From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752167AbbIQO6b (ORCPT ); Thu, 17 Sep 2015 10:58:31 -0400 Received: from eu-smtp-delivery-143.mimecast.com ([146.101.78.143]:52152 "EHLO eu-smtp-delivery-143.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751633AbbIQO63 convert rfc822-to-8bit (ORCPT ); Thu, 17 Sep 2015 10:58:29 -0400 Message-ID: <55FAD512.5030206@arm.com> Date: Thu, 17 Sep 2015 15:58:26 +0100 From: Kapileshwar Singh User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Steven Rostedt CC: "linux-kernel@vger.kernel.org" , Arnaldo Carvalho de Melo , Namhyung Kim , Javi Merino , David Ahern , Jiri Olsa Subject: Re: [PATCH] tools lib traceevent: Mask higher bits of str addresses for 32-bit traces References: <1442488476-15366-1-git-send-email-kapileshwar.singh@arm.com> <20150917091154.575d031f@gandalf.local.home> In-Reply-To: <20150917091154.575d031f@gandalf.local.home> X-OriginalArrivalTime: 17 Sep 2015 14:58:26.0617 (UTC) FILETIME=[4E8FBA90:01D0F159] X-MC-Unique: WISY5BUnSZ2cavZMMmyKDw-1 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Steve, Thanks for looking into this! On 17/09/15 14:11, Steven Rostedt wrote: > On Thu, 17 Sep 2015 12:14:36 +0100 > Kapileshwar Singh wrote: > >> When a trace recorded on a 32-bit device is processed with a 64-bit >> binary, the higher 32-bits of the address need to be masked. >> >> The lack of this results in the output of the 64-bit pointer >> value to the trace as the 32-bit address lookup fails in find_printk. >> >> Before: >> burn-1778 [003] 548.600305: bputs: 0xc0046db2s: 2cec5c058d98c >> >> After: >> burn-1778 [003] 548.600305: bputs: 0xc0046db2s: RT throttling activated >> >> The problem occurs in PRINT_FEILD when the field is recognized as a pointer >> to a string (of the type const char *) > > Actually, there's two bugs here. You only fixed one of them. > >> >> Cc: Steven Rostedt >> Cc: Arnaldo Carvalho de Melo >> Cc: Namhyung Kim >> Cc: Javi Merino >> Cc: David Ahern >> Cc: Jiri Olsa >> Reported-by: Juri-Lelli >> Signed-off-by: Kapileshwar Singh >> --- >> tools/lib/traceevent/event-parse.c | 11 +++++++++++ >> 1 file changed, 11 insertions(+) >> >> diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c >> index 4d885934b919..39163ea4a048 100644 >> --- a/tools/lib/traceevent/event-parse.c >> +++ b/tools/lib/traceevent/event-parse.c >> @@ -3829,6 +3829,17 @@ static void print_str_arg(struct trace_seq *s, void *data, int size, >> if (!(field->flags & FIELD_IS_ARRAY) && >> field->size == pevent->long_size) { >> addr = *(unsigned long *)(data + field->offset); > > addr is of type unsigned long. That means if we read a 64 bit record on > a 32 bit machine (which is supported), this will be truncated. > > Perhaps we need to make addr into a unsigned long long, and then add: > > addr = (pevent->long_size == 8) ? > *(unsigned long long *)(data + field->offset) : > (unsigned long long )*(unsigned int *)(data + field->offset); I agree, we need to handle both cases: * Traces recorded using 32-bit addresses processed on a 64-bit machine * Traces recorded using 64-bit addresses processed on a 32-bit machine The change you suggested fixes both these cases. Will send a v2 of the patch with the changes. Regards, KP > > > > -- Steve > > >> + >> + /* In case the long_size is 4. The higher 32bits >> + * need to be masked for a successful lookup in >> + * in the printk table. As the pointers are 32-bit >> + * long. This could happen if a trace recorded on >> + * 32-bit platform is processed using a 64-bit >> + * binary >> + */ >> + if (pevent->long_size == 4) >> + addr = addr & 0xffffffff; >> + >> /* Check if it matches a print format */ >> printk = find_printk(pevent, addr); >> if (printk) >