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| author | Mathias Krause <minipli@googlemail.com> | 2017-02-12 22:12:08 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2017-03-11 14:30:24 +0100 |
| commit | 6415813bae75feba10b8ca3ed6634a72c2a4d313 (patch) | |
| tree | 4edada3a7e79ccb1110ffac55b43282a0e0a56ae /arch/x86/mm/init_32.c | |
| parent | x86/cpu: Drop unneded members of struct cpuinfo_x86 (diff) | |
| download | linux-6415813bae75feba10b8ca3ed6634a72c2a4d313.tar.xz linux-6415813bae75feba10b8ca3ed6634a72c2a4d313.zip | |
x86/cpu: Drop wp_works_ok member of struct cpuinfo_x86
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 d560bc61575e ("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 a5c2a893dbd4 ("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: Mathias Krause <minipli@googlemail.com>
Acked-by: Borislav 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.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86/mm/init_32.c')
| -rw-r--r-- | arch/x86/mm/init_32.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c index 2b4b53e6793f..4dddfaf6569a 100644 --- a/arch/x86/mm/init_32.c +++ b/arch/x86/mm/init_32.c @@ -716,15 +716,17 @@ void __init paging_init(void) */ static void __init test_wp_bit(void) { + int wp_works_ok; + printk(KERN_INFO "Checking if this processor honours the WP bit even in supervisor mode..."); /* Any page-aligned address will do, the test is non-destructive */ __set_fixmap(FIX_WP_TEST, __pa(&swapper_pg_dir), PAGE_KERNEL_RO); - boot_cpu_data.wp_works_ok = do_test_wp_bit(); + wp_works_ok = do_test_wp_bit(); clear_fixmap(FIX_WP_TEST); - if (!boot_cpu_data.wp_works_ok) { + if (!wp_works_ok) { printk(KERN_CONT "No.\n"); panic("Linux doesn't support CPUs with broken WP."); } else { @@ -811,8 +813,7 @@ void __init mem_init(void) BUG_ON(VMALLOC_START >= VMALLOC_END); BUG_ON((unsigned long)high_memory > VMALLOC_START); - if (boot_cpu_data.wp_works_ok < 0) - test_wp_bit(); + test_wp_bit(); } #ifdef CONFIG_MEMORY_HOTPLUG |