diff options
| author | Andy Lutomirski <[email protected]> | 2016-01-19 13:38:58 -0800 |
|---|---|---|
| committer | Ingo Molnar <[email protected]> | 2016-01-20 11:39:14 +0100 |
| commit | 320d25b6a05f8b73c23fc21025d2906ecdd2d4fc (patch) | |
| tree | 811660369c7225b275700592f8617eb020a53d44 | |
| parent | 43c75f933be26422f166d6d869a19997312f4732 (diff) | |
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 <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Arjan van de Ven <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Pavel Machek <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephen Smalley <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/2b544627345f7110160545a3f47031eb45c3ad4f.1453239349.git.luto@kernel.org
Signed-off-by: Ingo Molnar <[email protected]>
| -rw-r--r-- | arch/x86/kernel/head_32.S | 6 | ||||
| -rw-r--r-- | arch/x86/mm/setup_nx.c | 5 |
2 files changed, 8 insertions, 3 deletions
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S index 6bc9ae24b6d2..57fc3f8c85fd 100644 --- a/arch/x86/kernel/head_32.S +++ b/arch/x86/kernel/head_32.S @@ -389,6 +389,12 @@ default_entry: /* Make changes effective */ wrmsr + /* + * And make sure that all the mappings we set up have NX set from + * the beginning. + */ + orl $(1 << (_PAGE_BIT_NX - 32)), pa(__supported_pte_mask + 4) + enable_paging: /* diff --git a/arch/x86/mm/setup_nx.c b/arch/x86/mm/setup_nx.c index 92e2eacb3321..78f5d5907f98 100644 --- a/arch/x86/mm/setup_nx.c +++ b/arch/x86/mm/setup_nx.c @@ -31,9 +31,8 @@ early_param("noexec", noexec_setup); void x86_configure_nx(void) { - if (boot_cpu_has(X86_FEATURE_NX) && !disable_nx) - __supported_pte_mask |= _PAGE_NX; - else + /* If disable_nx is set, clear NX on all new mappings going forward. */ + if (disable_nx) __supported_pte_mask &= ~_PAGE_NX; } |