Date: Mon, 11 Feb 2008 18:07:43 +0100 From: Roman Divacky <rdivacky@freebsd.org> To: Andriy Gapon <avg@icyb.net.ua> Cc: freebsd-emulation@freebsd.org Subject: Re: bug in recent linux mmap changes ? Message-ID: <20080211170743.GA4866@freebsd.org> In-Reply-To: <47B074D5.1020602@icyb.net.ua> References: <47B074D5.1020602@icyb.net.ua>
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On Mon, Feb 11, 2008 at 06:16:21PM +0200, Andriy Gapon wrote: > After upgrading two machines, one to 6.3 and the other to 7.0-RC1, I can > not run linux heroes3 anymore (statically linked, threaded application > originally written for kernel 2.2.X). On 6.3 the process "hangs", on > 7.0-RC1 one of the threads/processes crashes with SIGSEGV. > Everything was OK as recently as 6.2. > > I can provide more diagnostics later, if needed, but in both cases I see > that the last system call in a troublesome thread/process is linux_mmap(). > I did a brief search through recent linux_mmap changes and I think that > there is a bug in the following commit (I am writing this hastiliy, so I > haven't yet tested a possible fix): > http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/i386/linux/linux_machdep.c.diff?r1=1.48.2.4;r2=1.48.2.5;f=h > > Namely, old code: > ==================================================== > /* This gives us TOS */ > bsd_args.addr = linux_args->addr + linux_args->len; > > if (bsd_args.addr > p->p_vmspace->vm_maxsaddr) { > [block folded] > } > > /* This gives us our maximum stack size */ > if (linux_args->len > STACK_SIZE - GUARD_SIZE) > bsd_args.len = linux_args->len; > else > bsd_args.len = STACK_SIZE - GUARD_SIZE; > > /* > [comment folded] > */ > bsd_args.addr -= bsd_args.len; > ==================================================== > > New code: > ==================================================== > if ((caddr_t)PTRIN(linux_args->addr) + linux_args->len > > p->p_vmspace->vm_maxsaddr) { > [block folded] > } > > /* This gives us our maximum stack size */ > if (linux_args->len > STACK_SIZE - GUARD_SIZE) > bsd_args.len = linux_args->len; > else > bsd_args.len = STACK_SIZE - GUARD_SIZE; > > /* > [comment foled] > */ > bsd_args.addr = (caddr_t)PTRIN(linux_args->addr) - > bsd_args.len; > ==================================================== > > Please now note that the new code doesn't have initial bsd_args.addr > assignment line. So, in summary, old code does the following: > bsd_args.addr = linux_args->addr + linux_args->len; > ... > bsd_args.addr -= bsd_args.len; > > While new code does: > bsd_args.addr = (caddr_t)PTRIN(linux_args->addr) - bsd_args.len; I think you are right.... does changing bsd_args.addr = (caddr_t)PTRIN(linux_args->addr) - bsd_args.len; to bsd_args.addr = (caddr_t)PTRIN(linux_args->addr) + linux_args->len - bsd_args.len; fix that? or possibly just bsd_args.addr = (caddr_t)PTRIN(linux_args->addr); can someone test this please? asap... it would be nice to squeeze this into 7.0R roman
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