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From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Ingo Molnar <mingo@kernel.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Nicholas Piggin <npiggin@gmail.com>
Subject: Re: [PATCH 5/7] powerpc/ftrace: Update ftrace_location() for powerpc -mprofile-kernel
Date: Tue, 18 Jun 2019 23:41:37 +0530	[thread overview]
Message-ID: <1560881411.p0i6a1dkwk.naveen@linux.ibm.com> (raw)
In-Reply-To: <20190618114509.5b1acbe5@gandalf.local.home>

Steven Rostedt wrote:
> On Tue, 18 Jun 2019 20:17:04 +0530
> "Naveen N. Rao" <naveen.n.rao@linux.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



WARNING: multiple messages have this Message-ID (diff)
From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, Nicholas Piggin <npiggin@gmail.com>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	linuxppc-dev@lists.ozlabs.org, Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH 5/7] powerpc/ftrace: Update ftrace_location() for powerpc -mprofile-kernel
Date: Tue, 18 Jun 2019 23:41:37 +0530	[thread overview]
Message-ID: <1560881411.p0i6a1dkwk.naveen@linux.ibm.com> (raw)
In-Reply-To: <20190618114509.5b1acbe5@gandalf.local.home>

Steven Rostedt wrote:
> On Tue, 18 Jun 2019 20:17:04 +0530
> "Naveen N. Rao" <naveen.n.rao@linux.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



  reply	other threads:[~2019-06-18 18:11 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-18 14:46 [PATCH 0/7] powerpc/ftrace: Patch out -mprofile-kernel instructions Naveen N. Rao
2019-06-18 14:46 ` Naveen N. Rao
2019-06-18 14:47 ` [PATCH 1/7] ftrace: Expose flags used for ftrace_replace_code() Naveen N. Rao
2019-06-18 14:47   ` Naveen N. Rao
2019-06-18 14:47 ` [PATCH 2/7] x86/ftrace: Fix use of flags in ftrace_replace_code() Naveen N. Rao
2019-06-18 14:47   ` Naveen N. Rao
2019-06-18 14:47 ` [PATCH 3/7] ftrace: Expose __ftrace_replace_code() Naveen N. Rao
2019-06-18 14:47   ` Naveen N. Rao
2019-06-18 14:47 ` [PATCH 4/7] powerpc/ftrace: Additionally nop out the preceding mflr with -mprofile-kernel Naveen N. Rao
2019-06-18 14:47   ` Naveen N. Rao
2019-06-19  5:14   ` Michael Ellerman
2019-06-19  7:10     ` Nicholas Piggin
2019-06-19  7:10       ` Nicholas Piggin
2019-06-19  9:53       ` Naveen N. Rao
2019-06-19  9:53         ` Naveen N. Rao
2019-06-19 10:41         ` Nicholas Piggin
2019-06-19 10:41           ` Nicholas Piggin
2019-06-19 17:14           ` Naveen N. Rao
2019-06-19 17:14             ` Naveen N. Rao
2019-06-18 14:47 ` [PATCH 5/7] powerpc/ftrace: Update ftrace_location() for powerpc -mprofile-kernel Naveen N. Rao
2019-06-18 14:47   ` Naveen N. Rao
2019-06-18 15:45   ` Steven Rostedt
2019-06-18 15:45     ` Steven Rostedt
2019-06-18 18:11     ` Naveen N. Rao [this message]
2019-06-18 18:11       ` Naveen N. Rao
2019-06-18 18:23       ` Naveen N. Rao
2019-06-18 18:23         ` Naveen N. Rao
2019-06-18 18:32         ` Steven Rostedt
2019-06-18 18:32           ` Steven Rostedt
2019-06-19  7:56           ` Naveen N. Rao
2019-06-19  7:56             ` Naveen N. Rao
2019-06-19  9:28             ` Steven Rostedt
2019-06-19  9:28               ` Steven Rostedt
2019-06-18 14:47 ` [PATCH 6/7] kprobes/ftrace: Use ftrace_location() when [dis]arming probes Naveen N. Rao
2019-06-18 14:47   ` Naveen N. Rao
2019-06-21 14:41   ` Masami Hiramatsu
2019-06-21 14:41     ` Masami Hiramatsu
2019-06-18 14:47 ` [PATCH 7/7] powerpc/kprobes: Allow probing on any ftrace address Naveen N. Rao
2019-06-18 14:47   ` Naveen N. Rao
2019-06-21 14:50   ` Masami Hiramatsu
2019-06-21 14:50     ` Masami Hiramatsu
2019-06-22  3:49     ` Joe Perches
2019-06-22  3:49       ` Joe Perches
2019-06-26  9:39     ` Naveen N. Rao
2019-06-26  9:39       ` Naveen N. Rao

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