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x86/mm/32: Set NX in __supported_pte_mask before enabling paging
There's a short window in which very early mappings can end up with NX clear because they are created before we've noticed that we have NX. It turns out that we detect NX very early, so there's no need to defer __supported_pte_mask setup. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Pavel Machek <pavel@ucw.cz> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/2b544627345f7110160545a3f47031eb45c3ad4f.1453239349.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
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2 changed files with 8 additions and 3 deletions
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@ -389,6 +389,12 @@ default_entry:
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/* Make changes effective */
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wrmsr
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/*
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* And make sure that all the mappings we set up have NX set from
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* the beginning.
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*/
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orl $(1 << (_PAGE_BIT_NX - 32)), pa(__supported_pte_mask + 4)
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enable_paging:
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/*
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@ -31,9 +31,8 @@ early_param("noexec", noexec_setup);
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void x86_configure_nx(void)
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{
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if (boot_cpu_has(X86_FEATURE_NX) && !disable_nx)
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__supported_pte_mask |= _PAGE_NX;
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else
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/* If disable_nx is set, clear NX on all new mappings going forward. */
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if (disable_nx)
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__supported_pte_mask &= ~_PAGE_NX;
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}
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