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Date: Tue, 6 Oct 2009 05:30:50 +0200 From: Bastian Blank <bastian@...di.eu.org> To: Jeremy Fitzhardinge <jeremy@...p.org> Cc: Ingo Molnar <mingo@...hat.com>, the arch/x86 maintainers <x86@...nel.org>, Stable Kernel <stable@...nel.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Xen-devel <xen-devel@...ts.xensource.com> Subject: Re: [Xen-devel] Re: [PATCH] xen: Disable stack protector for irq helper On Mon, Oct 05, 2009 at 05:36:02PM -0700, Jeremy Fitzhardinge wrote: > On 10/05/09 15:43, Bastian Blank wrote: > > On Mon, Oct 05, 2009 at 10:21:01AM -0700, Jeremy Fitzhardinge wrote: > >>> Save all caller-saved registers on x86_32 for the paravirt callee saved > >>> registers. > >> That looks better, but it is still overkill. We only need to save the > >> set of registers the ABI requires the callee to preserve. What > >> additional register(s) gets clobbered by stack-protector that need to be > >> saved? > > Well, exactly the two, ecx and edx. eax is still clobbered by the return > > value. Anyway, it works in praxis. > I'm confused. It already saves ecx, so what else needs saving? The original version saves ecx, but not edx. Both are official caller-saved registers. > Besides, most of the code in that file isn't used unless you're using a > very old version of Xen; it will generally prefer to use the ones in > xen-asm_X.S. Well, my call stack say something different. It crashs during early startup without a console. The modifications to the function pointers is done much later. Bastian -- Vulcans never bluff. -- Spock, "The Doomsday Machine", stardate 4202.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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