linux-kernel - Re: [PATCH v5 06/10] Uprobes: Support SDT markers having reference count (semaphore)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <f5a39a88-c21e-4606-a04d-11b5f32016b8@linux.ibm.com>
Date:   Wed, 4 Jul 2018 10:23:19 +0530
From:   Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
To:     Oleg Nesterov <oleg@...hat.com>
Cc:     srikar@...ux.vnet.ibm.com, rostedt@...dmis.org,
        mhiramat@...nel.org, peterz@...radead.org, mingo@...hat.com,
        acme@...nel.org, alexander.shishkin@...ux.intel.com,
        jolsa@...hat.com, namhyung@...nel.org,
        linux-kernel@...r.kernel.org, corbet@....net,
        linux-doc@...r.kernel.org, ananth@...ux.vnet.ibm.com,
        alexis.berlemont@...il.com, naveen.n.rao@...ux.vnet.ibm.com,
        linux-arm-kernel@...ts.infradead.org, linux-mips@...ux-mips.org,
        linux@...linux.org.uk, ralf@...ux-mips.org, paul.burton@...s.com,
        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
Subject: Re: [PATCH v5 06/10] Uprobes: Support SDT markers having reference
 count (semaphore)

Hi Oleg,

On 07/03/2018 10:55 PM, Oleg Nesterov wrote:
> On 07/03, Oleg Nesterov wrote:
>>
>> In short. There is a 1:1 relationship between uprobe_write_opcode(is_register => 1)
>> and install_breakpoint(), and between uprobe_write_opcode(is_register => 0) and
>> remove_breakpoint(). Whatever uprobe_write_opcode() can do if is_register == 1 can be
>> done in install_breakpoint(), the same for is_register == 0 and remove_breakpont().
>>
>> What have I missed?
> 
> Ah. I missed the fact that uprobe_write_opcode() doesn't do update_ref_ctr() if
> verify_opcode() returns false.
> 
> Now I understand what did you mean by "for each consumer". So if we move this logic
> into install/remove_breakpoint as I tried to suggest, we will also need another error
> code for the case when verify_opcode() returns false.

Ok so if we can use verify_opcode() inside install_breakpoint(), we can probably
move implementation logic in install/remove_breakpoint(). Let me explore that more.

Thanks,
Ravi