Date: Sun, 5 Dec 2010 19:24:55 +0200 From: Kostik Belousov <kostikbel@gmail.com> To: pfgshield-freebsd@yahoo.com Cc: freebsd-amd64@freebsd.org, avg@freebsd.org, bug-followup@freebsd.org Subject: Re: amd64/124134: [kernel] The kernel doesn't follow the calling convention in the SVR4/i386 ABI Message-ID: <20101205172455.GB184@deviant.kiev.zoral.com.ua> In-Reply-To: <739586.26564.qm@web113517.mail.gq1.yahoo.com> References: <201012051355.oB5Dtex4077823@freefall.freebsd.org> <739586.26564.qm@web113517.mail.gq1.yahoo.com>
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--2B/JsCI69OhZNC5r Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sun, Dec 05, 2010 at 07:08:07AM -0800, pfgshield-freebsd@yahoo.com wrote: > The code has certainly changed a lot ... >=20 > Reading the posting on the link with a possible fix: >=20 > "... > Can you try to add to kernel sources, into file sys/amd64/amd64/machdep.c > function exec_setregs(td, entry, stack, ps_strings) > somewhere at the end >=20 > pcb->pcb_flags |=3D PCB_FULLCTX; > ... " >=20 > We don't have anything similar to this in exec_setregs(), and from my und= erstanding the issue could not be easily fixed without breaking binary comp= atibility so I would think the issue is still there. >=20 > This PR was only for reference though as it doesn't cause trouble for us:= I'm OK with the PR being closed. >=20 I looked at the PR before. Looking again now, I have the same conclusion, that is I do not understand what is the issue. On the first return into usermode after the successfull execve(2), kernel sets the following registers: - %rsp (properly aligned) - %rdi (1st parameter in usermode ABI; contains the pointer to startup frame, i.e. &argc) - all other GP registers are zeroed. ABI rev. 0.99 requires the following setup: - %rsp properly aligned and has the value &argc - %rdx points to a function to be registered with atexit(3), or NULL. We do satisfy the ABI requirement for %rdx content in the trivial way, by passing 0. The layout of the startup frame also seems conforming. --2B/JsCI69OhZNC5r Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (FreeBSD) iEYEARECAAYFAkz7yuYACgkQC3+MBN1Mb4g0+gCdHr3LI4WutdnTD8He0+hFYF72 Z6IAoMXjfMPwXwmBlJhaxXlG+gV9vs4t =yePc -----END PGP SIGNATURE----- --2B/JsCI69OhZNC5r--
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