Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1312521 > unrolled thread

[PATCH v2 1/2] x86_32/mm: Set NX in __supported_pte_mask before enabling paging

Back to article view | Back to linux.kernel

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  [PATCH v2 1/2] x86_32/mm: Set NX in __supported_pte_mask before enabling paging Andy Lutomirski <luto@kernel.org> - 2016-01-19 22:40 +0100
    [tip:x86/mm] x86/mm/32:   Set NX in __supported_pte_mask before enabling paging tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2016-01-20 12:20 +0100

#1312521 — [PATCH v2 1/2] x86_32/mm: 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>
---
 arch/x86/kernel/head_32.S | 6 ++++++
 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;
 }
 
-- 
2.5.0

[toc] | [next] | [standalone]

#1313131 — [tip:x86/mm] x86/mm/32: Set NX in __supported_pte_mask before enabling paging

Commit-ID:  320d25b6a05f8b73c23fc21025d2906ecdd2d4fc
Gitweb:     http://git.kernel.org/tip/320d25b6a05f8b73c23fc21025d2906ecdd2d4fc
Author:     Andy Lutomirski <luto@kernel.org>
AuthorDate: Tue, 19 Jan 2016 13:38:58 -0800
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 20 Jan 2016 11:39:14 +0100

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>
---
 arch/x86/kernel/head_32.S | 6 ++++++
 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 6bc9ae2..57fc3f8 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 92e2eac..78f5d59 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;
 }
 

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web