[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [PATCH] livepatch: do not use .livepatch.funcs section to store internal state


  • To: Roger Pau Monné <roger.pau@xxxxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Thu, 16 Nov 2023 15:05:20 +0100
  • Arc-authentication-results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=suse.com; dmarc=pass action=none header.from=suse.com; dkim=pass header.d=suse.com; arc=none
  • Arc-message-signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=QkdsCKI4qP6vqJtLhRogv5kDL8rgwy9kycoa4MIX0ZE=; b=k2RevJRqmqIQ+Iyn59tWgite+kTyE1B8icmsObRyX3FrYUULBukPZuRoAZhx/47fYn9PQStWeXVtGKoehkGQqt7mxLCZEjOH5hgg7J79iwd6NN3++UXFM188d8ptl2HROEbxoCjeAUpws2+/zUjtYgvXjvHRFMKe3saHJ8QBSXCYjvPtZXJFKDz/+Jbxv2dNiLv5PnyJYlCGV4Hq1x9FiQ9R/T3KFkuPEeJOB+491lSkif+9xzVgqP5yjW2XTvpJFr1dnJCawNEuPWwYI7BHld83lIK4m01qhVWlNfleVHPtKkv36Su+V5bSu6haoSNY/jmLgkgIbmB5Y/I+e8Jn/Q==
  • Arc-seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=oWkrDQRG7FoVChN03BgYnBxiAfoPPeVRKvhy1gl9Sl1HR4BYyPd8Z7KrJfwYluc1xIatf6DIs52oCFVtAJM9Oz2wSjpZQnMnlge+eclnTsSpBSPqz8wo1ULe3Sq6bi0139MRQTvuEf90Nrkpb4BjHOMLENPk1eBxyA95JBACPJ2C8QMWJ9Wo1rUm3e6wcUIBlNGnlOO7nZyiEu76TnriuFfkEEVhkoYXT3TsxiSpbCr8SGKCbdFylB0Z/ZkMNV85oOgJvc/AH1l1NW5YcyhAsC0iKV0JnCzerBFlyGfV6TA6LDTfmeSAuTXTF+d/zuQ6a0xchmBhEijGcPF/0OpApQ==
  • Authentication-results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=suse.com;
  • Autocrypt: addr=jbeulich@xxxxxxxx; keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL
  • Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>, Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Bertrand Marquis <bertrand.marquis@xxxxxxx>, Michal Orzel <michal.orzel@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, George Dunlap <george.dunlap@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
  • Delivery-date: Thu, 16 Nov 2023 14:05:37 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 16.11.2023 14:54, Roger Pau Monné wrote:
> On Thu, Nov 16, 2023 at 01:39:27PM +0100, Jan Beulich wrote:
>> On 16.11.2023 12:58, Roger Pau Monne wrote:
>>> --- a/xen/include/public/sysctl.h
>>> +++ b/xen/include/public/sysctl.h
>>> @@ -991,10 +991,7 @@ struct livepatch_func {
>>>      uint32_t new_size;
>>>      uint32_t old_size;
>>>      uint8_t version;        /* MUST be LIVEPATCH_PAYLOAD_VERSION. */
>>> -    uint8_t opaque[LIVEPATCH_OPAQUE_SIZE];
>>> -    uint8_t applied;
>>> -    uint8_t patch_offset;
>>> -    uint8_t _pad[6];
>>> +    uint8_t _pad[39];
>>
>> Should this be LIVEPATCH_OPAQUE_SIZE+8 and ...
> 
> Hm, I'm not sure that's any clearer.  In fact I think
> LIVEPATCH_OPAQUE_SIZE shouldn't have leaked into sysctl.h in the first
> place.
> 
> If we later want to add more fields and bump the version, isn't it
> easier to have the padding size clearly specified as a number?

If new fields (beyond the present padding size) would need adding,
that would constitute an incompatible change anyway. Until then imo
it would be clearer to keep the reference to the original constant.
But thinking about it again, the difference is perhaps indeed only
marginal. Anyway, I'll leave this to the livepatch maintainers.

One further related remark though: Now that you pointed me at the
other use of the constant in the public header, don't you want to
update the comment there, for it to not become stale (in referring
to struct livepatch_func)?

Jan



 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.