linux-kernel - Re: [PATCH] Whinge in paging_init if noexec is on with a non-PAE kernel

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Message-ID: <20061212023805.GE4044@athena.road.mcmartin.ca>
Date:	Mon, 11 Dec 2006 21:38:05 -0500
From:	Kyle McMartin <kyle@...ntu.com>
To:	akpm@...l.org
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Whinge in paging_init if noexec is on with a non-PAE kernel

On second thought, this is probably better since most people will
presumably be booting non-PAE kernels, generating this message when
they've not tried to force the issue seems silly.

This way, the user will only see a warning if they actually go
out and specify "noexec=on" on the command line.

Sucks to have to do #ifdef #else though, I wonder if there's a
better way to initialize that.

Cheers,
	Kyle

diff --git a/arch/i386/mm/init.c b/arch/i386/mm/init.c
index 84697df..ff389f1 100644
--- a/arch/i386/mm/init.c
+++ b/arch/i386/mm/init.c
@@ -422,7 +422,15 @@ void zap_low_mappings (void)
 	flush_tlb_all();
 }
 
+/* disable_nx = 0 will generate unwanted warnings if it is
+ * the default case for non-PAE kernels, but we probably want
+ * NX by default on kernels built with PAE.
+ */
+#ifdef CONFIG_X86_PAE
 static int disable_nx __initdata = 0;
+#else
+static int disable_nx __initdata = 1;
+#endif
 u64 __supported_pte_mask __read_mostly = ~_PAGE_NX;
 
 /*
@@ -512,6 +520,9 @@ void __init paging_init(void)
 	set_nx();
 	if (nx_enabled)
 		printk("NX (Execute Disable) protection: active\n");
+#else
+	if (!disable_nx)
+		printk("NX (Execute Disable) only supported with CONFIG_HIGHMEM64G\n");
 #endif
 
 	pagetable_init();
-
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