/simple; bh=IQYpl+fCq2H5NORUixnSFb3mnEyzzn9b34t7uIu/PKQ=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=WvIFVXv7DGRBHICsKng2OSGjI4QGyBjuinc40t2i9CDleFIFpTn0PnrzO3qZKa/yOokBl/39J9OSZZllyEH/x1GTBYz7FPGrMgQ1I9gm9ZCGHr4lGLoK35+PgxF9MmGkEnsvmVUX6Q6lkQR02B/Eixhctpy3s/rWFrD37hdjyQM= 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 32D10C116B1; Wed, 12 Jun 2024 23:20:06 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.97) (envelope-from ) id 1sHXGT-00000001daV-1OGS; Wed, 12 Jun 2024 19:20:25 -0400 Message-ID: <20240612232025.190908567@goodmis.org> User-Agent: quilt/0.68 Date: Wed, 12 Jun 2024 19:19:35 -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 v6 01/13] ring-buffer: Allow mapped field to be set without mapping References: <20240612231934.608252486@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)" In preparation for having the ring buffer mapped to a dedicated location, which will have the same restrictions as user space memory mapped buffers, allow it to use the "mapped" field of the ring_buffer_per_cpu structure without having the user space meta page mapping. When this starts using the mapped field, it will need to handle adding a user space mapping (and removing it) from a ring buffer that is using a dedicated memory range. Signed-off-by: Steven Rostedt (Google) --- kernel/trace/ring_buffer.c | 37 +++++++++++++++++++++++++++---------- 1 file changed, 27 insertions(+), 10 deletions(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 28853966aa9a..a240bdc0f2d8 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -491,6 +491,7 @@ struct ring_buffer_per_cpu { unsigned long pages_removed; unsigned int mapped; + unsigned int user_mapped; /* user space mapping */ struct mutex mapping_lock; unsigned long *subbuf_ids; /* ID to subbuf VA */ struct trace_buffer_meta *meta_page; @@ -5224,6 +5225,9 @@ static void rb_update_meta_page(struct ring_buffer_per_cpu *cpu_buffer) { struct trace_buffer_meta *meta = cpu_buffer->meta_page; + if (!meta) + return; + meta->reader.read = cpu_buffer->reader_page->read; meta->reader.id = cpu_buffer->reader_page->id; meta->reader.lost_events = cpu_buffer->lost_events; @@ -5280,7 +5284,7 @@ rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) cpu_buffer->lost_events = 0; cpu_buffer->last_overrun = 0; - if (cpu_buffer->mapped) + if (cpu_buffer->user_mapped) rb_update_meta_page(cpu_buffer); rb_head_page_activate(cpu_buffer); @@ -6167,7 +6171,7 @@ rb_get_mapped_buffer(struct trace_buffer *buffer, int cpu) mutex_lock(&cpu_buffer->mapping_lock); - if (!cpu_buffer->mapped) { + if (!cpu_buffer->user_mapped) { mutex_unlock(&cpu_buffer->mapping_lock); return ERR_PTR(-ENODEV); } @@ -6191,19 +6195,26 @@ static int __rb_inc_dec_mapped(struct ring_buffer_per_cpu *cpu_buffer, lockdep_assert_held(&cpu_buffer->mapping_lock); + /* mapped is always greater or equal to user_mapped */ + if (WARN_ON(cpu_buffer->mapped < cpu_buffer->user_mapped)) + return -EINVAL; + if (inc && cpu_buffer->mapped == UINT_MAX) return -EBUSY; - if (WARN_ON(!inc && cpu_buffer->mapped == 0)) + if (WARN_ON(!inc && cpu_buffer->user_mapped == 0)) return -EINVAL; mutex_lock(&cpu_buffer->buffer->mutex); raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); - if (inc) + if (inc) { + cpu_buffer->user_mapped++; cpu_buffer->mapped++; - else + } else { + cpu_buffer->user_mapped--; cpu_buffer->mapped--; + } raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); mutex_unlock(&cpu_buffer->buffer->mutex); @@ -6328,7 +6339,7 @@ int ring_buffer_map(struct trace_buffer *buffer, int cpu, mutex_lock(&cpu_buffer->mapping_lock); - if (cpu_buffer->mapped) { + if (cpu_buffer->user_mapped) { err = __rb_map_vma(cpu_buffer, vma); if (!err) err = __rb_inc_dec_mapped(cpu_buffer, true); @@ -6359,12 +6370,15 @@ int ring_buffer_map(struct trace_buffer *buffer, int cpu, */ raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); rb_setup_ids_meta_page(cpu_buffer, subbuf_ids); + raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); err = __rb_map_vma(cpu_buffer, vma); if (!err) { raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); - cpu_buffer->mapped = 1; + /* This is the first time it is mapped by user */ + cpu_buffer->mapped++; + cpu_buffer->user_mapped = 1; raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); } else { kfree(cpu_buffer->subbuf_ids); @@ -6392,10 +6406,10 @@ int ring_buffer_unmap(struct trace_buffer *buffer, int cpu) mutex_lock(&cpu_buffer->mapping_lock); - if (!cpu_buffer->mapped) { + if (!cpu_buffer->user_mapped) { err = -ENODEV; goto out; - } else if (cpu_buffer->mapped > 1) { + } else if (cpu_buffer->user_mapped > 1) { __rb_inc_dec_mapped(cpu_buffer, false); goto out; } @@ -6403,7 +6417,10 @@ int ring_buffer_unmap(struct trace_buffer *buffer, int cpu) mutex_lock(&buffer->mutex); raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); - cpu_buffer->mapped = 0; + /* This is the last user space mapping */ + if (!WARN_ON_ONCE(cpu_buffer->mapped < cpu_buffer->user_mapped)) + cpu_buffer->mapped--; + cpu_buffer->user_mapped = 0; raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);