linux-kernel - Re: [PATCH 5/7] powerpc/ftrace: Update ftrace

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Message-Id: <1560881411.p0i6a1dkwk.naveen@linux.ibm.com>
Date:   Tue, 18 Jun 2019 23:41:37 +0530
From:   "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>
Subject: Re: [PATCH 5/7] powerpc/ftrace: Update ftrace_location() for powerpc
 -mprofile-kernel

Steven Rostedt wrote:
> On Tue, 18 Jun 2019 20:17:04 +0530
> "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com> wrote:
> 
>> @@ -1551,7 +1551,7 @@ unsigned long ftrace_location_range(unsigned long start, unsigned long end)
>>  	key.flags = end;	/* overload flags, as it is unsigned long */
>>  
>>  	for (pg = ftrace_pages_start; pg; pg = pg->next) {
>> -		if (end < pg->records[0].ip ||
>> +		if (end <= pg->records[0].ip ||
> 
> This breaks the algorithm. "end" is inclusive. That is, if you look for
> a single byte, where "start" and "end" are the same, and it happens to
> be the first ip on the pg page, it will be skipped, and not found.

Thanks. It looks like I should be over-riding ftrace_location() instead.  
I will update this patch.

- Naveen