Date: Thu, 12 Dec 2002 11:27:03 -0500 (EST) From: John Baldwin <jhb@FreeBSD.org> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: freebsd-hackers@FreeBSD.ORG, Chuck Tuffli <chuck_tuffli@agilent.com> Subject: Re: RE: registers not saved Message-ID: <XFMail.20021212112703.jhb@FreeBSD.org> In-Reply-To: <200212120259.gBC2x97R092440@apollo.backplane.com>
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On 12-Dec-2002 Matthew Dillon wrote: >:> function A calls function B which uses ecx as a loop index. The bad part is function B never >:> saves/restores the value of ecx and function A starts dereferencing garbage. >:> >:> An informal sampling of my driver seems to indicate that ebx gets >:> pushed/poped at entry/exit but ecx and edx don't. Does any of this >:> sound familiar? Thanks! >: >:Yes, eax, ebx, and edx are not "call-safe" registers. If you are writing >:your own function in assembly and you call a function you need to either >:save those registers yourself or reload their values. If you are writing >:... >:John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ >:"Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ > > I think you meant ecx there. eax, ecx, and edx are not call safe. > ebx is. Yep. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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