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Message-ID: <20160805103713.GA8106@amd> Date: Fri, 5 Aug 2016 12:37:13 +0200 From: Pavel Machek <pavel@...x.de> To: "Rafael J. Wysocki" <rjw@...ysocki.net> Cc: the arch/x86 maintainers <x86@...nel.org>, Linux PM list <linux-pm@...r.kernel.org>, "Rafael J. Wysocki" <rafael@...nel.org>, Thomas Garnier <thgarnie@...gle.com>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, "H . Peter Anvin" <hpa@...or.com>, Kees Cook <keescook@...omium.org>, Yinghai Lu <yinghai@...nel.org>, LKML <linux-kernel@...r.kernel.org>, kernel-hardening@...ts.openwall.com Subject: Re: [PATCH] x86/power/64: Do not refer to __PAGE_OFFSET from assembly code On Wed 2016-08-03 01:19:26, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki <rafael.j.wysocki@...el.com> > > When CONFIG_RANDOMIZE_MEMORY is set on x86-64, __PAGE_OFFSET becomes > a variable and using it as a symbol in the image memory restoration > assembly code under core_restore_code is not correct any more. On a related note... we should really have page_offset variable in such case, and use that -- having __FOO_BAR not being a constant is ugly/confusing/dangerous. > To avoid that problem, modify set_up_temporary_mappings() to compute > the physical address of the temporary page tables and store it in > temp_level4_pgt, so that the value of that variable is ready to be > written into CR3. Then, the assembly code doesn't have to worry > about converting that value into a physical address and things work > regardless of whether or not CONFIG_RANDOMIZE_MEMORY is set. > > Reported-and-tested-by: Thomas Garnier <thgarnie@...gle.com> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com> Acked-by: Pavel Machek <pavel@....cz> Is similar patch needed for i386? Best regards, Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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