Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761714AbXKILQV (ORCPT ); Fri, 9 Nov 2007 06:16:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751874AbXKILQO (ORCPT ); Fri, 9 Nov 2007 06:16:14 -0500 Received: from smtp2a.orange.fr ([80.12.242.139]:18438 "EHLO smtp2a.orange.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751859AbXKILQN convert rfc822-to-8bit (ORCPT ); Fri, 9 Nov 2007 06:16:13 -0500 X-ME-UUID: 20071109111611476.745A7700008F@mwinf2a07.orange.fr Date: Fri, 9 Nov 2007 12:11:29 +0100 From: Philippe Elie To: linux-kernel@vger.kernel.org Cc: Linus Torvalds , Andrew Morton , Sami Farin Subject: [PATCH 1/1]: oProfile: oops when profile_pc() return ~0LU Message-ID: <20071109111129.GB2890@zaniah> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: 8BIT User-Agent: Mutt/1.4.2.2i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2997 Lines: 84 From: Philippe Elie Instruction pointer returned by profile_pc() can be a random value. This break the assumption than we can safely set struct op_sample.eip field to a magic value to signal to the per-cpu buffer reader side special event like task switch ending up in a segfault in get_task_mm() when profile_pc() return ~0UL. Fixed by sanitizing the sampled eip and reject/log invalid eip. Problem reported by Sami Farin, patch tested by him. Signed-off-by: Philippe Elie --- drivers/oprofile/cpu_buffer.c | 7 +++++++ drivers/oprofile/cpu_buffer.h | 1 + drivers/oprofile/oprofile_stats.c | 4 ++++ 3 files changed, 12 insertions(+), 0 deletions(-) diff --git a/drivers/oprofile/cpu_buffer.c b/drivers/oprofile/cpu_buffer.c index a83c3db..c93d3d2 100644 --- a/drivers/oprofile/cpu_buffer.c +++ b/drivers/oprofile/cpu_buffer.c @@ -64,6 +64,8 @@ int alloc_cpu_buffers(void) b->head_pos = 0; b->sample_received = 0; b->sample_lost_overflow = 0; + b->backtrace_aborted = 0; + b->sample_invalid_eip = 0; b->cpu = i; INIT_DELAYED_WORK(&b->work, wq_sync_buffer); } @@ -175,6 +177,11 @@ static int log_sample(struct oprofile_cpu_buffer * cpu_buf, unsigned long pc, cpu_buf->sample_received++; + if (pc == ESCAPE_CODE) { + cpu_buf->sample_invalid_eip++; + return 0; + } + if (nr_available_slots(cpu_buf) < 3) { cpu_buf->sample_lost_overflow++; return 0; diff --git a/drivers/oprofile/cpu_buffer.h b/drivers/oprofile/cpu_buffer.h index 49900d9..c66c025 100644 --- a/drivers/oprofile/cpu_buffer.h +++ b/drivers/oprofile/cpu_buffer.h @@ -42,6 +42,7 @@ struct oprofile_cpu_buffer { unsigned long sample_received; unsigned long sample_lost_overflow; unsigned long backtrace_aborted; + unsigned long sample_invalid_eip; int cpu; struct delayed_work work; } ____cacheline_aligned; diff --git a/drivers/oprofile/oprofile_stats.c b/drivers/oprofile/oprofile_stats.c index f0acb66..d1f6d77 100644 --- a/drivers/oprofile/oprofile_stats.c +++ b/drivers/oprofile/oprofile_stats.c @@ -26,6 +26,8 @@ void oprofile_reset_stats(void) cpu_buf = &cpu_buffer[i]; cpu_buf->sample_received = 0; cpu_buf->sample_lost_overflow = 0; + cpu_buf->backtrace_aborted = 0; + cpu_buf->sample_invalid_eip = 0; } atomic_set(&oprofile_stats.sample_lost_no_mm, 0); @@ -61,6 +63,8 @@ void oprofile_create_stats_files(struct super_block * sb, struct dentry * root) &cpu_buf->sample_lost_overflow); oprofilefs_create_ro_ulong(sb, cpudir, "backtrace_aborted", &cpu_buf->backtrace_aborted); + oprofilefs_create_ro_ulong(sb, cpudir, "sample_invalid_eip", + &cpu_buf->sample_invalid_eip); } oprofilefs_create_ro_atomic(sb, dir, "sample_lost_no_mm", - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/