• Mathias Krause's avatar
    x86/cpu: Drop wp_works_ok member of struct cpuinfo_x86 · 6415813b
    Mathias Krause authored
    Remove the wp_works_ok member of struct cpuinfo_x86. It's an
    optimization back from Linux v0.99 times where we had no fixup support
    yet and did the CR0.WP test via special code in the page fault handler.
    The < 0 test was an optimization to not do the special casing for each
    NULL ptr access violation but just for the first one doing the WP test.
    Today it serves no real purpose as the test no longer needs special code
    in the page fault handler and the only call side -- mem_init() -- calls
    it just once, anyway. However, Xen pre-initializes it to 1, to skip the
    test.
    
    Doing the test again for Xen should be no issue at all, as even the
    commit introducing skipping the test (commit d560bc61 ("x86, xen:
    Suppress WP test on Xen")) mentioned it being ban aid only. And, in
    fact, testing the patch on Xen showed nothing breaks.
    
    The pre-fixup times are long gone and with the removal of the fallback
    handling code in commit a5c2a893 ("x86, 386 removal: Remove
    CONFIG_X86_WP_WORKS_OK") the kernel requires a working CR0.WP anyway.
    So just get rid of the "optimization" and do the test unconditionally.
    Signed-off-by: default avatarMathias Krause <minipli@googlemail.com>
    Acked-by: default avatarBorislav Petkov <bp@alien8.de>
    Cc: Jesper Nilsson <jesper.nilsson@axis.com>
    Cc: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
    Cc: Arnd Hannemann <hannemann@nets.rwth-aachen.de>
    Cc: Mikael Starvik <starvik@axis.com>
    Cc: Geert Uytterhoeven <geert@linux-m68k.org>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: "David S. Miller" <davem@davemloft.net>
    Link: http://lkml.kernel.org/r/1486933932-585-3-git-send-email-minipli@googlemail.comSigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    6415813b
processor.h 23.1 KB