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d=suse.com; s=susede1; t=1624531746; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=y4fD5hqVesnHw7dttchRE1TXShszbzoY78Pp0FZZxmg=; b=V02XwH7sTa5N2CLSPCHmyWa153Y2J784ujVyOpksRBlUyMjKkuwFdslj3wEU4ztBfefaU5 CCGLmLkVBUoNVoj8A3qM/45WyqF1T20XUTM/9IQnMXDbECotm+rC/8YawiVUsN5sktY8jm TI5ZGB6TuyXvy9ekkyN9OtE3hh40JC0= Received: from director2.suse.de ([192.168.254.72]) by imap3-int with ESMTPSA id rJiDDyJj1GANbgAALh3uQQ (envelope-from ); Thu, 24 Jun 2021 10:49:06 +0000 Subject: Re: [PATCH v2 01/24] x86/xen: Mark cpu_bringup_and_idle() as dead_end_function To: Peter Zijlstra , jpoimboe@redhat.com, tglx@linutronix.de Cc: linux-kernel@vger.kernel.org, joro@8bytes.org, boris.ostrovsky@oracle.com, x86@kernel.org, mbenes@suse.com, rostedt@goodmis.org, dvyukov@google.com, elver@google.com References: <20210624094059.886075998@infradead.org> <20210624095147.693801717@infradead.org> From: Juergen Gross Message-ID: <1ee219ca-7159-e640-8553-f6bd182279a9@suse.com> Date: Thu, 24 Jun 2021 12:49:05 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.0 MIME-Version: 1.0 In-Reply-To: <20210624095147.693801717@infradead.org> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="OMcRH9tAoiYnqMH6nqDRlqV61CT8MuSTH" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --OMcRH9tAoiYnqMH6nqDRlqV61CT8MuSTH Content-Type: multipart/mixed; boundary="0JqgY8STcpYcIbl6q8KR7pC3yRSF3tNd7"; protected-headers="v1" From: Juergen Gross To: Peter Zijlstra , jpoimboe@redhat.com, tglx@linutronix.de Cc: linux-kernel@vger.kernel.org, joro@8bytes.org, boris.ostrovsky@oracle.com, x86@kernel.org, mbenes@suse.com, rostedt@goodmis.org, dvyukov@google.com, elver@google.com Message-ID: <1ee219ca-7159-e640-8553-f6bd182279a9@suse.com> Subject: Re: [PATCH v2 01/24] x86/xen: Mark cpu_bringup_and_idle() as dead_end_function References: <20210624094059.886075998@infradead.org> <20210624095147.693801717@infradead.org> In-Reply-To: <20210624095147.693801717@infradead.org> --0JqgY8STcpYcIbl6q8KR7pC3yRSF3tNd7 Content-Type: multipart/mixed; boundary="------------564AA9002B8FF88338A9CC8D" Content-Language: en-US This is a multi-part message in MIME format. --------------564AA9002B8FF88338A9CC8D Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable On 24.06.21 11:41, Peter Zijlstra wrote: > The asm_cpu_bringup_and_idle() function is required to push the return > value on the stack in order to make ORC happy, but the only reason > objtool doesn't complain is because of a happy accident. >=20 > The thing is that asm_cpu_bringup_and_idle() doesn't return, so > validate_branch() never terminates and falls through to the next > function, which in the normal case is the hypercall_page. And that, as > it happens, is 4095 NOPs and a RET. >=20 > Make asm_cpu_bringup_and_idle() terminate on it's own, by making the > function it calls as a dead-end. This way we no longer rely on what > code happens to come after. >=20 > Fixes: c3881eb58d56 ("x86/xen: Make the secondary CPU idle tasks reliab= le") > Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Juergen Gross Juergen --------------564AA9002B8FF88338A9CC8D Content-Type: application/pgp-keys; name="OpenPGP_0xB0DE9DD628BF132F.asc" Content-Transfer-Encoding: quoted-printable Content-Description: OpenPGP public key Content-Disposition: attachment; filename="OpenPGP_0xB0DE9DD628BF132F.asc" -----BEGIN PGP PUBLIC KEY BLOCK----- xsBNBFOMcBYBCACgGjqjoGvbEouQZw/ToiBg9W98AlM2QHV+iNHsEs7kxWhKMjrioyspZKOBy= cWx w3ie3j9uvg9EOB3aN4xiTv4qbnGiTr3oJhkB1gsb6ToJQZ8uxGq2kaV2KL9650I1SJvedYm8O= f8Z d621lSmoKOwlNClALZNew72NjJLEzTalU1OdT7/i1TXkH09XSSI8mEQ/ouNcMvIJNwQpd369y= 9bf IhWUiVXEK7MlRgUG6MvIj6Y3Am/BBLUVbDa4+gmzDC9ezlZkTZG2t14zWPvxXP3FAp2pkW0xq= G7/ 377qptDmrk42GlSKN4z76ELnLxussxc7I2hx18NUcbP8+uty4bMxABEBAAHNHEp1ZXJnZW4gR= 3Jv c3MgPGpnQHBmdXBmLm5ldD7CwHkEEwECACMFAlOMcBYCGwMHCwkIBwMCAQYVCAIJCgsEFgIDA= QIe AQIXgAAKCRCw3p3WKL8TL0KdB/93FcIZ3GCNwFU0u3EjNbNjmXBKDY4FUGNQH2lvWAUy+dnyT= hpw dtF/jQ6j9RwE8VP0+NXcYpGJDWlNb9/JmYqLiX2Q3TyevpB0CA3dbBQp0OW0fgCetToGIQrg0= MbD 1C/sEOv8Mr4NAfbauXjZlvTj30H2jO0u+6WGM6nHwbh2l5O8ZiHkH32iaSTfN7Eu5RnNVUJbv= oPH Z8SlM4KWm8rG+lIkGurqqu5gu8q8ZMKdsdGC4bBxdQKDKHEFExLJK/nRPFmAuGlId1E3fe10v= 5QL +qHI3EIPtyfE7i9Hz6rVwi7lWKgh7pe0ZvatAudZ+JNIlBKptb64FaiIOAWDCx1SzR9KdWVyZ= 2Vu IEdyb3NzIDxqZ3Jvc3NAc3VzZS5jb20+wsB5BBMBAgAjBQJTjHCvAhsDBwsJCAcDAgEGFQgCC= QoL BBYCAwECHgECF4AACgkQsN6d1ii/Ey/HmQf/RtI7kv5A2PS4RF7HoZhPVPogNVbC4YA6lW7Dr= Wf0 teC0RR3MzXfy6pJ+7KLgkqMlrAbN/8Dvjoz78X+5vhH/rDLa9BuZQlhFmvcGtCF8eR0T1v0nC= /nu AFVGy+67q2DH8As3KPu0344TBDpAvr2uYM4tSqxK4DURx5INz4ZZ0WNFHcqsfvlGJALDeE0Lh= ITT d9jLzdDad1pQSToCnLl6SBJZjDOX9QQcyUigZFtCXFst4dlsvddrxyqT1f17+2cFSdu7+ynLm= XBK 7abQ3rwJY8SbRO2iRulogc5vr/RLMMlscDAiDkaFQWLoqHHOdfO9rURssHNN8WkMnQfvUewRz= 80h SnVlcmdlbiBHcm9zcyA8amdyb3NzQG5vdmVsbC5jb20+wsB5BBMBAgAjBQJTjHDXAhsDBwsJC= AcD AgEGFQgCCQoLBBYCAwECHgECF4AACgkQsN6d1ii/Ey8PUQf/ehmgCI9jB9hlgexLvgOtf7PJn= FOX gMLdBQgBlVPO3/D9R8LtF9DBAFPNhlrsfIG/SqICoRCqUcJ96Pn3P7UUinFG/I0ECGF4EvTE1= jnD kfJZr6jrbjgyoZHiw/4BNwSTL9rWASyLgqlA8u1mf+c2yUwcGhgkRAd1gOwungxcwzwqgljf0= N51 N5JfVRHRtyfwq/ge+YEkDGcTU6Y0sPOuj4Dyfm8fJzdfHNQsWq3PnczLVELStJNdapwPOoE+l= otu fe3AM2vAEYJ9rTz3Cki4JFUsgLkHFqGZarrPGi1eyQcXeluldO3m91NK/1xMI3/+8jbO0tsn1= tqS EUGIJi7ox80eSnVlcmdlbiBHcm9zcyA8amdyb3NzQHN1c2UuZGU+wsB5BBMBAgAjBQJTjHDrA= hsD BwsJCAcDAgEGFQgCCQoLBBYCAwECHgECF4AACgkQsN6d1ii/Ey+LhQf9GL45eU5vOowA2u5N3= g3O ZUEBmDHVVbqMtzwlmNC4k9Kx39r5s2vcFl4tXqW7g9/ViXYuiDXb0RfUpZiIUW89siKrkzmQ5= dM7 wRqzgJpJwK8Bn2MIxAKArekWpiCKvBOB/Cc+3EXE78XdlxLyOi/NrmSGRIov0karw2RzMNOu5= D+j LRZQd1Sv27AR+IP3I8U4aqnhLpwhK7MEy9oCILlgZ1QZe49kpcumcZKORmzBTNh30FVKK1Evm= V2x AKDoaEOgQB4iFQLhJCdP1I5aSgM5IVFdn7v5YgEYuJYx37IoN1EblHI//x/e2AaIHpzK5h88N= Eaw QsaNRpNSrcfbFmAg987ATQRTjHAWAQgAyzH6AOODMBjgfWE9VeCgsrwH3exNAU32gLq2xvjpW= nHI s98ndPUDpnoxWQugJ6MpMncr0xSwFmHEgnSEjK/PAjppgmyc57BwKII3sV4on+gDVFJR6Y8ZR= wgn BC5mVM6JjQ5xDk8WRXljExRfUX9pNhdE5eBOZJrDRoLUmmjDtKzWaDhIg/+1Hzz93X4fCQkNV= bVF LELU9bMaLPBG/x5q4iYZ2k2ex6d47YE1ZFdMm6YBYMOljGkZKwYde5ldM9mo45mmwe0icXKLk= pEd IXKTZeKDO+Hdv1aqFuAcccTg9RXDQjmwhC3yEmrmcfl0+rPghO0Iv3OOImwTEe4co3c1mwARA= QAB wsBfBBgBAgAJBQJTjHAWAhsMAAoJELDendYovxMvQ/gH/1ha96vm4P/L+bQpJwrZ/dneZcmEw= Tbe 8YFsw2V/Buv6Z4Mysln3nQK5ZadD534CF7TDVft7fC4tU4PONxF5D+/tvgkPfDAfF77zy2AH1= vJz Q1fOU8lYFpZXTXIHb+559UqvIB8AdgR3SAJGHHt4RKA0F7f5ipYBBrC6cyXJyyoprT10EMvU8= VGi wXvTyJz3fjoYsdFzpWPlJEBRMedCot60g5dmbdrZ5DWClAr0yau47zpWj3enf1tLWaqcsuylW= svi uGjKGw7KHQd3bxALOknAp4dN3QwBYCKuZ7AddY9yjynVaD5X7nF9nO5BjR/i1DG86lem3iBDX= zXs ZDn8R38=3D =3D2wuH -----END PGP PUBLIC KEY BLOCK----- --------------564AA9002B8FF88338A9CC8D-- --0JqgY8STcpYcIbl6q8KR7pC3yRSF3tNd7-- --OMcRH9tAoiYnqMH6nqDRlqV61CT8MuSTH Content-Type: application/pgp-signature; name="OpenPGP_signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="OpenPGP_signature" -----BEGIN PGP SIGNATURE----- wsB5BAABCAAjFiEEhRJncuj2BJSl0Jf3sN6d1ii/Ey8FAmDUYyEFAwAAAAAACgkQsN6d1ii/Ey9E jgf8DerWyCDT1r9uQB0B7Ookb35QMkstaJTzzugKYxmxhzqHmCIBszozkEHHgWvHcX1mZT+Lsbsa ah+zcDo+pRuJAm6XipPvaoFYhzxZv5rY0Ui9QgFz8LcS46NFOhgX6T417w6a4Bpe+p8uDt27qa1C Al3rBGnBdJ7mkhj4L/wcgFWTbIAkdS88M+Le0Qd8WODoXgfqjrve36aRZGskJzIQ8640aCUSjbr0 3B8+j1eqEGipWbWiG4RXUZyuxKD8tCh6KUnQtXXSRk9SwoT1lUt8/UByfEbMlOpG41O62tufMKqR +mvk6s8ziQy4pkNRs9tEjjPthroNg4GpM+k7R51aNQ== =uong -----END PGP SIGNATURE----- --OMcRH9tAoiYnqMH6nqDRlqV61CT8MuSTH--