From:   Nadav Amit <namit@vmware.com>
To:     Dave Hansen <dave.hansen@intel.com>
CC:     "Masami Hiramatsu (Google)" <mhiramat@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        X86 ML <x86@kernel.org>,
        kernel list <linux-kernel@vger.kernel.org>,
        Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH] x86/kprobes: Fix 1 byte conditional jump target
Thread-Topic: [PATCH] x86/kprobes: Fix 1 byte conditional jump target
Thread-Index: AQHZONzOlqQ9zgLH5EacMBCbCDIQPq7CQ9CAgAAGPYCAADuhAIAAJgkAgADyRgCAAAN3AIAA+40AgAAGTACAAAB+AA==
Date:   Wed, 8 Feb 2023 06:58:45 +0000
Message-ID: <835C41C0-7E42-4220-8F21-D8419937CBEF@vmware.com>
References: <20230204210807.3930-1-namit@vmware.com>
 <a75c134d-8278-b17c-e05e-409b70ad15b0@intel.com>
 <C4863EDA-106B-4AF9-8D39-D603EEE4BEDC@vmware.com>
 <dc964552-dca7-dd83-52a2-283be7f51555@intel.com>
 <20230207095424.42f4c0147f693a8cef25757c@kernel.org>
 <20230208002132.63b70cb9d6e5badad45fb828@kernel.org>
 <9fb39b3a-2edb-7fd3-2b7c-3a347478083f@intel.com>
 <B790D31A-A0BE-4707-BA01-398B5668C3D8@vmware.com>
 <b1300308-8f29-fa73-5542-25d06925ca84@intel.com>
In-Reply-To: <b1300308-8f29-fa73-5542-25d06925ca84@intel.com>
Accept-Language: en-US
Content-Language: en-US
x-ms-exchange-antispam-messagedata-chunkcount: 1
x-ms-exchange-antispam-messagedata-0: =?us-ascii?Q?pbqlhbjxWNncdFUW7lemIZSXRehe1KYijQsgz3u0mjDieAdAnyYGrMRSe31p?=
 =?us-ascii?Q?1cHESIY+5GcD3rwTnzldGqF9jXNVbRGUEZlgO/Emymy8+NMCivTXigoGjN9d?=
 =?us-ascii?Q?ayfp471XYo1ePsFK3QtjezhtK0gVOC3tuGNps9w1AAUcfn31HaUzIXwBvjZY?=
 =?us-ascii?Q?C4SHKWG10AYP5j95hdtneoRWSq7/M6A7VTc5DOKZXkvhezc6jLYlv+blBQcj?=
 =?us-ascii?Q?RW+NiGUbrhxOtXR82kQDIeIdWoyY4udq7WkOKN6POw9NJDtq4RDwXI8ISpA6?=
 =?us-ascii?Q?HGSMWalBMeWv4y0pAoFzvZdmaNcXUpvoVs6PsEtsPFEnrFzJ+i+kXnVlTPGA?=
 =?us-ascii?Q?qHQU8Nizk+ZaQNnEcsEQecu720476a+yxVZMKMNLg2yeYN8R4fYAf25mvN1J?=
 =?us-ascii?Q?MHphashNlCHL4g3TN1+t9S5TF40ETvnhEROUe+JYBKUtDYx3DZXrv0Vwlqos?=
 =?us-ascii?Q?0Kx4zZWlbgogxsRaREC53RtjiTvu9YqTSgrh5KllEerqKdEbG2hrZF7ZKIkS?=
 =?us-ascii?Q?bAL/E1+URxQ0c1s1sH/lkc1diezlFAXKE82z20OKAt++eXNntM+WZWTKz3nX?=
 =?us-ascii?Q?3vG3Ym8nXunt5hmxlCY6etgoXEV9IpoT63HoZdL0b7RiudRCMmPl6VCWYdIm?=
 =?us-ascii?Q?W8iqb0sRNibiC7gpOrLtMbKFUbwoYsWS9UavswemlVGz9B/gX/82rQ+okiM8?=
 =?us-ascii?Q?tCmQPGAZv7mcYPCmtmqU8vuGJj+W27MovYrW5qs6su+C2YdJkszLSdgk2tpA?=
 =?us-ascii?Q?YmALMdt4BG5E+QOoj5jpakvgNKSHpCBZKub9+Z26rakh23y8Mmcic4rzpsSH?=
 =?us-ascii?Q?K/94xC/LKsQ7KUJscQeY7YFaU5HxyJLNfDAhq4BgQD02GG8NhHiAi6SOuBfX?=
 =?us-ascii?Q?OcSG/87y2DI2awF9s1L5eQFzuwkTR0jvLZIOmd6hrFySmTEqk/dLLncGqtm8?=
 =?us-ascii?Q?3VAZgPMdzUUD74CAYjSL9EsNpWB3/fYrmoqqWERjXYauf69/vK0EVBZRa0Xu?=
 =?us-ascii?Q?OfpOV3RCqV+MyTikg7nntG3JkEK5Rz0VpfgkpLtTbl2rIzEpBsNDHPUeUm0s?=
 =?us-ascii?Q?FR9UT/gXkgS8/TpPpyRIyiWMfS6Hj6BdsItlu41/VYwQXvwaEdHq7d49pucM?=
 =?us-ascii?Q?QDn9Ygy7ChEzPeGWn9MvY8zU0ujDXjnbC6KrXDC0oIQohSuzp00YOQdMC+9/?=
 =?us-ascii?Q?aJYRunJZGnGdIeb+L/aiJoe8TD1vrjZRAM8WMhmRIHe61rG3tx+URe3+icYw?=
 =?us-ascii?Q?jusBUgftz9dxZSrde5XkEKYUgg+bXxu9xe1HcwDAN3ob2rbsadNKmesloyg8?=
 =?us-ascii?Q?ECrvmendxCH9ayzIH8Uh/0Y1cK1/H6MobuQIp8Pky6O8f7IbL/1NrnwewIiI?=
 =?us-ascii?Q?819rk92xUFGwHqwPxUlA1geFnPEZeJ/mFihkCEnC33BhAixU/pQPtFYamaPX?=
 =?us-ascii?Q?LAtfEU/nBmlK2Z4On271atNC2zl46T2DNcGIhtTgSYdhnetFEFmJJzWrkrTf?=
 =?us-ascii?Q?H7+GG5KH1ZUL09nIEPATE4OG4JkIJicObAIZQ2apxolwpjefG/GQpJsHdlTA?=
 =?us-ascii?Q?rY2V1H7omLzyUJPeHdoJjXuFFcztBi5rhdH76IkA?=
Content-Type: text/plain; charset="us-ascii"
Content-ID: <812C20612F29FC458C321F92112C9489@namprd05.prod.outlook.com>
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-OriginatorOrg: vmware.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-AuthSource: BY3PR05MB8531.namprd05.prod.outlook.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 89d29153-e34f-41cb-c1c8-08db09a1ebd1
X-MS-Exchange-CrossTenant-originalarrivaltime: 08 Feb 2023 06:58:45.3365
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: b39138ca-3cee-4b4a-a4d6-cd83d9dd62f0
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: xwsDa+QeIcRMl+j80jOo53lhPVOg42axtNzCcacj96jHQWaqGpsminGIs6nbBnlNDhUMr2DMozUADsSQuYSlZw==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BLAPR05MB7281
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org


> On Feb 8, 2023, at 8:56 AM, Dave Hansen <dave.hansen@intel.com> wrote:
>=20
> !! External Email
>=20
> On 2/7/23 22:34, Nadav Amit wrote:
>> As you said, I guess the change you and Masami proposed can be done on t=
op of
>> this patch, which is (and was) only intended to fix the bug, and should
>> therefore go into 6.2.
>=20
> Nadav,
>=20
> To fix this issue, you proposed:
>=20
>        p->ainsn.rel32 =3D *(s8 *)&insn->immediate.value;
>=20
> But, this is, um, rather obfuscated and potentially less correct
> compared to:
>=20
>        p->ainsn.rel32 =3D insn->immediate.value;
>=20
> I'd appreciate it if you could update your patch to do this simpler
> thing and resend, unless there is a strong reason to do what you
> originally proposed.

I thought it makes sense to make this change for all the other cases
in one pass, but whatever makes you happy.

I will send v2 soon.

Thanks again,
Nadav=