Re: [PATCH] x86/power/64: Do not refer to __PAGE_OFFSET from assembly code

From	Pavel Machek <pavel@denx.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH] x86/power/64: Do not refer to __PAGE_OFFSET from assembly code
Date	2016-08-05 12:40 +0200
Message-ID	<s2KHM-6gz-7@gated-at.bofh.it> (permalink)
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On Wed 2016-08-03 01:19:26, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.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@google.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Acked-by: Pavel Machek <pavel@ucw.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

Thread

[PATCH v1 2/2] x86/power/64: Fix __PAGE_OFFSET usage on restore Thomas Garnier <thgarnie@google.com> - 2016-08-01 19:10 +0200
  Re: [PATCH v1 2/2] x86/power/64: Fix __PAGE_OFFSET usage on restore "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-08-02 02:50 +0200
    Re: [PATCH v1 2/2] x86/power/64: Fix __PAGE_OFFSET usage on restore Thomas Garnier <thgarnie@google.com> - 2016-08-02 16:50 +0200
      Re: [PATCH v1 2/2] x86/power/64: Fix __PAGE_OFFSET usage on restore Thomas Garnier <thgarnie@google.com> - 2016-08-02 23:00 +0200
        Re: [PATCH v1 2/2] x86/power/64: Fix __PAGE_OFFSET usage on restore "Rafael J. Wysocki" <rafael@kernel.org> - 2016-08-02 23:20 +0200
          [PATCH] x86/power/64: Do not refer to __PAGE_OFFSET from assembly code "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-08-03 01:20 +0200
            Re: [PATCH] x86/power/64: Do not refer to __PAGE_OFFSET from  assembly code Pavel Machek <pavel@denx.de> - 2016-08-05 12:40 +0200
              Re: [PATCH] x86/power/64: Do not refer to __PAGE_OFFSET from assembly code "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-08-05 16:40 +0200
                Re: [PATCH] x86/power/64: Do not refer to __PAGE_OFFSET from assembly code Thomas Garnier <thgarnie@google.com> - 2016-08-05 17:30 +0200
                Re: [PATCH] x86/power/64: Do not refer to __PAGE_OFFSET from  assembly code Pavel Machek <pavel@denx.de> - 2016-08-06 22:10 +0200
                Re: [PATCH] x86/power/64: Do not refer to __PAGE_OFFSET from assembly code "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-08-06 23:00 +0200
      Re: [PATCH v1 2/2] x86/power/64: Fix __PAGE_OFFSET usage on restore "Rafael J. Wysocki" <rafael@kernel.org> - 2016-08-03 15:40 +0200

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